19
NOTE:
Seal openings around piping and electrical connection to prevent
air leakage. Failure to do so could reduce the unit
’s cooling performance.
2.10. Piping
•
All refrigerant piping should be is Type L Air Conditioning Refrigeration (ACR) hard drawn
copper pipes. Soft copper is unacceptable.
•
When brazing refrigerant lines, an inert gas should be passed through the line at low
pressure to prevent scaling and oxidation inside the tubing. Dry nitrogen is preferred. No
soldering allowed.
•
Completely de-burr and clean tube end and inside surface of piping.
•
Use only a suitable silver alloy on suction and liquid lines. Limit the flux to the minimum
required to prevent contamination of the joint internally. Flux only the male portion of the
connection, never the female. After brazing, remove excess flux.
•
All refrigeration piping materials are subject to changes in temperature and will expand
and contract with temperature change. Installation techniques must allow for expansion
and contraction changes for piping connections, this will prevent stresses which may
buckle and rupture the copper tube piping or joints.
•
Proper piping practices should be employed to ensure adequate oil return, even under
minimum load conditions with special consideration given to the size and proper slope of
the tubing coming from the evaporator. See section
2.14 Recommended Line Sizing, Air
for more information on line sizes.
•
Tubing returns from the evaporator should be designed so as not to trap oil and to prevent
oil and refrigerant migration back to the compressor during compressor off cycles.
Piping should be designed with adequate three-dimensional flexibility. It should not be in contact
with the surrounding structure, unless a proper tubing mount has been installed. This protection
proves necessary to avoid excess vibration, which can ultimately result in connection or tube
failure due to fatigue or wear from abrasion. Aside from tubing and connection damage, excess
vibration may be transmitted to the surrounding structure and generate an unacceptable noise
level within the structure as well.
When piping, use copper tubing with appropriate supporting devices (supporting saddles, etc.).
All field piping must be installed according to local codes. Avoid piping runs through noise-
sensitive areas, such as office walls and conference rooms.
Piping and to the ASHRAE Refrigeration Handbook for general, good-practice refrigeration
piping.
All piping below the raised floor must be located so that it does not restrict airflow. Plan the
piping layout under the raised floor to prevent the airflow from being blocked. When installing
piping on the subfloor, it is recommended that the pipes be mounted in a horizontal plane rather
than stacked one above the other. Whenever possible, the pipes should be run parallel to the
airflow.