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The relations between pressure and correspond­ing temperatures in Fahrenheit degrees of R-12 and R-22 are given in the chart below. For example, at a pressure of 21 psi, the temperature of R-12 will be 20°F. If the pressure is increased to 77 psi, the temperature will increase to 75°F, etc. 

Chap 1   Chap 2    Chap 3    Chap 4   Chap 5   Chap 6   Chap 7

The reason why a torch should not be used to heat a tank of refrigerant is evident. The torch flame temperature is so high that pressures above the tank safety capacities can too easily be reached. The tank could rupture and explode. 

Pressures at or below the tank safety limits may still be too high for the connection hoses when the tank valve is opened. For safety's sake, use nothing warmer than hot water if you wish to warm a refrigerant drum or tank. 


In the foregoing discussion it has been observed that one of the requirements of an ideal refriger­ant is that it must be nontoxic. In reality, how­ever, all gases (with the exception of pure air) are more or less toxic or asphyxiating. It is therefore important that wherever gases or highly volatile liquids are used, adequate ventilation should be provided, because even nontoxic gases can produce a suffocating effect, by displacing the oxygen in the air. 

pt chartssss.JPG

R-12 is not irritating and can be inhaled in considerable concentrations for a short period with­out serious consequences. It should be remem­bered, however, that liquid refrigerants will freeze or remove heat from anything with which they come in contact when released from a container, as in the case of an accident. In other words, liq­uid refrigerant spilled on any part of the body will produce freezing. A physician should be called immediately to treat the affected area. 


It is of the utmost importance to handle cylin­ders of refrigerant with care (see Fig. 1), and to observe the following precautions : 

1.    Never drop cylinders nor permit them to strike each other violently.
2.    Never use a lifting magnet or a sling (rope or chain) when handling cylinders.
3.    Caps for valve protection, when provided, should be kept on the cylinders except when the cylinders are in actual use.
4.    Never overfill cylinders. CAUTION: Never recharge throwaway type cylin­ders. To do so may result in serious injury or possible death. Whenever re­frigerant is discharged from or into a cylinder, immediately thereafter weigh the cylinder and record the weight of the refrigerant remaining in the cylinder.
5.    Never mix refrigerants in a cylinder.
6.    Never use cylinders as rollers, for sup­ports, or for any purpose other than to carry refrigerants.
7.    Never tamper with the safety devices in valves or cylinders.

8.    Open cylinder valves slowly. Never use wrenches or tools except those provided or approved by the manufacturer.
9.    Make sure that the threads on regulators or other unions are the same as those on cylinder valve outlets. Never force con­nections that do not fit.
10.    Regulators and pressure gauges provided for use with a particular gas must not be used on cylinders containing other gases

11.    Never attempt to repair or alter cylin­ders or valves.
12.    Never store cylinders near highly flam­mable substances such as oil, gasoline, waste, etc.
13.    Always wear safety goggles when work­ing with refrigerants.
14.    Never heat cylinders with an open flame to remove refrigerant; tank rupture or explosion could result.

Refrigerant Container Color

& Class by Refrigerant

Refrigerant    Color                  

11                  Orange                               

12                  White                

I13                 Light Blue (Sky)

13B1             Pinkish-Red (Coral)

14                 Yellow-Brown (Mustard)

22                 Light Green

23                 Light Blue-Grey

32                 Light Blue-Green

113               Dark Purple (Violet)

114               Dark Blue (Navy)

116               Dark Grey (Battleship)

123               Light Blue-Grey

124               Deep Green (DOT Green)

125               Medium Brown (Tan)

134a             Light Blue (Sky)

236fa            Dark Grey (Battleship)

245fa            Maroon

401A             Pinkish-Red (Coral)

401B             Yellow-Brown (Mustard)

401C            Blue-Green (Aqua)

402A             Light Brown (Sand)

402B             Green-Brown (Olive)

403B             Light Purple (Lavender)

404A             Orange

407A             Lime Green

407B             Cream

407C             Medium Brown (Brown)

407D             Dark Brown (Chocolate)

407F             Green-Yellow-White

408A             Medium Purple (Purple)

409A             Medium Brown (Tan)

410A             Rose

411A             Dark Purple (Violet)

411B             Blue-Green (Teal)

413A             Deep Blue

414A             Beige

414B             Medium Blue (Blue)

416A             Yellow-Green (Lime)

417A             Green

422A             Yellow-Orange

422D             Green-Yellow

423A             Wedge Wood Blue

424A             Black

426A             Pastel Orange

427A             Green-Blue (Jungle Green)

428A             Traffic Yellow

434A             Sulfur Yellow

437A             Royal Blue

438A             Blue Jay

442A             Night Blue

500               Yellow

502               Light Purple (Lavender)

503               Blue-Green (Aqua)

507A             Blue Green (Teal)

508B             Dark Blue (Navy)

tank colors.jpg


The quantity of matter which a body contains is called its mass. 

The space a body occupies is called its volume. 

The quantity of matter contained in a given volume is called its density. 

The specific gravity of a solid or liquid is the ratio between its weight for a given volume and the weight of the same volume of water. 

Atmospheric pressure is considered to be 14.7 psi at sea level. 

Gauge pressure is that pressure above atmospheric pressure. 

Absolute pressure is the sum of gauge pressure and atmospheric pressure.

With temperatures constant, the volume of a given weight of gas de­creases as its pressure increases.

At a constant pressure, the volume of a gas increases as its temperature increases. 

At a constant volume, the pressure of a gas increases as its temperature increases. 

With the volume held constant, the temperature of a gas will decrease if its pressure is decreased. 

Power is the rate of doing work. 

One horsepower is the power required to raise 33,000 pounds one foot in one minute. 

A BTU is the measure of a quantity of heat. 

One BTU is the amount of heat energy that must be added to one pound of water to raise its temperature one Fahrenheit degree. 

All matter contains heat in lesser or greater quantities. 

Heat will pass only from a body at a higher temperature to a body with a lower temperature. 

Water boils at 212° F at sea-level pressure. 

Water freezes at 32° F at sea-level pressure. 

Specific heat is the capacity of a substance for absorbing heat. 

Sensible heat is that heat that can be detected and felt and measured with a thermometer. 

Latent heat is hidden heat which brings about a change of state in a substance with no change in pressure or temperature. 

Refrigerants are mediums which absorb heat at a low temperature level and release heat at a higher temperature level. 

Class 1 refrigerants are used in home refrigerators, dehumidifiers, air conditioners, etc. 

Fluorocarbon refrigerants are colorless, nearly odor-free, nontoxic, non­corrosive, nonirritating, and nonflammable. 

All gases are more or less asphyxiating and can cause death under certain conditions by displacing the oxygen in the air to cause smothering. 

Liquid refrigerant spilled on any part of the body will produce freezing. 

Throwaway-type refrigerant cylinders must never be recharged under any circumstances. 

Care should be exercised in handling and storing refrigerant cylinders. 

Never heat a refrigerant tank or drum with a flame or torch. 

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