Refrigeration Piping Charging Residential AirConditioning R

Piping & Tubing
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Refrigeration Piping
Refrigeration is the process of moving heat from one location to another by the use of
refrigerant in a closed cycle. The piping and tubing system must be designed, installed and
maintained to provide proper flow of refrigerant in both liquid and gaseous states. A
successful refrigeration system depends on a good piping design and an understanding of the
required accessories. The first skill that any refrigeration apprentice mechanic learns is to
make a soldered joint. Running pipe is so common a task that its critical importance in system
performance is often overlooked.
Tubing Inspection & Leak Check
The object of a good visual inspection of system tubing design is to note obvious oil traps.
Also look for long vertical suction lengths without p traps and inadequate OD tubing size If the
system is known to be leaking or if oil is present around mechanical fittings, solder joints,
gaskets or seals, recover the refrigerant and repair the leaks. Pressurize the system with a
residual amount of refrigerant and dry nitrogen using the recommended test pressure on data
plate. Maximum test pressures should be approximately 150 psi for high-pressure AC/R
systems. In chiller applications, controlled hot water or heater blankets will raise pressure
adequately for a leak check, which should never exceed 10 psi for low pressure chillers. After
a thorough inspection with a good leak detector, apply a deep vacuum to 500 microns. A good
triple evacuation, with dry nitrogen and then deep vacuum is the preferred method.
Piping Basic Principles
Refrigeration piping involves extremely complex relationships in the flow of refrigerant and oil.
Fluid flow is the study of the flow of a gas or a liquid, and the inter-relationship of velocity,
pressure, friction, density and the work required to cause the flow. The design of a
refrigeration piping system is a continuous series of compromises. It is desirable to have
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