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Pump performace
2

Pump performace

Pump performace

(OP)
Hello Friends,
I have a question for you regarding lubricants additives.

At this point I have a gear pump 1.5'' 1.5 Kw 3P (victor pump R40G44BF+Y do be exact). Inlet pipe is 4 meters long(1.5'') made of plastic reinforced tube. The outlet is 5 meters long same plastic tube that is then connected to 8 meters CS 2'' pipe (4 meter horizontally and 4 meters vertically).
I connect the inlet tube to a tilted drum of viscous liquid. It takes 1 Hr to empty the drum (about 3kg/min).

This is how I currently operate.
In order to make things better, I was offered a progressive cavity pump that is expected to deliver about 13 l/min. The supplier has said that my pump is “choked” by the suction tube and the several meters of hose. The pressure losses are quite remarkable he said.

If I shorten the suction tube how much difference will it make?
I have another gear pump that is 2'' diameter, I don't use it because 2'' plastic tube is hard to operate, but Is there a calculation that can be done to calculate the expected delivery rate?

Thanks

Best Regards
Roman Katz

RE: Pump performace

I don't think your problem is your pump. That said...

You left out some critical information - how viscous is the liquid? What is the discharge pressure? If this is a very high viscosity liquid, then yes, you can be supply-side limited on liquid flow. Gear pumps can usually only pull 20'-ish of suction, so that is the available "pull" on the suction side to get your liquid to flow.

I do not believe replacing the pump will net you additional flow - a 1.5" 2HP gear pump can pump far more than 3 kg/min with normal liquids, even normal viscous liquids.

Last question - what are the pump head rpms? In situations like this, you can sometimes see improvement in flow rate by slowing down the pump.

RE: Pump performace

This is what drum pumps are for. They fit inside of the drum through the bung hole and can be driven by an electric motor or compressed air. Compressed air is often the best choice as it is simpler, safer, lighter and will stall (stop automatically) when the discharge is closed.

The fact that the pump is inside the drum means no suction piping. For very viscous materials the suction can be equipped with a reciprocating scoop that actually extends out of the suction of the pump into the fluid and the scoops the material into the pump. Grease pumps will use this, in addition to a follower plate, which fits into open head drums and scrapes the walls as the level falls. This is for materials that will not slump due to gravity.

https://www.amazon.com/Grease-Pump/s?k=Grease+Pump

RE: Pump performace

This is the performnce sheet http://www.vicm.de/d/409292.pdf

Which one is your pump and fluid?

What do you mean by "tilted"? How tilted"

Yes you can estimate the impacts of different hose lengths and sizes, but you need to know your fluid - "Viscous liquid" isn't good enough. You need to know how visocus and at what temperature you can pump it at. That is an easy way to win more flow is another 20-30C

But assuming this is like some sort of treacle, the shorter your inlet pipe the better.

As stated earlier you have a maximum on the inlet side of a bit less than 1 bar pushing the fluid through the pipe to the pump. On the discharge side it is whatever the pump can suppply. Note however that most gear pumps have an internal relief valve to stop you destroying the pump if you try to get it to pump against too big a back pressure or turn the outlet valve off.

Looking at the data from victor if you're doing 3kg/hr,are you running at 720 Rpm?

Unless the supplier has a lot more information than we do?? then he is just guessing and trying to sell you anew pump. That's what salesman do.

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

RE: Pump performace

(OP)
The viscosity is about 11,000CST at room temp. This stuff is like a diluted honey.
It comes in a drum and I use a drum lifting device to lift and tilt it like 45deg.

Checked the outlet pressure it was about 0.7 bar.

This pump is connected via omega to the motor, there is transmission ratio between the motor and the gear, so RPM of the motor is not the RPM of the pump. right? I assume to increase the torque?

Best Regards
Roman Katz

RE: Pump performace

Hi ,
By chance can you heat the drum to improve the fluidity of the material ? Hot box or Electrical blanket or Hot Bath .

Pierre

RE: Pump performace

(OP)
I have a hot box that use for other materials, the question is will shortening the tube or enlarging the diameter to 2'' can improve delivery?

Best Regards
Roman Katz

RE: Pump performace

What is "via omega?"

You need to know the RPM of the motor so that you can see if the pump is performing as it should according to the data sheet I linked to.

Hence also need density of the product as the pump information is in m3/hr or l/min

Lower speed is required more that the viscous fluid can enter the pump without causing a vacuum to develop at the pump inlet.

That pump is good for 8 bar so you're not being held back by the discharge pipe.

It is always best to reduce inlet losses. Looking at your data, 3kg/min means a drum of 180 kg? and flow of about 3 l/min?

For a viscosity of 12000CSt the lowest rpm shows 18l/min therefore something looks to be seriously wrong.

What is the minimum length of inlet tubing you can get?

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

RE: Pump performace

Hi,
Yes indeed the reduction of the pipe length, the diameter increase and the reduction of the viscosity will improve the performance of your system , less head losses !
Pierre

RE: Pump performace

LI, I believe he is referring to the gearbox between the pump head and the motor when he says "omega".

RomanKatz, I believe you need to determine rpms on the pump. Look at the gearbox to get a gear reduction ratio (or model number that you can get the gearing ratio from the manufacturer). Is the pump on a VFD or just a motor starter? Steps I would take, in order, would look something like this:

  • Heat the drum of material via heat band/hot box/whatever - check with the supplier for max allowable product temperature.
  • If flow does not improve with temperature, explore reducing rpms on the pump, if possible.
  • If reduction in rpms is not possible or does not improve flow, look at upsizing/shortening the suction piping.
  • If the suction piping change does not improve flow, look at purchasing an in-drum pumping system similar to what CompositePro suggested.

RE: Pump performace

I worked that out but have no idea what this mysterious "omega" is.

The model no is known, the pump performance with the fluid is known, what is missing is the pump rpm.

but unless this omega thing is making it do about 60 rpm, the pump is seriously underperforming if the given flow rate of 3kg/min is correct.

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

RE: Pump performace

(OP)
Got the info from the quote for the pump:

The gear is 2 Hp, 1450/450.
I quote, "pump can be used up to 18000CST producing 40LPM at 4 bar".

It's the viscous material that I get 3kg/min, there are other additives that run 40LPM, much less viscous.

Best Regards
Roman Katz

RE: Pump performace

What that means is that the pump can operate between 1450 and 450 rpm. Not sure how you're controlling speed but at 450 it should be delivering 40 l/min.

At an SG of 1 that's 40kg/min. You're doing less than 10%.

Time to shorten the inlet hose or make it bigger as much as you can, not buy another pump. IMHO.

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

RE: Pump performace

Have you or the pump vendor applied the appropriate "internal slip" derate on pump capacity to account for high viscosity of 11e3 cSt?

RE: Pump performace

Georgeverghese, I believe slip is only applied to fluids with viscosities of 300 cP or less. High viscosity fluids do not exhibit internal recirculation (slip) due to their nature (high viscosity, tight tolerances).

RE: Pump performace

Well we don't know the actual ID of the inlet pipe but using about ID of 1.5" 40l/min needs a velocity of about 0.6m/sec.

For a fluid with a viscosity of 11000 CST that sends very high and for 4m length would need a significant pressure.

So the OP needs the largest shortest tube he can possibly get to get a higher flow rate. The pump is not the issue.

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

RE: Pump performace

The OP's pump flow is being limited by cavitation in the suction line, so the pump specs are irrelevant. Higher viscosity decreases slip inside the pump, not increase.

RE: Pump performace

Well the pump specs are relevant because they show the pump is only pumping less than 10% of what it is set up to do.

Roman has confirmed that less viscous fluids pump at 40l/min so the RPM would seem to be 450.

On the data we have the velocity in the inlet tube in reality is about 6cm per second, which for a fluid described as "diluted honey" sounds about right...

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

RE: Pump performace

(OP)
I have changed the inlet tube from 1.5'' to 2'' and of much shorter length, just 1 meter long. Changed the outlet tube as well for 2'', about 50 cm long to the CS pipes.

It worked great, just 15 min per drum that during the summer took 1 hr.

Thank you all.

Best Regards
Roman Katz

RE: Pump performace

I'm glad it's better, but it really should be doing even better than that.

You're not likely to get to 40l / kg/ min with that stuff, but with an even shorter or bigger inlet hose you could get it down to 10 minutes per drum...

Could you actually just tip it all into a bigger bucket directly attached to the pump? A bit like a hopper on a concrete pump? then it becomes how fast will it pour out of the drum before your pump starts pumping air...

But glad we've saved you the expense on a new pump when it wasn't the pumps fault.

Thanks for letting us know how it went, so many posters just vanish and we never know what happened.

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

RE: Pump performace

Hi,
Thanks for the feedback!
Did you try to warm up the product in the hot box prior to use after pipe modification?
Good luck
Pierre

RE: Pump performace

(OP)
I am considering ordering dump dumpers to easy the flow of the material from the drum to the pump.

There is no much difference for me if it is 10 of 15 min per drum, the fact that it works means that I can change the filling process from the bottom to the top and that's what I am working on now.

I know that when a question is raised and people assist, they want and need to know how it turned out so I wanted to share the outcome with all of you.

Best Regards
Roman Katz

RE: Pump performace

(OP)
Hello Friends,

Following this thread, I have installed a 2'' pump. same model gear pump.

It worked great, Amazing. Like 7 min per drum.
After some time(2-3 months) I have noticed a strange noise. Pump has 1 m inlet plastic tube and 1 m outlet tube. When I connect the drum and turn the pump on, there is a pressure build up on the outlet side of the pump. The outlet 1 m tube is under high tension and the pump is like vibrating and moves from side to side. I can't say that the material is more viscous than before, same drums and same additives.
I thought that the floor is dirty and the pump slips so I cleaned the floor. But that wasn't it.

Any idea why is this happening?

Best Regards
Roman Katz

RE: Pump performace

Not easy to say, but sounds like a blockage to me in the discharge line.

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

RE: Pump performace

Hi,
Did you clear and clean the gears ? That's part of normal operation .
If you suspect the pipe , it should not be too expensive to replace 2*1m plastic tube to see if there a noticeable improvement .
My 2 cents
Breizh

RE: Pump performace

If the outlet pipe is "under high tension" it implies the blockage is further downstream.

The pump should have an internal bypass line to prevent it stalling, but action of this would create some movement of the pump.

If it has no internal line then the gears are possibly jamming then moving, then jamming as the pressure gets too high. Not a good move.

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

RE: Pump performace

(OP)
I think that because of the hot summer here, I am not heating the additives anymore. so I think that the additive is less viscous, but still viscous enough to cause this pressure.

If I replace the plastic outlet tube with a much tougher one, threaded and fix the pump to the floor will that work?
Or the pressure will damage the gear?

Best Regards
Roman Katz

RE: Pump performace

If the pump has an internal relief valve then you're OK. But if not they yes, you could damage the pump.

but it's not a good idea to let the pressure get that high - much better to heat it a bit.

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

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