Accessories

The trouble-free function of a metering pump mainly depends on correct installation conditions and process fluid characteristics. Properly selected and sized accessories turn the pump into a functional system.

 

LEWA has the know-how and the accessories for an optimum match of pump and system.

 

Dirt traps

Many fluids contain contaminants which can disrupt the function of the pump valves ranging from minor flow fluctuations to complete failure of the metering process. This can be avoided with the installation of a strainer in the suction line.

 

Pulsation dampers

Metering pumps have a pulsating flow. During each stroke, the column of fluid in the suction and the discharge lines must be accelerated and then decelerated again. Pulsation dampening can be required for two reasons:

 

	To reduce high, non-permissible pressure fluctuations
	To achieve a nearly continuous flow

 

The simplest and most economical way to meet either requirement is the use of pulsation dampers. The use of a multiplex pump will achieve a similar result.

 

Safety valves

They prevent pressure overload of pump and system. Metering pumps are positive displacement devices and always must be protected against dead-heading if there is any possibility of blockage of the discharge line during operation (e.g. due to sedimentation build-up in the pipeline, closed shut-off valves during commissioning, etc.). Hydraulically actuated diaphragm pumps are protected by a pressure limiting valve integral to their hydraulic circuit.

 

Back pressure valves

They prevent uncontrolled flow through the pump (over-metering) when – due to static or dynamic reasons – the pressure at the suction flange is higher than at the discharge flange. Usually the retaining pressures required are low.

 

Condition monitoring

Condition monitoring systems allow the monitoring of the pump by recording and evaluation of suitable physical values. Mobile offline as well as local online systems with continuous data recording and evaluation are possible.