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Flexible metering pumps
Keywords Michael Smith Engineers, Pumps, Metering
A new range of mechanically flexed leak-proof diaphragm pumps which are said to provide accurate, repetitive and reliable metering of liquid chemicals at low costs, have recently been introduced by liquids handling specialists Michael Smith Engineers (Plate 2).
Plate 2 Flexible metering pumps from Michael Smith Engineers
The Medo range of pumps can be supplied in three different configurations, with six models covering capacities from 0.7 lit/hr up to 15 lit/hr at discharge pressures between 5 and 12 bar. These pumps have an adjustable stroke length of between 20 and 100 per cent and a stroke frequency ranging from 5 to 125 strokes per minute, so a turndown of 125 to 1 is believed to be possible. It is also reported that in addition to continuous dosing operation the pumps can also dose proportionally to reed switch contact impulses and 0-20mA analogue signals.
Wetted materials include PVC heads and joints, EPDM O-rings and seats, glass balls and PTFE coated diaphragms. The manufacturers consider that this means that the pumps are well suited to handling aggressive and corrosive fluids used in water and effluent treatment applications, such as sodium hypochlorite, hydrochloric acid, sulphuric acid, hydrogen peroxide and caustic soda. The pump motors incorporate an accumulator which stores energy on the back stroke and releases energy on the forward motion. This additional thrust force generated by the motor reportedly improves efficiency and allows the use of motors with smaller wattage than previously possible for comparable duties.
In the event of over-pressure or closed valve condition the pumps are said to be automatically switched off and the status of an internal contact is switched so that an alarm can be raised. This protects the pumps from mechanical or electrical damage and eliminates the need for relief valve protection.
The pumps are IP65 rated so they can operate outside and in wet or damp locations. Other features claimed include the ability of the pump head to be rotated through 90° to enable horizontal or vertical mounting to suit the application and a pump base size which means they can be fixed directly onto a water meter.
Details available from: Michael Smith Engineers Ltd, Tel: Freephone: 0800 316 7891; Fax: +44 (0)1483 723110; E-mail: info@-michael-smith-engineers.co.uk