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Pump pressure

Pump pressure

Pump pressure

(OP)
Hello all.

I’ve worked on trying to find this equation all day and am desperate for help 🤣.

I have a 200’ 3/8” ID hose, 100’ of it is totally vertical and the other 100’ is laying on the ground running to a pump 12” off the ground. The hose is some sort of plastic, there is no writing on the hose to verify what it is. The grease has a 80 minute viscosity and the temperature is 40 deg F. In the event that hose is fully primed, how much pressure would it take to overcome that static friction?

Thanks in advance, please share your work!

RE: Pump pressure

The viscosity there needs some work. The units of minutes is not conventional, or correct. I dont recognize "m". Have a look here. Maybe you can convert it to centiPoise.

https://www.engineersedge.com/fluid_flow/kinematic...


Use 200 feet for the length when calculating friction loss.
Plastic has an absolute roughness of around 0.0005 in/in

Add 100 feet of head, for the lift static pressure. You will need the density of the grease.
PSI = 100 ft lift x density pcf /144

There are some friction loss calculators in the additional links on that Web page.

Let us know if you need more help.

RE: Pump pressure

(OP)
Hey guys thank you, I am working nights and will jump on working on this first thing this evening and send my findings to verify accuracy, cheers!

RE: Pump pressure

What are you trying to find?

Static head is your 100ft x density. Your looking about 50 to 55 psi.

"Static friction" is a strange term.
Without flow there is no friction losses. There may be some sort of pressure required to break the gelling of the grease, but that isn't viscosity.

Now if the question is about what flow you will get or what pressure you need for a certain flowered then you either need your flow rate or the discharge pressure of the pump.

If this is grease I guess this is some sort of P D pump??

If you describe what your issue is or what you're trying to do will help everyone. When you wake up.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Pump pressure

(OP)
Littleinch, the Wireline guys are running SLB greaseless cable. Schlumberger manufacture recommendation is running a 1” hose with a high volume 1:140 grease pump. Through some other surface indicators, I am certain the cable is getting zero lubrication. The set up they have is a pneumatic hand help pump used for greased drive lines ETC. So in short I would like to know what kind of pressure it would take to move grease up that grease hose. I realize there are several more restrictions with a few fittings and a couple other factors. How would you go about working this problem? I will be back on tower @ 04:00 mountain time and can get the density of that grease.

RE: Pump pressure

OK 80 minutes is about 1000cP

That's as close to treacle as you want to be.

I have a feeling grease at that viscosity is anon newtonian fluid so need to have some shear going on to flow and then the pressure drop reduces.

I don't fully understand what a 1:140 pump is but sounds like a pressure ratio.

A house that length is not ideal. The risk is that the pressure pulse simply expand the hose and doesn't move the grease down the tube.

The only real way is to test it in action. I suspect you will need 3 ro 4 times the minimum static pressure to get any grass found down that hose. But the hose may be not the right thing.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Pump pressure

(OP)
Yessir, the 1:140 is a volume related metric. We laid our lubricator down today and put 2000 PSI on that with a pump line and were unable to move any grease. I am certain our running gear is not correct. I was just wanting to have the math ready for a conference call we have tomorrow. Sitting down to work this math out now! Sorry for the delay we are having to rig coil up. 🤬

RE: Pump pressure

The other thing to do is use your 2000psi and try half the length, then half again if no flow. Then you'll find out the pressure per length to initiate flow.

I think your grease is gelling due to the cold and you need a large differential pressure per ft of hose to break the gel. Once it breaks the pressure required could fall significantly if you can maintain flow.

These things are not easy to calculate without good data on the fluid.

What is your 80 minutes of viscosity based on in terms of temperature?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Pump pressure

I did a little more looking out of curiosity and what I said above seems to be true, ie. cold grease is a non newtonian fluid which requires a significant pressure to break the gel at which point the flow improves / pressure drop decreases so long as you keep it moving / flowing. I don't know what that pressure is and the smallness of the tube / hose won't help.

Some of these things you can't calculate and once you get into gel break pressure you need test data really with your particular hose and grease.

In my units, a 60m long 10mm ID hose full of "grease" at 5C is as close to bitumen as you will get. If you've tried 2000psi differential and it still won't move its time to find a different method. A bigger hose might help but then you need to fill it with grease.

Or trace heat and insulate it?

Or make your hose a LOT shorter - like 5m.

Let us know hw you get on.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: Pump pressure

I sense that the high viscosity of the grease will be problematic on the 100'long plastic tubing. I have not worked out the pressure value but I believe that you will experience rupture of the plastic tube. I worked for a bridge builder who had a maintenance shop with a dozen bays for his heavy equipment. The types of lubricants were rear axle grease, transmission and brake fluids. All of these lubricants were stored in 55 gallons drums and the piping supplying these fluids to the mechanics was metal which had rises of about 25 ft and runs of 200 ft. Instead of plastic think about the installation of copper or steel piping. Talk to your suppliers of the products to be used for additional input.

RE: Pump pressure

Sadly Jeremy is a one time poster who has either got his answer or gone off shift and not told us any more...

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

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