The effect of heat

The effect of heat energy on pressure and volume : since there are millions of molecules of a refrigerant gas in even the smallest container, the molecules move or bump against each other and hit into the walls of the container. Any rise in the temperature of the gas is accompanied by an increase in the speed of the molecules. As the bombardment against the walls of a container increases, so does the pressure increase.

The cylinders or containers of a gas must be built strong enough to resist the greatest forse or pressure that may be exerted against the walls. Such a pressure builds up according to the highest temperature to be met. This highest temperature must take into consideration that for some operations, where tanks of a liquid or gas must be transported, there is direct exposure to the sun's rays. Two of the safety precautions that must be taken are :
1. Cylinders should be protected against exposure to these rays.
2. Care must be taken in disposing of used throw-away containers to be certain they are not thrown on trash fires.

Pressure used for refrigerant controls : the change of pressure which accompanies change of temperature may be put to good use in operating refrigerant controls. For instance, the "thermostatic valve" which is one of many metering devices, responds to pressure change. This change is caused by the change insuperheat of the refrigerant gas.