Valve types diaphragm

The most popular types for bioprocessing plants are the diaphragm and ball valves types. The latter are more robust but contain crevices making sterilisation more difficult. Barnsleystated a preference for diaphragm valves since they are reasonably crevice free the material EPDM (ethylene propylene diene modified) was the preferred diaphragm material. 

Straight-through diaphragm valve— flexible diaphragm extends across the pipe. There is very little pressure drop across this type of valve. 

Valve Type A.A Butterfly O Ball Q Globa V Disc 0 Cone X,+ Diaphragm... 

However, for optimum control and accuracy a dispense valve is fitted and there are many different types available including pinch valves, poppet valves and diaphragm valves. Valve control can be manually triggered from a foot switch or automatically activated via a proximity switch as the component is offered up to the nozzle tip. 

Bellows or Dia.phra.gm Meters. Bellows meters use flexible diaphragms as the metering chambers. A series of valves and linkages control the filling and emptying of the chambers. Movement of the flexible walls is regulated for a constant displacement per stroke. Meters of this type are widely used in the gas industry as residential meters (see Gas, natural). 

A bladder or diaphragm-type aeeumulator should be supplied to provide proper lube oil supply to the bearings during expander-eompressor eoast-down in the event lube oil pressure is lost. The aeeumulator must be fitted with a preload filling system and neeessary bleed and bloek valves. 

An important eomponent in the lube oil system is the aeeumulator. It must be periodieally eheeked for proper eharge and bladder or diaphragm integrity. This ean be done at any time. With bladder-type aeeumulators, elose aeeumulator bloek valve, open drain valves, and observe the eharge pressure. If there is no pressure, eharge the bladder to the speeified pressure. If pressure cannot be maintained, the bladder is defective and must be changed. 

As regards valves, diaphragm types are the most satisfactory but most valves have to withstand extremely turbulent conditions, and as with pumps, even the best designs need to be constructed of resistant materials, or be coated with a suitably durable material such as silastomer or neoprene. 

If the pump is protected using a diaphragm-type pressure switch, then the pump will be switched on automatically. If a combination of roots pump and roughing pump is to convey highly volatile substances such as liquids with a low boiling point, then it is advisable to use a roots pump which is equipped with an integral bypass line and a valve which will respond to a pre-set pressure. Example Roots vacuum pumps RUVAC WAU / WSU. 

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