Maximum lift for diesel fuel at ambient temperature

[NoelOPEC]

If you you could draw a perfect vacuum in a vertical pipe what height could you lift automotive diesel fuel, before it would start to vaporize at 40 Deg C.

 

[ione]

???????? If you had perfect vacuum then your liquid would certainly experience vaporization as its vapor pressure is positive value (approx 0.114 psi at 40 °C)

 

[hydromech]

I suspect that 'perfect vacuum' means good sealing on the pump inlet, not letting air in.

Of course, at absolute zero the diesel would be boiling anyway.

Starting at atmospheric pressure, the lift height can only be a maximum of 10m.

0.114 PSI = 0.00786 BAR(NOT CHECKED)

Under gravity 1 BAR = 10m HEAD

This suggests that you could lift the fluid almost 10m, how accurate do you need to be?

Adrian

 

[BigInch]

Noel, a perfect vacuum is not possible over a liquid. The lowest pressure that can be achieved would be equal to the vapor pressure of the liquid at the liquid's indicated temperature. When the vapor pressure is reached and you attempt to reduce the pressure further, the liquid simply vaporizes to fill any "empty space" above it with its vapor and thereby keeps the pressure from falling any further.

Take Ione's vapor pressure into consideration, but as I recall, various grades of diesel at high ambient temperatures can have vapor pressures of up to just under 0.5 psi, and I'll use that, just to be conservative. With 14.73 lbs/in2 of absolute atmospheric pressure on one side and 0.5 psia vapor pressure on the other, 14.73-0.5 = 14.23 psia pressure differential, which will lift diesel by roughly 14.23 psia * 144 in2/ft2 / [(Specific Gravity of Diesel_40[°]F=0.82) * (den_water_60F = * 62.4 pcf)] = 40.0 feet or appx. 12.2 meters.


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hydromech, 1 Bar will lift water 10 meters, but will lift diesel by 12.2 meters. SG for diesel is not same as SG of water.

We are more connected to everyone in the world than we've ever been before, except to the person sitting next to us. Lisa Gansky

 

[vpl]

This sounds like a school question? Is it?

Patricia Lougheed

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[BigInch]

I was thinking the same thing. It hit me right after I posted my response.

We are more connected to everyone in the world than we've ever been before, except to the person sitting next to us. Lisa Gansky

 

[BigInch]

But now that it's here, let's see how many of us get it wrong.

We are more connected to everyone in the world than we've ever been before, except to the person sitting next to us. Lisa Gansky

 

[NoelOPEC]

Thanks for the replies
I have been away for the weekend
My question was related to a pumping question for diesel fuel as I was not sure how far diesel could be lifted before it would vaporize and not be able to be pumped which is around -14.2 PSI which = 12.2M not taking into account any flow or friction loss.
Would any know of a computer program to calculate flow rates friction losses and pipe sizes for correct pumping of diesel fuel.
Noel

 

[pmover]

NoelOPEC,

if you do not know how to solve your problem, how in the heck do you expect a computer program or us to solve the problem for you?

How is your fluids class progressing?

good luck!
-pmover

 

[blacksmith37]

I am pretty old, but when I was in school; pumps pushed, they didn't suck, so pump capabilites relied on NPSH.

 

[NoelOPEC]

I believe you are still correct Blacksmith37, in my industry most pumping problems are on the low pressure side of systems, the NPSH is the starting point for a pumping system for me, although working out the NPSH can be ambiguous at times, obtaining accurate losses for all the equipment and fitting on the low pressure side can be time consuming, the forum has people with a vast amount of knowledge and experience that is shared freely, it is a great place to solve problems and gain knowledge.
Noel