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Peter_1
17-05-2008, 09:09 PM
In http://www.refrigeration-engineer.com/forums/showthread.php?p=106279#post106279 i added some pictures from a serious problem we're having now.
Any help or comments are welcome.

nike123
17-05-2008, 10:05 PM
In http://www.refrigeration-engineer.com/forums/showthread.php?p=106279#post106279 i added some pictures from a serious problem we're having now.
Any help or comments are welcome.

Any possibility of freezing of water during standstill period?

US Iceman
18-05-2008, 03:38 AM
From the appearance of the front of the PHE I would say there has to have been some substantial pressure from some source.

If the pressure relief valve works, then that eliminates the water pressure? Have you checked the relief valve Peter, or just looked at the tag?

A second guess would be from hydraulic pressure in the plates (from refrigerant). If the plates contained liquid refrigerant and the PHE was somehow isolated from the refrigerant piping, the warm water could have greatly increased the pressure causing this.

My recommendation is to cut apart the PHE and see what it contains. If it has scale in it, then it might be something else. However, I think this is related to one of the conditions above.

Peter_1
18-05-2008, 09:57 AM
My best guess US Iceman was indeed severe liquid build up in the PHE during standstill or for some other reason resulting in a hydraulic compression of the liquid when the compressors starts up again, delivering a high speed flow, too fast for the liquid to escape immediately out of the PHE.

But liquid build up is almost impossible because there's always a load in the factory and the compressors never stops for more then 10 minutes.

You can see also a little bit how my discharge lines are going: compressors, upperside PHE, out down the PHE , then straight up tot the ball valve, to the right, horizontal +/- 4 feet to the wall, 2 feet vertical up, then 7 feet horizontal along the wall over the switch-cupboard, and then 3 feet vertical downwards going then to the aircondenser outside the machineroom.

So this the only line which can flow backs.

Another possibility is that the water is mostly cold and many times colder hen the outside temperature. Liquid can back up then perhaps.
Anyhow, the burst happened when it was winter here, so cold to mild outside conditions.

There's no NRV in the discharge nor liquid but lines are sloped correctly....I think.
I better check this Monday once again and take also some pictures from the condenser and the lines going the condenser.

The pressure relief valve on the water boiler worked because most of the R404a came into the water reservoir of 3000 l (790 gallons) and via the sewer, all the R404a was released.
They already noticed 'air' :( was coming out the watervalves in the factory.

I'm also sure that the watertank can't hold a high pressure. It's pressure tested at 10 bar (145psi)

I will grind it open and post the pictures here.

750 Valve
18-05-2008, 11:08 AM
Darn peter those suction filters are pretty sad, looks like you have your work cut out for you thats for sure.

SteinarN
18-05-2008, 12:09 PM
As I have learned it, brazed PHE is very resistent to excessive pressures. They generally withstand several cycles of total freezing before failure arise. Also, if some sort of liquid hammering arise, that will normaly be seen from a bulge on the back side of the PHE of the same size as the connections and directly in line with the connections.

I can see some green substance on the side of the PHE. I suppose this is from copper corosion. I know there exists some limits to the quality of the water for copper corosion not to arise. I dont know what those limits is.

It would be very interesting to see whats inside the PHE. If it's copper corosion, then you should be able to see it when you cut open the PHE. The plates should be separated in the water channels but not in the refrigerant channels. You should also be able to see the copper coroded away and missing in the water channels.

monkey spanners
19-05-2008, 12:01 AM
Just remembered a Packo ice builder i worked on with an air cooled condenser. The icebuilder coil leaked and the compressor pulled in water and pumped it.
The result of this was about ten burst 'u' bends on the condenser. I wouldn't have believed the compressor could develope enough pressure to do this had i not seen it.
How much water is there in the fridge system?
Does any of the pipework show signs of over pressure?

Jon

Peter_1
19-05-2008, 12:17 AM
As you probably know, Packo is here in my backyard, I can see it through my window.
How much water? about 3000 l but most of the water was released via the pressure relief valve to the sewer.
We haven't seen any other signs of over pressure...yet.
Will also have a look at the condenser tomorrow.
We will install tomorrow also a drier in the suction of the freezer because they're on the same discharge.

Peter_1
18-06-2008, 09:49 PM
System is running now 2 weeks with green moisture indicators.Finally.

Brian_UK
18-06-2008, 11:27 PM
Well done Peter, go get a beer :)