chiller freeze up

[cletus]

I had a chiller freeze up and filled the evap and cond full of water, we have blown it out with nitro and have had vac pumps on it for about 2 months, also blowing it down once a week. We are at about 2400 microns but cant seem to get any lower ( we did fix the chiller tubes) any suggestions


cletus

[slingblade]

did you drain the oil out of the compressor?

[jamcool]

what about heat lamps on the evap and cond. when vac.
? this might aide in getting more moisture out? if no leaks

[cletus]

It does hold a vacum when the pumps are off, and every weekend I put a 90lb nitro pad on it and blow it down on Monday.

I have not checked the compressor. THANKS

[cletus]

I talked to the maint tech who evacted the system, all the oil is out of the compressor, THANKS

[slingblade]

if the oil has been drained then there is obviously no water underneath it. its possible that water has pooled somewhere else. if blowing nitro is not moving it then it may be time to run the unit and leave the rest to frequent drier and oil changes to remove. any other things on system oil sep, accumulator etc. ? just a thought. and are you sure there are no leaks. does it hold pressure? how big is the system out of interest? i had a 40 hp chiller on vac for 2 weeks once following a burst.

[cletus]

It will hold 90lbs all weekend long, also it is a 213ton unit

SCOTT

[cletus]

Just wondering if I hooked up the vac pump on a low point would that work better

SCOTT

[slingblade]

Good luck. drill a hole in the suction and braze a line in. 3/8" should port to a standard vac pump. put your vac pump direct on tube with a hand valve in the line {no gauges}. energise any sol. valves and wait. this may take some time. does the vac pump oil emulsify quickly (turn milky)?

[frank]

drill a hole in the suction and braze a line in.

I would only do this on a new piece of pipe not fixed in the system so that I could get rid of the swarf. It's better to blow a hole with an oxy/act torch on an existing system.

We don't want all them little bits of copper getting back to the compresser now do we ?

[al]

is there a shaft seal on the chiller, if so this could be dry and preventing full vac.

Al

[Lazarus]

... any safety valves, oil coolers, OFN !!

[cletus]

It dont take long for the oil to get milky looking, I do have a low point on the evep side that I could get in to.
I have been running 90 degree water thru the tubes to keep it warm

[cletus]

It does have a oil cooler on it

[slingblade]

It dont take long for the oil to get milky looking

yep, thats full of water. once the vac oil is mixed with water you lose performance on the pump. all i can suggest is just keep at it.

[cletus]

this morning I went out to check the big unit and it was down to 1321 microns: Heating it up for the last 2 days must of helped

[Cofreth]

Did you change the vacuum pump oil everyday?

[cletus]

I have been changing oil about every 4 to 5 hrs

[dannyd]

try removing line components (solenoid internals etc), go to the base of the condenser coils (if air-cooled) and make sure that low-level pipework has been opened and physically checked for presence of water. Blowing through with Nitro won't shift all the moisture completely and i'll guess the vac pump oil may be getting heavily contaminated?

[Tycho]

I just went through the same operation last year.

The only way to speed things up a bit is to find the lowest point of every component that might have filled up with water and drill a hole (unless there is a valve there).

I had a system normally charged with 1300Kg of ***** fill up with water. I drilled, holes on both ends of the chiller, two on the center about a meter apart and on the liquid inlet line (connected to the bottom of the chiller, so it was the lowest point), drained the oil seperator and oilcooler.

Then I welded the holes shut after flushing it a few times with nitrogen...

had a 9Kw heating fan blowing at the chiller, still took about a month to get it down to 3mbar.

So I guess you just have to hang in there, or start looking for the drill.


-Cheers

Tycho

[Andy]

Hi Scott
poor vaccum pump or micron gauge.

Did you pressure test, 90lb would be low, you would need to strength test to above the relief valve setting, my bet is probably a leak. Section isolate and test and vacum each section not the whole system. By this I mean test the whole system and isolate each section and check the pressure individually, same witth the vaccum.
Kind Regards. Andy

[dogma]

Try connecting a filter/dryer between the vac pump and the system. It will work out cheaper to replace the core several times rather than changing the oil.


Do you have a condensation pot on your vac pump?

[mxstar]

2400 micron is a pretty good level of vacuum. What level of vacuum do you believe you need to reach? If system holds the given level of vacuum then all should be well.

[US Iceman]

...you would need to strength test to above the relief valve setting

I think this is a little dangerous. If you pressure test with the pressure this high, the relief valve will open. If you take the relief valve off for the pressure test, something could go boom!

80% of the design pressure should be sufficient. This would allow the relief valve setting to still be above the test pressure without relieving. If the relief valve opens during the pressure test, it may not reset properly, and leak afterwards,

[Tycho]

I think this is a little dangerous. If you pressure test with the pressure this high, the relief valve will open. If you take the relief valve off for the pressure test, something could go boom!

80% of the design pressure should be sufficient. This would allow the relief valve setting to still be above the test pressure without relieving. If the relief valve opens during the pressure test, it may not reset properly, and leak afterwards,

DNV (Norwegian Veritas) requires all our ship plants to be tested at 1.17 times the safety valve release pressure.
meaning we test our HP side at 29.5 bar (~430 PSI) and LP side at 18 bar (~260 PSI).

besides, it's better that something goes boom above sfv release pressure during commisioning, then going boom before the sfv opens after the plant is charged and comissioned

ofcourse, you will need to blind the sfv, or remove it and put on a blind flange instead.

some people put a blindflange with a valve on the outlet of the sfv, raise the pressure on the outlet side to the same as the testpressure to nullify the diff. pressure needed for the valve to open (same pressure on both sides)

[Andy]

I think this is a little dangerous. If you pressure test with the pressure this high, the relief valve will open. If you take the relief valve off for the pressure test, something could go boom!

80% of the design pressure should be sufficient. This would allow the relief valve setting to still be above the test pressure without relieving. If the relief valve opens during the pressure test, it may not reset properly, and leak afterwards,

We have a great directive in place called the Pressure Equipment Directive. Strength tests are required under it to the standards in the BSEN378 (local code) this indicates a strenght test between 1 and 1.3 times the allowable pressure, which was once called the design pressure. The relief valve setting.

And yes it is a bit dangerous for the engineer testing, risk assesments are usually put in place, ie stand behind a wall or 20' from the piping being tested.

Anyway it's all the Americans fault for encouraging the us to create the EU

Kind Regards Andy

[Tycho]

We have a great directive in place called the Pressure Equipment Directive. Strength tests are required under it to the standards in the BSEN378 (local code) this indicates a strenght test between 1 and 1.3 times the allowable pressure, which was once called the design pressure. The relief valve setting.

And yes it is a bit dangerous for the engineer testing, risk assesments are usually put in place, ie stand behind a wall or 20' from the piping being tested.

Anyway it's all the Americans fault for encouraging the us to create the EU

Kind Regards Andy

I usually do the top test pressure on new plants while the yard is having lunch break, so the ship is deserted.

I always have a hose to a nitrogen battery on shore...
I dont very much fancy the thought of being anywhere onboard if the 800+ gallon liquid tank should burst

[mxstar]

2400 microns is a good level of vacuum. What level were you expecting to reach?

[mxstar]

2400 micron is a good level of vacuum. What level where you looking to achieve?

[US Iceman]

...Anyway it's all the Americans fault for encouraging the us to create the EU

Well I guess it had to be somebodies fault then. Might as well blame the Americans for this too.

besides, it's better that something goes boom above sfv release pressure during commissioning, then going boom before the sfv opens after the plant is charged and commissioned

No argument with that!

I am aware that the EU has some regulations to deal with. The PED is one of them. My reason for writing what I did was to make sure other people who read this are aware of the dangers. Someone who is new to the refrigeration field will not be thinking of this...

I have seen 4" rupture disks blow out during pressure test at 320 psig. If you want an excuse to buy new pants, this is one way of doing it.

One precaution is two use a two-stage nitrogen regulator, so that the system cannot be exposed to the bottle pressure accidentally. This might seen simple and common sense, but I've seen it done before.

[wambat]

[QUOTE=cletus]Just wondering if I hooked up the vac pump on a low point would that work better

SCOTT[/QUOTE

Have you tried using a cold trap, it helps lower the vapor pressure and contamanation time of the vacuum pump oil also large short hoses and does the blank off on the pump pull down to say 50 microns. pulling a hi vacuum must be done with greal care and attention to detail.All connections must be absolutely tight and when you take a reading, remember that the location of the gauge tube will affect the reading. The closer the gauge is to the vacuum pump, the lower the reading will be. To get the most reliable reading, isolate the vacuum pump using a vacuum valve assembly. Let the pressure equalize throughout the system, then take a final reading.

[dogma]

what is the required vaccum on new and old plant in the EU guys? We use 1000microns and I think it is 500 on water chillers. But in the factory I work we arn't allowed to be any higher than 50microns. We have a double cheeck system with thermistor and vacustat.

I can't remember the size of our pumps but they are 3feet by 2 by 2. Pretty big suckers.

[Andy]

[QUOTE=dogma]what is the required vaccum on new and old plant in the EU guys? We use 1000microns and I think it is 500 on water chillers.

QUOTE]


1000 Microns would be standard enough for field assembled equipment.

50 microns probably not easily obtainable on large plant out in the field, but certainly obtainable in a factory on packaged equipment

Kind Regards. Andy

[jsimon]

the best way to check would be at a much higher pressure 250/300 psi and leak check
are all your solinoid valves open
can you section off the system eg high side low side and recheck

[dogma]

after further reasearch andy, i found that industry standard in aus is 50-100 micons in aus for dry systems and 1000 for wet. still 500 for water chillers.

guys i'm pissed, big night just starting so my spelling and grammer may be off.

cheers guys.

get it up ya.

[slingblade]

after further reasearch andy, i found that industry standard in aus is 50-100 micons in aus for dry systems and 1000 for wet. still 500 for water chillers.

guys i'm pissed, big night just starting so my spelling and grammer may be off.

cheers guys.

get it up ya.

thats ok. its sunday morning and im hung over, what did i do last night?

[Andy]

thats ok. its sunday morning and im hung over, what did i do last night?

Probably didn't involve vacumn pumps

or at least you would hope not

Kind Regards. Andy

[nick_nst@aapt.n]

Do you mean that by blowing it down with dry nitrogen that you are using dry nitrogen to raise the pressure to 0 psi and letting it sit for a while before re-applying the vac pumps.( Breaking it with dry nitrogen )
Is the vacuum staying the same or does it change indicating a leak
As I've also removed the rupture disc and pressure tested it at a higher level to ensure no leaks.
nick


d a chiller freeze up and filled the evap and cond full of water, we have blown it out with nitro and have had vac pumps on it for about 2 months, also blowing it down once a week. We are at about 2400 microns but cant seem to get any lower ( we did fix the chiller tubes) any suggestions


cletus[/QUOTE]

[CCLPaul]

I had a 100hp one of these a few years ago. I ended up removing the entire system in bits to the workshop. Each section and component was flushed with R11, vacced down while a space heater took the temperature up to 35C. After rebuilding the compressor and the entire system, when recommissioned it went down on a blockage a few times before continual changes of driers eventually sorted it. The compresor was rebuilt again after 2 months. That was approximately 10 years ago and the system is still operational. It can be done, but your customer will need a deep wallet.

[dogma]

R11






omg!


10yrs ago? How long since R11 was outlawed??

[CCLPaul]

SHHHH sadly none left now

[Gwyn]

you have to have the system pipe work etc. warm or you will not remove any water from this system!
is the location temp. to cool for the water to be removed, whats the ambiant of the plant room?