Lesson 8. HVAC Science, Refrigerant Gas

HVAC Science, Refrigerant Gas

Gas Laws

There are hundreds of gases that have been used in Air Conditioning but there are only two in wide use today.  The older refrigerant, R-22 and the replacement refrigerant R410A.  Low temp refrigeration will use several other refrigerants designed for low and medium temp applications.

Some basic concepts must be understood with particular attention to the relationships between pressure and temperature of gases.
• The volume of gas will increase when the pressure decreases.  The volume of gas will decrease when the pressure increases.  Gas expands when pressure decreases.
• Gas also expands when it is heated and as a result, in a closed system the pressure will increase with heat.
• Mixed gases will expand at different temperatures and pressures.  The total pressure is the sum of the pressures of the different gases.

Different refrigerants are selected for their properties.  Lower pressures are desirable.
Get a pressure/Temperature chart for the common refrigerants used in air conditioning and carry it with you.  You can refer to this chart to assist in analysis of the conditions you find when troubleshooting the temperature and pressures in the field.

Go ahead and obtain a gauge manifold set.  Your gauges may be marked with pressure temperature for the common gases.  R410A operates at a higher pressure than R22 and gauges and hoses will need higher pressure ratings for this gas.  Many HVAC techs have a separate manifold and gauges for each refrigerant so they don’t accidentally mix gases.

Refrigerants are highly regulated and require an EPA section 608 Certification before you use your gauge manifold set.  Our EPA Study Guide with sample test questions contains detailed explanations of the history of regulation and a much deeper explanation of the handling of different gases.  Getour EPA Study Guide” There are fines for anyone using refrigerants without a certification so get certified as soon as possible.

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