Need help Computer Room Air-con(CRAC) Problem

[ksm]

Hi,
I'm a facilities technician and working at the data center.Inside this data center,one of the rooms has 6 CRAC units and most of the units are sweating at compressor.Please advise Is it normal or something happened?

Suction Pressure - around 60~68 psi
Discharge Pressure-around 220~235 psi
Scroll compressor

I'm new in this site and sorry if my question is wrong.
Thanks.

[frank]

Your question isn't wrong....just posted in the wrong section, but I've moved it now.

Suction and discharge pressures mean nothing if you don't tell us what refrigerant it is? The air on and air off temperatures are also important.

Also, the pressures should be converted to temperature to be of any use in determining if the system is operating correctly.

[ksm]

Thanks,Frank.
Refrigerant is R-22 and air on and air off temperaturs are 17 and 21 deg F.

[lana]

Hi there,

Suction pressure seems OK. Discharge pressure with water cooled condenser is OK. Or with air cooled condenser with ambient temperature of around 30°C is OK.

Measure super heat and sub cooling.

If ambient humidity is high sweating is normal. If you have low super heat then there is a liquid flood back.

Cheers

[ksm]

I'd like to know what ambient humidity is considered as high ambient humidity?

Thanks.

[goshen]

above 50% rh but all dependes on temp!!! u should use a enthalpy table and that will tell u what your duepoint is!

[ksm]

Thanks a lot.

[Gary]

... air on and air off temperaturs are 17 and 21 deg F.

That can't be right. Measure again.

We are talking about the air temperature entering the evaporator coil and the air temperature leaving the evaporator coil, measured close to the coil.

[Magoo]

ksm,
hopefully you are talking air temps expressed in degrees C.
Generally in data centres you need to keep the humidity level up by adding moisture with humidifiers, due to high sensible heat loads, get the humidity too low will create static problems in computers. And create the sweaty compressor problems you have.

[Gary]

If the numbers are correct and indeed in degrees C, then the coil is running warmer than it should and the humidity is too high. Either unloading set too high or blower running too fast.

But we really don't know if these systems have any form of unloading... and we don't know if the temperatures provided are accurate.

[Sridhar1312]

Reltive Humidity depends on the local ambient.If you are talking about Singapore it should be around 35 degree C and wet bulb temperature of 26 to 28 degree C and RH will be 50 to 80 %.
When the suction of compressor has temperature(surface) less than dew point sweating will take place. And it is normal.
From the way you have explainted it appears it is out door condensing unit and the ambient RH being high it must be sweating on the surface of suction side of compressor

[ksm]

Ok,thanks.Gary.
I will check again.Thanks all.