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Programme to optimise pumps

Edited by the Engineeringtalk editorial team Dec 5, 2005

Hargraves develops OEM programme to optimise and configure a miniature diaphragm pump, miniature vacuum pump or micro air compressor using standard components.

Hargraves Technology has developed an OEM programme to optimise and configure a miniature diaphragm pump, miniature vacuum pump or micro air compressor to the fluid transport systems application using standard components.

The design permits configuration flexibility to affect the fluidic performance of the miniature diaphragm pump in different ways.

The stroke length is the principal contributor to how much flow and pressure the pump produces - the higher the offset, the higher the flow and pressure-vacuum.

Hargraves can make different stroke lengths and hold them to tight tolerances.

The internal shape of the pump head has an effect on the pressure-vacuum levels that the pump can achieve.

Various chamber geometries are available that allow pumps to reach higher pressure-vacuum levels in a smaller package size.

The stiffness of the diaphragm elastomer is measured in durometer.

The higher the durometer, the stiffer or harder the diaphragm will be.

This will result in pumps capable of higher pressures and flows.

A lower durometer diaphragm will produce lower pressures, but requires less energy to operate.

The diaphragm shape dictates the flow and pressure level that the pump or compressor can achieve.

Several shapes are available that can be used depending on the application requirements.

The flat diaphragm can operate in an alternating vacuum-pressure mode.

However, there are limits to the stroke offset that can be used with this diaphragm.

If the application requires higher flow, a moulded or shaped diaphragm can be used with a higher offset.

To eliminate premature diaphragm failures, Hargraves developed a version of the traditional ethylene propylene diene rubber material (EPDM) configuration that has been tested to last ten times longer.

The life of these diaphragms can exceed 20,000 hours depending on the application.

Viton and Teflon coated versions are also available for applications where the media is not chemically compatible with EPDM elastomers.

Viton is used in applications such as auto emissions analysers and Teflon in many ink and solvent-based applications.

There are several variables when selecting the inlet and outlet valves in the pump head.

The standard valve used is a butterfly design, which has efficient and low noise characteristics.

Hargraves though still offers its original valve shape, the flapper, in some applications.

The material that is used for the valve depends on the media being pumped.

The standard material is EPDM, but the valve is also available in Viton, Perfluro and the EPDM version mentioned above.

The durometer of the valve has an effect on the flow, noise and several other aspects of the performance.

The rev/min and torque of the DC motor have several effects on the performance of the pump.

The rev/min setting will impact the flow rate and the time to achieve pressure or vacuum.

The lower the torque, the lower the stalling pressure of the pump.

Additionally, the rev/min level will have an impact on the overall pump noise.

If a low sound level is critical, then the applications team will select a pump that can be tuned down to achieve the needed performance and reduced noise.