Operating principle

The differential pressure control valve (DPCV) is a special kind of control valve whose action is related to a measured pressure difference. In practice, the DPCV is used in several applications as will be further explained basically, its goal is to maintain a constant pressure difference across a certain part of the hydraulic network. Inside the DPCV, two cavities are separated by means of a membrane. One cavity is internally connected to the upstream side of the DPCV while the other one is connected with a remote location by means of a small capillary pipe. This way, the differential pressure across the membrane equals the pressure difference between the upstream measuring point and the DPCV. The resulting spindle travel depends on the force balance between the membrane and the spring.

Individual components and parameters

Balance valve for primary balancing
Differential pressure control valve

How to use in Hysopt

You can view the following examples via this token: OTg3fEZYMWdrZ0xk

The DPCV aims to increase the system controllability by maintaining a constant pressure difference across a certain part of the circuit:

Constant differential pressure across a balance valve
Constant differential pressure across a control valve
Constant differential pressure across a branch

When the DPCV is applied across a balance valve (BV), the flow through the balance valve remains constant even if the pressure difference across the BV-DPCV combination changes. This might be useful in specfic situations in which the hydraulic system balance must be assured in partial load working conditions.

If the differential pressure across a control valve is maintained constant by means of a DPCV, the control valves authority is theoretically 1 and completely insensitive to hydraulic interactivity. This way the control performance of the respective control loop might be increased. Via the token you can find 2 examples, in which a DPCV is placed over a control valve. The difference between the two examples is the position of the balance valve in the pressure measurement.

Instead of installing a DPCV on each individual control valve it might be satisfactory to apply one single DPCV which maintains a constant differential pressure across a complete branch. This way, the pressure dierences across the individual control valves are not perfectly constant anymore. However, the installation costs are reduced significantly.

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