TXV/TEV equalizing line size?

Whats the correct size for these lines? they are all 1/4" on the valves and i have seen them piped in 1/4" and in 1/8" as well.

Usually i just get one of those ready made coiled copper pressure switch lines and cut it in half to use as an equalising line, any thoughts on whether i should be making up a propper 1/4" one instead of being lazy :rolleyes::D

Jon

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Originally Posted by monkey spanners

Whats the correct size for these lines? they are all 1/4" on the valves and i have seen them piped in 1/4" and in 1/8" as well.

Usually i just get one of those ready made coiled copper pressure switch lines and cut it in half to use as an equalising line, any thoughts on whether i should be making up a propper 1/4" one instead of being lazy :rolleyes::D

Jon

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Hi mate.

It is only an equalising line.
Refrigerant does not flow through it, it only transfers the pressure from one end to another.

So I do not think the diamiter of the pipe maters too much.
On an internal equalised valve the ballence port is only 1 mm in diameter.

Cheers taz.

.

Cheers Taz,

Thats what i thought. I did wonder though if the smaller bore pipe would be likely to get blocked with oil, especially in freezer aplications.

Jon

Hi Jon,

Just like you I'm being lazy, with one small difference, I have them prepared shorter - 60cm long.

Never had any problems in TEV performance.

Equalizer line has no flow (well it should not) and only sensors pressure, so line size itself is not important, I do exactly what you do, cut a pre made pressure couple in half, if no flare is required, I just use capillary of a similar size.

I'm with taz. I normally use 6mm flexible capillary hose.

I agree with No Nick and MF. But if external is frosted the TX is by-passing through pushrods . A common problem with Sporlan TEXV's.
magoo

Cheers guys,

Now let just say a valve has just started passing by into the equalizing line, now if its been piped with small bore that can't flow enough to stop the pressure rising at the txv, will this cause the valve to open up to try and match the temperature at the bulb to the now false pressure at the txv?

Jon :)

I've had a think about it and plotted some pressure and temperature on a graph and now think this will cause the valve to shut down as it will lower the percieved superheat.

I shall be interested to here what you guys think :D

Quote:

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Originally Posted by monkey spanners

Cheers guys,

Now let just say a valve has just started passing by into the equalizing line, now if its been piped with small bore that can't flow enough to stop the pressure rising at the txv, will this cause the valve to open up to try and match the temperature at the bulb to the now false pressure at the txv?

Jon :)

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Jon, this is a fault. You may want to guarantee fault tolerance to the system and clearly, the smaller the capillary, the higher chance of reevaporating the spilled liquid, but you will easily detect the fault by noticing the formation of ice around the capillary.

Cheers NoNickName,

I'm just wondering what effects having a txv leaking down the equalizing line will have on the txv's opening position if the equalizing line is restricting the leaked refrigerants flow into the suction line.


I've only seen two txv's fail in this way in 28 years so i know its not a common problem! I guess being stuck at home due to snow has got me wondering :D

Actually I am still somewhat confused about the location of storage / expansion Bulb position either external or internal TXV, the distance between the TXV and Bulb Bulb also the position of those facing where? what influences of these errors Bulb position?
Thanks