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ben chaib
28-02-2002, 09:26 PM
As we know the location of sensing bulb of T.E.V is very important.It must be in good thermal contact with the evaporator outlet and followed by the external equalizer tube.Always in the refrigeration field and in the technical books that (from the evaporator outlet)we found the sensing bulb and then the equalizer tube but and specialy in the FRIGHA BHON evaporators I found that the equalizer is located in the midlle of the collector.My question is what the purpose for thet specialy position of the equalizer adobted by the frigha-bohn.
N.B for 17 years I work in refrigeration air conditioning field( instalation+maintenance+reparation)I prefer to have firgha -bhon evaporators because they are good designed.befor I asked the frigha-bhon distrutors I didn't get the answer.

Prof Sporlan
28-02-2002, 09:49 PM
I found that the equalizer is located in the midlle of the collector.My question is what the purpose for thet specialy position of the equalizer adobted by the frigha-bohn.

The Prof will assume the 'collector' here is the suction header. There are a number of acceptable locations for the equalizer connection. The best is, of course, on a hortizontal section of suction line at a 12 o'clock position just downstream of the TEV sensing bulb.

Why would one connect the equalizer line to the suction header? Convenience most likely... :)

herefishy
28-02-2002, 11:18 PM
Originally posted by Prof Sporlan


Why would one connect the equalizer line to the suction header?

I think that the reason that manufacturers provide the equalizer connection (at all) is to (help) ensure that a externally equalized valve is installed, if indeed the mfgr's data (regarding PD) indicates that an externally equalized valve would be required for proper control. Thus limiting the liability of the mfgr in failure of the C.U. (compressor) due to improper refrigerant control...... and such. Or... maybe it's a reminder! "INSTALL EXTERNALLY EQUALIZED VALVE!"

Of course the manufacturer isn't going to stub out 12" from his cabinet and locate the eq. connection.... The crating would cost too much (not to mention the copper).

What is the net affect of the "upstream" pressure connection on valve operation/coil feeding? Is it merely the heat transference from the "warm" valve body to the evaporator outlet? Should the field techs be cutting the factory connections out (after they are reminded of the application) and properly locate such facility?

Gary
01-03-2002, 01:09 AM
Equalizer lines are located after the TXV bulb because small amounts of liquid refrigerant can (and often will) leak past the seals into the equalizer line.

This liquid, if it contacts the bulb, can effect it's operation, destabilizing the coil. If the equalizer line is after the bulb however, it will merely result in minor de-superheating.

ben chaib
04-03-2002, 10:06 PM
Originally posted by herefishy


Should the field techs be cutting the factory connections out (after they are reminded of the application) and properly locate such facility?
really it was my first intention and i changed the the mfgr's equalizer position in some frigha bhon evaporators( i serviced maybe more than 100)but i was always traying to have the right reason for that frigha bhon position.in the other evaporators you can see the right position in the horizontal line in the evapo outlet and the technician should know that an evporator with distributor and a colector must have the external equalzer t.e.v.
thanks for help:confused:

herefishy
04-03-2002, 11:53 PM
Originally posted by ben chaib

i was always traying to have the right reason

WHERE'S THE PROFESSOR?!!!!!!!!!!!!!!!!!!!!

Referencing Gary's note regarding liquid bypassing through the eq. seals; Would a properly located TEV sensing bulb, downstream, at 4 or 8 o'clock (if applicable in regard to line size) in such an "UN-by-the-the-book" scenario make re-piping the OEM configuration worth the while?

Prof Sporlan
05-03-2002, 04:08 AM
WHERE'S THE PROFESSOR?!!!!!!!!!!!!!!!!!!!!

Referencing Gary's note regarding liquid bypassing through the eq. seals; Would a properly located TEV sensing bulb, downstream, at 4 or 8 o'clock (if applicable in regard to line size) in such an "UN-by-the-the-book" scenario make re-piping the OEM configuration worth the while?
Not really..... The problem with liquid bypassing thru the TEV pushrod seals and then down the equalizer line isn't as much of a problem anymore. In the 1960s and prior, pushrod seals were used extensively in TEVs. But as manufacturing techniques improved, it was possible to precisely hold pushrod hole tolerances to the point where seals were no longer needed for "conventional" TEVs. Balanced port TEVs, however, would continue to require a pushrod seal due to its design. But these seals are typically formed neoprene seals that do not leave much room for error. About the only way you can create a pushrod leak in a balanced port TEV is to overheat the valve.

That said, it is still a good idea to locate the equalizer line downstream of the sensing bulb. The old tried and true methods still have a place in modern refrigeration... :)

ben chaib
06-04-2002, 03:28 PM
RECENTLY I GET THE ANSWER FROM THE FRIGHA- BOHN . IT IS AN INSTALLATION INSTRUCTIONS DATA SHEET.
FROM THE FRIGHA-BOHN:

(EXTERNAL EQULIZER.
THE EXTERNAL EQUALIZER LINE SHOULD BE MOUNTED BETWEEN THE SUPPLIED VALVE FITTING AND THE SUCTION LINE,NEAR THE UNIT OUTLET. A 1/4" TUBE BRAZED TO THE COIL HEADER IS SUPPLIED FOR THAT PURPOSE.
NOTE:WITH THE MODERN HIGH QUALITY EXPANSION VALVES,THE SMALL REFRIGERANT LEAKAGE THROUGH THE EQUALIZER LINE IS AT A MINIMUM AND THE VALVE OPERATION IS NOT AFFECTED.THUS ,THE EXTERNALEQUALIZER CONNECTION COULD BE EITHER UPSTREAM OR DOWNSTREAM OF THE BULBE.):)

Dan
06-04-2002, 03:36 PM
There you go. In dference to the professor and Friga Bohn, I have only seen the sort of bypassing that would cause trouble in rare instances.... and I suspect they were all over heated balance port valves.

Gary
06-04-2002, 04:49 PM
Call me old fashioned, but I try to avoid rare instances. :)