Hi Guys,

Could anyone advise on this, pls?

On Variable Speed Drive (VSD)Fin Fan Coolers downstream of Gas Compressors or reboilers, what is the efficient of VA survey? I mean at what speed? 25% or 50%, 75% or 100% or all?

Any feedback is appreciated!

Thanks - Brighton

Brighton,

I would bring fan to 100% speed to ensure maximum load and repeatable data for each survey. You may want to measure vibration at other speeds to determine any speeds to avoid that resonant vibrations occur or to resolve high vibrations observed by others.

Walt

Mr Bringhton and Mr Walt,is your finfan motors are driving finfan with gear boxes or through pulley.all your 25%,50%,75%,100% speed should be well away from system resonance.as such variable speed drive should be efficient at any speed as that of 100% speed.so conduct vibration survey at any of the operating speed using skf motor manager or equivalent to detect/predict electrical malfunction.

Hi Brighton,

If you have no easy control on the loading of the fin fan, you should use spectral analysis tools (like CPB measurements) and restricted classes for the 25%, 50%, 75% and 100% loading condition. This has been applied on many fin fan systems throughout the world with very good results. Any other solution not using these restricted classes concept will lead to false alarms as you need to measure under the same conditions.

I have a very fundamental doubt about fin-fans vibration monitoring is it that so criticality issue. Keep it running until it fails there could be many fin-fans that can take care of heat load in that bank until the maintenance is done. More money is wasted in the name of conditioning monitoring on fin-fans say when you take the reading no vibration is observed but your vibration monitoring cannot predict when vibration gets stared something like “how do I know when I get caught with cold after getting the cold it will go by itself what I can do after caught by cold nothing few pills”. Similarly monitoring vibration may prevent any catastrophic failures (for which switches are installed in event of too high acceleration to trip the motor) but not routine failures they fail by their own natural frequency. Once vibration is recorded in your instrument that means it has to be fixed one day but my point is the vibration monitoring can reveal upfront that the vibration reading will become more significant towards damage with in some duration at this stage what any one can do wait until the maintenance window and fix it what more can a condition monitoring will do. I would say as long as effective and optimum lubrication plan is followed as per the seasons to fin-fans and all one to one pumps (pumps with stand by) do not require any regular condition monitoring until any operating staff reports for any abnormality with such equipment.

hi gert hoefakker,thank you for ur 'cpb measurements' suggestion we have 134 fin fan coolers and what about installation cost? i will come back to u

hi AZY,condition monitoring will bring u very close to solve the machinery problem if not solving at times.in some plant break down maintenace suits because it depends on how critical the equipment usage.if it is not critical and spares is cheap / available break down maintenance is the best. if fin fan coolers are critical equipment then condition monitoring programe is the best

Hi Pal,

You can contact me direct at gert.hoefakker@bkvibro.nl in case you have specific questions. cpb spectral measurements with restricted classes have shown very good results with minimum false alarms.

thank u very much for ur reply.iam on vacation i will keep in touch with ver sooner ao later - palani