MAXIMATOR VP30, Maintenance Information, Page: 5 / 42

VP30/VP500
MAINTENANCE INFORMATION
Unloaders
Every time the compressor stops, gas pressure is retained in the cylinders and coolers of each
stage. This gas pressure must be vented to allow the compressor to be started ‘off-load’. The
unloader system is an automatic system for venting this pressure. The system is operated by oil
pressure from the lubrication system, which prevents the gas from each stage from venting to the
unloader vent. Therefore, when the compressor stops and the oil pressure subsides, the unloader
valves will open and the gas will be vented. The Microfilter is also connected to the unloader
system, and its contents, including any condensed oil, will be vented every time the compressor is
stopped.
Stage Pressure gauges Stage Pressure gauges
After each cooler there is a pressure gauge, which shows the gas pressure for each stage when
the compressor is running. The gauges should all reduce to zero after the unloader has vented the
gas from each stage when the compressor stops.
Safety valves Safety valves
After the cooler at each stage is also fitted a safety valve, which prevents each stage from
becoming over pressurised. If a safety valve begins to ‘blow’ (or vent gas to atmosphere), it is
normally a sign that the compressor needs to be serviced.
Outlet
At the compressor outlet, there is a non return valve (check valve). This stops gas from the HP gas
receivers and pipes from venting back through the compressor’s unloader system to atmosphere
when the compressor stops.
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