Some essential factors concerned about the operation of hydraulic pressure regulators are its set pressure, cracking pressure, full-flow pressure, pressure-override, closing pressure, overpressure, blowdown, and backpressure. These useful terms are defined in the following sections:
Set Pressure
It is the inlet pressure, under the specified service conditions, at which a PRV is set to open.
Cracking (Opening) Pressure
It is the value of increasing the inlet pressure of a PRV at which there is a measurable lift of its poppet, and there is a continuous discharge of the fluid through it.
Textbook on ‘Hydraulic Power Packs in the SI Units’
By Joji Parambath
The book deals with power pack components such as hydraulic reservoirs, pumps, pressure relief valves, unloading valves, filters, accumulators, and power pack control units. It also presents the noise reduction techniques for hydraulic systems. Next, the book highlights power packs with standardised assemblies. The book uses the SI system of units.
Textbook on ‘Power Packs in Hydraulic Systems in the English Units
By Joji Parambath
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Full-flow Pressure
The pressure at the inlet of a PRV, when it is passing its rated maximum flow, is called the full-flow pressure.
Pressure Override
The difference between the full-flow pressure and the cracking pressure of a PRV is called the pressure-override or the pressure build-up over the set point of the PRV.
Closing Pressure
It is also known as ‘reseat’ pressure. The closing pressure of a PRV is the value of decreasing inlet pressure at which the poppet of the PRV re-establishes a firm contact with the seat.
Overpressure
It is the pressure increase above the set pressure of a PRV, expressed in pressure units or as a percentage.
Backpressure
It is the pressure that exists at the outlet of a PRV as a result of the pressure in the discharge system. It may be subdivided into superimposed and built-up backpressures.
Superimposed Backpressure
This is the backpressure acting on the outlet of a closed PRV. It is the effect of the pressure in the discharge system coming from multiple sources.
Built-Up Backpressure
It is the increase in the pressure in the PRV’s discharge header when the fluid is flowing through the PRV.
Joji Parambath
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