MAX DISCHARGE PRESSURE

[gorkus]

Operating conditions:
product: gas oil
Phase: Liquid
Max Suction operating pressure: 2.4 bar G
Average operating pressure. 6 to 7bar
Max discharge pressure ( closed valve): 19 barG

Characteristics:

required total Dynamic head: 80 m


What is the working pressure or differencial pressure ? 6 to 7 bar. or 19 bar ?


thanks in advance

 

[BigInch]

Operating pressure at the discharge will be 2.4 + 6 to 7 Barg = 8.4 to 9.4 Barg. 80 meters of gasoil is around 2 bars of pressure head and you have 9.4, so you will have way more pressure than you need, in fact too much pressure. You may consider a discharge pressure control valve to cut it down to 2 barg, but don't look for any efficiency out of that pump when you cut the pressure down so much, assuming that it outputs somewhere near the flowrate you need at around 9 Barg.

You will have to design downstream piping for the shutoff head to be safe, because if the downstream pipeline outlet is closed, or clogged, you may expect to have 2.4 + 19 = 21.4 barg total discharge head at shutoff, assuming that the 19 BAR is actually a pump differential head. Note: You do NOT read discharge head off a pump curve, if that is where you got it. If 19 BARG is a measured gage head at discharge, then it already presumedly includes the 2.4 suction pressure and the pump differential head added is 16.6 BARS to get a total of 19 Barg at shutoff. If you want to design the downstream pipeline for less pressure, say 2.4 + 2 barg or so, say 5 Barg total, you will need that pressure control valve and a relief valve with set pressure equal to 5 Barg to do that safely.

So, design pressure without the control valve should be either 19 Barg, or 21.4 Barg, depending on if the 19 is a gauge pressure or a differential pressure.

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[gorkus]

sorry but is not possible 80 m of gasoil equual 2 bar.??

 

[BigInch]

Right you are. 80 ft is. Let's say 7 Bars then for the 80 meters, 2.4 + 7 = 9.4 Barg

So back to 9.4 Barg, or 19, or 21.4.
Without the pressure control and relief valve to cut that shutoff pressure to 10 Barg, you'd still have to design your pipe for the same 19, or is it 21.4. Barg to be safe.



Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso

 

[gorkus]

Well so if try to do this job with a volumetric pump , I would have to set the pump internal safety valve 19 or 21.4 barg.

Is it right?


Diferencial pressure will be 19 or 21.4 barg , ok??

thank you very much.

 

[BigInch]

Somehow you have to keep pressures less than your pipe design pressure. If you can do that with the pump relief set pressure, or by including a press control valve and external relief valve, or by raising the pipe design pressure above the pump's max discharge (shut-in) presssure, that's what you need to do.

Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso