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Re-Fuelling flow rate vs Pressure

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Re-Fuelling flow rate vs Pressure

Old 14th Mar 2018, 14:58
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Re-Fuelling flow rate vs Pressure

Ladies and Gentlemen,

I would like to ask if any of you people have a formula for converting fuel bowser flow rates into psi for a standard pressure refuelling bowser.

The reason for my question is that many business jets have a pressure limitation for refuelling but I have never seen a pressure guage on a bowser, only a flow meter. I have often told the refueller’s to turn down the flow rate when refuelling to ensure safety and I advise others to do it. However it would be nice if I was actually able to see if the refuelling pressure is in limits.

Thank you

MM
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Old 14th Mar 2018, 15:11
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Online Conversion - convert flow rate to pressure ?

I suppose you would need to know the size of the pipes and the difference in flow rate between inlet and outlet.
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Old 14th Mar 2018, 16:31
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Why dont you trust the automation , has there been incidents on you type?
I would imagine that it is certified for pressure refueling as per whatever standard, or NOT.
The 737-800 takes max 930 liters a minutes, I forgot the Psi.
A lot of places it is slower.
But I never interfere with the job.
A simple process,best left to professionals.
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Old 14th Mar 2018, 19:03
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Bluesideup

You are quite correct in that I do not trust the automatics. I have always tested the automatic cut off at start of refuelling but I am aware of several cases over the years, one very recently, where a fuel system rupture has happned; Probably due to exess pressure or hydraulic hammering during refuelling.

It is true that you need to know the bore of the pipe but I am not clever enough myself to work out flow rate along a known bore pipe into pressure.

MM
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Old 14th Mar 2018, 22:07
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If you want to know what the pressure is in any given piping system, it's not simply a case of knowing all the pipe diameters involved. You also need to know the pipe roughness, the fluid properties, the way that any changes in diameter take place, how many & how sharp bends are. You even need to know header tank pipe entry geometry and discharge geometry plus the pressure in the header tank & receiver.

Not Seemples.
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Old 14th Mar 2018, 22:07
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Actually the pressure within your aircraft’s fuel manifold (which is the pressure of interest here) for a given flow rate will be specific to your aircraft more so than to the fuel truck. And that pressure to flow rate will depend on how you have your fuel system. Example, the plane I fly can have fuel flowing to up to 8 tanks at tha same time. The pressure/fuel flow relationsip will be different when only one fill valve to one tank is open than when all 8 valves are open. But we don’t have to worry about the pressure fuel flow limit as our refuelling panel has a pressure gauge which displays the fuel pressure at the hose fitting ( or very close to it anyway.) So as long as the gauge reads below the max pressure limitation you don’t need to worry about flow rates.
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Old 15th Mar 2018, 01:05
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Safe pressure limitations for refueling the 737 is circa 50 odd PSI, although for manual fueling ops, where the uplift is controlled by the bowser, higher pressures can be tolerated. Most US airport kerosene hydrants routinely provide between 1,500 and upwards of 3,000 liters per minute.
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Old 16th Mar 2018, 00:53
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Originally Posted by TURIN
Online Conversion - convert flow rate to pressure ?

I suppose you would need to know the size of the pipes and the difference in flow rate between inlet and outlet.
If there's a difference in flow rate between inlet and outlet, there's a leak!
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Old 19th Mar 2018, 11:25
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Originally Posted by Chu Chu
If there's a difference in flow rate between inlet and outlet, there's a leak!
Or more than one outlet.
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Old 20th Mar 2018, 09:44
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Fuel line rupture!

Miles
Now that is something to be avoided.
Was that on Your type and which type would that be, a bit curious.
I have not done any refueling myself lately, but in some French airports we have to do the switching our self after the fueler has connected.
Have sometimes wondered about the effect of a leak/ rupture as i stand on that ladder,,,

Anyways
Turns out I forgot the numbers on the 737-800.
It is supposed to be max refuel rate of 918kg/min or 1135Liter/min and max 55psi.
Bill Bulfers " Cockpit Companion" set me straight.

Lastely:
Have fun out there!!
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