We have several Hoffman Multi-Stage blowers here in our plant, and I was wondering during the course of several months and even years is it necessary to shut these down and re-check the alignmnet?

I have a blower here that is about .030 to .045 out of alignment, both vertical and horizonal, which was aligned back in 2005. I just finished aligning it within .002, and now have to add a shim in the inlet for heat growth...

Lets just say under normal circumstances is it required that we should periodically re-align these?

Thanks,

RB

I don't have much experience with Hoffman's, but don't they warm up pretty good after being put in service, especially the discharge end? The ideal thing to do is align while hot. But to answer your question to align periodically, yes. This should be done during the PM, either twice a year or yearly. Shaft alignment is checked, corrected if needed, at our site when the PM's are done, whether a vibration problem was noticed or not. Well worth the money and not much man hour cost involved.

I've been aligning these blowers for about 5 years now, but we always groped for the proper formula when doing the smaller blowers vs the larger ones, (different growth rate on outlet)...

Hoffman came up with a formula which is what they use no matter what size blower it is. See attachment...

Seems to be working well with ours.

And just to add to that, what I do is take temperature readings off the blower next to the one I'm aligning,(same size blower) and apply those measurements. The temps are within 5-10 degrees, so will not affect the shims added to the inlet of the blower, or motor. It would be so miniscule it wouldn't even register. I have checked these temps and confirmed it, but if you would rather do two alignments thats up to you. I do it all with just one, and prefigure the shims under the outlet using that formula provided by Hoffman...

Only thing I was not sure of was should we check these alignments on a regular basis. We get so busy working on fans during our shut-downs there is just not enough time to check all these blowers, for lack of people...

Thanks for the feedback,

RB

Sorry about the large attachment, I figured 150 kb was pretty small. Guess I'll have to take these down a bit.

RB

Rod, if you don't have it already, go to the link below and download Microsoft's Image Resizer. Once it's installed on your PC, you can right-click on any image file and select the size you want and it will save the resized file with a new name. I use it all the time for pictures or images I use on this board or in reports.

Microsoft Image Resizer PowerToy

I saved your image (large bitmap by default I guess), then opened and saved it as a JPEG file (190Kb) and then resized it using the 'small' option (for 640 x 480 screen) and the 38Kb file appears below. Apparently it's not so much the file size, as it is the pixel resolution that determines if it fits on the screen or not.

This message has been edited. Last edited by: rustythevibeguy,

I use the advanced jpeg compressor at home. I can size it to whatever I want without losing much on the actual size. I figured the vibration forum site automatically resized it.

Thanks for the link.

If you don't have 'hot alignment' fixtures (Acculign) use OEM specs. It is a must that they are set to hot specs.

In addition many Hoffman blower are fitted with Thomas couplings where a gear type is better suited. I've changed many to gear type couplings to realize much better and smoother operation. Do you have a problem with broken disc.

AND: check the feet very closely (remove paint if necessary) for stenciled numbers as these are the OEM hot specs.

No problem with disk packs breaking, or separating. We use the 350 & 375 series. Years ago they used the ones which take grease, but got tired of having to shut them down for service.

According to the formula and the inlet / outlet differential temps, I added .018 to the outlet, and likewise under all four motor feet.

I'm in the carbon black industry so much of our problem over time is contamination to the blowers, and impellers. I saw evidence of this when I went to HSI Services in Houston and saw the inside of one we just pulled out of service...Had a large 1X vibration which looked like imbalance, and the g forces were increasing...

Rod