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CHANNEL CAVITATION:

Characteristic

"NEAR 1000 Hz." THIS IS NOT NOT NOT "CAVITATION" AS, THE TERM IS GENERALLY USED PUMP MANUFACTURERS, but is as used by control valve manufacturers.

DESCRIPTION

i) Short bursts
ii) High frequency
iii) Moderate to low amplitude
iv) 4:1 Dp ratio

a) CAUSE

Supply Pipe too small diam.or pump being run above design speed for the valves - valve opens too slowly, but supply pressure high enough, once the supply column starts to surge forward, to bounce valve once. Strongish spring makes tiny gap before close. What we are seeing is disturbance from bubble implosions inside the pump chamber.

b) DETRIMENT

Valve seat replacement. Certainly prohibits use of straight tube coriolis type mass transfer meters - which have aprox the same frequency for their excitation.

c) SOLUTION

Live with it unless above residual allowable amplitude spec. Use a run-time of PulseView. Weaken the valve springs - or - put a suction loss Preventor close to the pump so that line size back from there doesn't have to respond to instant need for mass acceleration.

d) INPUT DATA NEEDED

As many details as possible It always hinges on the DETAIL DETAIL DETAIL

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Liquid Dynamics provides pipeline and pump user problem analysis, diagnostics, and prediction by software. For water hammer and shock solutions pulsation dampening and shock alleviating devices can be obtained from our associate websites PulseGuard and ShockGuard.

For Hardware see our associate websites:

www.PulseGuard.com and www.PulseGuard.co.uk for further information about pulsation dampeners and pumping systems.

www.Shock-Guard.com and www.ShockGuard.co.uk to find large gas bag vessels, jumbo bladders, float separator and big bellows type pipeline shock attenuators and expansion / contraction volume compensators.

www.Pulsation-Dampers.co.uk for more about pulse dampers in pumping systems and water hammer.

Water Hammer  and www.Shock-Alleviators.co.uk for more on water hammer, pump start up surge, shut down back flow, & valve closure hammer.

www.Accumulators-Hyd.com and www.Accumulators.co.uk for information about energy saving in pumping systems, standby emergency power, and safety shutdown systems.

www.Pulsation-Shock.com for a quick view of how each different type of pulse dampener is matched to a pump installation. Pumps make flow, system resistance to flow is pressure, systems make pressure and pressure pulsation.

www.Flow-Guard.com to find protection against excess flow. Guard against toxic spills when pipes burst, guard against gushers and fluid loss when hoses split, Flow-Guard guards against excess flow floods.