pressure drop behind pump
pressure drop behind pump
(OP)
Hi, i have de following situation: vertical diesel tank with aprox. 7m height above the outlet. next i have a coalescent filter that has a pressure drop of 0,4 bar (clean) to 1,0 bar (change-out). next i have a pump for 50 l/min and 0,6 bar head. it pumps to a consumer at 50m distance and with no level difference in relation to the pump.
Would be any problem in the aspiration of the pump because of the pressure drop of the filter??
Thanks
Would be any problem in the aspiration of the pump because of the pressure drop of the filter??
Thanks





RE: pressure drop behind pump
What's the elevation difference between bottom of diesel tank and pump centerline?
And do you have the NPSHR required by the pump at 50 l/min
Independent events are seldomly independent.
RE: pressure drop behind pump
From the vague data you have provided, at worse case for the filter, high temp and low tank level, it would look like there is potential for cavitation and problems with flow. Is this built and operating or are you doing design? Normally you wouldn't put a filter like this on the suction side of the pump as it creates too much pressure drop.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: pressure drop behind pump
The difference between the bottom diesel tank and the centerline of the pumps is aprox 400mmm. (i can increase a little bit this)
This is in design stage
RE: pressure drop behind pump
Also give us the data in the attached file and then we might get somewhere. Min liquid level is what we really need in m above the pump centreline.
Oh altitude can become important so let us know what height above seal elvel you are.
I suspect you will need to move the F/C downstream of the pump and get a bigger pump, but let's see what comes back
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: pressure drop behind pump
Thanks.
Please see the attachment.
I've attached also the pump and the filter specifications. Let me tell you i'm only analysing 1 pump, but i will have 3 in parallel and the idea was to put only 1 filter for the whole system.
RE: pressure drop behind pump
RE: pressure drop behind pump
If we take piping losses (friction) as 1m (short distance, reasonable size), vapour pressure as zero.
It looks like the pump would like about 5m absolute head (it's a pretty basic pump). Pressure drop at 1 bar across your filter / c is 13m, 6m at min DP based on SG of 0.8.
So, low liquid level in tank + max DP across filter, available head is 14 - 1 - 13 = 0, < 5 required = cavitation / no flow
high liquid level, low DP, avaialble is 19 - 1 - 6 = 12, > 5 so OK.
You can do the other combinations (low liquid, low DP etc), but I think you might need a pump the other side of the F/C, or raise your tank / lower your pump by 5m for worst case condition
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: pressure drop behind pump
Independent events are seldomly independent.