technical specification duct

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TECHNICAL SPECIFICATIONS

INTRODUCTION

This specification covers the minimum requirements for the engineering, procurement,

installation and commissioning of the HVAC system to be provided inside the new LIBRARYbuilding at IACS.

1.0 STANDARD SPECIFICATION

1.1 Scope of Work

The complete scope of work shall cover supply, erection, testing and commissioning ofthe entire HVAC system as detailed under specification.

1.2 Basis of Design

The entire system has been based and designed on climatological data available as givenunder Basis of Design and Scheme.

1.3 Terms and Definitions

The followings terms have been used in the tender specifications, drawings etc.

ISI : Bureau of Indian Standards.

ASHRAE : American Society of Heating Refrigeration & Air-conditioningEngineers, USA.

B.S. : British Standards.

CMH : Cubic Meter per Hour.

RPM : Revolutions per Minute.

BTU/Hr. : British Thermal Unit per Hour.

Kcal/Hr. : Kilo Calories per Hour.

HZ : Hertz.

H.P. : Horse Power

SAG : Supply Air Grills.

SAD : Supply Air Diffuser.

SAF : Supply Air Filters.

FD : Fire Damper.

VCD : Volume Control Damper.

RAD : Return Air Damper.

FAD : Fresh Air Damper.

RH : Relative Humidity.

DB : Dry Bulb Temperature.

WB : Wet Bulb Temperature.

DP : Drain Point.

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1.4 The codes, regulation as detailed below shall be followed in this contract :-

1. Safety code for air-conditioning (revised)amendment 1

: IS 659 : 1964 (reaffirmed 1991)

2. Safety code for mechanical Refrigeration : IS 660 : 1963 (reaffirmed 1991)

3. Testing of refrigeration compressors : IS 5111 : 1993

4. Aircooled heat exchangers (amendment 1) : IS 10470 : 1983 (reaffirmed1991)

5. Packaged Air-conditioner(amendment 1991) : IS 8148 : 1976 (reaffirmed1991)

6. Thermostats for use in refrigeration etc. : IS 11338 : 1965 (reaffirmed1991)

7. Metal Duct Work : IS 655 : 1963 (reaffirmed 1991)

8. Steel for general structural purpose : IS 2062 : 1992

9. Refrigeration : As per ASHRAE / ISIAirconditioning & RefrigerationAir-conditioning instituteStandards.

10. Hot Dip Zinc Coated Steel Tubes : IS 4736 : 1968

11. Colour code for the identification of pipe lines : IS 2379 : 1963

12. Specific requirements for the direct switching ofthe individual motors.

: IS 4064 ( Part II) 1978

13. PVC insulated ( HD) Electric Cables forworking voltage up including 1100 Volts.

: IS : 1554 ( Part I)

14. HRC Cartridge fuse links upto 650 Volts. : IS 2208 : 1976

15. Starter : IS 8554 ( Part I) 1979

16. Inspection and testing of installation : IS 732 ( Part III) 1979

17. Galvanized steel wire for fencing : IS 277 : 1977

18. Three phase induction motors : IS : 325

19. PVC insulated ( heavy duty ) cables forworking voltage up to 1.1. KV and up to 11 KVGrade respectively.

: IS 1554 : 1981 Part I & II

20. Code for practice for electrical wiringinstallations.

: IS 732 : 1989

21. Code for practice for earthing : IS 3043

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22. Specification for single phase small A/C &universal motors

: IS : 996

23. Circuit breaker A.C : IS 2516 : 1980 Part I & II

24. Contactors for A.C for voltage upto 1100 V. : IS 2959 : 1975

25. Low voltage switch gear and control gearassemblies.

: IS 8623 : 1993 Part I & II

26. Code of practice for selection of starters for ACinduction motors

: IS 3914

27. Specification for cables glands : IS 4821

28. Code for selection, installation & maintenanceof switch gear and control gear.

: IS 10118 :1982 Part I to IV

29. Conduits for electrical installations : IS 9537 : 1981 Part I to IV

30. Permissible limits of noise level for rotatingelectrical machines.

: IS 12065 : 1987

31. Code of practice for installation andmaintenance of motors

: IS 3106 : 1966

32. HRC catridge fuse links upto 650 volts : IS : 2208

33. PVC insulated ( heavy duty) electric cables forworking voltage upto & including 1100 watts. : IS ; 1554 ( Part I)

34. Method for testing Panel type air filters for ACpurposes.

: IS 7613 : 1975 (reaffirmed1991)

35. Unbounded glass wool for thermal insulation(1st. Revision)

: IS 3690 : 1974

36. Expanded polystrene for thermal insulationpurposes. ( 1st. revision)

: IS 4671 ; 1984 (reaffirmed)

1.5 Safety Codes

The following IS codes shall be followed:

Safety code for mechanical refrigeration : IS 660

Safety code for air conditioning : IS 659

Safety code for scaffolds & ladders : IS 3696

Code of practice for fire precaution in Welding &cutting operations

: IS 3016

Code for safety procedures and practicesIn electrical works

: IS 5216

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Code of practice for safety and health Requirements inelectrical & gas welding And cutting operations.

: IS 3696

1.6 Spacs

All shop drawings shall be prepared by the A.C Contractor after examining thearchitectural & AC drawings.

2.0 DESIGN CONDITIONS

The design parameters to be used for detailed design of the air conditioning system asfollows:

2.1 Outside Ambient Conditions

Summer : DB: 40 oC (105 oF) & WB: 28.33 oC (83 oF).

Monsoon: DB: 32.2 oC (90 oF) & WB: 30 oC (86 oF).

Equipment performs to the above ambient conditions and not fail in conditions of 43 oCDB (dry bulb).

2.2 Inside Design Condition:

Room Temperature : 23 oC + 1.1 oC

Relative Humidity : 55% + 5%

Detail Input conditions are mentioned below:Sl.No.

A.Cspace

Area (Sft) Occu-pancy

Lighting(W/sft)

Equip-ment(KW)

FreshAir(cfm)

Sensi-bleLoad(BTU/ hr)

Totalload(BTU/ hr)

ADP(oF)

DehmfdAir (cfm)

Remarks

1 2 3 4 5 6 7 8 9 10 11 12

Firstfloor

Library 12877.00 150.00 1.50 5.00 2250 560,131 602,985 54 21,884

3.0 DESIGN PARAMETES

3.1 Ducting work

a) Method of Duct Design Equal friction method :

b) Maximum air velocity in supply duct FPM : 1200.0

c) Maximum air velocity in return duct FPM : 800.0

d) Friction loss in duct (maxm) MM Wg in 100 Mt run : 6.66

e) Maximum Velocity at supply air grill outlet FPM : 150.0

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3.2 Insulation

Maximum temperature rise in the supply air duct from Air-handlers outlet to farthestoutlet in C 1.10

4.0 NOISE AND VIBRATION CONTROLS

4.1 The air conditioning contractor must take all necessary precautions to have minimumnoise generation and its transmission. Minimum vibration as permitted by IS relevantcode shall be ensured. A few points for guidance only are given below:

a) Double fire retardant flexible connections shall be provided from air discharge tooutlet of air-handler to the duct.

b) Vibration isolation pads of suitable thickness commensurate to loading for isolationof vibration shall be provided under all equipments. in consultation withmanufacturer for proper selection of vibration isolators

c) Flexible conduit connections of minimum diameter of 50mm to motors shall beprovided. All loops should be large enough to allow connections to remain flexible.

d) All conduit connection where conduits are 60mm or larger shall be made of 1.2meters minimum length conduit installed in the shape of U and grossly slack toprovide maximum vibration isolation.

e) The floor supported piping shall be mounted on pipe supports with 7.5mm ribbedneoprene pads between the base plate of the pipes and the floors.

f) All items suspended from false ceiling shall be isolated on separate hangers.

g) In case of ducts, conduits, pipes & tubes the annular space between constructionand penetrating element shall be sealed with sand cement plaster.

h) The supply duct starting from air handling unit & plenum shall be provided with 12mm thick acoustic lining as indicated in the tender drawings.

i) The air-conditioning contractor shall take all other precautions or shall make hisown arrangements even if not specified in the tender documents for eliminatinghigh noise levels & shall minimize vibrations in all mechanical equipments withoutany additional cost.

5.0 GENERAL DESCRIPTION AND SPECIFICATION OF THE SYSTEM PROPOSEDThe air-conditioning of the IACS Kolkata shall be based on the air cooled Floor MountedType package unit for 1st Floor area.

The 1st Floor area shall be air-conditioned by the Air Cooled Floor Mounted typepackaged air conditioning unit. The Installed capacity of the A. C. Unit shall be 90 TR(approximately) (4 Nos 15 TR Air Cooled Scroll Package Unit as working + 2 Nos 15 TRunit as standby)

The Condenser for the package unit shall be located outside the building and on a MSstructure. The Supply air main ducting from the package Units shall be run above the

false ceiling to the conditioned space as per layout enclosed with tender. TheConditioned air shall be distributed through the ceiling mounted type diffuser/ Grill as perdistribution arrangement indicated in the drawings.

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The return air shall be mixed with fresh air before passage over the cooling coils.

The fresh air intake shall be complete with Air Intake Louvers with insect screen, &Manual & Motorized Volume Control damper. The Motorized VCD will be controlledthrough a CO2 Sensor and a controller. Vendor has to select the controller in such a waythat, set point of CO 2 level and actual CO 2 quantum can be seen on the controller andthe controller can give necessary 0-10mA output to the Motorized damper in such a waythat based on the actual level of CO2 the fresh air damper will open / Close. TheController should be such that, the minimum & Maximum value of the operating rangecan be adjusted in the controller.

The Ductwork shall have provision for Volume control dampers for balancing the system.The entire supply air duct shall be insulated with the CLASS O ANTIMICROBIAL type 13mm thick Nitrile rubber with Al. Foil Faced. All the Terminal Diffuser / Grill also with Al.Volume Control damper to have proper air distribution inside Conditioned area and forbalancing purpose. To control the Noise level inside area as per noise level mentionedabove, acoustic lining shall be provided inside the Duct up to three meters (3M) from theindoor unit mouth as mentioned in the drawing. Necessary Motorized Type Fire damperwith spring return type actuator for supply air duct and Fusible link type fire damper asper UL555 shall be provided for Return air path for fire protection. Necessary electricalinterlocking arrangement shall be provided with fire damper & Evaporator fan motor toshut down the AC fan on detection of fire.

5.1 Air cooled Package A. C. System

Evaporator Section (Indoor unit):

The evaporator fan should be with DIDW type centrifugal fan of AMCA certified having

with the minimum followings: C45 carbon steel shaft Anti corrosion paint on shaft for durability Self-aligning and hermetically sealed durable ball bearings Tab-lock blades Statically and dynamically balanced to grade G4 (according to ISO 1940)

The capacity of the each Evaporator fan for 16.5TR unit should be 6800 CFM. TheStatic pressure for the fan should be 35mm WG. The fan motor should have belt driventype with variable pitch pulley to adjust the CFM during commissioning & maintenance.The evaporator section should have with 4R deep cooling coil and with 50mm thickSynthetic washable type pre filter with 90% efficiency down to 10 micron.

The Filter & Coil face velocity should not be more than 500 FPM. Each unit should havemultiple scroll compressors. The unit should also with either Thermostatic or Electronicexpansion valve. The drain pan of the indoor unit should be insulated with propersandwich insulation to protect condensation. Oppose blade type Volume control damperto be provided outside the mouth of unit with ON / OFF marking for proper controlling &adjustment of Air quantity as per design condition.

Following Protections should be considered for Each Package unit:

1. Single Phase & Phase reversal protection2. High Pressure Cut out

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3. Low pressure cut out.4. Over Voltage & Under Voltage Protection.5. Over load trip .

The Microprocessor Controller should have the following features:

1. In the power saving mode, when the compressor is off, the condenser fan shouldalso remain off.

2. Room temperature set point and the actual room temp. to be displayed thoughElectronic temperature sensor.

3. Programmable operation feature for one year with real time clock.

4. Auto restart after restoration of power.

5. Fault Diagnosis feature.

6. Anti recycle feature.

Condenser

The Air Cooled Condenser should be with aerofoil type low power consumption fan, heatexchanger to be coated with golden anticorrosive on aluminum Fins surface. TheCooling coil to be design in such a way that the package unit can work upto 45 oC.

Refrigerant Pipe:

The indoor & outdoor unit to be connected with the hard drawn copper pipe of minimum18G thickness. All the elbow & reducer should be with the same thickness of the pipe.The size of the refrigerant pipes to be done by the vendor based of actual pipe lengthetc. The Refrigerant pipes should be Pressure tested at 400 PSI / 200 PSI and shall holdthe pressure for 24 hrs. Proper Vacuuming should be done before charging of therefrigerant.

Pipe Supports

All refrigerant piping shall be supported to prevent deflection, bulking and vibration.Piping shall be supported at all changes in direction and at intervals of not more than 1.2meters on straight runs. Pipe supports and clamps shall be subject to approval of

consultant. Pipe work on roofs and floors shall be supported on off-set clamps, floor. ThePipe support stands shall be bolted to the concrete slab or steel members. Vertical pipework shall be supported with trapeze hangers with rods suspended from inserts.Condensate drain pipe supports shall be capable of vertical adjustment after installationof piping. All pipe works passing through the walls, floors and roof slabs shall beprovided with pipe sleeves of adequate size to allow the passage of insulation.

Electrical Cabling

All the connected Power cable should be with Al. Ar. Cable of 1100 V grade & controlcable should be with Cu. Ar. Cable of 1100 V grade. The minimum size of Power cableshould be 4 sqmm Aluminium & for control cable 2.5 sqmm copper. The incoming supplyof the MCC should be with MCCB & all outgoing feeder should be with MCB & forcompressor MCCB of suitable rating. The Outdoor Structure should be such that propermaintenance is possible and isolators to be provided near condensers with necessary

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interlock with package unit, so that for maintenance / emergency condensers can switchoff.

Noise Levels

Noise level inside the conditioned area resulting from the units shall not exceed thefollowing:

- NC 35 for office area

All running equipments shall be isolated from the building structure and the supportisolated from other items of equipment.

All the units shall have anti-vibration mountings of approved make and these shall besubject to approval of the consultant.

All the Air distribution system should be designed in such a way so that inside noise levelshould be within NC 35.

Vibration Isolators

All plant shall be isolated from the building structure and the support isolated from otheritems of equipment.

The package units shall have anti-vibration mountings of approved make subject toconsultants approval.

Multi-layer rubber pads with square grid convolutions on both sides, spaced with steelshims and of a thickness to suit the points of uniform loading of the plant item but of aminimum thickness of 32 mm shall be spaced not more than 750 to 1000 mm apart.

6.0 DUCTWORK

STANDARD SPECIFICATION FOR AIR CIRCULATION SYSTEM

This section deals with supply, erection, testing & balancing of GI sheet metal duct workand air registers conforming to specifications as given below:

Material for Ducing

The duct shall be fabricated out of galvanised sheet, class VIII (Zinc coating 120gm/mnas per the parameters given below which are conforming to IS 655-1963.

Maximum Thickness Type of Transverse Bracing

Upto 600 0.63 S-drive, pocket or bar,slips, on 2.5 m ceners

None

601 to 750 0.63 S-drive, pocket or bar,slips, on 2.5 m Centers,S-drive 25 mm pocket, or25 mm bar slips on 2.5 mcenters.

25 x 25 x 3 mm, angles,1.2 m from joint.

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751 to 1000 0.80 Drive, 25 mm pocket or25 mm bar slips, on 2.5 mcenters 40 x 40 mmangles connections.

25 x 25 x 3 mm angles, 1.2m from joint.

1001 to 1500 0.80 40 mm bar slips, with 35 x3 mm bar reinforcing on2.5 m centers

40 x 40 x 3 mm angles, 1.2m from joints.

1501 to 2250 40 x 40 mm angleconnections, or 40 mmbar slips, 1 m maximumcenters with 35 x 3 mmbar reinforcing.

40 x 40 3 mm diagonalangles, or 40 x 40 x 3 mmangle 60 cm from joint.

* Ducts 2250 mm and larger require special field study for hanging and supportingmethods.

In addition to above the following points should be also taken into account whilefabrication of ducts.

a) All ducts of size larger than 450mm shall be cross broken.

b) All ducts shall be supported from the ceiling / slab by means of MS rods of dia 9mmwith MS angle of size 40 x 40 x 5 mm at the bottom with neoprene pad in betweenthe duct & MS angle. The ducts shall be suspended from the ceiling with the help ofdash fasteners. Provision for necessary ancillary materials required for hanging the

ducts shall be arranged by the contractor.c) The vanes shall be provided wherever required and shall be securely fastened to

prevent noise & vibration.

d) The rubber gasket shall be installed between duct flanges in all connections and joints.

e) All flanges and supports should be primer coated.

f) The flexible joints shall be fitted to the delivery side of AHU fans with Fire RetardantDouble canvass. The length of flexible joints should not be less than 150 mm and

not more than 300 mm between face.

g) The ducting work can be modified if deemed necessary in consultation with theEngineer in Charge to suit actual site conditions in the building.

h) Box Type Dampers & Splitters

These dampers shall be provided in the ducting work for proper control andbalancing of air distribution. All dampers shall be louver type robust construction.These dampers shall be fitted with easily accessible operating mechanism,complete with links, levers, quadrant for proper control and setting in a desiredposition. The position of the handle of the damper operating mechanism shall beclearly visible and shall indicate the position of the damper in the duct. All dampers,splitters shall be fabricated out of G.S. sheet of two gauges higher than the duct

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piece having these fittings. Dampers shall be installed in duct at all requiredlocations. No extra payment shall be made separately since these form part ofAir Circulation System.

NOTE : In case angle iron supports are not feasible to be installed for supporting theducts due to height constraint then the contractor shall support the ducts with M.Sflats of at least double the thickness of the angle iron supports.

A) THE SUPPLY AND RETURN AIR GRILLS AND CEILING DIFFUSERS

The supply and return air grills and ceiling diffusers shall be made of powder coatedextruded aluminum sections. The supply air grills / diffusers shall be provided with screwoperated opposed blade volume control device made of extruded aluminum in blackanodized finish. All grills / diffusers shall have soft continuous rubber / foam gasketbetween the periphery of the grills / diffusers and surface on which it has to be mounted.The colour of grills / diffuser shall be as per the approval of the Engineer in Charge.

B) LINEAR SUPPLY AND RETURN GRILLS

The linear continuous supply / return air grills shall be made of powder coated extrudedaluminum construction with fixed horizontal bars. The thickness of fixed bar louvers shallbe 5mm in front and the flange shall be 20mm wide with round edges. The register shallbe suitable for concealed fixing and horizontal bars of the grills shall mechanically crimpfrom the back to hold them.

The colour of grills shall be as per the approval of the Engineer in Charge. The volumecontrol device made of extruded aluminum construction in black anodized finish shall beprovided in supply air duct collars only.

C) SQUARE / RECTANGULAR CEILING DIFFUSERS

The square / rectangular ceiling diffusers shall be made of powder coated extrudedaluminum construction with flush fixed pattern. The diffusers shall have Anti-Smudge ringand spring loaded removable central core in various pattern for air flow direction. Thediffusers shall be mounted by concealed screw fixing arrangement. The volume controldevice of extruded aluminum construction in black anodized finish shall be provided insupply air diffusers. The colour of diffuser shall be as per the approval of the Engineer inCharge.

D) VOLUME CONTROL DEVICE

The opposed blade volume control device shall be made of Powder Coated extrudedaluminum construction in black anodized finish. Opposed blades shall be pivoted toextruded aluminum frame with Nylon bushes. Specially designed blade shall have anoverlapping lip which shall ensure a tight closure.

E) FRESH AIR INTAKE LOUVERS WITH BIRD SCREEN

The fresh air intake louvers at least 50mm deep will be made of powder coated extrudedaluminum construction. Bird / insect screen will be provided with the intake louvers. Theblades shall be inclined at 45 degree on a 40mm blade pitch to minimize water ingress.The lowest blade of the assembly shall be extended out slightly to facilitate disposal ofrain water without falling on door / wall on which it is mounted.

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The intake louvers shall be provided with factory fitted aluminum construction volumecontrol dampers in black anodized finish.

PAINTING

All ducts collar / shoot behind the grills / diffuser shall be given at least two coats oil blackenamel paints.

TESTING

The complete duct system shall be tested for air leakage & complete air distributionsystem shall be balanced in accordance with air quantities indicated on the approveddrawing

STANDARD SPECIFICATION OF THERMAL / ACOUSTIC INSULATION

This section deals with supply and fixing of thermal / acoustic insulation of ducts, pipesetc. as per the specification given in this section.

MATERIAL OF INSULATION

The insulation material of the following kind shall be used for cold insulation.

a) FOR DUCT INSULATION WITH CLASS O ANTI-MICROBIAL TYPE13MM NITRIAL RUBBER HAVING FOLLOWING SPECIFICATION:

- Insulation material shall be Closed Cell Elastomeric Nitrile Rubber

- Density of Material shall be between 40 to 60 Kg/m3

- Thermal conductivity of elastomeric Nitrile rubber shall not exceed 0.033W/mK at mean temperature of 0C

- Insulation material shall have anti-microbial product, which is EPA(Environmental Protection Agency), USA approved, as an integral part ofinsulation that cannot be washed off or worn off.

- It shall give enhanced level of protection against harmful Microbes such asbacteria, mold, mildew and fungi and should confirm to followingstandards:Fungi Resistance ASTM G21 and Bacterial resistance ASTM 2180 / ASTM G 22.

- The insulation shall have fire performance such that it passes Class 1 asper BS476 Part 7 for surface spread of flame as per BS 476 and also passFire Propagation requirement as per BS476 Part 6 to meet the Class OFire category as per 1991 Building Regulations (England & Wales) and theBuilding Standards (Scotland) Regulations 1990

- Material should be FM (Factory Mutual), USA approved.

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- Water vapour permeability shall not exceed 1.74 x 10-14 Kg / (m.s.Pa), i.e.Moisture Diffusion Resistance Factor or value should be minimum10000.

- The Insulation materials should be with self adhesive type and with Al. FoilFaced to protect against mechanical damage.

The Thermal conductivity values in W/m. K of fiberglass shall confirm to following:

Mean Temperature oC Density in Kg/cmt Thermal Conductivity W/m.k

For Duct Lining

25 oC 32 0.03250 oC 32 0.035

The sample of insulation material shall be submitted for approval to the Engineer inCharge and the sample shall be tested for thermal conductivity values by the contractor athis own expense. Adhesive used for setting the insulation shall be non-flammable, vaporproof, CPRX compound.

INSULATION ON SHEET METAL DUCTING

The thickness of insulation used on ducting shall be as detailed below:

Conditioned space

a) Supply Air Duct Insulated with 13 mm thick Aluminium faced Close cellNitril Rubber

The application of insulation should be carried out in workman like manner as detailedbelow

Insulation of Ducting with Aluminium FACSD Fibre Glass

a) Duct surface to be cleaned thoroughly

b) To apply two coats of adhesive Compound.

c) To fix factory pre-laminated aluminium faced self adhesive type close cell Nitrilrubber of specified thickness.

d) Fix self-adhesive aluminum tape of 50 mm width on all longitudinal / Transverse joints.

e) Finally fix PVC straps of 19mm width at every 300mm centre to centre.

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ACOUSTIC LINING OF DUCT

The material to be used for duct lining shall be 25mm thick resin bonded fiber glasshaving a density of 32 Kg/m or 12 mm thick fibre glass rigid board of density 48 Kg/m &

covered with 0.5 mm thick perforated aluminum sheet. The lining of initial length of theduct shall be done as shown in the tender layout drawings & shall be carried out asfollows.

a) Clean the duct piece thoroughly,

b) To apply two coats of CRPX compound.

c) Fix the fiber glass of suitable thickness & cover with fiber glass tissue paper.

d) Cover the insulation board with 0.5mm thick perforated aluminium sheet with atleast 20% to 25% perforations

e) Secure the aluminium sheet with GI frame work with cadmium coated self tapingscrews with washers.

Special Notes:

1. All the party should submit the Equipment rating chart at different temperature / outside condition.

2. Compressor ratting chart should be submitted along with tender for propertechnical evaluation of the capacity offered.

3. Vendor should submit the technical Data Sheet & Shop drawing within 7 daysfrom date of issue of order for necessary approval by consultant before physicallystart the work at site.

4. After Commissioning vendor should conduct performance testing of the entiresystem for 72 hrs.

5. Vendor should submit the complete operation & maintenance manual containingAs Built Drawing, Dos & Dont, Operation procedure, Set points of differentparameters, Catalogue & Technical details etc.

technical specification duct

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