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Pump Unloader Control DN16-DN65 PN420


  • Electro- hydraulically actuated valve
  • Pump unloader control consisting of 2/2-way valve, non-return valve and pre-control valve with connection plate and filter
  • The valve seats seal ae hermetically sealed and prevent internal leaks
  • Internal pilot pressure (no external pressure source required)
  • All parts are made of corrosion-resistant materials and are easily replaceable
  • flange design for direct mounting to pumps or separate blocks


Control function

The pump bypass valve (1), the pilot valve (4) and the connection plate (6) form a valve unit for controlling a pump in a pressure supply system. Depending on the system pressure, the valve controls the work cycle of the pump, „pressure build-up“, „load accumulator“ or „pressure less circulation“. The P port is connected to the pressure port of the pump, the A port to the pressure line of the system and the T port to the pressure less tank.

The fl ow of the pump enters the pump bypass valve at the P connection. The pump fl ow is connected to the pressure port of the pilot valve (4) via the filter (5). In the unload position, the pressure on the control piston (3) of the 2/2-way valve (2) on the control side is discharged, the 2/2-way valve is open, and the pump flow is discharged from P to T without pressure.

By switching over the pilot valve (4), the piston (3) is pressurized on the control side and the 2/2-way valve (2) closes and blocks the connection P to T. At the same time, the check valve (7) opens and connects the lines P to A. The pump flow is supplied via the A port, to the system.




Technical data

measured with HFA medium 97/3%, at 20°C


Weightsee Order information
Installation positionany
Ambient temperature-10 to 50°C (hydraulic fl uids, heed standard requirements)
Material Valve parts
Material Seals
Stainless steel


Pumpenumlaufventil H30, H300

Hydraulic pressure connector P, A, A1≤ 420 bar
Hydraulic pressure connector MP, MA≤ 420 bar
Hydraulic pressure connector Y≤ 2 bar
Hydraulic pressure connector≤ 2 bar
Direction of flowP→T, P→A
Pressure fluid
- Medium - Temperature range
- Medium - Quality
- min. filter fineness connection A, B
- min. filter fineness connection X
Water, HFA
5 to 40°C
see Hauhinco media requirement, water, HFA
Filter fineness 100µm
Filter fineness 25µm (control pcb with filter inserts)
Pressure fluid
- Medium - Temperature range
- Medium - Quality
Mineral oil HLP according to DIN51624-2
5 to 50°C
Cleanliness class -/19/16 according to ISO 4406
max. switching rate of the valve unit0,2 Hz
Use of other pressure fl uids on request.
Note: The maximum decrease volume flow of the consumer and the size of the
pressure accumulator control the switching rate of the pump circulation control system.


Additional information

The latest generation of Hauhinco pump circulation controls has a modular design and can be individually assembled as a construction kit.

See example drawing number 6602632, on the following page.

All other pump controls are available on request.

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