We have a vertical turbine pump that requires a long ladder to get to the grease fittings (30 foot). What would be wrong with running tubing down to the 5 foot level (25 feet of tubing) so we don't have to use the long ladder to regrease the electric motor bearings?

quote:

---

Originally posted by Mike Dacus:
We have a vertical turbine pump that requires a long ladder to get to the grease fittings (30 foot). What would be wrong with running tubing down to the 5 foot level (25 feet of tubing) so we don't have to use the long ladder to regrease the electric motor bearings?

---

Certainly, it is possible to do it, but is it wise? Remember that while you are greasing this bearings, you also perform some type of inspection (checking temperature and signs of overheating, contamination/environment, “funny” odors and vibration). Also, while you are down, overgreasing of bearing is less likely to happen. I am not sure you can do all of those important steps from the above deck.

Thanks for the reply. Perhaps more info would be helpful:
This pump is driven by a 1500 HP motor.
It sits on top of an eddy-current clutch which is on top of the pump base, thus the 30 feet to the top of the motor. We used to reach it from a bucket truck but new equipment in the area makes it unreachable from the bucket truck. We have no platforms around the pump/motor.

The greasing can be accomplished by routing the tubing to the bearing and grease using an "ultrasonic based system". This could be done by fitting a permanent vibration transducer onto the bearing housing and monitoring the HFD value while greasing (the size and criticality of this motor more than likely justify online monitoring). Alternatively, probably the better choice for the specific application, you could fit a permanent transducer detecting in the ultrasonic range (most ultrasonic instruments sense from 20 kHz up to 100 kHz). This will enable you to grease based on the condition (relative to the UT "noise" or dB emitted) prevent over-greasing.

An ultrasonic system based on detection and analysis of modulations of bearing resonance frequencies provides subtle detection capabilities, whereas conventional methods are incapable of detecting very slight faults.

However, involve your OEM! Warranty claims related to a bearing failure, on "over- / under lubrication", can result in dragged out disputes. Calculate the optimal grease quantity in conjunction to OEM specs and apply using ultrasonic monitoring.

Be SAFE!

This message has been edited. Last edited by: Stefan Minnaar,

Lubrication by ultrasonic detection would be the preferred method. I must ask a question that has not been raised. What type of environment is this motor in? Is it outside with no protection? What is the temperature range, if it is outside? If it is extreme cold temperatures wouldn't this have negative effects by running 25 ft of tubing? With this length of tubing will it be thoroughly purged?
You can install an automated lubrication system, at ground level, to correct the safety issue you have with accessability, if the surrounding environment is not an issue.

Jim

The motor is outside. The weather is "Arkansas" so it is not extremely cold very often. We see very few days that approach zero degrees F. It does get pretty warm for several days per year. We have a few days each year over 100 F. Maybe 30 days over 90 F.

By purging the tubing, do mean purging the tubing initially or each time the bearing is greased.

We typically regrease the bearings every 6 months. This motor does not run 24/7/365. It runs less than 50% of the year.

Good Question Mike,

You have highlited a condition prevelent in the industry. If I can't make it simple and safe it won't get done. Some fairly expensive solutions have been proposed. However to support the direction you are asking about we have installed many many many long lube lines to equipment over the years with complete and total sucess. Most of these lines being hydraulic hose. If you look at the lube distribution systems on haul trucks, rotary blast hole drills and even electric shovels. There are lube line runs in excess of 70 feet, and these run outdoors in the north where the temperatures get down to -40. Yes special lubes need to be used and but all of that is taken into consideration. You can check with your lube supplier about the amount of pressure drop that you would see in 30 feet of XX diameter of tubing at a certain minimum temperature, but the information is almost useless because you are not talking about a steady state discharge. The volume you are talking about here is probably less than an ounce every 6 months. Albiet you are pumping ~15 grams in a 5-10 minute interval. There is little or no value in purging the tubing however you might want to consider a check valve close to the discharge to minimise reintroducing any contamination (wear debris) back into the rolling element path.
You are not asking about re-inventing the wheel here with this question. The solution you are questioning is tried and proven.

Just to play devils advocate consider that the lube line is 1/4 ID and that you will have 25 feet this means that there will be approximately 300 grams of lube in the line. So if you pump in 15 grams to each bearing every 6 months. That means that from the time you first pump grease in the line to the time the grease gets into application it could be 9 years. Reduce the tubing to 1/8 ID and the pressure drop goes up considerably but the retention time goes down to 2-1/4 years an acceptable interum storage period. Consider SS for tubing.

How do you allow for the excess grease in the EM bearing to purge? Do you use pressure relieving vent valves?


regards.....

If there would be votes taken on offered solutions, my choice would be Stefan Minnaar's suggestion (adding “permanent transducer detecting in the ultrasonic range. This will enable you to grease based on the condition (relative to the UT "noise" or dB emitted) prevent over-greasing”. I have no personal experience with these systems, but it really sounds good and logical.