R-134A has _______ Ozone Depletion Potential.

During each vacuum decay test, it is observed that after the vacuum is created, the pressure of the system increases to greater than 0 psig and stops at some point, then _____.

The refrigerant could be trapped in the system

If the system has a leak, the pressure increases to 0 psig (atmospheric pressure) and stops. If the pressure is greater than 0 psig and stops at some point, refrigerant or water is still evaporating in the system.

Stratosphere is located between ______ above the sea level.

10 and 30 miles

Stratosphere is located at lower part of Earth’s atmosphere above Troposphere. Troposphere extends from Earth’s surface to 10 miles. Stratosphere extends from 10 miles to 30 miles above Earth atmosphere.

Tendency to leak of the refrigerant depends on which of the following?

Molecular weight

The lower the molecular weight of the refrigerant compound is, the easier the refrigerant escapes from the small leak because the size of the molecules are small.

Lifetime of CFCs is believed to be in the range of ______.

20 to 100 years

CFCs are highly stable in lower atmosphere and have a lifetime of about 20 to 100 years. This higher lifetime helps in diffusing CFCs into stratosphere where CFC molecule reacts with UV radiation, which depletes ozone layer.

During the evacuation of the refrigerant, the larger the diameter of the suction hoses is, the _____ the recovery rate of the refrigerant will be.

Faster

The larger the diameter of suction hose is, the lower the pressure drops and the faster the recovery rate will be.

R-134a is the most common replacement for which of the following refrigerants?

R-12

R-134a (HFC) is a possible replacement for R-12 (CFC) in new household refrigerators. R-134a pressure-temperature characteristics are similar to R-12. However, some modifications to lubrication, thermal expansion valve, compressor & filter dryer must be made.

The Montreal Protocol entered into force in mid ______.

1987

Montreal Protocol is signed on Sep 16th, 1987 to regulate the use and production of chemicals responsible for ozone layer depletion. This agreement called for a phase out of certain CFCs, HCFCs, and halons.

Asphyxia is caused due to a lack of ________.

Oxygen

Refrigerants are heavier gases compared to air (oxygen). If refrigerants leak in a closed room, they will displace oxygen. Asphyxia is a lack of oxygen, which may lead to heart irregularities, unconsciousness and even death.

______ leak detector listens for the noise of gas leakage.

Ultrasonic leak tester

Ultrasonic leak tester made of electronics can able to filter the low frequency noise and reveal high frequency sound associated with gas leak.

It is to be ensured that the refrigerant recovery cylinder is not filled to more than _____ of its capacity.

80 percent

If the refrigerant is filled beyond 80% during an increase in temperature, it expands, resulting in an increase in pressure inside the cylinder and bursting of cylinder.

An azeotrope mixture does not have a temperature glide.

True

Azeotrope mixture is made up of two or more refrigerants which act as single refrigerant compound over its entire temperature and pressure range. Azeotrope refrigerant mixtures will not have temperature glide (temperature difference between saturated vapor & saturated liquid at constant pressure). Zoetrope & near azeotrope mixtures will have temperature glide.

HFCs are highly stable in lower part of the atmosphere.

False

The presence of Hydrogen in HFC refrigerant compound makes it unstable at lower levels of the atmosphere.

What is the responsibility of the Clean Air Act?

All the options are correct

Clean air act is US Federal Law designed to reduce air pollution.

If your recovery unit does not have a sub-cooling feature, the recovery rate will be _____.

Slower

A recovery unit with a sub-cooling feature accelerates the rate of recovery as it lowers the temperature of the recovery tank.