What is the reason for low lube oil pressure in Reciprocating air compressor , Belliss & Morcom 2

[nishanxavierchammany]

What is the reason for low lube oil pressure in a 3 stage Reciprocating air compressor , Belliss & Morcom Model number WH28H3N,Located in Saudi Arabia?,
The Lube oil used is Machinery oil ISO VG 100.The Lube oil gear pump, which is mounted on the compressor is a new pump.
Relief valve is not passing, and Atmospheric temperature is 50 degreeC,
Crank case oil level is okay.
There is No pump suction line leakage.
The Normal oil pressure is between 55 PSI to 60 PSI, even with new filters
but now it is 45 psi.

 

[crshears]

Two possibilities:

[1] New pump does not have the same physical characteristics as the previous one and physically pumps less oil. Would not usually expect this, but if pump manufacture has been off-shored there may have been something lost in translation when it comes to what you actually get as an end product.

[2] (a) Bad oil batch, off-spec status not caught, or (b) oil spec has changed slightly without any change made to the published data sheet.

Having been a three-stage compressor operator for decades, not only of Belliss & Morcom but also Revell, Ingersoll-Rand, etc., etc., I would not be overly concerned about this slightly off-normal operating pressure . . . unless over the course of time it continues to drop; I'd say the compressor bears watching, with a written or equivalent hard copy kept of reading sheets for at least one year to see if there is any further pressure degradation.

Hope this helps.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[TugboatEng]

I always laugh when troubleshooters start their low lube oil pressure chase by replacing the oil pump. Oil pumps NEVER wear out.

 

[crshears]

Hey Tug, I never thought of it that way [ probably because I never saw an oil pump replaced ], but I take your point: they have to be the most lubricated part of anything!!!

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[TugboatEng]

They're usually a sealless design as well so there isn't even a seal to start leaking.

 

[Doug Hunter]

It could be the elevated temperature. Were you seeing the higher pressure at 50C or perhaps lower temperatures?

 

[nishanxavierchammany]

Thanks so much for your valuable inputs

 

[nishanxavierchammany]

Hi TUGBoatEng,
we may have to consider the below for lube oil pump wear out:-

1.Mechanical Wear and Tear:
Like any mechanical component, a lube oil pump experiences wear and tear over time due to the continuous operation.
The moving parts, such as gears, bearings, and seals, are particularly prone to degradation.

2. Contamination:
The presence of contaminants in the lube oil, such as dirt, metal particles, or sludge, can accelerate the wear of the pump’s internal components.
These particles can cause abrasive wear or lead to blockages.

3. Cavitation:
Cavitation occurs when vapor bubbles form in the oil due to low pressure and then collapse, causing small but powerful shockwaves. This can lead to pitting and erosion of the pump components, leading to premature failure.

4. Improper Lubrication:
If the pump is not properly lubricated, it can experience increased friction, leading to overheating and excessive wear. This is particularly important for components like bearings and seals.

5. Operating Conditions:
Harsh operating conditions, such as extreme temperatures, high pressure, or excessive vibration, can shorten the lifespan of a lube oil pump.

6. Material Fatigue:
Over time, the materials used in the construction of the pump can fatigue, leading to cracks, deformation, or other failures.
This is particularly common in pumps that are subjected to cyclic loading or high stress.

Therefore, while a well-maintained lube oil pump can last a long time,
it is not immune to wear and will eventually need to be repaired or replaced.

 

[TugboatEng]

Consider these things:

Mechanical wear and tear: your lube pump is the most important component for preventing mechanical wear and tear and should be designed to avoid it. I think you'll find that most are.

Contamination: that means a failure has already occurred elsewhere and is not the fault of the lube pump.

Cavitation: maybe, have you been operating the equipment with insufficient oil level?

Improper lubrication: the oil pump is likely much less subject to damage from improper lubrication than other components in the compressor as it is designed to operate at low stress levels.

Extreme conditions: your compressor has babbit bearings. These are much less tolerant of extreme conditions than a gear pump would be. Again, the lube pump would fail last.

Material fatigue: lubricating oil pumps operated at low stress levels as they are extremely critical to the survival of the rest of the machine. They are designed to operate at low stress levels to prevent fatigue, deformation, or other failures.


I recently tried to renew an oil pump on one of our z-drives. The pumps were damaged by corrosion from water intrusion but so were the drives they were lubricating. However, one pump had a damaged gear set. It turns out the pump was a counterfeit.

You've already ruled out the pump as a cause, do you have any other questions?

 

[LittleInch]

So did the change in pressure happen at the same time as the new pump?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[nishanxavierchammany]

I greatly appreciate everyone's insightful feedback.
We are contemplating switching to ISO VG150 oil, as it is well-suited to handle summer temperature ranging from 45 to 60 degrees Celsius and winter conditions from 0 to 20 degrees Celsius.
Respectfully,
Nishan