Hussmann Proto-Aire Installation Manual page 104

Protocol™ Installation and
Service Manual
Open Power Supply
Compressors – Open circuit breakers to all compressors.
Isolate
Compressors – Front seat service valves on suction and discharge.
Pressure Transducers – Close angle valves.
Open
Valves – to condenser, heat reclaim, receiver.
Liquid Line Solenoid Valve(s) – Solenoid should be energized.
Verify
Refrigerant requirements for system, compressors, and TXV's in merchandisers and
coolers.
Electrical supply and component requirements.
Test Charge
Using properly regulated dry nitrogen and refrigerant mixture, pressurize the system with
vapor only. Bring the system pressure up to 150 psig. Use an electronic leak detector to
inspect all connections. If a leak is found, isolate, repair, and retest. Be sure system is a
150 psig and all valves closed to repair the leak are re-opened. After the last leak is
repaired and retested, the system must stand unaltered for at least 12 hours with no pressure
drop from 150 psig.
Evacuation
Nitrogen and moisture will remain in the system unless proper evacuation procedures are
followed. Nitrogen left in the system may cause excessive head pressure. Moisture causes
TXV ice blockage, wax build up, acid, oil, and sludge formation.
Do not simply purge the system because this procedure is illegal, expensive, harmful to the
environment, and may leave moisture and nitrogen.
Do not run the compressor to evacuate because this procedure introduces moisture into the
compressors crankcase oil and does not produce adequate vacuum to remove moisture from
the rest of the system at normal temperatures.
Setup
Using an 8 CFM or larger vacuum pump, connect to the access port on both the suction and
discharge header of the Protocol™ unit. Connect one micron vacuum gauge at the pump,
and one at the furthest point in the system from the compressor. Plan procedures so
breaking the vacuum with refrigerant will not introduce contaminates into the system. The
vacuum pump must be in good condition and filled with fresh oil to achieve desire results.
Procedure – Triple Evacuation
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