DMH Positive Displacement Diaphragm

 DMH Positive Displacement Diaphragm   Dosing Pump


DMH dosing pump range are hydraulically actuated piston diaphragm dosing pumps.

5The DMH is a series of extremely strong, robust pumps for applications requiring a reliable dosing and high-pressure capability, such as process engineering. The DMH has been especially designed for high-pressure applications from 4 up to 25 bar. The range is highly versatile: it covers a wide flow range and offers a variety of dosing head sizes, materials and accessories – available in simplex and duplex versions.

Accurate dosing – all the time.  DMH pumps have a very high dosing accuracy and allow an exact reproducibility. The dosing flow fluctuation is < ± 1.5 % within the 10-100 % control range, and the linearity deviation is ± 2 % of the full-scale value.

Smooth and low-pulsation dosing:

The DMH range combines sophisticated drive technology and gear kinematics to ensure smooth and low-pulsation dosing without pressure peaks. This means less stress to all system components, such as tubes and valves, and leads to longer service intervals for the entire system.


Motors to match application needs:

For applications with specific motor requirements, the versatile DMH range offers high-quality motors for 50 Hz, 60 Hz, 100 Hz (optional with Variable Frequency Drive VFD), as well as EX classified or ATEX-certified motors (optional), if required.

Perfect material selection – for housing and liquid-wetted parts

The DMH models have a robust cast-aluminum housing with epoxy coating to meet all application needs (grey cast-iron if API 675 is required, optional). Investment costs and running costs for spare parts are kept low over the years: A wide choice of materials for dosing head, valves and accessories allow selecting exactly the degree of chemical resistance required. All liquid-wetted parts need to be resistant to the chemicals used. The diaphragm is made of full-PTFE material.

Safe and trouble-free operation:

The serially integrated pressure relief valve and active diaphragm protection system (AMS) keep the pump and entire system protected against overpressure, if the discharge line is blocked. In addition, the degassing valve at the pump guarantees high functional safety of the pump, the installation and the whole process. Due to aluminum enclosure and the piston diaphragm technology, DMH pumps have a very long operating life and long service intervals.

Applies only to pumps with ATEX / API – Approvals and certificates

For potentially explosive areas we offer EX classified or ATEX-certified motors and pumps. For applications in petro chemistry we provide special versions of our DMH dosing pumps with API 675 certificates.

Flexibility – in pump configuration and applications:

A number of different product configurations are available to match requirements: Flexible control concept for flow rate: manual or automatic stroke-length adjustment with electric servomotor (optional). Pumps fitted with double diaphragm with failure indication (optional), or special dosing heads with electrical heating (optional). Universal fields of application are possible for this pump series due to the full-PTFE dosing diaphragm. Wetted parts are available in material combinations that suit virtually all dosing tasks.

Electronics features: Applies only to pumps with AR control

  • Stroke frequency adjustable
  •  Pulse control with multiplier and divisor (optional)
  •  Analog input 0/4-20mA (proportional stroke frequency, weighting of current input)
  •  Continuous-operation button for function test and dosing head deaeration
  •  Memory function (stores a maximum of 65,000 pulses)
  •  Two-level tank-empty signal (e.g. via Grundfos tank-empty sensor)
  •  Stroke signal/low-level signal (adjustable)
  •  Diaphragm leakage detection (only with sensor – optional)
  •  Access-code-protected settings
  •  Remote on/off, alarm relay output, analog output
  •  Hall sensor (for motor monitoring)
  • Operating hours counter

Servomotor for stroke length adjustment: Applies only to pumps with servomotor

  •  Automatic adjustment of stroke length (mA-input signal or switching supply voltage on/off)
  •  Feedback potentiometer for optimum control
  •  Servomotor protection with two limit switches
  •  Wide control range due to an adjustment angle up to 270°
  • Precise control due to short actuating time – depends on pump model
  •  For further specifications please refer to servomotor data