PRESSURIZING
Pressure-testing or cleaning refrigeration and air-conditioning systems can be dangerous!
Extreme caution must be used in the selection and use of pressurizing equipment. Follow these procedures:
1. Never attempt to pressurize a system without first installing an appropriate pressure-regulating valve on the nitrogen or carbon dioxide cylinder discharge. This regulating valve should be equipped with two functioning pressure gauges. One gauge indicates cylinder pressure. The other gauge indicates discharge of downstream pressure.
2. Always install a pressure-relief valve or frangible disk type of pressure-relief device in the pressure-supply line. This device should have a discharge port of at least 1/2 inch national pipe thread (NPT) size. This valve or frangible-disk device should be set to release at 175 psg.
A system can be pressurized up to a maximum of 150 psig for leak testing or purging (see Figure 14.1).