J&E Hall JEHSD-0400-B3-M-3, Technical Manual

Page: 15 / 44

Issue: 01.08.2020 Page 15
Installation
Pressure testing
The condensing units are pressure tested in the factory prior to dispatch. All units come with a holding charge of oxygen free
nitrogen. Remove the holding charge indication tag which is tied to service valve before installation.
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.
Always pressurize the system slowly, preferably in stages up to the maximum required pressure. Maximum test pressures
applicable to the unit are as follows:
Test pressure
High side Low side
28 barG
(405 psiG)
19 barG
(275 psiG)
Listen for any possible leaks and check all joints with bubble spray. If any leaks are discovered, release pressure slowly from
system until empty, repair leak and then restart pressure testing procedure. Never attempt to repair a leak on a pressurized
system.
A strength test should also be incorporated (to installed pipework only) according to applicable standards.
Once testing has been completed satisfactorily, release the pressure from the system gradually and safely to external
atmosphere.
Evacuation & Charging
Once pressure testing has been completed, the system can now be evacuated to remove air and any moisture from the piping.
This can be done as follows:
•
Ensure any nitrogen charge is safely released from the system.
•
Connect a gauge manifold to the connections on the service valves on the condensing unit.
•
Connect a vacuum pump and vacuum gauge to the system.
•
Ensure all gauge manifold and service valves are open as required.
•
Evacuate the system until vacuum is below 250 microns (0.25 torr).
Note: A triple evacuation procedure is recommended for all new systems or where moisture is suspected.
Once the system is isolated and the vacuum pump is switched off, any rise in pressure indicates that either there may be a leak in
the system or moisture is still present. In this case, recheck the system for leaks, repair as necessary, and then restart the
evacuation procedure. Once completed satisfactorily, the vacuum pump and vacuum gauge can be removed.
At this point, the refrigerant charge can be added to the system as required. Refrigerants must be charged in the liquid phase.
Charging of liquid into the suction side of the system should ONLY be done with a metering device.
Use calibrated weighing
scales to record the amount of refrigerant added to the system.
Important Note:
Moisture prevents proper functioning of the compressor and the refrigeration system. Ensure that a good
quality vacuum pump is used to pull a minimum vacuum of 250 microns (0.25 torr).