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Page 16 of 169
Procedure:
Testing by visual examination, and a proprietary bubble solution. Ensure your supply cylinder of Oxygen Free
Nitrogen (OFN) is fitted with a pressure limiting device set at just above your maximum test pressure value. Never
move a cylinder with a regulator fitted.
At this stage the refrigeration compressors must remain electrically isolated from the system.
Open all liquid and suction valves and ensure that no system circuits are isolated by closed solenoid valves or non-
return valves etc. First introduce dry oxygen free nitrogen (OFN) at a pressure of 3 barg to the system and check
for audible leaks. If all components and pipe-work is sound, before proceeding to the second stage it is necessary
that the following components are isolated:
1. Compressors
2. Pressure Switches
3. Transducers
The test pressure should now be increased to 10 barg using dry oxygen free nitrogen in stages of no more than 3
bar at a time. Listen for audible leaks and watch the gauge for pressure loss at each increment. Use leak detection
soapy water at each joint to identify any small leaks. Leaks encountered should be repaired with the system de-
pressurised.
When the test pressure has reached 10 bar, thoroughly test all joints and components etc. for leaks. The pressure
should then be increased to no more than the maximum leak test pressure allowed for the particular section of the
system, isolating any PRV's or controls etc. which may be susceptible to the test pressure, and all components
should again be checked for leaks.
Strength Test
Follow the above procedure then prove the system. The system should be held at test pressure for at least 15
minutes. If the pressure has not significantly reduced then the system can be slowly vented to the leak test
pressure value. At which point the system should be checked again for leaks.
After all tests are completed the system should be de-pressurised gradually.
13.2 Electrical Testing
BEFORE commencing any testing procedure, a check must be made to ensure that NO electronic or extra low
voltage devices are connected. COMPLETE isolation of these items must be achieved prior to testing.
1. Test for earth continuity. This test is to verify that in no instance should the resistance between the earth
conductor (or control panel main earth terminals) and the metal parts exceed 0.1 ohm.
The electrician MUST ensure that the resistance in the earth conductor between the mains incoming supply and
our control panel earth terminal does NOT exceed the figure quoted above. It is also the responsibility of the
electrician to ensure that the earth conductor into our control panel is sized in accordance with the latest edition of
I.E.E. regulations.
A current of 25 amps should be passed between the control panel main earth terminal and all exposed metal parts
in turn. The test shall be made at a voltage not exceeding 6v ac.
Small isolated metal parts on, in or through non-conducting material, and separated by such material from current
carrying parts in such a way they cannot become live, should not be included in the test.
2. A test of polarity should be made and it should be verified that all fuses and single pole control devices are
connected in the phase conductor only.
Copyright HPL March 2021
P4367 Rev 01
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