Noisy Vacuum Pump

Is loud operation a trouble sign with a vacuum pump? May 6, 2009

I have a 5x10 router with a 10 hp Becker VTLF 250 pump. It works good most of the time but I find that a little more vacuum would be good. I picked up a used Becker 10 hp VTLF 250 SK. It had new vanes installed and was a good price. I finally got the thing hooked up and it pulls great. But it is a lot noisier than my other one which is only six months old. This other one is the same model but older and is a little bigger. Are these older pumps that much noisier or should I maybe be looking at bad bearings or some other problem.

Forum Responses
(CNC Forum)
From contributor X:
Becker pumps some make noise but if it is excessive then you better do some maintenance soon or it will be a lot more expensive to fix later. I had two pumps that were rebuilt by local Becker service center and after the rebuilt they were very quiet. Check the bearing and lubrication on the bearings. Make sure you check both the front and the back bearings on the main shaft.

From contributor H:
My Gast pump was making a disastrous sounding clang sort of noise and I thought I was in trouble. Close examination though showed that I had a loose motor fan that was bumping the housing. Check all external mechanical connections before getting in deeper.

From contributor T:
As the carbon vanes wear, they pump will inherently be more noisy. The key things to watch here is vacuum level and periodically measuring the vanes as they approach the manufacturers specified minimum ( this info should be found in your operators manual or can be obtained from Becker).

Bearing wear sounds different than vane wear but both can be intertwined making it hard to differentiate. The front bearing on Beckers is relatively easy to get to, so you can remove and inspect. Inspect by spinning it in your hand and feeling for tight or flat spots. It should feel smooth as you rotate it. Another option is to pack the bearing heavily with (high temperature) grease and see if there is a noticeable decrease in noise. Typically you will get your answer when you inspect the bearing.

From the original questioner:
Thanks for your responses. I have decided that the noise is excessive and I am going to take this thing apart. I looked at the parts breakdown schematic and it does not look too complicated, just big and heavy. I did check the front bearing and it looks fine, the vanes are new. There seems to be some kind of coupling assembly between the motor and the fan which I would like to see, maybe this is worn and causing the noise.

From contributor V:
Before you tear it apart I will let you know that if it is an older pump it will be noisier as we have a 10hp VTLF250 pump on our six year old Rover 24 and 2- 10hp VTLF250 pumps on our one year old Rover B. The pump on the six year old machine has always been much louder than the new pumps are. There are some differences in these pumps although they have the same model number. The older one exhausts much more air then the new ones. The old one has two extra filters on the bottom of the intake side and the new only has the one large intake filter. The old pump you can hear anywhere in the shop, the new ones you can barely hear running. So if you’re comparing an older pump to a newer pump there will be some difference.

From the original questioner:
Yes what you are describing is what I have, a newer pump and an older one. I think the noise is coming from the squirrel cage fan area which does seem to exhaust a lot more air. And yes the newer pump can barely be heard over the other noises in the shop.

From contributor F:
From what I have been told, the "exhaust" out of the pump is directly related to the amount of atmospheric pressure (air leaks) back into the vacuum. The more air leakage back into the pump the louder the operation because the pump is working harder against pressure to create vacuum. If not already install a vacuum gauge in line and check the In. Hg. in operation with the valve open and closed.