No pulse, no problem: seal-less triplex dosing pump MT8

Dosing pumps are always in demand when a process requires more than just the transfer of liquids. This can mean pumping a fixed amount of liquid into a running process or a variable amount of liquid controlled by the needs of a running process. The technology for manufacturing metering pumps has hardly changed over the past decades. Consequently, conventional single-diaphragm metering pumps have operational limitations and higher follow-up costs. The Hydra-Cell pump product range consists of innovative multi-diaphragm pumps that combine highest dosing accuracy with a practically low pulsation flow rate. They meet and exceed the performance standards of API 675 and are also available as ATEX versions.

The Hydra-Cell "Metering Solutions Pump" group has introduced evolutionary new technologies into the world of metering pumps over the last ten years. Our latest innovation: The seal-less triplex metering pump MT8. The Hydra-Cell MT8 triplex metering pump has been designed to meter very low flow rates at high pressure. The robust and compact pump can be adjusted from 0.227 to 30.28 l/h and simultaneously reaches a maximum pressure of 241 bar! With the small footprint of approx. 36 x 30 cm a lot of space can be saved and an efficient dosing system can be built.

The patented hydraulic oil management system ensures that even extremely low flow rates can be precisely dosed. At the same time, this system protects the diaphragms against diaphragm rupture during suction vacuum and dry running. The triplex metering pump MT8 is capable of dry running and can pump solids (<0.2 mm). The MT8 operates according to the proven Hydra-Cell working principle and thus offers you an almost pulsation-free flow rate as well as unmatched accuracy, repeatability (± 3 %) and linearity (± 3 %), with precise, constant dosing (± 1 %). As a result, the MT8 meets and exceeds the performance standards and requirements of API 675.

Diaphragm position control

The diaphragm position control protects diaphragms from suction-side vacuum conditions. If the liquid in the suction line becomes constricted, this leads to a vacuum. The patented diaphragm position control prevents overfilling of the hydraulic cell and protects the diaphragm from rupture with a shuttle and overfill valve.

This robust design protects the diaphragm from a blocked suction line, which can be caused by a blocked strainer, a closed suction valve or an operating error, for example.

Internal, adjustable pressure relief valve

The pressure relief valve protects the hydraulic part of the pump from damage caused by excessive pressure. This pressure relief valve is set at the factory to 10-15% above the nominal pump pressure of 241 bar and can be adapted to the process on site. It can also be used to support the suction process if required.

The relief valve provides internal protection in case of overpressure in the pump and does not negate the need for an external relief valve, as always recommended by a number of the major oil and gas companies.

Diaphragm return mechanism

The patented diaphragm return mechanism not only ensures accuracy that exceeds the performance requirements of API 675, but also provides diaphragm protection. It prevents the diaphragm from moving too far forward or backward, while protecting the diaphragm from damage when suction conditions are blocked. This diaphragm return mechanism allows the pump to run dry indefinitely.

Optimized flow paths

Gas inclusions are a common problem with dosing pumps. For this reason, conventional dosing pumps often have to be vented or pre-filled before start-up. The flow paths of the Hydra-Cell MT8 are optimized to effectively evacuate gas from the pump head. This ensures easy commissioning and trouble-free operation. 

Valve cartridge assembly

The valve cartridge assembly with the unique double-sealed ball valve makes on-site maintenance particularly easy. The double seal eliminates the need for a second valve assembly and enables the MT8 triplex metering pump to handle liquids with suspended solids down to 0.2 mm (at 15% concentration).

Pressure Sealing Oil Cap

The pressure-sealing oil cover made of nickel-plated steel seals the hydraulic end up to a pressure of 2.7 bar. In addition, it protects the hydraulic end from water ingress into the drive housing.

No pulse, no problem!

How often and how well a pump refills the fluid into the pump head has a considerable influence on the accuracy of the pump. In a conventional dosing pump, refilling is only carried out when a vacuum is registered in the pump head or a mechanical valve is opened by a fully retracted diaphragm.

The single diaphragm movement causes considerable pulsation. This influences the dosing accuracy and thus also the feeding accuracy of the pumped liquid. This can be of considerable importance, for example, with chemicals. Although this can be compensated for with the assistance of pulsation dampers, it means further costs and additional installation and maintenance work. 

The MT8 uses a refill system which compensates the outgoing fluid with each stroke, thus ensuring optimum accuracy.

The triplex design of the MT8 minimises the negative effects of pulsation:


In addition, the resulting linear flow allows for the precise delivery of process fluids that remains constant. The ability of a metering pump to deliver laminar flow that can be accurately measured at any point in the delivery create tremendous advantages over the operation of traditional metering pumps. This is the unique advantage of the Hydra-Cell metering pump line! 

Curious? Watch this video to learn more about Hydra-Cells "No Problem" Pumps:

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