ZR250 Atlas Copco Compressor LP Element Jammed

Add to those your bearing condition, radial runout and thrust element failure, those conditions can change normal running position of rotor in casing, adding unusual heat through the bearing journals into the rotor, not to mention heat from rubbing of the rotor on the casing, radial and/or axial.

accelerometer measurement at the bearing locations will let you know early of dangerous wear conditions, modern analytical techniques can measure unusual conditions in individual rolling elements of each bearing, looking at amplitude and frequency, just knowing the model of the bearing, for instance.

Thank You sir for your response.

Wee had opened both the elements HP & LP, The LP Elements' bearing got broken and also the LP elments screw is jammed with the housing. HP was found to be ok ie. it is freely rotating. Atlas copco engineers are telling us to replace the LP element as whole. they say only bearing cant be replaced as the screws have rubbed with the housing. is it ok if we change only the bearing start using it.

You mean with the damaged housing? ...or do you plan to repair the damage in some way?

There is a special coating on the screws that has likely been compromised. You may have the option of removing the LP assembly and sending it to their factory and seeing cost to refurbish, my guess is the cost for a new one is less and lower risk, that’s why they recommend replace. They don’t need the income for a LP unit, they also like to see your machine run well.

The actual failure detail will be helpful to understand why the compressor did not protect itself, if the failure was indeed preventable.

The temperature of the air exiting the LP stage will vary according to the consumption rate and the inlet temperature, it will perhaps give you some warning of a problem with the wear of the rotor surfaces, how much of your mechanical energy is being used to actually compress the air.

One other useful indicator is the cooling medium valve position required to attain your intercooler outlet temperature. If too much heat is generated in the LP stage, the cooling valve will open more to get the same outlet temperature, at a given production rate. You could keep track of these conditions, perhaps by testing during defined conditions, such as full output after 15 minutes, to give the components time to stabilize temperature at new production rate, if your load is too variable.

Also, stabilize inlet air temperature, which should stabilize moisture content, when testing.

Also monitor the LP stage cooling jacket flow and temperature rise, at that same air production standard. These will help assess fouling of the cooling jacket passages. If the jacket water temperature is not rising in proportion to the production rate, you are not removing the heat of compression as designed.

if the temperature rises too much, and you have sufficient water flow, that could be a precursor of mechanical problems with the screws, though this will not be as sensitive as vibration monitoring.

The damaged bearing of the LPm Element

FYI perusal