Screw Comp with EEV,S

[RIZZLA]

Hi

Has anyone experiened flood back problems with eev,s, due to them passing when valve is closed.Ive been told you require a differant type of eev armature with screw packs

Regards

Riz

[Latte]

Hi Rizzla,

That's a new one on me

I have only come accross Danfoss AKV Valve's and never had any major problems with them (Apart from blocking up after instalations not being done very well)

Mark Fiddy is your'e man on this one, drop him a PM so he picks it up on his e-mail. I havn't seen him online recently, he must be busy at work

Regards

Raymond

[Mark]

Hi

If its a standard AKV and the valve is letting by, when off cycle there is a problem.

To name one example,The AKV orifice can easily be over-tightened,damaging the seat causing the armature to let by.

Can you elaborate on the problem.

[RIZZLA]

Hi mark

I will get more info,I,ve not been in the supermarket game long but from what i,ve been told if you have screw compressors then you need a different armature in the valve as the spring becomes week and passes liquid (freezer).Would you fit the same electronic exp valves with screws and recips.

regards

[chillyhamster]

What has an eev passing by got to do with what type, size, make or colour of the compressor doing the pushing and pulling at the plant end of the system. The eev controls the flow of liquid into the evaporator, this pressure is controlled by the cooling effect of the condenser. The only effect plant may have on the valve, is the control and fluctuation of the suction pressure.

Would this be a Sainsbury's site with a Moducel Lt screw plant, and would the eev control device you refer to be an Egelhof stepper valve. If so, these valves can have damaged needles which do not break off accross the needle but obliquely which allows them to pass liquid whilst seemingly shut

[RIZZLA]

ok chill chillymaster,I am only trying to understand a problem that was cured by fitting a different armature seeminly the ones that were fitted expanded on hot gas defrost and were sticking.I thought it was a common problem and was only looking for a better explanation from you more experienced grumpy chaps.As its not a common problem I kill the thread here

thankyou

riz

[Andy]

Hi RIZZLA
I have seen akva valve armatures sticking on reverse cycle NH3 plants, the part of the armature that contacts the the outer sleeve that the valve coil goes on is a plastic type material, this would be to reduce wear. The plastic expands and sticks. Simple pump it down strip it and with emery paper or a fine file take a bit off the plastic until it only contacts the armature outer sleeve, not sticks in it.
I would say the oil used in some screw plants, (Poly alpha Oilafin) would be the cause.

Kind Regards. Andy

[Richard1000]

The only situation i know of is regarding original akv armatures and zurice oil (which sainsburys use on there R22 screw packs) i know i had to change 30 armatures at a sainsburys site, which was their request. Had no probs since. As far as i know, the new armatures are purely an updated design. But yes have witnessed it. Zurice is a 'heavy' oil. I think on an old spring, the resistance is too much, and hence valves were not closing properly. Very noticable on electric defrost cases.