Minimum Rotating Speed For Splash Ring Lube Oil System

It is unlikely that the specification is available in any form of published article.

However, from the information posted, the operating organisation realises that the multistage pump is to be operated above 400rpm to prevent damage. This is called experience, and it's valuable.

300rpm has been mentioned. If 400rpm is too fast for this particular application, then the engineer needs to consider a number of possibilities:

• What modifications need to take place to the lubrication system to ensure it is effective at the lower speeds?
• What substitutions of equipment are available that would enable the same process conditions to be achieved while operating within an acceptable lubrication/speed envelope?
• What process conditions might be changed that would enable the existing pump to operate within its acceptable lubrication/speed envelope?

The correct forum for such a review to take place is a http://en.wikipedia.org/wiki/Hazop Study. Don't leave anyone out!

Hi Ronizam,

I am very interested in this subjected and wonder where you and your plant are.I was part of a team that did a few tests with a pump that had a clear upper section of and we found that up to 200 rpm the lubrication started but was very poor.Whar material are you using for your journal bearings.What pumps are you using and what are you pumping.

I am in Africa and we have developed a product that replaces journals made of metal.

Best

Flegelo

I would think that the effective rpm would change with the viscosity of the oil being used.

I agree, looks like a multi-viscosity oil would be a primary consideration.

LETS NOT FORGET PUMP DESIGN?OR SPLASH RING IN THIS CASE? IS OIL AT PROPER LEVEL IN SIGHT GLASS OR IS IT POSSIBLE DIP STICK IS BROKE MISSALIGNED OR WRONG ONE SEEN THAT ONE IN THE PAST SOS caps on

Hi,

the splash ring will be much more effective at low speed if you sharpen the edge.

Or you can install a scraper that removes some oil from the sides of the splash ring and
redirects it to the bearings.

RHABE

Since we are on this topic, what is the advantage of using a splash ring versus the disc. My own opinion, the disc is more reliable as it is continuosly turning with the shaft (attached by grub screws) whereas the splash ring has the tendency of not turning if oil level is top up too high or will be jumping if oil level is too low.

Thanks for all the comments in this discussion so far.

Dear members/guests of CR4, hydodynamic bearings are my business and I would like to add two items to the raised discussion:

1.) There is no reliable information available where bearing lubrication by splash ring or a fixed oil disk is working sufficiently. On one hand this knowledge is experimental knowledge in hands of bearing makers - and this experience depends a lot on bearing and oil ring design. Means: there is no method known how to calculate the oil supply ratio on hands of known application parameters like design, viscosity, etc. Further more the TRUE minimum demand on lubrication for an idividual hydrodynamic bearing application (to prevent it from damage) can't be calculated either.
These two constrains makes it very difficult/impossible to set up reliable rules which would meet the reality sufficiently!

2.) The operation of a splash ring (also known as "loose oil ring" - in difference to a fixed disk the splash ring does not retate with same angular speed than the driving shaft) is dependent, so far as known, on a couple of applications parameters but not on shaft speed. Instead the shaft speed the shaft surface velocity is important. This means, we should know the diameter of the shaft together with the rotation speed. It would be of help as well to find some information about the bearing design: ratio diameter to width, how the splash ring is arranged in the bearing, what oil viscosity is used, what geometry and material for the ring, the immersion depth of the ring. Is the bearing a journal bearing only or is a thrust section to be lubricated as well? A sketch would be fine.

The preference whether to apply a splash ring or a fix lubrication disk depends on bearing design, journal surface velocity, how the oil will be discharged from the ring and where the oil has to go before it finds the lubrication pockets. It would be a wrong approach saying a fix-disk would perform better than a splash ring - without knowledge of conditions as mentioned above!

Albert

Most informative. Thanks Albert.

Do you have a possibility to calculate onset of half frequency whirl and whip in your hydrodynamic bearings?

RHABE

You should indicate :

- the type of splash ring used for your research with diameter and viscosity of oil during tests

- the type of splash ring in the pump with diameter

The requirement of lubrication is less at lower speeds but should not go under a limit characteristic for the type of bearing you consider and the load actually acting on the bearing.

The analysis is a good suggestion but first you should compare what you get with what you need. Did the pump supplier give any indications ? as for instance load versus speed ?

One moor quick thought that I have seen is mechanic used sealed brg and not open ended with no oil to get in sealed brg will last for a awile before failing.

Oil has to fulfill different goals in a bearing. Among others to evacuate the heat generated by friction. A minimal flow is needed so that the temperature will not grow too much and reduce under the acceptable limits the oil viscosity which is very important for the oil film load carying capability.

Lubrication & Reliability HB by MJ neale has some very good graphs on this.

GB Agoram

The parameters to check are

1) pressure on babit bearing should be < 200 psi

2) whether D*N value is safe

3) whether oil visc at bearing temp is sufficient

Also try grooved oil splash rings or flingers.

Following link may help

http://books.google.co.in/books?id=VfEf3CRjjfAC&amp;printsec=frontcover&dq=mj+neale#PPT264,M1

http://www.heinzbloch.com/docs/Reliability_Advantage_Volume_2.pdf

GB Agoram