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Anonymous Poster #1

Air Bubble in Pump Discharge

04/26/2012 6:38 AM

What are all the reasons possible to have air bubble in the discharge line of Centrifugal pump.
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bigg
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#1

Re: Air bubble in Pump discharge

04/26/2012 6:46 AM

1. Air in the pump suction

2. Leak in low pressure area of pump

Is your pump suction sub-atmospheric?
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PWSlack
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#2

Re: Air bubble in Pump discharge

04/26/2012 7:00 AM

3. No liquid in the pipe or the pump - incorrect operating procedure.

4. Temperature increase in the casing extraordinarily high.

5. Pipe velocity too low to sweep bubbles out of high spots in the discharge piping system.

6. Reverse flow in the discharge piping.

7. Pneumatic testing being carried out in the discharge piping system.

8. Hydraulic testing procedure in the discharge piping system hasn't fully purged out the air in it.

9. Discharge piping broken.

10. Discharge piping assembly incomplete.

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Anonymous Poster #1
#7
In reply to #2

Re: Air bubble in Pump discharge

05/02/2012 10:25 AM

Thank you for the reply.

Could you explain bit detail about the Reverse flow in the discharge line causing air bubble?
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PWSlack
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#8
In reply to #7

Re: Air bubble in Pump discharge

05/14/2012 8:10 AM

The pump has been connected to an air line, the pressure of which exceeds the discharge pressure of the pump?

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tquad
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#9
In reply to #7

Re: Air bubble in Pump discharge

05/21/2012 8:39 AM

Let me try to recollect .

Reverse flow you mention is probably the inlet recirculation, which is the flow recirculation at the inlet of the pump. This may happen at low flow condition or operating way of BEP ( best efficiency point) This phenomenon is like but not classical cavitation . May cause noise , bubbling etc
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mathewkyle
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#3

Re: Air bubble in Pump discharge

04/26/2012 7:24 AM

Had the same problem once. Was hell of an issue. The pipe (PVC) was refitted after some maintence, but was not sealed well at a joint (coupler). Air got in and mad my day terrible. I had to keep refilling the inlet to bleed off the air.

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mike k
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#4

Re: Air Bubble in Pump Discharge

04/26/2012 9:53 AM

Air can sneak in the seal on the shaft if suction vacuum is high. It may not leak water out, but can leak air in.

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durtieduck
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#5

Re: Air Bubble in Pump Discharge

04/28/2012 4:37 PM

all good answers. could it be from cavitation?
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#6
In reply to #5

Re: Air Bubble in Pump Discharge

04/29/2012 4:11 PM

If a supersaturation of dissolved gasses (air) existed in the fluid being pumped then cavitation could cause air bubbles in the discharge.

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