expention valve equalizer

[chemi-cool]

this is a question to Prof Sporlan but other views are welcome,
In all of my installations through the years using TEV`s with ext. equalizer, the length of the of that 1/4 tube is allways different.
sometimes short and sometimes longer. On big evaporators it is very long. I do not recall that any manufacturer gives any specific istructions.
I would like to hear (read) your view, and others of course are most welcome to post any idea.

thanks, chemi

[Peter_1]

Since there is almost no flow - it is only a pressure egalisation - in this 1/4 tube, i should say that it makes no difference.

[Dan]

You want the equalizer line to connect to the suction line downstream of the TEV bulb. If you reuqire a long capillary on the bulb, you will also require a long equalizing line.

[Prof Sporlan]

As Daliti notes, there is normally little to no flow thru the external equalizer line when the TEV is in proper working order. As a result, you can run your 1/4" OD equalizer line as far as you need. 1/8" OD equalizer lines are also popular.

If you see sweating and/or frosting on the equalizer line near the TEV, that would be an indication of valve pushrod leakage which would result in excess flow thru the equalizer line. It would be a good idea to replace the valve in this case.

[chemi-cool]

Thank you all,
I belive that the subject is coverd.

chemi

[Peter_1]

Originally posted by Prof Sporlan

If you see sweating and/or frosting on the equalizer line near the TEV, that would be an indication of valve pushrod leakage which would result in excess flow thru the equalizer line. It would be a good idea to replace the valve in this case.

This was a good tip for me. Never thought that was the reason but saw it many times. I always thought this was normal. I will make a note here in the company with your tip.
Thanks Prof.

[Gary]

If you see sweating and/or frosting on the equalizer line near the TEV, that would be an indication of valve pushrod leakage which would result in excess flow thru the equalizer line. It would be a good idea to replace the valve in this case.

I would add that this is the reason the equalizer line should be after the TXV bulb, else this leakage will fool the TXV into starving the coil. With the equalizer line after the bulb the result will be slightly decreased superheat in the suction line but otherwise the valve should still work okay. Leakage was common in the older valves, but pushrod seal materials have improved over the years and this problem is far less common now.

[herefishy]

Great!.. I need to learn something, everyday... and I just did

[Gary]

When so much liquid leaks into the equalisation chamber that a false high suction pressure is indicated then the valve does tend to close some. On an AC system you will tend to end up with a starved evaporator and some frost buildup earlier on in the starved evaporator.

This would depend upon the amount of leakage and the equalizer line sizing. If the line is large enough or the leak small enough, then the pressure in the equalization chamber would not be substantially effected. But yes, if we are talking about extremes, then I would agree.

[chemi-cool]

hi Gary,
since there is no way to measure that amount of leakage, I would suggest that " WHEN THERE IS A DOUBT - THERE IS NO DOUBT" and replace the TEV.

CHEMI

[Frig Pig]

It really depends on who you talk to on where to place an ex. line. Danfoss I believe prints in their instruction sheets to place the TX bulb BEFORE the ex. line so the valve will have better control but on the other hand Copeland on several occasions has told me to mount the TX bulb AFTER the ex. line to stop flood back to the compressor even though the pressure drop across the push rods would almost certainly boil off any liquid before it ever got back to the compressor. Basically a lot of discussion over something that to be honest is a little trivial in real life situations. I agree 100% with chemi-cool. " WHEN THERE IS A DOUBT - THERE IS NO DOUBT" ……replace the TEV if you see frosting on a ex. line

[Ahmed_LNG]

sorry, but may i ask TEV is abbreviation of what?

[star882]

Thermal Expansion Valve. Sometimes called TXV.

[Ahmed_LNG]

thx star
is TEV is the JT valve up stream any chiller(evaporator)

[Lc_shi]

is there any difference for the senser bulb installed vertically or horizontally ? thx

rgds
LC

[Renato RR]

Always horizontal becose of thermostatic charge in sensing bulb.

Renato RR

[Lc_shi]

Always horizontal becose of thermostatic charge in sensing bulb.why???

[Peter_1]

You can mount it also vertical with capillary upright. Done it 100 times and more.

[Temprite]

Always horizontal becose of thermostatic charge in sensing bulb.why???

G'day Ic_shi

Upside down and with capillary at bottom and contents will leave sensing bulb.

Most manufacturers have instructions with valve.

[rpbuenaflor]

I am very empressed to everyone showing their briliant explaination and advice for the TEV external equalizer. I am new here needs more information about the deffirent in external TEV equalizer and internal equalizer. Which most probably used the TEV with internal equalizer?

Please, I need to be inlighten.

rudi