Rotary Compressors

Pressure regulator working properly?

Yes Regulator is working. Compressor does not stop, keeps running, but will not increase pressure.

Have you checked for restrictions in the intake? Maybe the filter is plugged or something and it cannot pull in enough air to achieve the psi requirements.

What prompted you to change the bearings?

If you have decided to change the bearing on the report of 'less through-put and discharge pressure', obviously the internals might have lost its functional/critical clearances. If this be the case just changing the bearings will not being back the required parameters. Re-establishing critical clearances or perhaps renewing the functional parts alone would serve. Any way what is your type: Screw or Sliding vane or what?

Good luck...

The Reason for bearing change was, the people starting the compressor,were Not checking the oil level. As a result, run out of oil. Damaged bottom end bearings. While apart changed all bearing (precaution Change). As you would know, if I didn't another would go. Is screw type.

"run out of oil"

Please elaborate and investigate for how long the machine ran without oil to bearing.

Had it run for a reasonable duration before it came to screeching halt it could have worn the screws and enlarged the functional clearances. Was there any tell-tale marks to suspect this kind of rub? Very minimal increase of screw clearance could raise substantial internal by-pass/slip.

How about the lub oil to screws? Is there an explicit lubricator for this purpose or internally ducted? If there a lubricator, how do you ensure its proper functioning? How do you monitor its condition and the right consumption of oil for this purpose?

Almostly completely Empty. Loud grinding sounds from bearing. Did not come to screeching halt. There was tell-tale marks to screw surfaces, and some pitting. Boss had apprentice rub they out. He did not appear to remove much. Screws pick up oil though what looks like a vacuum Type method of oil ways.

1 ensure that the clearance of bearing is as per standard

2 check the sealing material is not damage while maintanance (most important)

3 basicaly in screw compressor oil is mainly responsible for sealing check for proper quantity of oil is get supplyed or not.

check the center distance of both screw is right.
ensure the sealing is proper between screw as well housing.

The original question did not specify what kind of compressor it is. How do you know it is a two rotor screw compressor?

If it is you are quite right.

A low pressure indicates faulty sealing, quite obvious. On a rotary screw it is the oil in combination with the gap. Either the oil film is missing or too small or the gap is too large.

Good points. The volume comes into play as well, quite so.

As per discussion i understand you have check/replace only bearing but not checked the clearance.This is positiove displacement type ewuipment check clearance or rotors and also any bypassing in down stream.

I Checked clearances before removal of bearings. Caps are same or smaller on bearing end. This is what I was told by compressor maintanence people.

flow rate and pressure relation its ok but qustion is that before servicing it was giving the out put pressure 40psi but after maintanance its giving problem that mean,
if bearing is ok then problem with sealing.

you can do one thing put the outlet valve close check the value for pressure in reciver by incresing and decreasing lubricating oil flow if ther is variation in pressure check for sealing material as well gap between screws and casing.

also temperature while working, viscosity of oil at working pressure but generally this thing will not happen after maintanance, never in my practice.

also check air leckage through bearing.............this may not possible but it can happen.

some time possibility of pressure loss in lubrication system.

because from oil seperator tank which is at out let oil goes to inlet of compressor this may possible.

is ther seperate pump for oil circulation or its work on pressure differance.
check out this.