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LUBRICANTS

LUBRICATION (OIL) Lubrication is the process by which the

moving parts such as bearings in the compressor are kept separate by a film of oil to maximize performance and reduce wear and tear.

Create a Fluid seal

Acts a coolant in compressor

Dampens noise in compressor crankcase

IMPORTANT OIL FUNCTIONS

Refrigerant oil must adequately perform four basic functions Lubricate Scaling off the high side from the

low side Transferring heat

IMPORTANT OIL FUNCTIONS

Damper compressor noise Oils should be chemically stable It should not react chemically with its

Refrigerants contained in the system Metals Motor insulation

Also it should not react readily to the presence of normal contaminants Non condensable Moisture Flux/ wax

REFRIGERATION SYSTEM LUBRICATION

As the name suggests, refrigeration system lubrication lubricates the system using Mineral Oil, Polyalkylene Glycol, Alkyl benzene and Polyol Ester depending on the type of refrigerant being used. It also has the following functions:

LUBRICATION (OIL) Viscosity…how thick or thin the oil is Floc point…the point at which the wax

will separate from the oil Pour point…the temperature at which it

ceases to flow Dielectric strength…a measure of a oils

resistance to electrical current Colour… refining to a lighter coloured

oil Specific gravity…weight Neutralization number…organic acid

content

LUBRICATION (OIL)

Oxidation resistance… resist water and O2

Moisture content…dryness of oil Chemical stability… in presence or

metal or refrigerants will chemicalsin the oils attack the metal and ref.

Flash point… the temperature at which the oil vapour flash burns

Fire point…the temperature at which the oil maintains combustion

OIL DEFINITIONS

Hygroscopic A Hygroscopic oil is one that easily

absorbs & releases moisture (has a high affinity for water).

Most refrigerant oils are hygroscopic An oil sample should be taken and

analyzed if a system has had a major component failure.

OIL DEFINITIONS

Viscosity The resistance that the oil offers to flow.

High viscosity means a thick oil, low viscosity means a thin oil. The body of the oil or its ability to perform a lubricating function. Sometimes referred to as the thickness of the oil.

OIL DEFINITIONS

Material Compatibility The oil or refrigerant must not react,

swell, shrink, deteriorate, weaken, pit, or extrude any materials used in refrigeration equipment.

OIL DEFINITIONS

Chemical Stability An oil’s ability to perform for an

extended life without breaking down or chemically reacting with other materials.

OIL DEFINITIONS

Dielectric strength An oil’s relative electrical resistance to

electrical current.

CONCLUSION

In general, there is no “best” oil. Follow manufacturers’ recommendations for best performance.

CONTAMINANTS

Refrigerant Contamination

There are four types of contamination that can occur in any refrigeration equipment which will hinder performance, efficiency and in extreme cases, system failure and damage of components which will be costly to repair and replace:

Refrigerant Contamination

Air Contamination Oil Contamination Water/Acid Contamination Cross Contamination with other

Refrigerants. (mixture of incompatible refrigerant)

Air / Non Condensable Contamination

Air or Non-Condensable gas is one of the most difficult contaminants to remove from an operating system.

Air in a system can cause excessive head pressure and higher operating temperatures. It also causes loss of heat transfer efficiencies by acting as an insulator around heat exchanger tubes.

Air / Non Condensable Contamination

This translates into higher utility costs, degradation of lubricant effectiveness, and premature compressor problems like increased compressor temperatures and pressures, reduced cooling capacity, increased compressor pressure ratios, potential compressor overheating, and finally, compressor motor burn-out.

Air / Non Condensable Contamination

Typically, a pressure more than 20 PSI above the saturation pressure indicates that a non-condensable gas problem may exist. If non-condensable gases are trapped in the system, recovering vapour from the condenser should remove these non-condensable gasses and reduce the pressure discrepancy.

Air / Non Condensable Contamination

Purging the system with nitrogen gas after removing the refrigerant using a recovery machine is also another service option. In addition, purging is best used with high efficiency purge unit or to reclaim the refrigerant after recovery.

Moisture/ Acid Contamination

The moisture and refrigerant combine to form acids that can destroy motor windings and result in motor burnout.

Oil sludge and particulates can clog coalescing oil filters and metering devices. Any water in the system will most likely freeze in the expansion valve because this is the point where refrigerant is cooled by the evaporation occurring as a result of the sudden pressure drop, and the expansion device also represents the smallest passageway in the overall system. This is the reason why liquid line filter-driers are typically located just upstream of the expansion device.

Moisture/ Acid Contamination

When this situation occurs, it is necessary to not only clean the refrigerant, but it is also imperative that the refrigeration system be totally dehydrated to remove all traces of water. It is usually desirable to also flush the system to remove rust and other particulates that may have developed while the refrigeration system was being repaired.

Oil Contamination

Over time it is very common for oil to migrate from the compressor. Oil accumulates in the evaporator and insulates the tubes. This inhibits maximum heat transfer and reduces system efficiency. Studies indicate that for every 1% of oil in the evaporator, a system loses 2% efficiency.

Oil Contamination

This translates into reduced comfort, higher utility costs, or both. The typical way of dealing with oil contamination is decontaminate the refrigerant with an oil purge unit or charge with new refrigerant after removal of the existing charge with a recovery machine.

For large systems like chillers, an oil purging unit is sometimes installed as a continuous prevention of oil contamination.

Cross Contamination

This type of contamination may result if the system is mistakenly charged with:

An incompatible refrigerant for the system.

Improper charging of blends resulting in incorrect proportional mixture.

An already contaminated refrigerant

In such cases, the refrigerant is recovered using recovery machine, purged of oil and contaminants and dehydrated prior to charging with clean refrigerant after checking the system for leaks and doing the necessary repair job.

SAFETY PROCEDURES

RECOVERYRECYCLERECLAIM

RECOVERY

Refrigerant recovery means to remove refrigerant in any condition from an appliance and store it in an

EXTERNAL CONTAINER. Refrigerant recovery takes place mainly at three major stages of

equipment lifetime.

When To Perform Recovery

during servicing when part or complete refrigerant charge shall be removed of the system,

when the system is converted to be run with a new refrigerant,

At equipment disposal

RECYCLE

To clean refrigerant for reuse by separating the oil from the refrigerant and removing moisture by passing it through one or more filter driers

Current recovery machines have filters that remove contaminants from the refrigerants including acids that will enable the refrigerant to be reused.

RECLAIM

To process refrigerant to a level equal to new product standards as determined by

chemical analysis. Reclaimed refrigerant must meet standards set forth in ARI 700 before it can be

resold.

BASIC TOOLS

MANIFOLD GAUGE REFRIGERANT LEAK DETECTOR VACUUM PUMP & MICRON GAUGE CHARGING SCALE RECOVERY TANK RECOVERY MACHINE

Insert topic Good Service practices

NEW SYSTEM REQUIREMENTS

INSERT THE VARIOUS MANIFOLD GRAPHICS

Talk about new refrigerants replacing CFC and HCFC like 134a and 400 series which operates at higher pressure.

Gauge manifold to cater for these new refrigerants should be used.

RECOMMENDED TOOLS

Insert more detailed gauge reading

Approved refrigerant recovery cylinders can easily be identified by their colors, YELLOW TOPS and GRAY BODIES. All refrigerant recovery cylinders should be inspected for RUST. If they show signs of rust or appear to not be secure they should be reduced to 0 psig and discarded.

RECOVERY CYLINDERS

Tunjuk tank besar

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TANK SAFETY CALCULATION

WE HAVE A RECOVERY TANK WITH A SPECIFICATION OF BA300 Q1: WHAT IS THE TEST PRESSURE? Q2: WHAT IS THE RELIEF

PRESSURE?

TANK SAFETY CALCULATION

TEST PRESSURE = SERVICE PRESSURE X 2 = 300 X 2 = 600 PSI

RELIEF PRESSURE = 75% X TEST PRESSURE = 75% X 600 PSI = 450 PSI

TANK SAFETY CALCULATION

Q3: CAN R22 GAS BE KEPT IN A BA300 TANK?

ANSWER: TAKE THE PRESSURE OF R22 AT 130F

TEMPERATURE FROM THE PT CHART R22 PRESSURE AT 130F IS 297 PSI THIS PRESSURE MUST BE LESS

THAN 5/4 X SERVICE PRESSURE OF BA300 TANK

TANK SAFETY CALCULATION

THEREFORE: 5/4 X 300 (SERVICE PRESSURE OF

BA300 TANK) => (5 X 300)/4 = 375 PSI

375 PSI IS MORE THAN THE PRESSURE OF R22 AT 130F THAT IS 297 PSI

SO, R22 CAN BE SAFELY KEPT INSIDE A BA300 TANK

TANK SAFETY CALCULATION

ADDITIONAL QUESTION CAN R507 GAS BE KEPT IN BA300

TANK? ANSWER

PRESSURE OF R507 AT 130F IS 368 PSI 5/4 X 300 (SERVICE PRESSURE OF BA300

TANK) => (5 X 300)/4 = 375 PSI 375 PSI IS MORE THAN THE PRESSURE OF

R507 AT 130F THAT IS 368 PSI SO, R507 CAN BE SAFELY KEPT INSIDE A

BA300 TANK

TANK SAFETY CALCULATION

ADDITIONAL QUESTION CAN R507 GAS BE KEPT IN BA300

TANK? ANSWER

PRESSURE OF R410A AT 130F IS 475 PSI 5/4 X 300 (SERVICE PRESSURE OF BA300

TANK) => (5 X 300)/4 = 375 PSI 375 PSI IS LESS THAN THE PRESSURE OF

R410A AT 130F THAT IS 475 PSI SO, R410A CANNOT BE KEPT IN A BA300

TANK SAFELY

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