Figure 4-3 Minimum Pressure/Check Valve - Gardner Denver EBB BB-7.5 HP Operating And Service Manual

FIGURE 4–2 – INLET VALVE
Damage will occur to the machine if it
is repeatedly restarted after high tem-
perature stops operation. Find and
correct the malfunction before re-
suming operation.
Relief Valve – A pressure relief valve(s) is (are)
installed in the final discharge line and set at the factory
to approximately 120% of the unit's full load operating
pressure for protection against overpressure. Periodic
checks should be made to insure its proper operation.
When the relief valve opens, a stream
of high velocity air is released, result-
ing in a high noise level and possible
discharge of accumulated dirt or oth-
er debris. Always wear eye and ear
protection and stand clear of the dis-
charge port when testing the relief
valve to prevent injury.
Never paint, lubricate or alter a relief
valve. Do not plug vent or restrict dis-
charge.
FIGURE 4–3 – MINIMUM PRESSURE/CHECK VALVE
Operation of the unit with improper
relief valve setting can result in se-
vere personal injury or machine dam-
age.
Insure
installed and maintained.
AIR CONTROL COMPONENTS – All units incorpo-
rate the following air control components.
FIGURE 4–1, page 15, for schematic tubing diagram.
Inlet Valve (FIGURE 4–2) – The inlet valve is a pilot–
actuated valve that closes to unload the compressor.
At shutdown the inlet valve closes to function as a
check valve and prevent backflow of air. Air pressure
is supplied to the cylinder by the Intake Controller to ful-
ly open the inlet valve.
Minimum Pressure/Check Valve (FIGURE 4–3) –
An internal spring–loaded minimum pressure valve is
used in the final discharge line to provide a positive
pressure on the oil system even when the air service
valve is fully open. The valve senses upstream pres-
sure. If demand for air exceeds the compressor capac-
ity, the valve throttles the flow to maintain a minimum
pressure on the upstream (oil reservoir) side of the
valve. When pressure rises above the minimum pres-
sure (standard setting 62 to 67 PSIG) the valve reach-
es the full open position.
A check valve incorporated in the minimum pressure
valve prevents backflow of air from the shop air line
when the unit stops, unloads or is shut down.
13–8–612 Page 16
properly set valves are
See