Overflow and pressure control valves


Pressure control valve / pressure relief valve

A pressure control valve (also know as an overflow valve) ensures that the pressure for the pressure control valve is maintained. This means that the pressure control valve closes if the pressure is too high to maintain the pressure for the valve. If the pre-pressure is below the set value, the pressure control valve is closed and when the set pressure is reached, the valve opens in order to keep the pressure for the valve constant.

Versions in stainless steel, PVC, PP and PVDF.

An overpressure valve is often confused with a safety device.

Difference between an overflow valve and a safety valve

See the difference of a safety valve vs. overflow / overpressure valve here.

The opening curve of an overpressure valve, overflow valve, pressure control valve, pressure relief valve is shown below. An overpressure valve may in principle blow off continuously and is therefore often used as an overflow on pumps to prevent the pump from continuing to pump against a closed valve.

Opening characteristic overflow valve

  1. Contact pressure is reached; pressure relief valve is still closed.
  2. Contact pressure is exceeded; the pressure relief valve is opened in proportion to the excess pressure.
  3. The pressure relief valve adjusts itself to the required amount of overflow.
  4. When the system pressure decreases, the pressure relief valve starts to close again.
  5. The system pressure decreases and the pressure relief valve continues to close.
  6. If the pressure is slightly lower than the response pressure, the pressure relief valve is closed again.

Fixed points are: 1 and about 6