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Parker Hannifin Corporation
Quick Coupling Division
Minneapolis, MN
www.parker.com/quickcouplings
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Valves
Valves
Multiple Hydraulic System Applications
Parker Check Valves are unidirectional flow control devices
used primarily in hydraulic systems to eliminate potential
damage caused by fluid back pressure. Offered in many
configurations, Parker can satisfy most hydraulic system
applications. Parker’s in-line style check valves are available in
a variety of sizes, pressure ratings, flow capacities and
crack pressures.
H1, HM1 and PV Series Pressure / Vacuum Relief Valves are
used to create and maintain a positive pressure in hydraulic
tanks and reservoirs. These pressurized reservoir valves
provide the following benefits:
•
Prevents pump cavitation by assuring a positive
supply of oil at the pump inlet
•
Minimizes the tank breathing of outside, moist,
contaminated air
•
Filters all incoming air
As oil is drawn from the reservoir and pumped to the circuit,
a vacuum is created in the reservoir. The vacuum relief valve
opens to allow filtered air to enter. As oil is pumped back into
the reservoir, air pressure builds. Additionally, as the oil heats,
the pressure inside the reservoir increases. When the pressure
exceeds the relief valve setting, the excess pressure is vented
to atmosphere. Normally, the pressure will fluctuate between
zero and the pressure relief setting without opening either
valve. This can significantly reduce the breathing of outside air
and minimize the chance for moisture and contamination to
enter.
TH Series Thermal Bypass Valves ensure efficient equipment
operation at any temperature. These valves are ideally
suited for hydrostatic drive circuits which require fast warm-
up, controlled fluid temperatures and low return line back
pressure. When installed in a return line of a hydraulic
circuit that utilizes an oil cooler, this valve will modulate fluid
temperature by either shifting return line flow through the
cooler, or bypassing directly to the reservoir. An integral
pressure relief function automatically releases excess pressure
to the reservoir if the cooler becomes restricted and the inlet
pressure becomes excessive.