O-UC12-FEB23-3
Page 2
Figure 1: Minimum Wall Distance and Drain Trap
Field piping
Use of incorrect pipe sizes affects the system’s
oil return and pressure drops. Refer
information given on
Page 3
. All local codes of
practice must be observed in the installation of
refrigerant piping.
To ensure satisfactory operation and performance, the
following points should be noted for field piping
arrangements:
•
Pipework routes must be as simple and as short as
possible.
•
Use of incorrect pipe sizes can affect system
pressures/temperatures and gas velocity for proper oil
return.
•
Avoid low points on pipework where oil can accumulate.
•
Use only clean, dehydrated refrigeration grade copper
tube with long radius bends.
•
When brazing use only silver alloy rods.
•
Run braze without over filling to ensure there is no
leakage into the tube.
•
To prevent oxidization, blow oxygen free nitrogen
through pipework when brazing.
•
Protect the casing of the unit when brazing connections.
•
Install insulation with a minimum wall thickness of 3/8” on
suction lines to prevent sweating and ensure only
superheated vapor is returned to compressor suction.
•
Adequately support all pipe work at a maximum of 2-
meter intervals.
Pressure testing
•
The unit cooler has been pressure tested in the factory
prior to dispatch. The indoor unit contains a holding
charge of oxygen free nitrogen.
•
Once the pipework installation is complete, it should be
pressure tested prior to evacuation to test for leaks.
•
A pressure leak test should be carried out using oxygen
free nitrogen (OFN). NEVER USE OXYGEN FOR
PRESSURE TESTING SYSTEMS. A calibrated nitrogen
pressure regulator must always be used. Before starting
any pressure testing, ensure the area surrounding the
system is safe, inform relevant personnel and fit warning
signs indicating high pressure testing. Also, use correct
PPE as required.
A simple procedure for testing as follows:
•
Connect a pressure hose from the regulator to the
schrader connection on the service port of the unit.
•
Pressure system slowly up to 3 bar (45 psi) for 5 minutes
and check for any signs of leakage.
•
Increase pressure slowly up to 10 bar (150 psi) for 5
minutes and check for any signs of leakage.
•
Increase pressure slowly up to 20 bar (300 psi) and
check for any signs of leakage. Leave system under
pressure for 24 hours.
