Bairds tackles water wear on pumps

?Witham, UK – Clean water at ambient temperature is often regarded as easy to pump.  However, many types of pump incorporate dynamic seals that rely on the pumped liquid for lubrication. 

Being a poor lubricant, water of any kind can pose early wear problems for a seal-reliant pump - especially one operating at relatively high pressure. The issue may be resolved by fitting a different type of pump - as shown at a UK grain malting plant, where seal-less Wanner Hydra-Cell pumps are replacing piston pumps on humidification systems.

Although the water they handle is clean, piston pumps fitted as original equipment on new water-saving humidification systems at the Witham plant of Bairds Malt proved to be ‘high maintenance’ components. The pumps needed very frequent oil changes, notes maintenance manager Alan Francis, adding that seal wear was another major limitation.

Bairds has five plants in the UK, producing malts for both brewing and distilling, home and abroad.  Witham, its second-largest establishment, concentrates on brewery malts.

At the Witham plant, where each pump serves two vessels, it delivers a fine spray mist to the underside of the circular grain bed, controlling moisture content in a deep mass of up to 215 tonnes over a four-day germination period. 

Meanwhile, the product is turned and kept loose by a slowly revolving blade (1 rpm/12 hours). The pump is in action throughout this process, maintaining system pressure at 70 bar for fine spray atomisation. Flow rate, up to 10l/min, is variable by VFD motor speed controller, depending on how many spray nozzles are in use. 

The nozzles are mounted in a chamber below the bed in each germination vessel - 60 nozzles for each vessel, arranged in banks of 40 and 20, giving three levels of humidification to suit conditions. Flow to the nozzle banks is switched on or off by solenoid valves in the pressure line.

Production is arranged to allow best use of plant capacity, said Francis, which means that the humidification pump is working virtually 24/7 for months on end. In case of a problem, the company has a back-up in the low-pressure pumping system.   

“It’s important that our high-pressure pump is performing as it should and is not taken out of service at inconvenient times. Piston ring seal wear lowers performance and before long needs attention on the workshop bench.  The pump we have replaced had its seals changed three times, and each time the new set wore sooner.

Since replacing the piston pump in November 2009, Francis said the G03 had worked “round the clock, recording more than 19,000 hours (up to February 2012). “No problems have emerged, no parts replaced. The oil in the drive end has been changed once.”