Pump Problems

Is this pump somehow creating a greater pressure differential than the other? Perhaps a restrictrion on the outlet...?

If the bearing is subject to a greater thrust then it stands to reason that it gets a bit hotter.

Is the 10 degrees taking the bearing above it's specified working temp? or it has failed a few times? How has this come up on your radar?

Hi, aXion_K!

And further to this, what is the load (on both sides...in and out) comparison between the two pumps? Heavier load, warmer bearings. [Unless, of course, the fluid being pumped is warmer in one of the pumps! ]

Mark

thank you for your cooperation

The load and temp of both pumps is same .

Thank you for your cooperation

The differential pressure of both pumps is same and discharg pipe is common.

May be the trust load of this pump slightly greater than other.both pumps was repaired earlier,beacuse pumps was jammed in initial commissioning and some internal parts was machied such as wear rings and balancing drums.but the clearances are almost specified,may there is afew difference about 0.15mm.

this temp is not specified,it is 90 degree C.

check the outer shell of that bearing, it might be rotating due tolerance problem, that shell should not rotate, the rotation makes friction, then heats up

I guess the problem is caused by the pump being not summetrical, thus pressure will create more friction on one side. How about axial bearings, are they ok?

Thank you for your cooperation

I think so.but the axial bearings are ok.

Hello,

What about the tank?If the B does the most work , the A which has got the same construction parameters does not (check the tank - outlet pipe) have enough fluid to handle - and you have tempreature rising.

Second- if you have bypass this also takes temp. higher.

thank you for your cooperation

If you are reading bearing drain temperature you are reading a mixture of oil that was actually in the pressure area of the bearing and all other oil supplied to the bearing. This can easily give an error of 10 degrees. Also some bearings are equipted with orfices in the inlet to limit the effect of that bearing failing, so if you are not reading metal temperature, establish what is normal for that machine, spit on the bearing if it doesn't spit back keep on trucking.

What, in fact, are the bearing temperatures?

Does the manufacturer specify maximum temperatures?

Are you exceeding the manufacturers recommendations re temperatures?

Are we talking degrees C or F?

Are the ambient conditions the same for both pumps?

Is the flow rate of coolant exactly the same to both pumps?

Is the pump gland a conventionally packed gland with a lantern ring? If so is the lantern ring aligned correctly in the stuffing box?

Are the pumps compounded for pressure or volume?

Are the suction and discharge pressures the same on each pump?

If your temperatures are such that the bearing is not overheating...........and that maybe quite on the cards..........don't worry about it.............something minor may be the problem, that you you cannot pick up. Unless temperatures are at the upper of recommended temperatures 10⁰C or F is generally nothing to worry about.

If the temperature does start to increase............search for a problem then. I have had simlar pump bearing temperatures over a greater spread than 10⁰C/F.

Remember although they may be the same types of pumps...........very seldom do they run exactly the same..........each pump is an "individual."

Thank you for your attention and cooperation

I answer your questions as above:

The bearing temp is now 90 degree c

Not exactly but I am worry about max allowable temp of oil,Now we need air flow to decreas temp to 80 c in bearig housing.

Yes

Degree c

Yes

Yes exactly

No

Yes

Yes

The bearing life is normal beacuse we dont permit temp rise higher than 80 c by air flowing.

Thank you for answering those questions, 90⁰C does not seem to be an excessively high temperature, certainly not for an oil lubricated bearing, or for that matter ,a grease lubricated bearing either...........personally I would not worry about it.

If you are concerned just keep a regular check on the bearing temperature for a couple of days..........if nothing out of the ordinary occurs (and I do not think it will)...............problem solved.

Honestly, my friend.........you do not have a problem.

Cheers, sleep well.

Thanks alot for your comments

Any change in temp is related to enviroment ,and I think you are exactly right.

Thank you again and best regards

Not a problem, my friend.............that's what we are all here for............to draw on each others experience and knowledge.

Cheers

Hi Saberian No two pumps will ever run at the same duty point there will always be differences due to pipe work etc if the hotter pump is not exceeding the bearing manufacturers maximum temp rating I suggest you dont worry about it. If you are burning out bearings then you need to dismantle the pump and check everything against specifications until you locate the problem

Thank you for your cooperation

The bearing temp is not specified ,its about 90 c,and oil is VG 68.

How about swapping place of the two pumps. Maybe the heat increase is only because the liquid temperature is rising through both pumps as a result of friction and pressure rice.

TCB

Hello

Please specify the temperature of each bearing for both pump.

And ore more thing, did you read the vibration of each pump? What is the level of vibration for every pump for the related bearings?

Assuming you are reading oil drain temperatures, a rule of thumb we used in the US Navy was the temp. rise across the bearing shouldn't exceed 50 deg F. The maximum outlet temp. at the drain shouldn't exceed 180 deg F.

We used that for years without a lot of problems.

Why is the temperature difference perceived as something worth eliminating?