diaphragm pump question

[micjk]

With a triplex diaphragm setup (this paticular setup has 3 EV2 pumps 120 deg phase difference) is it possible for a worn coupling to affect the "timing" enough to cause flow deviations. These deviations are within our tolerances, but we would rather see a smoother trend. The couplings are EPDM grid type made by TB woods. I've taken vibe data on the heads close to the discharge ball check to try and pick up anything out of the ordinary. What I have found is that Head 1 and H2 have basically "sinusoidal" harmonic amplitudes of 1X whereas H3 shows peak then basically straight fall of harmonics. After replacing grids H3 became "sinusoidal". Is it possible that worn grid could cause a "lag" effect with third head attributing to trend deviations. We are considering "hard" type coupling to eliminating this. Just curious if anyone else has experienced this phenomenom. Or should we be looking elsewhere Roy Gariepy
Maintenance and Reliability Dept.
Bayer Corporation Dorlastan Fibers Div.
Goose Creek, South Carolina USA

 

[inControl]

Hi,

If you want a smoother (non-pulsating) flow, then gear-pumps or tri-lobe pumps might be a good idea?

Cheers!

 

[saxon]

micjk, with reciprocating action in pumps, you will always have pulsating type flow which shows up in the frequency response. This type of behaivor is more pronounced in the lower number of pump systems, such as duplex or triplex, but is also apparent in the higher number systems such as, septuplex and nonuplex systems, but the pulsating flow is not as pronounced.

One solution to the problem is to install pulsation dampeners on the suction and discharge side of the pumps, or to install, or modify the piping such that it becomes a Helmholtz Resonator, Quarter Wave Stub, Surge volume, or a Helmholtz Filter. The choice of any of these items is dependant upon the Attenuation characteristics exhibited by the system and the properties of the process medium. There is a good study on this in the Cameron Hydraulic Data book put out by Ingersoll-Dresser Pumps.

Another solution is to replace the reciprocating action with rotary action. Since the diaphragm pump was probably spec'd. for the fluid characteristics, a progressing cavity pump would probably do the job for you, if you want to make the capital investment.

Hope this helps.

saxon