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mgtet
26-11-2006, 08:56 AM
I just wondered how realistic the new industry standards are. After a recent city and guilds refrigerant handling course i was informed that the new ratio for pressure testing is 1.43x the mwp. 55 degrees c is used for air cooled to obtain the mwp meaning r410a would have to be pressure tested at just over 50 bar:eek: . This should hold for four hours and then leak tested at 1.1x mwp and this should be left for four hours. Finally the system should be evacuated to 200 microns and then vac pump switched off and 200 microns maintained for 4 hours!!
This procedure should be carried out on all systems and when ever they have been opened, meaning if you just want to change a drier you have to reclaim all refrigerant and carry out the procedure as mentioned.where there are prvs they should be removed and capped off.
I can't see my customers being too happy about about paying for 3-4 days work for something that can be done in half a day.
Am I on my own?!!!!

Andy
26-11-2006, 11:09 AM
Hi Mgtet:)

common sense is a good thing:)

changing a drier required only a quick pressure test, anything more and the valves may not hold and you will end up with nitrogen in your refrigerant.

BS EN378 requires a strength test between 1 and 1.3 times the PS or design pressure. If you are not pressure testing the receiver you will not require any blanking of the relief valve (I would test a newly installed component to 1.1 times PS).

Comply with legislation, but in a common sense manner;)

Kind Regards Andy:)

mgtet
26-11-2006, 02:03 PM
i was told that if any components are changed the whole procedure as mentioned should be carried out as you are altering the structure of the system.
I agree with everthing you say, it is pretty obvious, was n't after advice just gauging opinions.

Andy
26-11-2006, 02:12 PM
i was told that if any components are changed the whole procedure as mentioned should be carried out as you are altering the structure of the system. I agree with everthing you say, it is pretty obvious, was n't after advice just gauging opinions.

Changing a drier or valve like for like is not altering the system, this is all down to translation and common sense(or the lack of it):)

Some people make good Civil Servants, agreeing with the law in minute detail, others get on with the real work:D

Kind Regards Andy:)

Pooh
26-11-2006, 10:30 PM
mgtet
out of interest were did you do your refigerant handling as the figures you mention do not seem correct, a strength test according to EN378 is to 1.3 x saturated pressure at 55 deg C but only requires holding for a couple of minutes at most. The idea is to see if anything bursts then reduce to 1.1 for leak testing.

Ian

Andy
27-11-2006, 09:41 PM
mgtet
out of interest were did you do your refigerant handling as the figures you mention do not seem correct, a strength test according to EN378 is to 1.3 x saturated pressure at 55 deg C but only requires holding for a couple of minutes at most. The idea is to see if anything bursts then reduce to 1.1 for leak testing.

Ian
Hi does the pressure even have to be as high a 1.3 times:confused: I think as long as it is above PS it is acceptable.

We have a spec where we test to 1.5 times the PS and leak test about 1.1 times, the consultant who wrote this spec felt that 1.3 was too close to 1.1 to be meaningfull:)

Kind Regards Andy:)

Pooh
28-11-2006, 01:03 AM
Andy
As far as we are aware 1.3 is the multiplier set out in EN378 we are aware that certain companies do require 1.5 for strength test but i cannot see the point.

Ian

lakshminathan
30-11-2006, 08:27 AM
what is low,medium,high static pressure in fan coil units?

Brian_UK
30-11-2006, 07:13 PM
what is low,medium,high static pressure in fan coil units?I believe a welcome to the forum is in order but as you haven't introduced yourself I'll pass at the moment.

The static pressure relates to the pressure than can be developed by the fan inside the unit.

Low pressure - no ductwork
High pressure - lots of ductwork.

mgtet
30-11-2006, 07:25 PM
it was a city and guilds 2078 refrigerant handling course taken last month and in the course notes the figures were as i stated. I do agree with andy though, on a system that has been in use I would pressure test at whatever the hp switch is set at, assuming the switch works you are never going to get up to 1.3x let alone 1.43x the mwp.