PTFE diaphragm pumps to handle solids?

[upm]

Gents,
We are planning to select a PTFE single diapfragm metring pump to pump gasoline. The pump will opertate at 50 meters diff. head and 1.2 m3/h flow. It pumps from the tank buttom and the stream contains solid particles, does this pump type fit the requirmentrs? Does PTFE handles such a process? the vendor (LEWA) guarantees 20,000 hours of opeartins as i questioned the realibilty of the diaphrgm. The NPSHA is very low (0.4 meters), can you pls. advice
upm

 

[abcmex]

Lewa is a well reputed supplier and I suppose they can be trusted. Diafragm pump are used in many applications with suspensions. As you already mentioned the diafragm some day will break, in case that this is a trouble for you, ask them to offer a double diafragm (with sensor) configuration. Do not forget to check with them the electrostatic accumulation problem (perhaps they offer conductive PTFE).
RGS

 

[smckennz]

To me, the NPSHA is very low for a diaphragm pump. Are you buying the pump from Lewa or a distributor? In either case, I would insist on a statement of satisfactory performance from Lewa based on your design conditions. PTFE is not a preferred material for suspended solids, as it is neither springy nor hard.However without knowing size distribution, hardness etc,etc a definitive opinion cannot be given.
Cheers

Steve

 

[saxon]

upm,Diaphram pumps are self priming to a limit, so the low Npsha should not be a problem. These type of pumps can also be used in dead heading conditions and the pressure and flow should not be a problem. They are also used extensively in slurry applications, so the particulate should not be a problem it it can pass through the pump.

The diaphrams can be subject to fatigue failure if there are pulsation problems in either the suction or discharge. Another problem can occur in the suction and discharge check valves if the particulate is sticky or fiberous (makes the valves hang up). Lewa is a reputable man'f. with many years of experience. If the proper process medium spec. was supplied, as well as flow and head requirements and Lewa did the spec'ing, the pumps should perform as intended.

Hope this helps.
saxon

 

[upm]

Thankx gents,
We are buying the pump from Lewa its self .
They confirmed the low NPSHA and the performance chart shows that this pump can handle such a low NPSH. However, what worries me is the solids, our process guyes could not estimate the soilds size and therfore, it is unknown for Lewa if the pump will nadle it..
Do you advice to ask for doube diaphragms????
upm

 

[abcmex]

both pumps work on the same principle; if a diafragm pump fail then an air operated double diafragm will face probably the same fate. No reputed supplier can guarantee anything without adequate data ;-)