Blocked driers

[monkey spanners]

Been on a job today, 15,000L Dx milk tank with two ZR90 scrolls on R22. Changed one of the compressors today due to it intermitently not pumping.

Two weeks ago a drier was changed by another company due to it being blocked. A week ago this was changed by us due to it also being blocked and today our replacement was found to be blocked when the new drier was fitted with the compressor.

I had changed the oil in the old compressor as it was the same colour as used engine oil :eek: last week as well as replacing the refrigerant. I removed 14 KG and only had to put back 10 KG.

The thermistor modules had been disconnected by another company.....

I checked the strainer in the tev and found that the gauze had broken up and you could see right through it:rolleyes: The other end of the orifice has lost its silver colour and is now coppery and looks to have been etched away by .3mm/.5mm....

New tev and orifice.

I cut the old drier in half to have a look and found a husk from a piece of grain:confused: and the core is a nasty brown colour. The felt pad at the outlet end is sticky black/brown and has set almost solid.

So what do you think caused it and more importantly what can we do to clean the system up???

Cheers Jon

[frank]

Are you sure it's on R22? Could R407C have been added by another company as all the symptoms you describe are very similar to what happens in a contaminated 407 system.

Oil very black and sludgy, sticky etc.

We've had this on a couple of occasions where the installers (one of ours once - but no longer with us) cut corners and didn't evacuate properly causing oil contamination.

[Lowrider]

Moisture!

Keep changing the oil until it's clear (will reguire changing the oil after running the unit for a couple of hours) and place a replaceable filter/drier and use a drier core specific for removing moisture. If you place the filter/drier between two valves it safe's alot of time recovering!

After a week or so do an acid test to see if the oil is ok, otherwise change the filter/drier again and replace the oil. Then a week later the same! Until it's good, not fine!!

[monkey spanners]

Frank,

Its very possible that the other company could have added R407C or any other refrigerant ,new or recliamed. I have seen their work before....
Two of their engineer where overheard by the customer saying "do you think its washed some sh*t out from somewhere" so you guess would be as good as mine as to what was in it.
Its had a pressure leak test a thorough vac and new R22 now.

Lowrider,

I couldn't tell by the sightglass as its been dyed black. I did try to braze in a new one but the fumes generated stopped the braze from sticking to the sight glass and copper pipe despite using flux. Yes i know, should have used OFN:confused: but its too late once you've started and beggered it up.
I think i will get a replaceable core drier and a ballvalve as you suggested.

If its likely its got acid in it would a HH core be the way to go?

Cheers Jon

[Lowrider]

use on of these, or a similai one: http://www.emersonclimate.com/flowcontrols/pdf/systemprotectors/catalog/ADKS%20Filter-Drier.pdf

and for a core: http://www.emersonclimate.com/flowcontrols/pdf/systemprotectors/catalog/Filter-Drier%20Cores%20and%20Filters.pdf

Make sure you place it between two valves, have the new sightglass after the filter drier and a schraeder installed in the filter/drier cover. Do a proper vac-out after changing the core!

Make sure you use the right size filter/drier. The way to calculate is in the first document!

[monkey spanners]

Cheers,

The system has only got a 6/7 m pipe run so the only space for the drier is on the unit. I can put it just after the reciever and with a ballvalve just after.

Had a quick look on the sporlan site and they do a replaceable core drier with an extra filter that fits inside the hollow centres of the core designed to catch fine particles which is what i suspect the system has as presumably enough metal has worn off the scroll mechanism to allow it to stop obitting properly, its got to be in the system somewhere.

Off to Climatecentre (wholesalers) in the morning i think :D

Jon

[PaulZ]

Hi Jon
If I were you I would recover all the refrigerant remove the compressor and flush the system with a good flushing agent. Installing a replaceable core drier with a valve after the drier is the go.
I have found if a system is badly contaminated you will spend days trying to clean up changing driers and oil.
The longer you run the compressor with that much crap in the system the more damage it will do.
Paul

[US Iceman]

If I were you I would recover all the refrigerant remove the compressor and flush the system with a good flushing agent. Installing a replaceable core drier with a valve after the drier is the go.
I have found if a system is badly contaminated you will spend days trying to clean up changing driers and oil.
The longer you run the compressor with that much crap in the system the more damage it will do.


I agree with this. It's better to just bite the bullet and do the necassary methods at one time. The trips back to keep changing driers and monitoring the site will probably be more expensive than the single "do it right" instance.

[monkey spanners]

Hi Jon
If I were you I would recover all the refrigerant remove the compressor and flush the system with a good flushing agent. Installing a replaceable core drier with a valve after the drier is the go.
I have found if a system is badly contaminated you will spend days trying to clean up changing driers and oil.
The longer you run the compressor with that much crap in the system the more damage it will do.
Paul

Cheers Paul,What flushing agent did you use? and did you need a special machine to pump it round?Years ago my dad had a special machine with a pump and a header tank for use with R11.This is the first system i've seen block up like this. The top unit has black oil too, i've changed this a couple of times as well. Take out shares in 3GS ;) I've got a big drier on order and a load of HH charcoal core as these are suposed to big good at collecting wax and cr*p.Luckily (or not) the site is quite local so we can nip in either in the morning or evening without too much trouble.Also while i think of it, am i the only one to break the little tab off those drier tins? Has anyone used a tin opener on them? Cheers Jon

[bernard]

Hi

De-cant ect,remove oil, pump endo-flush with a normal oil pump.Follow the instructions so now the system is clean fit new exp valve drier vac and charge.

Regards Bernard

[US Iceman]

Also while i think of it, am i the only one to break the little tab off those drier tins?


:D

Nothing spells fun like trying to get the cans open, huh?

The best thing I have found to use when this happens is to pry up a small section of the sealing strip and then grab it with a pair of linemans pliers and pull very carefully. The strips are like spring razors.:rolleyes:

[snoring beagle]

Also while i think of it, am i the only one to break the little tab off those drier tins? Has anyone used a tin opener on them? Cheers Jon

I use needle nose pliers as a the key to wind that strip.

Arlen

[PaulZ]

Hi Jon
We use ERG flushing agent no sure what you would get in the UK. Just make sure it is the type that leaves no residue and will evaporate totally when vacced out. We use a small electric gear pump and a drum and circulate it through the system in both directions if possible.
Paul

[monkey spanners]

Thanks for the replies,

I'll have to give climate centre a call tomorow for a price on endoflush as going by their trade price it'll cost about 1.2k to fill the system up:rolleyes::rolleyes: let alone buying a pump.

Still at least its not just me who snaps those drier tabs off :D

Cheers Jon