Grundfos Mechanical Dosing Pump DMH
The Grundfos DMH series is a range of high-precision dosing pumps designed for demanding applications in various industries. These pumps are known for their accuracy, reliability, and durability. Here are the detailed usages and advantages of Grundfos DMH pumps:

Usages of Grundfos DMH Pumps

1. Water Treatment:

   • Municipal Water Treatment: Used for dosing chemicals such as chlorine, fluoride, and coagulants.
   • Wastewater Treatment: Doses flocculants, coagulants, and disinfectants to ensure the treated water meets regulatory standards.

2. Chemical Processing:

   • Industrial Processes: In industries like petrochemicals, pulp and paper, and textiles, these pumps dose various chemicals precisely to ensure product quality and process efficiency.
   • pH Adjustment: In chemical processing plants, DMH pumps are used to adjust pH levels by dosing acids or alkalis.

3. Food and Beverage:

   • Clean-in-Place (CIP) Systems: Utilized for dosing cleaning agents and sanitizers to maintain hygiene standards.
   • Additive Dosing: Ensures precise dosing of flavorings, colorants, and preservatives.

4. Pharmaceuticals:

   • Process Dosing: Used for precise dosing of raw materials and active ingredients.
   • Water Purification: In pharmaceutical water treatment systems, these pumps dose various chemicals to achieve the required purity levels.

5. Power Generation:

   • Boiler Water Treatment: Doses chemicals like oxygen scavengers, scale inhibitors, and corrosion inhibitors to protect boiler systems.
   • Cooling Towers: Doses biocides and scale inhibitors to maintain cooling tower efficiency.

6. Agriculture:

   • Fertilizer Injection: Used in irrigation systems to dose fertilizers and nutrients.
   • Pest Control: Doses pesticides and herbicides accurately.

Advantages of Grundfos DMH Pumps

1. High Precision and Accuracy:

   • The DMH series offers precise and accurate dosing, ensuring the correct amount of chemical is delivered every time. This is critical in processes where even small deviations can lead to significant issues.

2. Robust and Durable Construction:

   • These pumps are built with high-quality materials that withstand aggressive chemicals and harsh operating conditions, leading to long service life and reduced maintenance costs.

3. Wide Range of Capacities and Pressures:

   • The DMH series offers a broad range of capacities (from 0.15 l/h to 2 x 1500 l/h) and can handle high pressures (up to 200 bar), making them suitable for a variety of applications.

4. Safety and Reliability:

   • Features such as leak detection, diaphragm rupture detection, and integrated pressure relief valves enhance the safety and reliability of these pumps.

5. Energy Efficiency:

   • Grundfos DMH pumps are designed to be energy-efficient, reducing operational costs and environmental impact.

6. Ease of Maintenance:

   • These pumps are designed for easy maintenance with readily accessible components, minimizing downtime and associated costs.

7. Versatile and Modular Design:

   • The modular design allows for customization to meet specific application requirements, providing flexibility in installation and operation.

8. Advanced Control Options:

   • The pumps can be equipped with various control options, including analog and digital signals, to integrate seamlessly with automated systems and ensure precise control of dosing processes.

9. Compliance with Standards:

   • Grundfos DMH pumps comply with various international standards and certifications, ensuring they meet industry requirements and safety regulations.

Conclusion

The Grundfos DMH series is a versatile and reliable choice for precise dosing in a wide range of applications. Its advantages in precision, durability, safety, and efficiency make it a valuable asset in industries where accurate chemical dosing is critical. Whether in water treatment, chemical processing, food and beverage production, pharmaceuticals, power generation, or agriculture, Grundfos DMH pumps deliver consistent performance and reliability.

1. Product introduction
Features and benefits
The preferred choice for complex tasks
The Grundfos DMH range is a series of extremely strong, robust pumps for applications requiring reliable dosing and highpressure capability, such as process engineering. The DMH 28x models have been designed especially for high-pressure applications from 50 up to 200 bar. The range is highly versatile: it covers a wide flow range and offers a variety of dosing head sizes, materials and accessories. Customers worldwide have enjoyed years of trouble-free operation from their DMH pumps. 

Accurate dosing - all the time
The diaphragm design makes sure that the dosing flow fluctuation and the linearity deviation are very low. This allows very precise dosing of chemicals - as much as necessary, as little as possible.

Smooth and low-pulsation dosing
Sophisticated drive technology and gear kinematics ensure smooth and low-pulsation dosing. 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 mechanical dosing pump range offers the following options:
• Ex-classified or ATEX-certified high-quality motors
• Motors with integrated variable frequency drive (VFD) are available on request.
Mechanical dosing pumps equipped with a motor with factory-mounted integrated VFD provide extended capacity range and functionality. They include analog inputs and outputs, an integrated potentiometer for precise and easy setting of speed, control and self-monitoring functions as well as an interface for field bus communication (Profibus, Profinet).

This option is only available for pumps that are able to run at 100 Hz. See performance data tables.
• Motors with PTC, prepared for operation with external variable frequency drive (VFD).

Mechanical dosing pumps equipped with a motor with PTC, planned to be operated by a VFD, the VFD is not supplied with the pump. The PTC protects the motor against locked-rotor conditions, continuous overload and high ambient temperature.
- Use a VFD that can operate at constant torque. The VFD should have a 150 % overload capacity for 60 seconds.
- Respect the limitations on minimum and maximum operating frequency to prevent gear breakdown or motor overheating. See performance data tables.

This option is not available for pumps selected for ATEX.
For more detailed information, please contact Grundfos.
Perfect material selection for housing and wetted parts
The DMH models have a robust cast-aluminium housing with epoxy coating to meet all application needs (grey cast iron if API 675 is required). 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 wetted parts must be resistant to the chemicals used. The diaphragm is entirely made of PTFE.
Safe and trouble-free operation The serially integrated pressure-relief valve and the AMS diaphragm protection system keep the pump and entire system protected against overpressure if the outlet 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 their aluminium enclosure and the piston diaphragm technology, DMH pumps have a very long operating life and long service intervals.

Approvals and certificates
For potentially explosive areas, we offer EX classified and ATEX approved motors and pumps. For applications in the petrochemistry, we provide special versions of our DMH dosing pumps with API 675 certificates.
Flexibility in pump configuration and applications
A number of different DMH pump configurations are available to match requirements:
• Flexible dosing-flow control concept: manual or automatic stroke-length adjustment with an electric servomotor
• Pumps fitted with a double diaphragm with failure indication
• Special dosing heads with electrical heating
Universal fields of application are possible due to the PTFE dosing diaphragm. Wetted parts are available in material combinations that suit virtually all dosing tasks. Choose the best configuration for your specific dosing task.

Ready for tough application areas
Power plants
• Dosing of various chemicals for the treatment of boiler feed water, cooling water and process water (raw water purification, chemicals for ion-exchangers, supplementary water treatment, effluent water neutralisation)
• Dosing of ammonia, hydrazine, phosphates in high-pressure areas (e.g. boiler feed water).

Petrochemical industry, oil and gas industry, refineries
• Dosing of chemicals for treatment of cleaning water and process water
• Dosing of inhibitors and anticorrosives to protect oil pipelines
• Dosing of wax as a lubricant in oil-pipelines
• Dosing of additives and catalysts
• Odorisation of gas for safety in case of leakages.

Treatment of process water and drinking water
• Rough environments (hot climate, desert, outdoor installations)
• High flow and pressure ratings.

ATEX approved pumps
EX classified and ATEX approved motors and pumps for potentially explosive areas are available on request. ATEX approved pumps
We offer ATEX approved DMH pumps in a variety of configurations. Some can be used for dosing combustible liquids. For more detailed information, please contact Grundfos.

EX zones
ATEX approved DMH pumps can be used in the following EX zones:
• ATEX Directive, Group II, category 2 (zone 1/21)
• ATEX Directive, Group II, category 3 (zone 2/22)
3. Functions and options

Dosing flow control
Depending on the application, DMH pumps can have different functions and options for setting and controlling the dosing flow:
• Standard DMH pumps have a stroke-length adjusting knob for manual dosing flow control.
• All DMH pumps can be fitted with a servomotor for remote stroke-length control.
• On request, DMH pumps can be fitted with a variable frequency drive (VFD) for motor-speed control.
• DMH AR variants with special single-phase motor can be equipped with AR control unit for automatic strokefrequency control, pulse control, analog signals, alarm relay (available for DMH models 251, 252, 253, 280, 281).

Electric servomotor
To facilitate automatic control of the flow rate, mechanical dosing pumps can be equipped with an electric servomotor in IP65 housing. The electric servomotor primarily consists of a digitally controlled stepper motor, reduction
gear and min/max limit switches. The electric servomotor is connected to the control slide of the dosing pump. This adjusts the active stroke length and the corresponding dosing flow. The electric servomotor is available as ATEX version, EX II2G Ex db IIB T4 for potentially explosive zones.

Variants
• Electric servomotors with different operating voltages
• Electric servomotors with 4-20 mA control and output signal and manual/automatic switch

AR control unit
The AR control unit contains convenient electronics in an IP65 housing, and is suitable for the following pump models:
• DMH 251, 252, 253 with special single-phase motor
• DMH 280, DMH 281 with special single-phase motor

Control modes
• Manual control: stroke frequency is manually adjustable from 1 up to the maximum strokes per minute.
• Pulse signal control: multiplier 1:n (n strokes per incoming pulse) and divisor n:1 (1 stroke per incoming n pulse), memory function (stores a maximum of 65,000 pulses).
• 0/4-20 mA analog signal control: adjustment of stroke frequency in proportion to the current signal and weighting of current input is possible.
• The AR control unit is mounted on the terminal box of the motor.

Inputs
• Pulse signal
• Analog signal
• Remote on/off
• Tank-empty sensor
• Dosing controller and diaphragm leakage sensor

Outputs
• Analog signal
• Error signal (fault)
• Stroke signal
• Low-level signal

AMS diaphragm protection system
The unique AMS diaphragm protection system has a tactile surface that touches the dosing diaphragm. If the inlet or outlet line is blocked due to a fault in the system, the tactile surface closes the hydraulic chamber. Although the
piston continues moving, the diaphragm cannot be overstretched.

Diaphragm leakage detection
DMH piston diaphragm dosing pumps with diaphragm leakage detection are equipped with:
• Dosing head with double-diaphragm system
• Contact pressure gauge with non-return valve.

Variable frequency drive (VFD)
Mechanical dosing pumps with integrated variable frequency drive provide extended capacity range and functionality. They include analog and digital inputs and outputs and an integrated potentiometer for precise and easy setting of speed and flow as well as control and self-monitoring functions. Mechanical dosing pumps can be prepared for variablefrequency-drive operation and include a variable frequency drive (VFD).