halton design guide en

Kitchen Design GuideMARINE AND OFFSHOREAddress: HALTON MARINE (Sales)HALTON OY (Factory)Pulttikatu 2

15700 Lahti

FINLAND

Telephone: + 358 3 583 411

Fax: + 358 3 583 4200

Email: [email protected]

Internet: www.haltonmarine.com

BALTIC COUNTRIES

(Sales)

Address: HALTON OY

Niittyvillankuja 4

01510 Vantaa

FINLAND

Telephone: +358 9 8254 0015

Fax: +358 9 8254 0070


BELGIUM

(Sales)

Address: HALTON N.V./S.A.

Interleuvenlaan 62

B-3001 Leuven

Telephone: +32 16 40 06 10

Fax: +32 16 40 22 64


DENMARK

(Sales)

Address: HALTON A/S

Nydamsvej 41

DK-8362 Hrning

Telephone: +45 86 92 28 55

Fax: +45 86 92 28 37


FINLAND

(Sales)

Address: HALTON OY

Niittyvillankuja 4

01510 Vantaa

Telephone: +358 9 825 4000

Fax: +358 9 8254 0010


FRANCE

(Sales)

Address: HALTON S.A.

94-96 rue Victor Hugo

94 851 IVRY/SEINE Cdex

Telephone: +33 1 45 15 80 00

Fax: +33 1 45 15 80 25


(Factory)


Technoparc Futura

BP 102

62402 BETHUNE Cdex

Telephone: +33 3 21 64 55 00

Fax: +33 3 21 64 55 10

(Factory)


Zone Industrielle-Saint Eloi

12, Rue de Saint Germain

60800 CRPY-EN-VALOIS

Telephone: +33 3 44 94 49 94

Fax: +33 3 44 59 18 62

GERMANY

(Sales)

Address: Halton Klimatechnik GmbH

Postfach 1254

35302 Grunberg

Alsfelder Strasse 45

35305 Grunberg

Telephone: +49 64 01 91 860

Fax: +49 64 01 91 86 20


MALAYSIA

(Sales, Factory)

Address: Halton Manufacturing Sdn. Bhd.

22, Jalan Hishamuddin 1

Selat Klang Utura

P.O. Box 276

42000 Port Klang

Telephone: +603 31 76 39 60

Fax: +603 31 76 39 64


NORWAY

(Sales)

Address: Halton AS

Lilleakerveien 4

N-0283 Oslo

Telephone: +47 22 061 300

Fax: +47 22 061 301


(Sales)

Address: Acti-Com AS

P.B. 6648 Rodelkka

N-0502 Oslo

Telephone: +47 22 38 60 50

Fax: +47 22 38 60 51


POLAND

(Sales)

Address: Halton Sp. z o.o

ul. Brazylijska 14 A/14

03-946 Warsaw

Telephone: +48 22 67 28 581

Fax: +48 22 67 28 591


RUSSIA

(Sales)

Address: Halton Oy

Niittyvillankuja 4

01510 Vantaa

FINLAND

Telephone: +358 9 8254 0015

Fax: +358 9 8254 0070


SWEDEN

(Sales)

Address: Halton AB

Box 68, Kanalvgen 15

SE-183 21 Tby

Telephone: +46 8 446 39 00

Fax: +46 8 732 73 26


THE NETHERLANDS

(Sales)

Address: Halton B.V.

Utrechthaven 9a

NL-3433 PN Nieuwegein

Telephone: +31 30 6007 060

Fax: +31 30 6007 061


UNITED KINGDOM

(Sales)

Address: Halton Products Ltd.

5 Waterside Business Park

Witham

Essex, CM8 3YQ

Telephone: +44 1 376 507 000

Fax: +44 1 376 503 060


USA

(Sales, Factory)

Address: Halton Company

101 Industrial Drive

Scottsville, KY 42164

Telephone: +1 270 237 5600

Fax: +1 270 237 5700


OTHER COUNTRIES

(Export)

Address: Halton Oy

Haltonintie 1-3

47400 Kausala

FINLAND

Telephone: + 358 5 740 211

Fax: + 358 5 740 2300


More contact information is available at our website

www.haltongroup.com

We Care for Indoor Air

www.haltongroup.com

We Care for Indoor Air

www.haltongroup.com

1HALTON DESIGN GUIDE FOR INDOOR AIR CLIMATEIN COMMERCIAL KITCHENS

ACKNOWLEDGEMENTS

Thank you to the many people and organisations who gave advice and information during the preparation ofthis Kitchen design guide.

First Edition: 2002 Halton FoodserviceAll rights reserved

Halton Foodservice, Rabah Ziane

3HALTON DESIGN GUIDE FOR INDOOR AIR CLIMATE INCOMMERCIAL KITCHENS

5The commercial kitchen is a unique space wheremany different HVAC applications take place within asingle environment. Exhaust, supply, transfer,refrigeration, building pressurisation and airconditioning all must be considered in the design ofmost commercial kitchens.It is obvious that the main activity in the commercialkitchen is the cooking process. This activity generatesheat and effluent that must be captured andexhausted from the space in order to control odour

DESIGN FUNDAMENTALS

Commercial Kitchen Ventilation Systems

and thermal comfort. The kitchen supply air, whethermechanical or transfer or a combination of both,should be of an amount that creates a small negativepressure in the kitchen space. This will avoid odoursand contaminated air escaping into surroundingareas. Therefore the correct exhaust air flow quantityis fundamental to ensure good system operation,thermal comfort and improved IAQ.Similar considerations should be given to washing-up, food preparation and serving areas.

Picture 1.

6Initial Design Considerations

The modes of heat gain in a space may include solarradiation and heat transfer through the constructiontogether with heat generated by occupants, lightsand appliances and miscellaneous heat gains as airinfiltration should also be considered.

Sensible heat (or dry heat) is directly added to theconditioned space by conduction, convection andradiation. Latent heat gain occurs when moisture isadded to the space (e.g., from vapour emitted bythe cooking process, equipment and occupants).Space heat gain by radiation is not immediate.Radiant energy must first be absorbed by thesurfaces that enclose the space (walls, floor, andceiling) and by the objects in the space (furniture,people, etc.). As soon as these surfaces and objectsbecome warmer than the space air, some of the heatis transferred to the air in the space by convection(see picture 2).To calculate a space cooling load, detailed buildingdesign information and weather data at selecteddesign conditions are required. Generally, thefollowing information is required:

building characteristics configuration (e.g, building location) outdoor design conditions indoor design conditions operating schedules date and time of day

However, in commercial kitchens, cooking processescontribute the majority of heat gains in the space.

Heat Gain and Emissions Insidethe Kitchen

Cooking can be described as a process that addsheat to food. As heat is applied to the food, effluent(1) is released into the surrounding environment. Thiseffluent release includes water vapour, organicmaterial released from the food itself, and heat thatwas not absorbed by the food being cooked. Often,when pre-cooked food is reheated, a reducedamount of effluent is released, but water vapour isstill emitted into the to the surrounding space.The hot cooking surface (or fluid, such as oil) andproducts create thermal air currents (called a thermalplume) that are received or captured by the hoodand then exhausted. If this thermal plume is not totallycaptured and contained by the hood, they becomea heat load to the space.There are numerous secondary sources of heat inthe kitchen (such as lighting, people, and hot meals)that contribute to the cooling load as presented intable 1.

Table 1. Cooling load from various sources

Load WLighting 21-54/m2

People 130/personHot meal 15/mealCooking eq. variesRefrigeration varies

1 Thermal plumes 2 Radiant heat

12

Picture 2. Heat gain and emission inside the kitchen

70 5 10 15 20 25 30 35 C

80

40

20

10

5

2

1

Per

cent

Dis

satis

fied

Radiant Temperature Asymmetry

Warm ceiling

Cool wall

Warm wallCool ceiling

Ventilation Effectiveness and Air DistributionSystemTHE EFFECT OF AIR SUPPLYVentilation effectiveness can be described as the abilityof ventilation system to achieve design conditions inthe space (air temperature, humidity, concentration ofimpurities and air velocity) at minimum energyconsumption. Air distribution methods used in thekitchen should provide adequate ventilation in theoccupied zone, without disturbing the thermal plume.

In the commercial kitchen environment the supplyairflow rate required to ventilate the space is a majorfactor contributing to the system energy consumption.Traditionally high velocity mixing or low velocity mixingsystems have been used. Now there is a thirdalternative that clearly demonstrates improved thermalcomfort over mixing systems, this is displacementventilation.

The supply air (make-up air) can be delivered to thekitchen in two ways: high velocity or, with low velocity to moderate mixing.

Thermal Comfort, Productivityand Health

Thermal Comfort

One reason for the low popularity of kitchen work isthe unsatisfactory thermal conditions.Thermal comfort is a state where a person is satisfiedwith the thermal conditions.

The International Organisation for Standardisation(ISO) specifies such a concept as the predictedpercentage of dissatisfied occupants (PPD) and thepredicted mean vote (PMV) of occupants.PMV represents a scale from -3 to 3, -from cold tohot -, with 0 being neutral. PPD tells what percentageof occupants are likely to be dissatisfied with thethermal environment. These two concepts take intoaccount four factors affecting thermal comfort:

air temperature radiation air movement humidity

The percentage of dissatisfied people remains under10% in neutral conditions if the vertical temperaturedifference between the head and the feet is less than3C and there are no other non-symmetricaltemperature factors in the space. A temperaturedifference of 6-8C increases the dissatisfiedpercentage to 40-70%.There are also important personal parametersinfluencing the thermal comfort (typical values in kitchenenvironment in parenthesis):

clothing (0.5 - 0.8 clo) activity (1.6 - 2.0 met)

Clo expresses the unit of the thermal insulation of

clothing (1 clo = 0.155 m2 K/W ).Met is a unit used to express the metabolic rate perunit Dubois area, defined as the metabolic rate of asedentary person, 1 met = 50 kcal/(hr.m2) = 58.2 W/m2.

Assymmetric Thermal Radiation

In the kitchen, the asymmetry of radiation between thecooking appliances and the surrounding walls isconsiderable as the temperature difference of radiationis generally much higher than 20 C.

Figure 1. PPD as a function of PMV

Figure 2. Assymmetric thermal radiation

8Refer to section Effect of Air Distribution System page39 for a detailed comparison between mixing anddisplacement systems in a typical kitchenenvironment.

air temperature. (C) 20 26air velocity (m/s) 0.15 0.25

HIGH VELOCITY OR MIXING VENTILATION

Everything that is released from the cooking processis mixed with the supply air. Obviously impurities andheat are mixed with surrounding air. Also the highvelocity supply air disturbs the hood function.

With a displacement system the intensity ofturbulence of about 10 %, one accepts velocitiesbetween 0.25 and 0.40 m/s, with the air between20 and 26C respectively with 20% of peopledissatisfied.

LOW VELOCITY OR DISPLACEMENTVENTILATION

Here, the cooler-than-surrounding supply air isdistributed with a low velocity to the occupied zone.In this way, fresh air is supplied to where it is needed.Because of its low velocity, this supply air does notdisturb the hood function.

In the case of mixing ventilation, with an intensityof turbulence from 30 to 50 %, one finds 20 % ofpeople dissatisfied in the following conditions:

Picture 3. Low velocity or displacement ventilation

Table 2. Air temperature/air velocity

Picture 4. High velocity or mixing ventilation

Picture 5. Recommended design criteria

9Productivity

Labour shortages are the top challenge thatcommercial restaurants face today. The average ageof a restaurant worker is between 16 and 24 years.In a recent survey conducted by the NationalRestaurant Association in USA, over 52% ofrespondents said that finding qualified motivatedlabour was their main concern.

Room air temperature affects a persons capacity towork. Comfortable thermal conditions decrease thenumber of accidents occurring in the work place.When the indoor temperature is too high (over 28 Cin commercial kitchens) the productivity and generalcomfort diminish rapidly.

The average restaurant spends about $2,000 yearlyon salaries in the USA, wages and benefits per seat.If the air temperature in the restaurant is maintainedat 27C in the kitchen the productivity of therestaurant employees is reduced to 80 % (see picture6). That translates to losses of about $40,000 yearlyon salaries and wages for an owner of a 100-seatrestaurant.

Picture 6. Productivity vs. Room Air Temperature

found to be mutagenic. In Asian types of kitchens, ahigh concentration of carcinogens in cooking oilfumes has been discovered. All this indicates thatkitchen workers may be exposed to a relatively highconcentration of airborne impurities and that cooksare potentially exposed to relatively high levels ofmutagens and carcinogens.

Chinese women are recognised to have a highincidence of lung cancer despite a low smoking ratee.g. only 3% of women smoke in Singapore. Thestudies carried out show that inhalation ofcarcinogens generated during frying of meat mayincrease the risk of lung cancer.

The risk was further increased among women stir-frying meat daily whose kitchens were filled with oilyfumes during cooking. Also, the statistical linkbetween chronic coughs, phlegm and breathlessnesson exertion and cooking were found.

In addition to that, Cinni Little states, that threequarters of the population of mainland China aloneuse diesel as fuel type instead of town gas or LPG,causing extensive bronchial and respiratory problems

Health

There are several studies dealing with cooking andhealth issues. The survey confirmed that cookingfumes contain hazardous components in bothWestern and Asian types of kitchens. In one study,the fumes generated by frying pork and beef were

among kitchen workers, which is possiblyexacerbated by an air stream introduced into theburner mix.

10

Ventilation Rate

The airflow and air distribution methods used in thekitchen should provide adequate ventilation in theoccupied zone, without disturbing the thermal plumeas it rises into the hood system. The German VDI-2052 standard states that a:

Ventilation rate over 40 vol./h result on the basis ofthe heat load, may lead to draughts.

The location of supply and exhaust units are alsoimportant for providing good ventilation. Ventilatingsystems should be designed and installed so thatthe ventilation air is supplied equally throughout theoccupied zone. Some common faults are to locatethe supply and exhaust units too close to each other,causing short-circuiting of the air directly from thesupply opening to the exhaust openings. Also,placing the high velocity supply diffusers too closeto the hood system reduces the ability of the hoodsystem to provide sufficient capture and containment(C&C) of the thermal plume.Recent studies show that the type of air distributionsystem utilised affects the amount of exhaust neededto capture and contain the effluent generated in thecooking process.

REDUCTION OF HEALTH IMPACT

The range of thermal comfort neutrality acceptablewithout any impact on health has been proposed asrunning between 17C as the lowest and 31C asthe highest acceptable temperature (Weihe 1987,quoted in WHO 1990). Symptoms of discomfort andhealth risks outside this range are indicated in table 3.

>

Sudden heart death Hypertension Hypotension Sudden heart death

Stroke Hypothermia Hyperthermia Heart failure

Respiratory infections Tachycardia Heat stroke

Asthma Heath insufficiency

Overheating Inappetence

Tachycardia Hypohydrosis

Reduced dexterility Hydromeiosis

Indolecense Indolence

Restlessness Fatigue

Mental slowing Lethargy

Depression Increased irritability

Reduced leaming capacity

Impaired memory

Table 3. Health effects of thermal microclimates lying outside the neutral comfort zone

31 C >>

11

Integrated Approach

Energy savings can be realised with various exhausthood applications and their associated make-up airdistribution methods. However with analysis thepotential for increased energy savings can be realisedwhen both extract and supply for the kitchen areadopted as an integrated system.

The combination of high efficiency hoods ( such asCapture-Jet hoods) and displacement ventilationreduces the required cooling capacity, whilemaintaining temperatures in the occupied space. Thenatural buoyancy characteristics of the displacementair helps the C&C of the contaminated convectiveplume by lifting it into the hood.

Third-party research has demonstrated that thisintegrated approach for the kitchen has the potentialto provide the most efficient and lowest energyconsumption of any kitchen system available today.

Picture 7. Displacement ventilation

12

KITCHEN HOODS

The purpose of kitchen hoods is to remove the heat,smoke, effluent, and other contaminants. The thermalplume from appliances absorbs the contaminants that arereleased during the cooking process. Room air replacesthe void created by the plume. If convective heat is notremoved directly above the cooking equipment, impuritieswill spread throughout the kitchen, leaving discolouredceiling tiles and greasy countertops and floors. Therefore,contaminants from stationary local sources within the spaceshould be controlled by collection and removal as close tothe source as is practical .

Appliances contribute most of the heat in commercialkitchens. When appliances are installed under an effectivehood, only the radiant heat contributes to the HVAC loadin the space. Conversely, if the hood is not providingsufficient C&C (Capture & Containment), convective and

Picture 9. Capture efficiency hoods

Picture 8. Cooking process

latent heat are spilling into the kitchen thereby increasingboth humidity and temperature.

Capture efficiency is the ability of the kitchen hood toprovide sufficient C&C at a minimum exhaust flow rate.The remainder of this chapter discusses the evolution anddevelopment of kitchen ventilation testing and their impact

on system design.

13

Evolution of Kitchen VentilationSystem

Tracer Gas Studies

Halton pioneered the research on kitchen exhaustsystem efficiency in the late 1980s, commissioning astudy by the University of Helsinki. At the time therewere no efficiency test standards in place. The goalwas to establish a test protocol that was repeatableand usable over a wide range of air flows and hooddesigns.

Nitrous Oxide (tracer gas), a neutrally buoyant gas, wasused. A known quantity of gas was released from theheated cooking surface and compared to theconcentration measured in the exhaust duct. Thedifference in concentration was the efficiency at a givenair flow. This provided valuable information about thepotential for a variety of C&C strategies. The CaptureJetTM system was tested using the Tracer Gastechnique and the results showed a significantimprovement in C&C of the convective plume at lowerexhaust air flows compared to conventional exhaustonly hoods.

Picture 10. Tracer gas studies

14

Around 1995, the standard adopted new methodsof determining the C&C using a variety of visualisationtechniques including visual observation, neutrallybuoyant bubbles, smoke, lasers, and Schlierenthermal imaging (discussed in more detail later in thissection).The test set up includes a hood system operatingover a given appliance. Several thermocouple treesare placed from 1.8 m to 2.5 m. in the front of the

ASTM F1704

In 1990, AGA Laboratories was funded by the GasResearch Institute to construct a state-of-the-artkitchen ventilation laboratory and research theinteraction between cooking appliances, kitchenventilation hoods, and the kitchen environment.In early 1993, the original Energy Balance Protocolwas developed to explain the interaction betweenthe heat loads in the kitchen. Mathematically, theenergy consumed by the cooking appliance can onlygo three places:

to the food being cooked out of the exhaust duct into the kitchen as heat load

In late 1993, this was introduced as a draft standardto be adopted by ASTM and was called the EnergyBalance Protocol. The original protocol wasdeveloped to only examine the energy interactionsin the kitchen with the goal of determining how muchheat was released into the kitchen from cookingunder a variety of conditions. This standard wasadopted by ASTM as F1704.

Schlieren ThermalImaging

Schlieren thermalimaging has beenaround since the mid1800s but was reallyused as a scientific toolstarting from the late20th century. During the 1950s Schlieren thermalimaging was used by AGA Laboratories to evaluategas combustion with several different burnertechnologies. NASA has also made significant useof Schlieren thermal imaging as a means of evaluatingshockwaves for aircraft, the space shuttle, and jetflows. In the 1990s Penn State University beganusing Schlieren visualisation techniques to evaluateheat flow from computers, lights, and people in typicalhome or office environments. In 1998 the kitchenventilation lab in Chicago purchased the first Schlierensystem to be used in the kitchen ventilation industry.In 1999, the Halton Company became the firstventilation manufacturer globally to utilise a Schlierenthermal Imaging system for use in their research anddevelopment efforts.By using the thermal imaging system we can visualiseall the convective heat coming off an appliance anddetermine whether the hood system has sufficientC&C. In addition to verifying C&C levels, the impactof various supply air and air distribution measurescan be incorporated to determine the effectivenessof each. By using this technology a more completeunderstanding of the interaction between differentcomponents in the kitchen (e.g., appliances, hoods,make-up air, supply diffusers, etc.) is being gained.

Figure 3. Capture & containment

hood system and are used to measure the heat gainto the kitchen space. This enables researchers todetermine the temperature of room air beingextracted into the hood.In theory, when the hood is providing sufficient C&C,all of the convective plume from the appliance isexhausted by the hood while the remaining radiantload from the appliance is heating up the hood,kitchen walls, floors, ceiling, etc. that are eventuallyseen as heat in the kitchen.

Picture 11. Capture JetTM ON.

15

ComputerModelling

Computational FluidDynamics (CFD) hasbeen used in theaerospace andautomobile industriesfor a number of years.Until recently, it wasextremely expensivefor wide spread use. The cost of the hardware alonemade it prohibitive for all but a few large companies.With improvement in processing speed and reductionin costs of some very powerful machines, CFD usehas become more widespread, specifically in theHVAC industry.CFD works by creating a three-dimensional computermodel of a space. Boundary conditions, in the caseof kitchen ventilation modelling, may include; hoodexhaust rates, input energy of the appliance, supplyair type and volume and temperature of supply air.Complex formulas are solved to produce the finalresults. After the solutions converge, variables suchas temperature, velocity, and flow directions can bevisualised. CFD has become an invaluable tool forthe researcher by providing an accurate predictionof results prior to full scale mock-ups or testing forvalidation purposes.

Conclusion of the Test Conducted by EDF:

The study on induction hoods shows that theircapture performances vary in relation to the airinduction rate. If this rate is too high (50 to 70%), theturbulence created by the hood prevents the efficientcapture of contaminants. If the Capture Jet air rate isabout 10% or lower, the capture efficiency can beincreased by 20-50%, which in turn leads to anequivalent reduction in air flow rates.

Consequently, the performances of induction hoodsare not due to the delivery of unheated air, but to theimprovement in capture.

DEFINITION:Induction Hood is a concept, which allows for theintroduction of large volumes of untreated make-upair directly into the exhaust canopy. The ratio of make-up air to exhaust air was as high as 80%.

Figure 4. CFD

Figure 5. Capture efficiency

30 50 70 100

Airflow (%)

Figure 6. Capture efficiency

30 70 80 90 100

Airflow (%)

16

Grease Extraction

The convection plume from the cooking operationunderneath the hood contains grease that has to beextracted as efficiently as possible. The amount ofgrease produced by cooking is a function of manyvariables including: the type of appliance used forcooking, the temperature that food is being cookedat, and the type of food product being cooked.The purpose of a mechanical grease filter is twofold:first to provide fire protection by preventing flamesfrom entering the exhaust hood and ductwork, andsecondly to provide a means of removing large greaseparticles from the exhaust stream. The more greasethat can be extracted, the longer the exhaust ductand fan stay clean, resulting in better fire safety.From a practical standpoint, grease filters should beeasily cleanable and non-cloggable. If the filterbecomes clogged in use, the pressure drop acrossthe filter will increase and the exhaust airflow will belower than designed.

What Is Grease?

According to the University of Minnesota, grease iscomprised of a variety of compounds including solidand/or liquid grease particles, grease and watervapours, and a variety of non-condensable gasesincluding nitrogen oxides, carbon dioxide, and carbonmonoxide. The composition of grease becomes morecomplex to quantify as grease vapours may cooldown in the exhaust stream and condense intogrease particles. In addition to these compounds,hydrocarbons can also be generated during thecooking process and are defined by several differentnames including VOC (volatile organic compounds),SVOC (semi-volatile organic compounds), ROC(reactive organic compounds), and many othercategories.

Grease Emissions By Cooking Operation

An ASHRAE research project conducted by theUniversity of Minnesota has determined the greaseemissions from typical cooking processes. Figure 7presents total grease emissions for severalappliances.

Figure 7. Total grease emissions by appliance category

Upon observing figure 7, it appears at first as if theunderfired broiler has the highest grease emissions.However when examining the figure closer you seethat if a gas or electric broiler is used to cook chickenbreasts, the grease emissions are slightly lower thanif you cook hamburgers on a gas or electric griddle.This is the reason that we are discussing cookingoperation and not merely the type of appliance.However, we can say that, for the appliances testedin this study, the largest grease emissions are fromunderfired broilers cooking burgers while the lowestgrease emissions were from the deep-fat fryers. Thegas and electric ranges were used to cook a spaghettimeal consisting of pasta, sauce, and sausage. All ofthe other appliances cooked a single food product.It is expected that the emissions from solid-fuel (e.g.,wood burning) appliances will probably be on thesame order of magnitude as under-fired broilers, butin addition to the grease, large quantities of creosoteand other combustion by-products may be producedthat coat the grease duct. Chinese Woks may havegrease emissions well above under-fired broiler levelsdue to high surface temperature of the Wokscombined with the cooking medium utilised forcooking (e.g. peanut oil, kanola oil, etc.) which willtend to produce extreme grease vaporisation andheat levels table 4 presents the specific foodscooked for the appliances presented in figure 8and figure 9.

17

It can be observed from figure 9 that, on a massbasis, cooking processes tend to produce particlesthat are 10 microns and larger. However, the broilersproduce significant amounts of grease particles thatare 2.5 microns and smaller (typically referred to asPM 2.5) regardless of the food being cooked on thebroiler.

Figure 9. Particle size distribution by cooking process

The components of grease were discussed earlierand a breakdown of the grease emissions into theparticulate and vapor phases is shown in figure 8.

Figure 8. Particulate and vapour grease percentages byappliance category

Upon examining figure 8, it becomes apparent thatthe griddles, fryers, and broilers all have a significantamount of grease emissions that are composed ofparticulate matter while the ovens and range topsare emitting mainly grease vapour. If you combinethe data in figure 7 with the data in figure 8 it becomesevident that the broilers have the largest amount ofparticulate matter to remove from the exhaust stream.The final piece of information that is important for

Table 4. Description of food cooked on each appliance

Appliance Food ProductGas Griddle Beef hamburgers, 113 g, 120 mm diameter, 20% fat contentElectric Griddle

Gas Fryer French fried potatoes, par-cooked, frozen shoestring potatoes,Electric Fryer 60 mm thick with 2.2% fat content.

Gas Broiler Beef hamburgers, 150 g, 120 mm diameter, 20% fat contentElectric BroilerGas Broiler Boneless, skinless chicken breast, frozen, 1115 g, 125 mm thickness.Electric Broiler

Gas Oven Sausage pizza with sausage, textured vegetable protein, mozzarella cheese,Electric Oven and cheese substitute. Each slice was 100 x 150 mm, 142 g.

Gas Range Two pots of spaghetti noodles, 2.266 kg. dry weight, one pot boiling water,Electric range two posts of tomato based spaghetti sauced,

3 litters each 1.360 kg of link style sausage cooked in a frying pan.

grease extraction is the size distribution of the greaseparticles from the different cooking processes,presented in figure 9.

18

Cyclonic Grease Extraction

One non-cloggable design of a baffle type greaseextractor is a cyclone. The extractor is constructedof multiple cyclones that remove grease from the airstream with the aid of centrifugal force.

Figure 10 presents Haltons KSA grease filter design.You can see the cyclonic action inside the KSA filter.

Filter Efficiency

VDI has set up a test procedure (September 1999)in order to compare the results of grease filters fromdifferent manufacturer.

KSA fi lters were supplied by Halton to anindependent laboratory. The fractional efficiencymeasurements were made at the flow rates of 80 l/s, 110 l/s, 150 l/s and 210 l/s.

Mechanical grease filters quickly lose grease removaleffectiveness as the particulate size drops below 6microns depending on the pressure drop across thefilters.Increasing the flow rate from 80 l/s to 210 l/s causesan increase in the efficiency.

Figure 11. Grease extraction efficiency curves for KSAfilter 500x330.

Figure 10. Halton KSA filter

2

13

1. air enters through a slot in the filter face

2. air spins through the filter, impinginggrease on the filter walls

3. the cleaner air exits the top andbottom of the filter.

210 l/s 240 Pa 110 l/s 60 Pa150 l/s 120 Pa 80 l/s 30 Pa

Comparison Test Filter Efficiency

When comparing to the other type of filters on themarket like Baffle filter, the results below show thatHalton has the most efficient filter on the market.

Figure 11 presents the extraction efficiency curve forHaltons KSA filter for four different pressure dropsacross the filter.

Research has shown that as far as efficiency isconcerned, slot filters (baffle) are the lowest, followedby baffle style filters (other type).Note how the KSA efficiency remains high even whenthe filters are not cleaned and loading occurs.

Halton KSA 330, 150 l/s Other filter type, 110 l/sHalton KSA 500, 150 l/s Baffle filter type, 150 l/s

Figure 12. Comparison test filter efficiency.

y

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10 11

particle size, microns

100

90

80

70

60

50

40

30

20

10

01 2 3 4 5 6 7 8 9 10 11


Filter Removal Efficiency

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6 7 8 9 10 11


100

90

80

70

60

50

40

30

20

10

01 2 3 4 5 6 7 8 9 10 11

Filter Removal Efficiency


19

Ultraviolet Light Technology

Ultraviolet Light What Is It ?

Light is the most common form of theelectromagnetic radiation (EMR) that the averageperson is aware of. Light is only a very small bandwithin the electromagnetic spectrum. Cosmic rays,X-rays, radio waves, television signals, andmicrowave are other examples of EMR.

EMR is characterised by its wavelength andfrequency. Wavelength is defined as the length fromthe peak of one wave to the peak of the next, or oneoscillation (measured in metres). Frequency is thenumber of oscillations in one second (measured inHertz).

Sunlight is the most common source of ultravioletradiation (UVR) but there are also many other sources.UVR emitting artificial light sources can be producedto generate any of the UVR wavelengths by usingthe appropriate materials and energies.

Ultraviolet radiation is divided into three categories UVA, UVB, and UVC. These categories aredetermined by their respective wavelengths.Ultraviolet A radiation is the closest to thewavelengths of visible light .Ultraviolet B radiation is a shorter, more energeticwave.Ultraviolet C radiation is the shortest of the threeultraviolet bands and is used for sterilisation andgermicidal applications.

UV technology has been known since the 1800s. Inthe past it has been utilised in hospital, wastewatertreatment plants, and various industry applications.HALTON has now developed new applications toharness the power of Ultraviolet Technology incommercial kitchens.

Evaluation of grease deposition

When the grease generated was used without theUV technology, grease did collect on the plates. Tests

Picture 12. KVL with Capture RayTM

How Does the Technology Work?

Ultraviolet light reacts to small particulate and volatileorganic compounds (VOC) generated in the cookingprocess in two ways, by exposing the effluent to lightand by the generation of ozone (UVC).As is commonly known, the effluent generated bythe cooking process is a fatty substance. From achemical standpoint, a fatty substance containsdouble bonds, which are more reactive than singlebonds. By using light and ozone in a certain manner,we are able to attack these double bonds andconsequently break them. This results in a largemolecule being broken down into two smaller ones.Given enough reactivesites, this process cancontinue until the largemolecule is brokendown into carbondioxide and water,which are odourlessand harmless. Unlikethe grease that resultsin these small molecules, CO2 and H2O will not adhereto the duct and will be carried out by the exhaust airflow.

20

showed that using UV technology reduces the greasedeposition on the duct walls and reduces the needfor a restaurant to have their ducts cleaned.

Evaluation of odour removal -Chemical Analysis

There was a significant reduction in the measuredpeak area of the chemical compounds.Results indicate that for cooking French fries, odourswere reduced by over 55% with the UV system. Forthe burgers, the odour was reduced by over 45%.This initial concept was studied in detail using acomputational fluid dynamics (CFD) model toinvestigate the airflow within the plenum that holdsthe UV lamps.

Conclusions

The results of this research indicate that the UVtechnology is effective at reducing both greaseemissions and odour. Based on chemical analysisthe odour was reduced for both the French fries andthe burgers. The grease deposition testing concludes

Picture 13. CFD model to investigate the air flow within the plenum that holds the UV lamps.

that there appears to be a reduction in grease build-up in the duct. The plenum design presented utilisesan exhaust airflow rate of 363 L/s with a volume of0.6 m3 resulting in an average reaction time of 1.6seconds in the plenum. In order to ensureeffectiveness under all cooking conditions this isrecommended as the minimum reaction time in theplenum. The remaining duct run from the hood towhere it exits the building provides a minimum of anadditional 0.4 seconds for the ozone to react withthe grease to achieve a total reaction time of 2seconds.

Benefits of Haltons Capture RayTM System

Reduces or eliminates costly ductcleaning.

Reduces odour emissions. Specifically engineered for your

cooking applications. Personnel protected from UV

exposure. Monitors hood exhaust flow rates. Improved hygiene. Reduces fire risk.

This initial concept was studied in detail using acomputational fluid dynamics (CFD) model toinvestigate the air flow within the plenum that holdsthe UV lamps.

21

Capture JetTM V bank IslandFor use with a single row of appliances in an islandconfiguration. This system incorporates the use ofthe jets on both sides of the V bank, directing risingheat and effluent toward the extractors.

Capture JetTM Water WashWater wash systems are often thought of in terms ofgrease extraction efficiency. In fact this type of systemhas little or no impact on the grease extractionefficiency of the hood but is a device to facilitatecleaning of the filters. The basic premise of the waterwash hood is the ability to wash down the exhaustplenum within the hood as well as the mechanicalgrease extraction device. A secondary benefit is saidto be an aid to fire suppression. Water wash hoodscome in a variety of configurations as far as hoodgeometry goes. These follow fairly closely the dryhood styles.

Types of Hoods

Kitchen ventilation hoods are grouped into one oftwo categories. They are defined by their respectiveapplications:TYPE I: Is defined for use over cooking processesthat produce smoke or grease laden vapours andmeet the construction requirements of NFPA-96TYPE II: Is defined for use over cooking anddishwashing processes that produce heat or watervapour.

Additional information on Type I and Type II hoodscan be found in Chapter 30 of the 1999 ASHRAEHVAC Applications Handbook. This section presentsinformation on engineered, low-heat hoods andcommodity classes of hoods as well as an overviewof the most common types of grease removaldevices.

Engineered Hood Systems

This subsection presents the engineered hoodproducts offered by Halton. These systems arefactory built and tested and are considered to behigh-efficiency systems.These systems have been tested using the tracergas technique, Schlieren visualization, and computermodeling to measure system efficiency. Common tothese designs is the use of Capture JetTM technologyto improve the C&C efficiency of the hood.

Capture JetTM Canopy HoodsThese wall style canopies incorporate the jettechnology to prevent spillage of grease-laden vaporout from the hood canopy at low exhaust rates. Asecondary benefit coupled with the low-pressureloss, high efficiency multi cyclone grease extractor

(Model KSA) is to create a push/pull effect within thecapture area, directing the grease-laden vaporstoward the exhaust. Performance tests indicate areduction greater than 30 % in the exhaust rate overexhaust only devices.

Capture JetTM fanWhere only small quantities of supply air are available,it is possible to fit a fan to the roof of the supplyplenum.

Capture JetTM double island canopyFor use over the back-to-back appliance layout. Thissystem incorporates two Capture JetTM canopies,back to back to cover the cooking line.

Picture 14. Island model


22

Picture 16. Back shelf hood

Capture JetTM Back Shelf HoodIncorporates the use of jets in a unique way. Due tothe proximity to the cooking surface, the jet is used asan air curtain, extending the physical front of the hoodtowards the cooking surface without impeding thethermal plume. The result from independent testingshows a 27% decrease in exhaust over conventionalback shelf design during full load cooking and a 51%reduction during idle cooking.

Basic Hood TypeThere are some applications where there is no greaseload from the cooking process and only small amountsof heat or water vapor are being generated. Threeoptions are presented here depending on theapplication.

Exhaust Only HoodsThese type systems are the most rudimentary designof the Type I hood, relying on suction pressure andinterior geometry to aid in the removal of heat andeffluent.

Design of the exhaust air flow is based upon the facevelocity method of calculation. We generally use 0.2m/s for a light and 0.4 m/s for a medium cooking load.

Condensate HoodsConstruction follows National Sanitation Foundation(NSF) guidelines.A subcategory of Type II hoods would includecondensation removal (typically with an internal baffleto increase the surface area for condensation.)

Picture 15. Water wash hood

Picture 18. Condensate hood

Heat Removal, Non-Grease HoodsThese Type II hoods are typically used over non-greaseproducing ovens. The box style is the most common.They may be equipped with lights and have analuminium mesh filter in the exhaust collar to preventlarge particles from getting into the ductwork.

Other Type of Hoods (Short Cycle)These systems, no longer advocated by the industry,were developed when the exhaust rate requirementsfollowed the model codes exclusively. With the adventof U.L. 710 testing and a more complete understandingof thermal dynamics within the kitchen, the use of shortcycle hoods has been in decline. The concept allowedfor the introduction of large volumes of untreated makeup air directly into the exhaust canopy. The ratio ofmake up air to exhaust air was as high as 80% and insome extreme cases, 90%. It was assumed that thebalance drawn from the space (known as net exhaust)would be sufficient to remove the heat and effluentgenerated by the appliances. This was rarely the casesince the design did not take into account the heatgain from the appliances. This further led to a dominoeffect of balancing and rebalancing the hood thatultimately stole air-conditioned air from the dining room.In fact, testing by hood manufacturers has shown thatthe net-exhaust quantities must be nearly equal to theexhaust through an exhaust-only hood to achieve asimilar C&C performance for short-circuit hoods.

Picture 17. Exhaust only hood

23

Figure 13. KVI with Capture JetTM off

Picture 19. Schlieren Image of KVI Hood.Capture JetTM Off

Picture 11. Schlieren Image of KVI Hood.Capture JetTM On

Hoods Comparison Studies

In this section a variety of techniques and researchfindings are presented that demonstrate theperformance and value that Haltons products offerthe end-user. There is a discussion on theineffectiveness of some hood designs offered byHaltons competitors followed by a discussion of howcapture efficiency impacts the energy use, and energybills, of the end-user.

KVI Case Study

Halton is using state-of-the-art techniques to validatehood performance. These include modeling ofsystems, using CFD, Schlieren imaging systems, andsmoke visualization. All the test results presented herehave been validated by third-party research.Haltons standard canopy hood (model KVI) utilizes

Capture JetTM technology to enhance hoodperformance, and consequently hood efficiency,versus the competition.In this case study, the KVI hood has been modelledusing CFD software. Two cases were modelled forthis analysis: one with the jets turned off in effectthis simulates a generic exhaust only canopy hoodand a second model with the jets turned on. As canbe seen from observing figures 13 and 4, at the sameexhaust flow rate, the hood is spilling when the jetsare turned off and capturing when they are turnedon.The same studies were conducted in the third partylaboratory. The Schlieren Thermal Imaging systemwas used to visualise the plume and effect of CaptureJetTM. As one can see the CFD results are in goodagreement with the Schlieren visualisation, seepictures 19 and 11.

Figure 4. KVI with Capture JetTM on

24

KVL Case Study

Independent research has been performed toevaluate the capture efficiency of Haltons back shelfstyle (model KVL) hood.The first set of results for the KVL hood demonstratethe capture efficiency using a Schlieren thermalimaging system. Note that the hood has beenmanufactured with Plexiglas sides to allow the heatinside the hood to be viewed. Pictures 20 and 21show the results of the KVL hood with the jets turnedoff and on at the same exhaust air flow, respectively.Once again, it becomes readily apparent that theCapture JetTM technology significantly improvescapture efficiency. The KVL hood is spilling with thejets turned off and capturing when the jets are turnedon.Another study conducted in-house was to modelthese two cases using CFD in order to see if the

Picture 20. Schlieren Image of KVL hood.Capture JetTM Off

Picture 21. Schlieren Image of KVL Hood.Capture JetTM On

Figure 14. CFD Results of KVL HoodWith Capture JetTM Off

Figure 15. CFD Results of KVL HoodWith Capture JetTM On

CFD models could predict what was observed in areal world test. Figures 14 and 15 present the resultsof the CFD models for jets off and jets on, respectively.Note that the jets in the KVL hood are directeddownwards, where they were directed inwards onthe KVI hood discussed earlier. If you were to placedownwards directed jets on the KVI hood, it wouldactually cause the hood to spill instead of capture.This is testimony to the importance of performing in-house research and is just one value added serviceprovided by Halton.

When you compare the CFD results to those takenwith the Schlieren system for the KVL hood, youllnote that they produce extremely similar results. Thisdemonstrates that not only can CFD models be usedto model kitchen hoods but they can also augmentlaboratory testing efforts.

25

VENTILATED CEILING

General

The ventilated ceiling is an alternative kitchen exhaustsystem. The ceiling should be used for aestheticreasons when open space is required, multiplekitchen equipment of different types is installed andthe kitchen floor space is large.

The ventilated ceilings are used in Europe especiallyin institutional kitchens like schools and hospitals

Ceilings are categorised as Open and Closedceiling system.

Open Ceiling

Principle

Open ceiling is the design with suspended ceilingthat consists of a supply and exhaust area.Supply and exhaust air ductworks are connected to

Picture 22. Open ceiling

the voids above the suspended ceiling. Open ceilingis usually assembled from exhaust and supplycassettes. The space between the ceiling and thevoid is used as a plenum. The contaminated air goesvia the slot where grease and particles are separated

Specific Advantages

Good aesthetics. Possibility to change kitchen layout.

Disadvantages

Not recommended for heavy load(gas griddle, broiler..).

Efficient when only steam is produced. Not recommended from a hygienic point of

view (free space above the ceiling used asplenum risk of contamination).

Expensive in maintenance. Condensation risk.

26

Panels Panels Panels

Halton ventilated ceiling is based on Capture JetTM

installed flush to the ceiling surface, which helps toguide the heat and impurities towards the extractsections. Supply air is delivered into the kitchenthrough a low velocity unit.Air distribution significantly affects thermal comfortand the indoor air quality in the kitchen.

There are also combinations of hoods and ventilatedceilings. Heavy frying operations with intensive greaseemission are considered to be a problem forventilated ceilings, so hoods are recommendedinstead.

Principle

Supply and exhaust units are connected straight tothe ductwork. This system consists of having rowsof filter and supply units; the rest is covered with infillpanel.

Closed Ceiling

There are various closed ceilings.Halton utilise the most efficient ceiling, which includesan exhaust equipped with a high efficiency KSA filter,supply air unit and a Capture JetTM system installedflush to the ceiling panels.

Specific advantages

Draught free air distribution into the working zone.from low velocity ceiling mounted panels.

High efficiency grease filtration using Halton KSAMulti-cyclone filters.

Protection of the building structure from grease,humidity and impurities.

Modular construction simplifies design, installationand maintenance.

Integrated Capture Jets within supply airsections.

Picture 23. Closed Ceiling

Figure 16. Closed ceiling

27

Ceiling Ventilation Testing

The performance of the KCE ventilated ceiling wasstudied by the Lappeenranta Regional OccupationalHealth institute. The goal was to establish a testprotocol that was repeatable and usable over a widerange of air flows and ceiling designs.

Tracer Gas Studies

The measurement was carried out with a tracer gas(N2O) released from the heated cooking surface. Theconcentration at different locations (P1, P2, P3, P4)was observed.When a steady state of concentration was attained,the tracer gas was shut off.Local air quality indices were calculated from theaverage breathing zone concentrations and theconcentration in the exhaust duct.

The graphs aside show the concentration at differentmeasurement points with different air flow rates ( 50,100, 150%) and with different Capture JetTM air flowrates.The column on the left hand side shows the tracergas concentration with Capture JetTM and the rightcolumn without capture air.

The study shows that:

The same level of concentration was achieved withthe capture jet ON as with 150% exhaust air flow rateand Capture JetTM OFF, thus the increase of exhaustair volume increases only the energy consumption.

The capture air prevents effectively the impurities from spreading into the space. The use of Capture JetTM is crucial to the proper function of the ventilated ceiling.

Results

Without Capture JetTM and with 150% air flow ratethe pollution level is still higher than with Capture JetTM

with 100% air flow rate (see table 5). So it is notpossible to get the same level even with 150% airflow rate.

The revelations are based on the concentrations ofthe occupied zone.

Figure 17. Tracer gas concentration with Capture JetTM.The right column without capture air.

Figure 18. Concentration study conducted by theLappeenranta regional occupational health institute.

Air flow rate 100% 150%

Measured Jets on Jets off values - locations (ppm) (ppm) P1 8 19 P2 10 37Table 5. IAQ difference

28

Computer modelling

CFD works by creating a three-dimensional computermodel of a space. Boundary conditions, in the caseof kitchen ventilation modelling, may include ;

Ceiling exhaust rates Input energy of appliance Supply air type and volume Temperature of supply air

Complex formulae are used to produce the finalresults.Two cases were modelled for this analysis: one withthe jets turned off and a second model with the jetsturned on.

Figure 19. Capture JetTM ON

Figure 20. Capture JetTM OFF

Comparison Studies

Temperature comparison:

In this case study, the KCE ceiling has been modelledusing CFD software.As can be seen from observing figures 19 and 20, atthe same exhaust flow rate, the thermal comfort(lower operative temperature) in the working area isbetter when the jets are turned ON.

The cold supply air will close the ceiling level and soguarentees comfortable thermal conditions in theoccupied zone.

The part of the cold supply air is dropping down inthe occupied zone and it increases the draft risk.

29

Concentration comparison

As can be seen from observing figures 21 and 22,there is a significant difference between the CaptureJetTM ceiling and the ceiling without the jet.

With Capture JetTM off the contaminant is mixed freelywith the supply air and the concentration in theworking zone is increased (see table 6).

The plume from the width of the kitchen appliance isbigger. The plume will stay near the ceiling level andthe average pollution level is much lower than whenthe Capture Jet is OFF.

Figure 21. Capture JetTM OFF - concentrations under the supply units increase

Figure 22. Capture JetTM ON

Measured

Values Jets on Jets off

Location [ppm] [ppm]

P1 8 21

P2 10 47

P3 4 19

P4 5 20Table 6. Measured concentrations

Concentrations measured at each of the points P1,P2, P3, P4 are about 4 times higher than with jetON.

Energy saving effect

In the design process, the main idea is to reach theset target value of indoor air quality. The enegyconsumption is strongly depending on the targetvalue. Thus energy consumption and thecontaminant level should be analysed at the sametime.Even if the exhaust rate is increased by 50% with noCapture Jet concept, it is not possible to reach aslow contaminant as with the Capture Jet system.For the energy saving, this target value approachmeans that with the Capture Jet it is possible to reachmore 50% saving in the energy consumption.

P1P2P4P3

P1P2P4P3

30

Recommended Minimum Distances

A minimum horizontal distance between the supplyair unit and the edges of cooking appliances shouldnot be less than 700 mm to ensure that there are nodisturbances (mixing) between displacement air andthe convection plume.

If the displacement unit is too close to the heat loadfrom the appliances it can cause induction. The airfrom the supply air flow is then contaminated andreaches the floor.

Duct Installation Requirement

31

DESIGN GUIDELINES

Design Principles

The design of the professional kitchen follows themethodology of the industrial design process. Thekitchen layout design and time dependent internalloads are specified through the understanding of aspecific restaurant and its food service process.Also, the target levels for the IAQ and ventilationsystem performance and the basic concept are tobe defined at an early stage of the design.

In the beginning of the kitchen design process, thedesigner defines the type and process type as aninput. The space dimensioning includes roomestimates for all functional areas, such as receiving,storage, preparation, cooking and dishwashing, thatis required to produce the menu items. The spacerequired for each functional area of the facility isdependent upon many factors. The factors involvedinclude:

number of meals to be prepared functions and tasks to be performed equipment requirements and suitable space for traffic and movement

First, the indoor air is selected by the designertogether with the owner and the end-user. It meansan evaluation of the indoor climate including targetvalue adjustment for temperature, humidity and airmovement. It should be noticed that if there is no air-conditioning in the kitchen, the indoor temperatureis always higher than the outdoor temperature.The fact remains that when the indoor temperatureand humidity are high ( over 27 C and 65%), thisalso affects a persons capacity to work and at thesame time decreases productivity (see curve page 9).With air conditioning, it is possible to maintain idealthermal conditions all year.

After that the ventilation strategy of the kitchen spaceis pre-selected which is one of the key input factorsfor kitchen hoods selection.The integrated design principle is the key elementwhen the exhaust airflow rates are optimised.According to the German guideline (VDI 1999), theapplication of a displacement ventilation systemallows for a reduction in exhaust air flow by 15%compared to a conventional mixing ventilationsystem.Deciding on the strategy in the design phase has agreat effect on investment costs and the energy costsof the whole system.Based on the kitchen equipment information suchas:

heat gain (Sensible / Latent) maximum electrical power surface temperature

Hoods are Chosen

Picture 24.

32

Picture 25. Wrong traffic pattern

Picture 26. Air draughts

Picture 27. Right traffic pattern

What Is the Solution

Experience has shown that such air draughts can havea much greater effective throw distance to produce agreater detrimental effect on the capture envelope thanone would normally expect.

Hood Sizing

The size of the exhaust hood in relation to the cookingequipment is an important design consideration.Typically, the hood must extend beyond the cookingequipment: on all open sides for a canopy style hoodand on the ends for a back shelf style system.In a typical situation, if a hood system is not capturingand containing the effluent from the cooking process,it will spill in the front corners of the hood.

Picture 28. Re-hing doors and add end panels

The mouvement of people can involve moving anobject of sufficient size and speed to createsecondary air currents which pirate effluent fromthe cooking process.While the effect of one individual is only momentary,it can be a problem if the traffic occurs continually.

Opening windows in the kitchen creates draughts andalso affects the ideal shape of the thermal plume.It can be one of the most difficult problems to solve. Itis difficult because it is often not suspected as theproblem.

33

When the cooking equipment and canopy aremounted against the wall, a rear overhang is notrequired. However, if the canopy is set out in a singleisland installation it is necessary to ensure that theproper distance of back overhang is provided inaddition to the front overhang.

When two hoods are used in back to back (doubleisland) installation, the pair of hoods negates theneed for a rear overhang. However, the need for afront overhang remains.

Kitchen ventilation canopies require some distanceof overhang on each end of canopy.

Picture 30. Whats wrong?

Picture 29. I feel hot!

Picture 31. Help! End overhang - wrong

Front or Back Overhang - Wrong

34

Overhang - Right

All canopy type kitchen ventilation requires front andend overhangs. In most instances, extending theoverhang of a hood system from the typical 300 mm

Picture 32. A wall model installed as an island model. Inthis case, overhang on the back is needed.

will help insure C&C in most kitchen settings.Recommended height from the floor to the loweredge of the canopy is 2000 mm.

Figure 23. Wall model KV-/1

Figure 24. Island model KV-/2

Picture 33. The hood should extend a minimum of 300mm beyond the cooking equipment.

Picture 14. Island model

Figure 25. End overhang

35

Dishwashing AreaRecommended Overhang

Hood type

Conveyor type

Figure 26. Conveyor type

Figure 27. Hood type

36

Many manufacturers of commercial kitchenventilation equipment offer design methods fordetermining exhaust based on cooking appliances.Any method used is better than no quantification atall. The method of determining exhaust levels basedon the heat generated by the cooking process isreferred to as heat load based design and is thepremise for this manual. It is the foundation ofaccurate and correct design fundamentals in acommercial kitchen environment.

The lower the exhaust air flow and the higher theexhaust duct temperature at full C&C the moreefficient the hood systems is. Many designers do notconsider hood efficiency. The box is a boxsyndrome is prevalent with many people. However,each and every hood system, due to internalconstruction and added performance variables, offersa differing efficiency when related to exhaust flowsrequired to obtain C&C. This section discusses thedimensioning of hoods and gives an in-depth look atheat load based hood design.

Heat Load Based Design

It is still common practice to estimate exhaust airflowrate based on rough methods. The characteristicfeature of these methods is that the actual heat gainof the kitchen appliance is neglected. Thus theexhaust air flow rate is the same whether theappliances under the hood are a heavy load like awok or a light load like a pressure cooker.

These rough methods are listed for information, butshould only be used for preliminary purposes andnot for the final air flow calculation. They will notprovide an accurate result.

floor area air change rate cooking surface area face velocity method (0.3-0.5 m/s) portions served simultaneously

Neither of these rules takes into account the type ofcooking equipment under the hood and typicallyresults in excessive exhaust air flow and henceoversized air handling units coupled with high energyconsumption rates.

Picture 8. Cooking process

37

The most accurate method to calculate the hoodexhaust air flow is a heat load based design. Thismethod is based on detailed information of thecooking appliances installed under the hood includingtype of appliance, its dimensions, height of thecooking surface, source of energy and nameplateinput power. All this data allows the way the particularappliance emits energy into the kitchen to becalculated. Part of this energy is emitted into thespace in the form of the convective plume hot airrising from the cooking surface. The other part isrejected into the space by radiation warming up thekitchen surfaces and eventually the air in the kitchen.

Kitchen hoods are designed to capture theconvective portion of heat emitted by cookingappliances, thus the hood exhaust airflow should beequal or higher than the airflow in theconvective plume generated by the appliance. Thetotal of this exhaust depends on the hood efficiency.

qex

= qp . Khoodeff . Kads (2)

qp = k . (z + 1.7Dh) 5-3 . Qconv 1-3 . Kr (1)

WhereKhoodeff kitchen hood efficiency.

Kads spillage coefficient taking into account the effect of the air

distribution system on convective plume spillage from under the

hood. The recommended values for Kads are listed in the table 7.

Whereqp airflow in convective pume, m

3/h

z height above cooking surface, mm

Qconv cooking appliance convective heat output, kw

k empirical coefficient, k = 18 for a generic hood

Kr = reduction factor, taking into account installation of

cooking appliance (free, near wall or in the corner)

Dh hydraulic diameter, mm

L,W length and width of cooking surface accordingly, mm

Dh =2L . WL +W

The amount of air carried in a convective plume overa cooking appliance at a certain height can becalculated using Equation

Picture 34.

N

LxW

Figure 28. Hydraulic diameter

38

The kitchen hood efficiency shown in equation 2 canbe determined by comparing the minimum requiredC&C flow rates for two hoods that have been testedusing the same cooking process.

Table 7 presents recommended values for the spillagecoefficient as a function of the air distribution system.

Table 7. Spillage coefficients as a function of the airdistribution system

For the short-cycle hoods equation 2 will change into

Whereqint internal discharge air flow, m

3/h

The Heat Load based design gives an accuratemethod of calculating hood exhaust air flow as afunction of cooking appliance shape, installation andinput power, and it also takes into account the hoodefficiency. The only disadvantage of this method isthat it is cumbersome and time-consuming if manualcalculations are used.Hood Engineering Layout Program (HELPTM) isspecially designed for commercial kitchen ventilationand turns the cumbersome calculation of the heatload based design into a quick and easy process. Itcontains the updateable database of cookingappliances as well as Halton Capture JetTM hoodswith enough information to be able to use Equations1 and 2 accurately to calculate hood exhaust air flow.

qex

= qp . Khoodeff . Kads + qint (2.1)

Type of air distribution system KadsMixing ventilation

Supply from wall mounted grills 1.25Supply from the ceiling multicone diffusers 1.2

Displacement ventilationSupply from ceiling low velocity diffusers 1.1Supply from low velocity diffusers locatedin the work area 1.05

Total Kitchen Ventilation System Design

Ms + M

tr =

MHood (3)

Where

Ms mass flow rate of air supplied in the kitchen (outside supply

air delivered through the air handling unit and makeup air), l/s

Ms = Mosa + MmuMtr mass flow rate of transfer air entering the kitchen from the

adjacent spaces, l/s

Mhood mass flow rate of exhaust air through the hoods, kg/s

The supply air temperature ts to maintain design airtemperature in the kitchen is estimated from theenergy balance equation shown below:

Where

cp specific heat of air = 1 kJ/(kg.C)

s, tr air density of supply and transfer air accordingly, kg/m3

tr kitchen design air temperature, C

ts supply air temperature, C

ttr transfer air temperature, C

Qsens total cooling load in the kitchen, kW from appliance radiation,

unhooded appliances, people, lights, solar load, etc.

Ms

. cp

. s (t

r t

s) + M

tr

. cp

.

tr (t

r t

tr) + Q

sens=

0 (4)

A properly designed and sized kitchen hood willensure that effluents and convective heat (warm air)from cooking process are captured; however, it isnot enough to guarantee the kitchen spacetemperature is comfortable. The radiation load fromappliances underneath the hood, heat fromappliances not under the hood, people, lights, kitchenshell (heat transfer through walls and ceiling), solarload, and potential heat and moisture from untreatedmakeup air are to be handled by the kitchen airconditioning system.It is recommended that a negative air balance bemaintained in the kitchen. A simple rule of thumb isthat the amount of air exhausted from the kitchenshould be at least 10% higher than the supply air flowinto the kitchen. This will guarantee that the odoursfrom the kitchen do not spread to the adjacent spaces.Equation 3 describes the air flow balance in a kitchen

Picture 7.

39

In cases where the supply air temperature tscalculated from equation 4 is below 14C (13C off-coil temperature with 1C duct heat gain), the supplyairflow rate Ms must be increased. The new value forMs is calculated from the same equation 4 by settingts= 14C. In this case, we recommend incorporatinga return air duct to increase supply air flow.

Since it is rare that all the equipment is simultaneouslyoperating in the kitchen, the heat gain from cookingappliances is multiplied by the reduction factor calledthe simultaneous coefficient, defined in Equation 5.Recommended values are presented in table 8.

Ksim =

Number of appliances in useTotal number of appliances in kitchen

(5)

Table 8. Recommended values for simultaneouscoefficient.

Kitchen type Simultaneous coefficientKsim

Hotel 0.6 0.8Hospital 0.7 0.5Cafeteria 0.7 0.5School 0.6 0.8Restaurant 0.6 0.8Industrial 0.6 0.8

Effect of Air Distribution System

Equation 4 assumes that a mixing air distributionsystem is being utilised and that the exhaust/returnair temperature is equal to the kitchen air temperature

Picture 35. CFD simulation of a kitchen with mixing (top) and displacement (bottom) air distribution system. Airtemperatures are shown.

(assuming fully mixed conditions). Conversely, adisplacement ventilation system can supply lowvelocity air directly into the lower part of the kitchenand allow the air naturally to stratify. This will result ina higher temperature in the upper part of the kitchenwhile maintaining a lower air temperature in theoccupied zone. This allows for improvement of thekitchen indoor air quality without increasing the capitalcosts of the air conditioning system.

Picture 35 demonstrates a CFD simulation of twokitchens with mixing and displacement ventilationsystems. In both simulations the kitchens have thesame appliances contributing the same heat load tothe space. The supply air flow and temperatures, andthe exhaust air flow through the hoods are the samein both cases. The air is supplied through the typicalceiling diffusers in the mixing system. In the case ofthe displacement system, air is supplied throughspecially designed kitchen diffusers located on thewalls. As one can see, the displacement systemprovides temperatures in the kitchen occupied zonefrom 22 to 26C while the mixing system, consumingthe same amount of energy as displacement, resultsin 2732C temperatures. This 2C temperatureincrease in the kitchen with the mixing air distributionsystem will result in approximately 10% reduction inproductivity (see picture 6. page 9).Halton HELPTM program allows kitchen ventilationsystems for both mixing and displacement ventilationsystems to be designed.

40

Mixing Ventilation

Mixed air supply diffusers supply high velocity air atthe ceiling level. This incoming air is mixed with roomair to satisfy the room temperature set point.Theoretically there should be a uniform temperaturefrom floor to ceiling. However, since commercialkitchens have a high concentration of heat,stratification naturally occurs. Consequently, theconditioned air does lose some of its coolingeffectiveness, gaining in temperature as it mixes withthe warmer air at the ceiling.

Research has shown that if mixing diffusers arelocated close to the hood, the high velocity airinterrupts the cooking plume, drawing some of it outof the hood (in effect causing the hood to spill) andfurther increasing the heat load on the space.

Displacement Ventilation

Thermal displacement ventilation is based on thenatural convection of air, namely, as air warms, it willrise. This has exciting implications for delivering fresh,clean, conditioned air to occupants in commercialkitchens.

Instead of working against the natural stratificationin a kitchen, displacement ventilation first conditionsthe occupied zone and, as it gains heat, continuesto rise towards the upper unoccupied zone where itcan be exhausted.

Picture 36. Mixing ventilation

Picture 7. Displacement ventilation

According to VDI 2052, application of aDisplacement Ventilation system allows for areduction in hood exhaust airflow by 15%compared to a conventional mixing system.

41

Design Practice

Introduction

It is still quite common practice to estimate exhaustair flow rates based on rough methods. Thecharacteristic feature of these methods is that theactual heat gain of the kitchen appliance is neglected.Thus, the exhaust air flow rate is the same: even whena heavy load like a wok or a light load like a pressurecooker is under the hood. These kinds of roughestimation methods do not produce optimalsolutions; the size of the whole system will beoversized and so the investment costs and runningcosts will increase.

The layout of the kitchen ventilation design wascomplex due to the provision of a logical structurecombined with good air flow distribution andperformance.

Technically it was a question of designing andproviding an air conditioning installation offeringconditions and a minimal variable temperature in thesurrounding area ie: 23C, 0/3C whilst also keepinga negative pressure between the kitchen and alladjacent areas.

The most sensitive space to be handled turned outto be the working zone, where the airflow to extractheat and steam produced by ovens or cooking potswere important.The steam emitted in the opening of cooking pots orthe brat pan should also be captured immediately.In this case of providing sufficient efficiency incapturing polluants, the necessity of having the lowestenergy consumption for the end user had to beconsidered.

In tackling these constraints, it has been decided toselect a model of hood using high technology offering,for the same connecting power installed in thekitchen, maximum efficiency and important energysavings.

Kitchen Design Process

The design of the professional kitchen environmentfollows the methodology of the industrial designprocess.

Picture 24.

42

Phase1: Background information of thekitchen available:

Layout, type and the dimensions of thekitchen.

Type and properties of the cookingequipment (sizes, source of energy,input power).

Target level for the IAQ and ventilationsystem performance.

Temperature design conditions 23C -Relative humidity 65%

Total design approach to consider bothIAQ and energy efficiency factors ( airdistribution system chosen).

The kitchen is a central kitchen and its layout anddimensions are presented in figure 29.

Dimensions of cooking area 11x8.3 -91m2, 3m high.

five people working in the kitchen

The kitchen is open seven days a week and fourteenhours a day. Simultaneous coefficient: 0.7.

Figure 29. Kitchen lay-out

Phase 2: Kitchen equipment definition

Table 9. Cooking equipment data-base

Item Qty Description Dimensions Elec. kW Gas kW

1 1 Kettle steamer 1200x800x900 182 1 Table 500x800x9003 1 Kettle steamer 1000x800x900 154 1 Kettle steamer 900x800x900 145 1 Braising Pan 1400x900x900 186 1 Braising Pan 1000x900x900 157 1 Braising Pan 1200x900x900 188 1 Braising Pan 1300x900x900 159 1 Table 1000x800x900

10 1 Braising Pan 1300x900x900 1811 1 Range (4 elements) 800x900x900 1612 1 Table 1000x800x90013 2 Fryer 400x800x900 1514 1 Table 800x800x90015 3 Convection (double stack) 100x900x1700 17

43

Calculation with traditional methods fortraditional hood (KVX type)

One of the rules for canopy hoods is to exhaustbetween 0.2 of hood face for light duty (boiler, bainmarie..) and 0.5 for heavy load ( broiler, bratt pan..).

Equation 1 is to calculate the exhaust airflow rate todetermine the volume of air to be extracted:

(1)

Where :V = capture velocity, m/sP = Perimeter of hood, mH= distance of hood to emitting surface, m

This method does not really take into account thecharacteristics of the appliances. For example, theactual heat load (more exactly the convection shareof the sensible load) is neglected.

Block I: 4200 x 2250 x 555Island type hood:Q = 0.33600(4.2+2.25+4.2+2.25)1.1= 15 325 m3/h

Block II: 4200 x 2350 x 555Island type hood:Q = 0.33600(4.2+2.25+4.2+2.25)1.1= 15 563 m3/h

Block III: 4400 x 1350 x 555Wall type hood:Q = 0.253600(4.4+1.35+1.35)1.1= 7029 m3/h

Total exhaust : 37 917 m3/h

Heat load based design methods

The most accurate method to calculate the hoodexhaust air flow is a heat load based design. Thismethod is based on detailed information of thecooking appliances installed under the hood includingtype of appliance, its dimensions, height of thecooking surface, source of energy and nameplateinput power.It should be mentioned that with the hood it ispossible to extract only the convection load of theappliances while the remaining radiant load is alwaysdischarged in the kitchen.

The amount of air carried in a convective plume overa cooking appliance at a certain height can becalculated using Equation 1 page 31

(1)

Kitchen hoods are designed to capture theconvective portion of heat emitted by cookingappliances; thus the hood exhaust airflow should beequal to or higher than the airflow in the convectiveplume generated by the appliance. The total of thisexhaust depends on the hood efficiency.

(2)

WhereKhoodeff kitchen hood efficiency.Kads spillage coefficient taking into account the

effect of the air distribution system.

The recommended values for Kads (VDI 1999) arelisted in the table 7 page 38. Based on this table therequested exhaust airflow with wall-mounted supply(Kads =1.25) is 19 % higher than with low velocity.

Since it is rare that all the equipment is simultaneouslyoperating in the kitchen, the heat gain from cookingappliances is multiplied by the reduction factor calledthe simultaneous coefficient (). Normally, thesimultaneous factor is from 0.5 0.8. This meansthat only 50 80 % of the appliances are used at thesame time.

Block I:A kitchen extraction hood measuring 4200 mm x2250 mmx 555mm is mounted 2 m above thefloor. The installation height of the hood is then1.1m above the appliances.

44

Item1: Kettle steamer

Dh hydraulic diameter, m

= 0.96 m

Qconv= P. Qs. b . in WQconv= 18. 200. 0.7 . 0.7 = 1764 w

= 1160 m3/h

Item2: table: No thermic flow



= 0.888 m

Qconv= P. Qs. b . in WQconv= 15.200 . 0.7 . 0.7 = 1470 w

=1013 m3/h



= 0.847 m

Qconv= P. Qs. b . in WQconv= 14. 80. 0.5 . 0.7 = 392 w

= 623 m3/h

Item5: Braising Pan


= 1.33 m

Qconv= P. Qs. b . in WQconv= 18 . 450 . 0.5 . 0.7 = 2835 w

=1557 m3/h

Item6: Braising Pan


= 0.947 m


= 1263m3/h

Item7: Braising Pan


= 1.028 m


= 1460 m3/h

N

L x W

45

Exhaust air flow for block I :Hood exhaust air flow should be equal to or higherthan the air flow in the convective plume generatedby the appliance. The total of this exhaust dependson the hood efficiency.

Kads = 1.05Kopt = 1.2 Optimisation of the equipment under

the hood (In island position always 1.2).qp = 7076 m3/h

qex = [707611.05]1.2+695 = 9520 m3/h

Block II:A kitchen extraction hood measuring 4200 mm x2350 mmx 555mm is mounted 2 m above the floor.The installation height of the hood is then 1.1m abovethe appliances.

Same calculation procedure as above

qex = 7613 m3/h

Block III:A kitchen extraction hood measuring 4400 mm x1350 mmx 555mm is mounted 2 m above the floor.The installation height of the hood is then 1.1m abovethe appliances.

Same calculation procedure as above

qex = 1867 m3/h

SUMMARY BLOCK I

TOTAL 7076

Item Qty Description Dimensions dh Qconv Net exhaust

m W m3/h1 1 Kettle steamer 1200x800x900 0,96 1764 11602 1 Table 500x800x9003 1 Kettle steamer 1000x800x900 0,88 1470 10134 1 Kettle steamer 900x800x900 0,847 392 6235 1 Braising Pan 1400x900x900 1,018 2835 15576 1 Braising Pan 1000x900x900 0,947 2362 12637 1 Braising Pan 1200x900x900 1,028 2835 1460

Comparison of Exhaust Air flow Rates

Using a heat load based design method gives moreaccurate and optimized air flow rates than traditionalrules.

Description Air flow based on Heat load

face velocity based Design

m3/h m3/h

Block I 15 325 9520

Block II 15 563 7613

Block III 7029 1867

Total 37 917 19 000

HALTON solution is the recipe for a healthy &productive kitchen environment

The Heat Load based design gives an accuratemethod of the calculating hood exhaust air flow as afunction of the cooking appliances shape, installationand input power, and it also takes into account thehood efficiency. The only disadvantage of this methodis that it is cumbersome and time-consuming ifmanual calculations are used.

Hood Engineering Layout Program, Halton HELP isspecially designed for commercial kitchen ventilationand turns the cumbersome calculation of the heatload based design into a quick and easy process. Itcontains the updateable database of cookingappliances as well as Halton Capture JetTM hoodswith enought information to be able to use Equations1 and 2 to accurately to calculate the hood exhaustair flow.

Table 10.

46

Phase 3-4: Kitchen hood design

INTELLIGENT DESIGN SELECTION BY USINGTHE HALTON HELP SOFTWAREFirst of all, Halton had to calculate the air flow preciselyand then measure rates and adjust them above eachappliance. This allows the minimal air flow that willenable the kitchen to work correctly when using aKVF hood with Capture JetTM technology to bedetermined. Indeed, by introducing air at the frontleading edge of the hood, at high velocity (>4m/s), itcreates a Venturi effect , leading the air directlytowards the filters, without increasing the exhaustair flow. Compared with a traditional system of hoods,the Capture JetTM system allows an exhaust flow upto 30 % lower, by only having 5-10% of net exhaust.

The KVF has been installed over the cookingequipment, Block I and Block II. These hoods areclassified as Island hoods.

Figure 30. Halton HELP Data entry Figure 32. Halton HELP Air conditioning inputs

The other KVF hoods are installed over the othercooking equipment and they are against the wall withthree sides open. These hoods are classified as wallhoods (Block III)

Figure 31. Halton HELP Kitchen lay-out

AIR CONDITIONING CALCULATION RESULTS

Figure 33. HELP print-out

47

Energy and Cost Comparison Using theHalton HEAT Software

This screen presents the annual heating, cooling andair conditioning operating costs for the three differenthood types. However, in this case we have onlyspecified inputs for the Capture JetTM and exhaustonly hoods. Pressing the Conclusion button on thetree brings up the report seen in figure 36.

This section shows the energy and cost benefits forthe end-user of utilising the Halton Capture JetTM

hood system versus the competition's exhaust onlyand short circuit hoods. The data entry screen forHalton HEAT software is shown in figure 34.

As shown in figure 35, we are comparing twosystems: a Halton model KVI hood with Capture JetTM

technology versus an exhaust-only hood.Using Halton HELP software, it can be shown thatthe exhaust flow of the Capture JetTM hood is only19 000 m3/h. The remaining data on the screen arefor the total fan pressure drop of each of the systemstogether with the total installed cost for the end-user,which includes the hoods, fans, labour etc. The finalstep on the main form is to press OK and to bring upthe screen shown in figure 35.

The energy savings report presents the financial andenvironmental benefits of investing in a Haltonsystem. In this case, the savings in air-conditioningwere less than the added cost of the Halton hoodproviding immediate payback to the end-user. Sincethe Capture JetTM hood requires a lower exhaust flowthan a competitors hood , less make-up air isrequired resulting in a lower air conditioning cost.

Figure 34. Halton HEAT Data entry screen

Figure 36. Halton HEAT Energy savings report

Figure 35. Halton HEAT Annual costs

48

Upon examining the table above, it becomesapparent that the KVF hood could save over 11153Euros in annual operating costs for Paris, France.Using the exhaust flow rate of 19 000 m3/h of theKVF hood as a basis, the exhaust only hood iscalculated to need 26 905 m3/h.The net effect is that the payback for the KVF isinstantaneous.

Being Helped Successfully

It was a quick decision to choose the highly efficientKVF canopy with Halton Capture JetTM technology,which allows the canopy to operate with up to 30%lower exhaust flows than traditional hood systems.

The make-up air for general ventilation is distributeddirectly into the working zone from the front face andfrom the low velocity supply diffuser at the side ofthe canopy.It is indeed the only hood currently on the marketcapable of combining the two features below:

Optimising the exhaust air flow rate andenergy saving

Guaranteeing the comfort of theworkers and improving theirproductivity with better indoor airquality.

Improving Comfort

In addition to energy savings there is a netimprovement in comfort due to the decrease in airvolumes calculated (i e : limitation of draughts) Otherfeatures include increase in hood efficiency and highgrease filtration efficiency. The low velocity diffusionof general supply air via the KVF also helps to improvecomfort.

Hood type KVF Exhaust-only

Fan energy 1755 3106

Heating energy 13321 20355

Cooling energy 4972 7649

Total 19958 31111

Table 11. Annual cost


Picture 37.

49

PRODUCT SUPPORT PACKAGE TOOLS

The hallmark of Halton design is the dedication toimprove indoor air quality in commercial kitchens,restaurants, hotels and bars. The Halton FoodserviceCD is a complete package for foodserviceprofessionals containing tools and material for easybut sophisticated design of working indoorenvironments.

Halton HIT interactive product catalogue Halton HELP 3D design and selection software

for kitchen hoods and ventilation systems Halton HEAT energy analysis tool for payback

time calculation and evaluation of environmentalimpacts

Commercial kitchen design guide Detailed technical data for Haltons kitchen

and restaurant ventilation range Halton references

Picture 37.

50

For any ventilation system to operate properly in acommercial kitchen, the airflows have to be measuredand balancing after the system has been installed toensure that the design criteria have been met. Thischapter provides information on balancing the supplyand exhaust systems in a commercial kitchen.

Balancing is best performed when manufacturers ofthe equipment are able to provide a certified referencemethod of measuring air flows, rather than dependingon generic measurements of duct flows or otherforms of measurement in the field.

MEASURING AIRFLOW & BALANCING HOODS

Exhaust & Supply air balancing

Halton offers a variety of means for determining theexhaust flow through their Capture JetTM hoods.Integral to all Capture JetTM hoods is the Test &Balance Port (T.A.B.). These ports are to be used indetermining both the exhaust and Capture JetTM airflows. Each incremental size of hood has been testedthrough the range of operable air flows and a curvehas been generated showing air flow as a functionof pressure drop across the T.A.B. Regardless of ductconfiguration, the T.A.B. ports will give you anaccurate reading of air flow.

Picture 38. Traditional way

FAN AND DUCT SIZINGIt is recommended when sizing the exhaust duct notto exceed 9 m/s for the main branch and 7 m/s forthe branch runs. This is due to the noise potential forthe h

halton design guide en

Documents

halton s

halton oyniittyvillankuja

halton b

halton n

halton products

halton asnydamsvej

halton oyhaltonintie

halton abbox