Positive displacement flowmeter pumps

Displacement flowmeters for both liquids and gases. In some cases, positive displacement pumps are employed for liquids. 

Resin and hardener flowrate Can vary as a result of worn pumps, viscosity changes with temperature, blockages or leaks in pipewoik and nozzles, sticking of non-retum valves, etc. Positive displacement, electromagnetic or coreolis flowmeters... 

The first two bubblers are filled with 80/20 isopropanol/ water, with glass wool plugs wetted with the solvent to aid dissolution of the SO2 and SO3. The third bubbler is filled with 3% hydrogen peroxide as a back-up absorption system. The sampling pump used is a positive displacement type, fitted with either a flowmeter or a flow counter. 

Centrifugal pumps with flowmeters can be used for the dosing of oleum, alkylbenzene, dilution water and caustic solution. Positive displacement pumps are more accurate, but also more expensive. Furthermore, when a positive displacement pump is used, there must be a pressure relief system to prevent the pressure in the discharge line becoming too high and there must also be a pressure (h per in the discharge line. 

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