Further Metering Information


  • Hydra-cell pump range
  • Pressure relief and back-pressure valves
  • Motor drives
  • Frequency inverters VFD
  • Speed reduction boxes
  • Flowmeters to verify and control
  • Calibration columns
  • Operator interface panel OIP


The simple design of the hydra-cell means that flexible solutions can be achieved for multiple fluids. In this case, two pumps metering two liquids can be driven by one gear box and motor. The simple versatile design means that the arrangement above can meter 4 different liquids in a ratio of 2:1 by using the manifold plates opposite.


  • Blowing agent dosing in polyurethane foam production
  • Hazardous material – required seal-less design
  • Specific formula – mandated accuracy of + – 1.3%
  • Space restrictions – necessitated compact size
  • Metering abrasive hand cleaner in production filling line
  • Bottle filling – mandated accuracy of + – 1.1%
  • Particulates – necessitated rugged construction
  • Applying adhesive to stamps and stickers
  • Precise application – required accurate, linear flow
  • Defaming chemical metering in paper-making
  • Using mag flow meter – required linear flow
  • Chemical variations – needed material choices
  • OEM supplier – demanded cost savings
  • Ingredient dosing in animal feed extruder
  • Amalgamates- needed ability to pump solids
  • Dosing celite into refinery slurry line
  • Expensive production process – insisted on reliability, lower maintenance and accquistion costs and accuracy

Hydra-cell metering solutions pumps comprise six standard modes, each with a wide range of low capacities and pressure ratings to lower costly stocking requirements.

Hydra-cell can also handle capacities greater than 3387 l p/h. Contact us for more information.

*350 PSI (24 bar) maximum with Kynar liquid end.

**consult factory for correct component selection for fluid temperatures above 71° C



API 675 (a common industry standard) has been used to define metering and dosing pumps. This specification was put together in 1994 and revised in 2000 but in essence, little has changed since its inception. API 675 stipulates not only performance characteristics, but also how the pump operates mechanically. Advances in variable frequency drive (VFD) and control technology, coupled with the fact that in recent years VFDs have dropped in price significantly, mean that the performance criteria of API 675 can now be met very economically but with pumps which have very different mechanical operation. Mechanical stroke adjustment is no longer the only way to obtain metering performance!!

API 675 stipulates performance in the three ways… linearity, repeatability and steady state accuracy. Hydra-cell pump performance has been confirmed to meet all these stipulated requirements.



When compared with traditional metering pumps the Hydra-cell can save on initial acquisition costs, the picture to the right demonstrates this very clearly. Both pumps can produce a maximum flow of 1500 l/h at 80 bar. The size comparison show how the savings can be made.


Using Hydra-cell gives the engineer the opportunity to design a system without including pulsation dampers.

The majority of the Hydra-cell product range has a pump head which contains multiple diaphragms. This produces a discharge with very low pulsation. The chart below compares the performance of a Hydra-cell pump with a leading global brand of metering pump and shows very clearly the low pulsation advantage of Hydra-cell pumps.

Cost savings are made when the system is installed and continue throughout the life of the system, as there are no damper maintenance costs!



When lower pulsation has been required by the customer,” multiplexing” is one solution which can be offered by traditional metering pump suppliers.

This is invariably an expensive option as the greater the number of pump heads required, the greater the initial capital cost and the greater the regular maintenance costs.

Hydra-cell multi diaphragm hydraulically balanced arrangement means low pulsations are already achieved in a single pump head.


Traditional metering pump suppliers rely almost exclusively on flat PTFE diaphragms.

This expensive material is 3 to 4 times more expensive than many elastomeric diaphragm materials.

Hydra-cell metering solutions now give the customer a choice of less expensive diaphragms with a wider process window and extremely long diaphragm life.

These include: i. Viton  ii: Buna  iii. EPDMi    iv. Neoprene. Teflon is also available if required.


Although a metering pump is usually specified for a particular application, in order to save costs, Plant Engineers will invariably try to reuse the pump if and when its initial duty finishes.

With the simple addition of a gearbox a single Hydra-0cell pump can cover a wide range of lows. To achieve this same effect with a traditional metering pump it is necessary to purchase new plungers and metering heads. A Hydra-cell metering solution using a G10 pump could cover a range of lows from 17 l p/h to 1740 l p/h.



When compared to most other pump technologies the life cycle cost of a Hydra-cell pump is lower. In a detailed study of the life cycle costs of a variety of pumps, carried out by Dr.-lng. Friedrich-Wilhelm Hennecke, former manager Engineering pumps and motors at BASF, his overwhelming conclusion was: “Hydra-cell is the most economic pump in the considered range.” (data available request)


Technical advantages

Performance advantages Hydra-cell metering solutions Traditional metering pumps
Flow control    Use VFD motor and controller to alter pump speed to change flow output use stroke adjustment speed to change flow output
  Modern technology outdated technology


  Digital input can prevent operator error Visual alignment and interpretation of vernier scale can lead to operator error
  Does not require electronic actuator or electronic servo motor to automate process Requires expensive actuator to automate process. Typically this would cost the same as the pump.


  Fast closing, spring loaded check valves achieve very good linear characteristics. This means that high turn down ratio’s can be achieved 30:1 for example Linearity is lost as the low rate is reduced to 10-30% of stroke length due to inefficient operation of ball valves.
Response time to change

In flow for an automated process

0-Max PRM 0.3 seconds (Virtually instantaneous) 0-100% stroke length at least 45 seconds. In some cases this could be 1 to 2 minutes.
Calibration Manual calibration with a column is made more easier and more accurate due to the

Smooth pulseless flow.

Manual calibration is made more difficult and open to the pulsed flow.
  Calibration of an automatic system is made simple. Volume per stroke is constant and a known value. Allows easy digital setting of desired flow. Volume per stroke is modified by the stroke length which may not be directly proportional to output.
Dependability Solid state electronics of VFD very reliable. Stepper motor or linear actuator is driving against pump load and subject to mechanical wear.


  Gear box oil and hydraulic oil are

Independent removing the danger of contamination of hydraulic oil.

Uses the same oil for gear box and hydraulic action.
Design advantages    


Size Save valuable space due to compact multi diaphragm design Become grossly over sized and over priced as flow and pressure requirements increase.
Versatility Each valuable covers an extensive

Range of flows and pressures.

Require many different plunger and liquid end sizes to accommodate increases in flow.
  Simple construction: low parts and maintenance cost. Complex construction higher parts and maintenance costs.
  Separate gearbox: flexibility to easily change flow range Integral gearing: flow rate changes can be expensive
  Due to compact size use of exotic materials cost less Large size means that the use of exotic materials is expensive
  Wide choice of elastomers for diaphragm material which could be a benefit if pumping strong oxidizing agents for example. Rely almost exclusively on PTFE.


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