refrigerator gas charging unit

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Refrigerator Gas

Charging Unit

SUBMITTED FOR THE PARTIAL FULFILMENT OF DEGREE OF

BACHELOR OF TECHNOLOGY IN MECHANICAL ENGINEERING

2010-2014

Submitted to: Submitted by:

Department of Mechanical Engg.

FET, Gurukula Kangri

Vishwavidyalaya

Under the guidance of

Mr. Sunil Sharma (Asst. Professor, ME Department)

FACULTY OF ENGINEERING AND TECHNOLOGY

GURUKULA KANGRI VISHWAVIDYALAYA

HARDWAR-249404

Ankit Gupta

Sumit Kumar Sharma

Suryaprakash Singh



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CERTIFICATE

Certified that this project report titled“Refrigerator Gas

Charging Unit” is a bonafide work of Ankit Gupta, Sumit

Kumar Sharma and Suryaprakash Singh who carried out the

project work under my supervision, for the fulfillment of

requirements for the award of degree of Bachelors of Technology

in Mechanical Engineering.

Place: Hardwar

Date:

MR. SUNIL SHARMA

Assistant Professor

Department of Mechanical Engineering

Faculty of Engineering and Technology

Gurukula Kangri Vishwavidyalaya

Hardwar

COUNTERSIGNED

MR. SUNIL LAMBHA

Head of the Department

Department of Mechanical Engineering

Faculty of Engineering and Technology

Gurukula Kangri Vishwavidyalaya

Hardwar



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ACKNOWLEDGEMENT

It is a matter of great pleasure to make this project report

towards the fulfillment of Minor project of Mechanical

Engineering.

We feel great pleasure in expressing our sincere and

profound gratitude to our guide Mr. Sunil Sharma who

has guided and made us useful suggestion for

undertaking this project work.

We also want to express our profound gratitude to Mr.

Sanjeev Lambha who rendered the valuable help from

time to time. We are very thankful for providing us

necessary facilities for this project work. We offer our

cordial thanks to our teachers.

Finally we express our regards to our parents who

inspired us throughout our studies and completion of

our project work. We are also very thankful to our friends

who gave us constant support and help us for improving

and testing project.

Team Members



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ABSTRACT

Refrigerator being a common household appliancenowadays in homes as well as industries, sometimes

faces problems related to gas filling, leaking etc. In order

to make the process of refrigerator gas charging easy and

efficient a ―Refrigerator Gas Charging Unit (RGCU)‖ can

be used. The principle of this method is that whenever a

charging is carried out by this set, the amount of gas

supplied to the refrigeration or air conditioning unit iscalculated with the help of spring balance and also

determine the pressure of the gas flowing through the

charging line with the help of compound pressure gauge.

This set being portable, is easy to carry and can be used

at homes by regular persons.



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CONTENTS

CERTIFICATE………………………………………………………………………………….1

ACKNOWLEDGEMENT ……………………………………………………………………...2

ABSTRACT ………………………………………………………………………………………3

CONTENTS……………………………………………………………………………………...4

INTRODUCTION………………………………………………………………………………



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INTRODUCTION

Refrigeration is defined as any process of heat removal.More specially, refrigeration is defined as the branch of

science that deals with the process of reducing and

maintaining the temperature of a space of material below

the temperature of the surroundings.

Multipurpose charging set is a single arrangement forcharging the refrigeration and air conditioning unit. This

charging set is different than other methods. This is a

portable device which can be transferred from one place

to another its construction is simple and portable. This

set is multipurpose device; with charging the unit it can

also achieve the vacuum in unit. The weight of gas and

pressure of gas going to the unit is directly measured at

the time of charging on this set so it is very useful device

for charging the refrigeration and air condition unit in

laboratories.



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PRINCIPLE OF PROJECT

Evacuation: -

Removing of fully air present in the refrigeration unit isknown as evacuation. The main purpose of evacuation

process is that for charging the refrigeration unit. The air

should not be present in it. If evacuation is not carried

out some amount of air is present in the refrigeration

unit carried out properly. The leakage problems are

rising in it.

Definition of Charging: -

Charging is the process of filling the gas in the

refrigeration and air-conditioning system.

Principle of charging set: -

This is a new method used for the charging of

refrigeration unit differ than the other method. Theprinciple of this charging set is that whenever a charging

is carried out by this set how many amount of gas is

supply to the refrigeration or air conditioning unit is

calculated with the help of spring balance and also

determine the pressure of the gas flowing through the

charging line with the help of compound pressure gauge.



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Isometric View of evacuation and charging set



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PART LIST

Sr.no. Part Quantity Material

1 3 way valve 2 Bronze

2 2 way valve 1 Bronze

3 Charging line 3 Rubber

4 Compound pressure 1

Gauge

5 Spring balance 1

6 Refrigerant gas 1 kg R-12

7 Vacuum Pump 1

8 Compressor 1



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VACUUM PUMP

A vacuum pump is a device that removes gas molecules

from a sealed volume in order to leave behind a

partial vacuum. The first vacuum pump was invented in

1650 by Otto von Guericke, and was preceded by

the suction pump, which dates to antiquity.

Root Blower

Root Blower: It is also called a booster pump, has

highest pumping speeds but low compression ratio.

TYPES

Pumps can be broadly categorized according to threetechniques

Positive displacement: pumps use a mechanism torepeatedly expand a cavity, allow gases to flow in fromthe chamber, seal off the cavity, and exhaust it to theatmosphere.



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Momentum transfer pumps, also called molecularpumps, use high speed jets of dense fluid or highspeed rotating blades to knock gas molecules out ofthe chamber.

Entrapment pumps capture gases in a solid oradsorbed state. This includes cryopumps, getters,and ion pumps.

Positive displacement pumps are the most effective forlow vacuums. Momentum transfer pumps in conjunctionwith one or two positive displacement pumps are the

most common configuration used to achieve highvacuums. In this configuration the positive displacementpump serves two purposes. First it obtains a roughvacuum in the vessel being evacuated before themomentum transfer pump can be used to obtain thehigh vacuum, as momentum transfer pumps cannotstart pumping at atmospheric pressures. Second thepositive displacement pump backs up the momentum

transfer pump by evacuating to low vacuum theaccumulation of displaced molecules in the high vacuumpump. Entrapment pumps can be added to reachultrahigh vacuums, but they require periodicregeneration of the surfaces that trap air molecules orions. Due to this requirement their available operationaltime can be unacceptably short in low and highvacuums, thus limiting their use to ultrahigh vacuums.Pumps also differ in details like manufacturingtolerances, sealing material, pressure, flow, admission orno admission of oil vapor, service intervals, reliability,tolerance to dust, tolerance to chemicals, tolerance toliquids and vibration.



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Uses of vacuum pumps

Vacuum pumps are used in many industrial andscientific processes including:

Composite Plastic moulding processes (VRTM)

Driving some of the flight instruments in older andsimpler aircraft without electrical systems.

The production of most types of electriclamps, vacuum tubes, and CRTs where the device iseither left evacuated or re-filled with a specific gas orgas mixture

Semiconductor processing, notably ion implantation, dry etch and PVD, ALD, PECVD and CVD depositionand soon in photolithography

Electron microscopy

Medical processes that require suction

Uranium enrichment

Analytical instrumentation to analyze gas, liquid, solid,surface and bio materials

Mass spectrometers to create an ultra-high vacuumbetween the ion source and the detector

Vacuum coating on glass, metal and plastics fordecoration, for durability and for energy saving, suchas emissivity glass

Hard coating for engine components (as in FormulaOne)

Ophthalmic coating

Milking machines and other equipment in dairy sheds

Vacuum Impregnation of porous products such aswood or electric motor windings.

Air conditioning service - removing all contaminantsfrom the system before charging with refrigerant

http://en.wikipedia.org/wiki/Lighting


http://en.wikipedia.org/wiki/Vacuum_tube

http://en.wikipedia.org/wiki/Cathode_ray_tube

http://en.wikipedia.org/wiki/Semiconductor

http://en.wikipedia.org/wiki/Ion_implantation

http://en.wikipedia.org/wiki/Photolithography

http://en.wikipedia.org/wiki/Electron_microscope

http://en.wikipedia.org/wiki/Uranium_enrichment

http://en.wikipedia.org/wiki/Mass_spectrometer

http://en.wikipedia.org/wiki/Formula_One


http://en.wikipedia.org/wiki/Milking_machine

http://en.wikipedia.org/wiki/Milking_machine



http://en.wikipedia.org/wiki/Mass_spectrometer

http://en.wikipedia.org/wiki/Uranium_enrichment

http://en.wikipedia.org/wiki/Electron_microscope

http://en.wikipedia.org/wiki/Photolithography

http://en.wikipedia.org/wiki/Ion_implantation

http://en.wikipedia.org/wiki/Semiconductor

http://en.wikipedia.org/wiki/Cathode_ray_tube

http://en.wikipedia.org/wiki/Vacuum_tube





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GAUGE, ABSOLUTE, DIFFERENTIAL, COMPOUND

AND VACUUM

It is important to understand the ―type‖ of pressure that

is required for an application. The terms ―Vacuum,‖

―absolute‖ and ―compound‖ are usually the basis for this

misunderstanding; often Demonstrated by incorrectly

combining terms such as ―absolute vacuum‖ or

―compound Vacuum.‖ First, let’s identify and define the 5

basic pressure types. Dial gauge configurations will bereferenced for each pressure type because they serve as

the best means of illustration.

1) Gauge Pressure. Because gauge pressure gauges

allow the surrounding ambient pressure to effect both

sides of the sensing element, the effects of barometricpressure are essentially negated. Therefore, a ―gauge

pressure‖ gauge with an open inlet port will start with

the pointer at zero, which means that the gauge is

indicating ―no pressure in excess of barometric.‖

2) Vacuum. Vacuum gauges measure negativepressures, i.e. the removal of atmospheric pressure.

Using ―gauge pressure zero‖ as the starting point, the

gauge will indicate the ―vacuum level‖ in positive

numbers as more pressure is removed. Vacuum gauges

usually position zero at 5:00 on the dial and rotate

counter clockwise. Most vacuum gauges are rated to a

full scale of 30 In Hg or 15 psi. Remember that since



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absolute reading, an absolute pressure gauge must have

the atmosphere removed from around one side of the

sensing element (referred to as an ―evacuated reference‖).

The result is that an absolute gauge with an open inletport will indicate the barometric pressure (which is

usually between 14 and 15 psi).

This will allow the user to either apply pressure causing

the gauge to read above the barometric pressure value,

or remove pressure (pull vacuum) causing the gauge to

read below the barometric reading. ―Absolute zero‖

should be achievable under full vacuum, since the

starting point is the actual barometric reading, and a full

vacuum will remove all of this existing pressure. On

absolute dial gauges, the zero point will be positioned at

7:00 on the dial and the pointer will rotate clockwise

when pressure is applied and counterclockwise when

pressure is withdrawn. Many customers will refer to―absolute‖ gauges as ―vacuum‖ gauges because they are

using them in vacuum applications, so there is likely to

be confusion regarding which pressure type is required.

Also, please keep in mind that ―Torr‖ is a unit of

measure equal to millimeters of mercury (mm Hg)

absolute. Please note that although all of illustrating the

different pressure types can be accomplished much

easier by depicting a dial gauge for each example, even if

the focus of the inquiry is a digital indicator or

transducer.



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TYPES OF PRESSURE GAUGES

PRESSURE GAUGE: - a gauge to measure and indicate

pressure using ambient pressure as a datum point.

VACUUM GAUGE

A gauge used to measure and indicate pressure belowambient, using ambient pressure as the datum point.

COMPOUND GAUGE

A gauge used to measure and indicate pressure both

above and below ambient pressure, using ambient

pressure as the datum point. Ambient pressure equals

pressure surrounding the measuring element, generally

Atmospheric pressure.

ABSOLUTE PRESSURE GAUGE

A gauge used to measure and indicate pressure abovezero absolute pressure, using absolute zero pressure as

the datum point.



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GAS COMPRESSOR

A gas compressor is a mechanical device that increasesthe pressure of a gas by reducing its volume. An aircompressor is a specific type of gas compressor.

Compressors are similar to pumps: both increase thepressure on a fluid and both can transport the fluidthrough a pipe. As gases are compressible, thecompressor also reduces the volume of a gas. Liquids arerelatively incompressible; while some can be compressed,the main action of a pump is to pressurize and transport

liquids.

TYPES OF COMPRESSOR

1. Centrifugal Compressor

Centrifugal compressors use a rotating disk or impellerin a shaped housing to force the gas to the rim of theimpeller, increasing the velocity of the gas. A diffuser(divergent duct) section converts the velocity energy topressure energy. They are primarily used for continuous,stationary service in industries such as oil refineries,chemical and petrochemical plants and natural gasprocessing plants. Their application can be from 100horsepower (75 kW) to thousands of horsepower. Withmultiple staging, they can achieve high output pressures

greater than 10,000 psi (69 MPa).Many large snowmaking operations (like ski resorts) usethis type of compressor. They are also used in internalcombustion engines as superchargers andturbochargers. Centrifugal compressors are used insmall gas turbine engines or as the final compressionstage of medium sized gas turbines.



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2. Diagonal or mixed-flow compressor

Diagonal or mixed-flow compressors are similar tocentrifugal compressors, but have a radial and axial

velocity component at the exit from the rotor. Thediffuser is often used to turn diagonal flow to an axialrather than radial direction.

3. Axial-flow compressors

Axial-flow compressors are dynamic rotating

compressors that use arrays of fan-like airfoils to

progressively compress the working fluid. They are usedwhere there is a requirement for a high flow rate or a

compact design.

The arrays of airfoils are set in rows, usually as pairs:

one rotating and one stationary. The rotating airfoils,

also known as blades or rotors, accelerate the fluid. The

stationary airfoils, also known as stators or vanes,

decelerate and redirect the flow direction of the fluid,

preparing it for the rotor blades of the next stage. Axial

compressors are almost always multi-staged, with the

cross-sectional area of the gas passage diminishing along

the compressor to maintain an optimum axial Mach

number. Beyond about 5 stages or a 4:1 design pressure

ratio, variable geometry is normally used to improveoperation.

Axial compressors can have high efficiencies; around

90% polytropic at their design conditions. However, they

are relatively expensive, requiring a large number of

components, tight tolerances and high quality materials.

Axial-flow compressors can be found in medium to large



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gas turbine engines, in natural gas pumping stations,

and within certain chemical plants.

4. Reciprocating compressor

Reciprocating compressors use pistons driven by a

crankshaft. They can be either stationary or portable,

can be single or multi-staged, and can be driven by

electric motors or internal combustion engines. Small

reciprocating compressors from 5 to 30 horsepower (hp)

are commonly seen in automotive applications and are

typically for intermittent duty. Larger reciprocatingcompressors well over 1,000 hp (750 kW) are commonly

found in large industrial and petroleum applications.

Discharge pressures can range from low pressure to very

high pressure (>18000 psi or 180 MPa). In certain

applications, such as air compression, multi-stage

double-acting compressors are said to be the most

efficient compressors available, and are typically larger,and more costly than comparable rotary units. Another

type of reciprocating compressor is the swash plate

compressor, which uses pistons moved by a swash plate

mounted on a shaft (see axial piston pump).

Household, home workshop, and smaller job sitecompressors are typically reciprocating compressors 1½

hp or less with an attached receiver tank.



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APPLICATIONS

Gas compressors are used in various applications whereeither higher pressures or lower volumes of gas areneeded:

In pipeline transport of purified natural gas from theproduction site to the consumer, a compressor isdriven by a gas turbine fuelled by gas bled from thepipeline. Thus, no external power source isnecessary.

Petroleum refineries, natural gas processing plants,

petrochemical and chemical plants, and similarlarge industrial plants require compressing forintermediate and end-product gases.

Refrigeration and air conditioner equipment usecompressors to move heat in refrigerant cycle.

Gas turbine systems compress the intakecombustion air.

Small-volume purified or manufactured gases

require compression to fill high pressure cylindersfor medical, welding, and other uses.

Various industrial, manufacturing, and buildingprocesses require compressed air to powerpneumatic tools.

In the manufacturing and blow moulding of PETplastic bottles and containers.

Some aircraft require compressors to maintain cabinpressurization at altitude.

Some types of jet engines — such as turbojets andturbofans) — compress the air required for fuelcombustion. The jet engine's turbines power thecombustion air compressor.

In SCUBA diving, hyperbaric oxygen therapy, andother life support devices, compressors putbreathing gas into small volume containers, such asdiving cylinders.



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In surface supplied diving, an air compressorfrequently supplies low pressure air (10 to 20 bar)

for breathing. Submarines use compressors to store air for later

use in displacing water from buoyancy chambers toadjust depth.

Turbochargers and superchargers are compressorsthat increase internal combustion engineperformance by increasing the mass flow of airinside the cylinder, so the engine can burn more fuel

and hence produce more power. Rail and heavy road transport vehicles use

compressed air to operate rail vehicle or road vehiclebrakes — and various other systems (doors,windscreen wipers, engine, gearbox control, etc.).

Service stations and auto repair shops usecompressed air to fill pneumatic tires and powerpneumatic tools.

Fire pistons and heat pumps exist to heat air orother gasses, and compressing the gas is only ameans to that end.



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REFRIGERANT

The substance, which carries the heat from low

temperature region and discharge, the same to the

higher temperature region is known as refrigerant.

Refrigerant removes the heat in the form of sensible heat

as in case of air refrigeration or in the form of latent heat

as in the case of vapour refrigeration. The refrigerants,

which carry the heat in the form of latent heat and also

dissipate in the form of latent heat, are more efficient

than the refrigerant, which carry the heat in the form of

sensible heat.

REFREGERANT IN COMMON USE

1. Ammonia (NH3):

Ammonia is one of the oldest refrigerant uses in

refrigeration system. Its excellence thermal property

make it an idea refrigerant for ice plant, cold storage etc.

Ammonia has the highest refrigerating effect per unit

refrigerant capacity. It is much less expensive compare

with any other refrigerant. Any moisture, which may

enter the system, will be dissolved in ammonia and it

attacks many foods, therefore it is not used for domestic

refrigerant or where there is danger of exposing foods to

leaking ammonia. It attack non-ferrous metal, brass and

bronze, but it is non-corrosive to iron and steel. It is

widely used in vapour absorption refrigerant system as it

soluble in water and easily expelled when heated.



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2. Freon – 12 or Discholorodifluro methane ( CCL 2F2) :

It is commercially term as F-12 or R-12. It is used for

domestic refrigerator. It is colourless odourless and non-

toxic. Therefore it is best suitable for domestic

refrigerator. It is used with all types of condenser, air-

cooled and water cooled.

The boiling point is – 29.80c at atmospheric pressure

make it suitable for high, medium and low temperature

application with any types of compressor. It is soluble in

oil; therefore, it is simplifies the problem of lubrication.But its disadvantage is that it is costly and leak cannot

be detected easily. Its leak detected with the halides

torch.

3. Freon -22 Difluromonochloro Methane (CHCIF2) :

It has a boiling Point -400C at atmospheric pressure. It is

used for low temperature production. It is also used in

packaged air conditioners, where, because of space

limitations, relatively small compressor displacement

required with R-22 water-cooled Condensers are used.

When air-cooled condenser is used with R-22 is not

used. The main advantage of R-22 over R-12 is thesmaller compressor displacement required for same

capacity.



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4. Carbon dioxide (CO2):

It is the oldest refrigerant used. Carbon dioxide is

Odourless, nontoxic, non-flammable, non-explosive and

non-corrosive Refrigerant. It used in hospitals, theaters,

hotels and marine service where safety is prime

consideration? Now days its use is limited for productionof dry ice. But the power required for 002 refrigerants is

high.

5. Sulphur dioxide (S02):

In olden days it was used in domestic Refrigerator. It is

now replaced by freon-12. It is colourless and suffocating

fluid. In presence of water it forms sulphurous acid, it

has low refrigerating effect Compared with other

refrigerant and it is heavy irritating and high toxic in

nature.



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PROPERTY OF IDEAL REFREGERANT

1 The boiling point should be low.

2 The condensing pressure should not be more.

3 Critical temperature should be high.

4 The latent heat of vaporization should be high.

5 Specific heat of liquid should be low.

6 It should not have corrosive action.

7 It should not be flammable and explosive.

8 It should be non-toxic.

9 It should be easily detectable for leaks.

10 It should have satisfactory heat transfer coefficient.

11 It should be easily available at low cost.



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5. CONSTRUCTION

This is a simple arrangement for charging the

refrigeration and air conditioning unit. The main feature

of this charging set is that the whole assembly is carried

on a rectangular base. This is portable device, which can

be transferred from one place to another its construction

is simple land decorative one.

A vacuum pump is fitted on the base plate. In front

vacuum pump a vertical rectangular angle set is attached

on which spring balanced is attached and the plywoodand valve are attached with the help of nut-bolt.

A vacuum pump is mounted for creating the vacuum in

the unit. An arrangement of spring balance is to be made

for calculating how many amount of gas is filled in unit.

For calculating the amounting of the gas refrigerant the

refrigerant cylinder is attached tom hook of springbalance with the help of into cylinder hanger

arrangement. On the front side of this charging set a

panel board is fixed for mounting 2 three – way valves

and compound pressure gauge.

Three charging lines are required for this set. One

charging line is joined between the vacuum to connector

disconnect the vacuum pump. The second charging line

is connected between the cylinder and valve V1 and end

of valve V2, which is always open. The third charging line

is connected between the refrigeration unit and common

end of valve V2 for the purpose of connect or disconnect

the unit whenever required. One end of valve V2 is

connected to the compound pressure gauge with the help



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of flare nut. These two 3-way valve V1 and V2 are

connected with the help of copper tube and flare nut.

So this is a simple arrangement of charging set.

6. WORKING

After assembling it is required to charge the system with

refrigerant gas. Many times charging is necessary after

repair and maintenance of the system.

Before charging the system evacuation of system is done.

With the help of vacuum pump air in the system is

removed and vacuum is achieved.

For this purpose the vacuum pump is joined to thecommon end of valve V1 and connection between

cylinder and valve is turned off from cylinder itself. Then

turn the valve V2 on for the purpose of removing oxygen

and nitrogen from the unit. The vacuum created in the

system should be below 300 mm of Hg.

After vaccumisation of the system, the vacuum pump is

disconnecting immediately with the help of valve V1 by

turning it at off position. In this way at the vacuum side

connection is off and remaining two connections is on

state. The hand shut-off valve is used during change of

line.



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Before charging the system, calculate the amount of gas

required for the system. Then place the refrigerate

cylinder with the help of cylinder hanger arrangement on

the spring balance to refrigerant into evacuated systemto exact quantity required. The purging should be done

before admitting the gas into system.

What amount of pressure present in the system is

indicated by compound pressure gauge. The amount of

pressure is required inside the system is controlled byvalve V2.After completing the process, pinch the process

tubes and seal it.

Circuit diagram



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7. ADVANTAGES AND APPLICATION

Advantages: -

The weight of gas and pressure of gas going to the

unit is directly measured at the time of charging.

It is multipurpose device.

The connection of vacuum pump to the unit is

directly connected with the help of valve andcharging line. So separate arrangement is not

required for achieving the vacuum in unit.

Simple in construction.

It is portable device, which can be transferred from

one place to another.

Less maintenance.

Time is saved due to whole accessories are mounted

on one table.

The initial and working cost is less.

Application: -

In refrigeration and air-conditioning industries.

In refrigeration shops and laboratories.

It is used for charging of ice plant domestic

refrigerator etc.



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8. HINTS BEFORE CHARGING

Use clean & moisture free drums for transfer &charging purpose.

The system should be evacuated particularly when it

is new.

The charging lines must be purged & it must bemade sure that all connections are tight air is not

drawn in the system with the refrigerant.

The suction pressure may not be allowed to rise

above 2 Kg.sq.cm. when charging. The pressure may

be controlled with the cylinder valve.

The refrigerant in the liquid from should under no

circumstances to the compressor.

The charging lines should not be flexible.

The head pressure must be watched for indications

of over charge.



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1) Bubble Method: -

This method of leak detection is the oldest one and is

universally used with all the refrigerants. A solution of

soap or some other leather forming liquid detergent is

applied with the brush over the subjected area or joint.

The leaking gas forms bubble, which can be easily been

seen. This method of leak detection can only be used

when the system has positive pressure. If there is

vacuum present in the system, it will pull in the moisture

or stop bubble, which will be quite harmful.

2) Halide Torch Method: -

A carbon element is heated by methyl alcohol or

hydrocarbon flame in the halide torch. A rubber tube

attached to the refrigerator. A refrigerant going on the

tube combines with the Flame to cause Perceptible

change in the Flame Colour.

This method of leak detection is slow and insensitive and

in brightly lighted area it is almost impossible to locate

small leaks.

3) Electronic Leak Detector: -

An electronic leak detector is more sensitive and faster

responding. The electronic detector contains an internalpump, which draws, and air leaking gas through a probe

and hose as the probe is passed over leaking joints. A

leak-detecting lamp Flashes at this moment. By

adjusting a knob on the Electronic detector the

magnitude of the leak can also be found.



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4) Special Method For detection of Ammonia and

Sulphur dioxide: -

Ammonia leak can be detected by bringing a burning

candle of sulphur near the suspected spot. The candle

will give a cloud of white smoke if ammonia vapour is

present there A solution of hydrochloric acid brought in

the vicinity of ammonia leak will also give white smoke.

The moistened strip of phenol Phalein Paper turns pink

when faintest trace of ammonia vapour comes in contact

with it.

Presence of sulphur dioxide can be detected by bringing

aqueous ammonia near the suspected area. It will give

white smoke in the presence of Sulphur dioxide. When

no ammonia is available leak may located by the soap

bubble or oil test.



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10. METHODS OF CHARGING

By using this set the methods of charging are as follows:

There are three methods of charging as given below:

1. Charging through the suction valve: -

A small installation, which needs to few kilograms of

refrigerant, is usually charged through the suction

service valve gauge port. For this method of charging the

system is fully evacuated and charged a follows.

Charging line is connected to the suction valve

gauge port. Attach a gauge to the discharge valve

and open half turn.

The other end of the charging lines us connected to

a refrigerant cylinder, which should be standing up

right. The cylinder valve is opened slightly and to flare nut

is loosened at the compressor end.

This operation removes air from the line, when the

sound of escaping gas is heard, the nut is tightened.

Suction valve is turned into close the suction line,

thus drawing the gas directly from the cylinder by

the compressor.

Compressor is started drawing the requisite quantity

of refrigerant. The suction pressure should not be

allowed to exceed 2 kg/sq.cm. Gauge.

The cylinder valve is closed and the compressor is

allowed to run sufficient time to reduce the pressure

in charging time to 0 kg/sq.cm.gauge.



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Compressor is stopped and the suction valve is back

seated. The charging line is detached and compound

gauge attached. The valve is turned in one half turn.

The system is thus ready for testing and normaloperation.

The refrigerant quantity to be charge is often

weighted. In that case the cylinder may be on the

weighing platform, or suspended from spring scale. The

tubing should be coiled and long enough to get true

weight. The cylinder may be kept in warm water to

quacked the process of charging.



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2. Charging through discharge valve: -

The method is used for certain conditions where it is

impossible or impracticable to add refrigerant by the

other methods. This is the least used to the three

methods.

The refrigerant is caused to flow by difference in pressure

between cylinder and high side. The compressor is not

operated while the unit is being charged. In order to save

time when charging by this method, it is imperative to

weight into an empty cylinder the exact amount of chargerequired by the system.

If this is known, all contents of cylinder transferred. The

system is evacuated and following procedure adopted:

The discharge and suction service value are back-

seated. The gauge port of each valve is plugged or

otherwise kept closed until the valves are wide open.

Compound gauge is attached to the suction valve

and the valve is turned in one-half turn. A pipe-to-

flare adapter is installed to the discharge valve port

and the charging line is connected to the adapter.

The other end of the charging line is connected to

the cylinder. The air is removed from line by losing

flare nut. The nut is tightened. The valve A is turned

in about half way.



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The cylinder is placed bottom side up since the

refrigerant will flow into the condenser in liquid

form.

After the refrigerant has flowed into the condenser,

the discharge valve is back-seated cylinder valve is

closed and the charging line is removed. The

pressure gauge is attached and the valve is ready for

testing and operation.



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3. Charging through the charging valve: -

Large machine normally have charging valve located inthe liquid line between the receiver valve and the filter or

dehydrator. This valve is always located in Ammonia

installation and is becoming more popular in other

installations requiring large quantities of refrigerants it

cuts upon the charge time.

The charging refrigerant cylinder acts as received when

connected to the charging valve. The refrigerant enters

the system in liquid form expanding the liquid control

valve before it enters the compressor. This avoids the

danger of liquid to enter the compressor and eliminates

high vacuum, which may cause the oil to leave the

crankcase. The procedure is described below.

System is evacuated and a pressure gauge attachedto the discharge valve port and a compound gauge to

the suction valve port. Both valves are opened wide

and then turned in one half turn so that the gauge

will read.

The receiver valve is closed.

Refrigerant cylinder is connected to the charging

valve by tubing.

The cylinder valve is opened slightly and the flare

nut is loosened at the charging valve to purge the air

from the line. When the sound of escaping gas is

hard the nut is lightened.



39

The cylinder is tipped to ensure liquid at the valve

and then charging and cylinder valves are opened

wide.

Compressor is started and the system is charged

with required quinsy. When cylinder becomes

empty, frost will form on the bottom of the cylinder

and the charging line.

After completing the charging close the cylindervalve and run the compressor for some time to

empty the charging line. Then close the charging

valve C, and remove the line. The charging valve is

capped to prevent leakage.

The receiver valve R is opened, the system is ready

for testing and operation.

When charging refrigerant into an ammonia plant

using the above method. It is necessary to lay the

cylinders have an internal gooseneck which makes

this necessary. Charging connections for ammonia

should be made rigid steel pipe and fittings. For

other refrigerants use copper tubing Flexible

connections, in the authors opinion are dangerous.



40

Charging through the charging valve



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11. CONCLUSION AND MODIFICATION

Conclusion: -

In the end we concluded that by using this instrument

we could evacuate and charge the refrigeration and air

conditioning system simultaneously.

This means that we can save a time by connecting and

disconnecting of the charging line. It is used in the

charging of refrigeration and air conditioning system in

an industries, laboratories etc.

Modification: -

1. It is possible to weight a refrigerant, which is supplied

to the system.

2. From the system we can evacuate and charged the

refrigeration and air conditioning system very fast.



References:-

1. Refrigeration and air conditioning,

S.C Arora , S. Domculwar

2. Refrigeration and air conditioning system,

S.L. Gavhale

3. Refrigeration and air conditioning system,

S.T. Ghan, R.M. Naphade.

refrigerator gas charging unit

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