Pressure testing for leaks on split a/c systems

[mrchatts]

Hi Guys & Girls

Hope someone can point me in the right direction.

I know the regulations for pressure testing pipework (EN378) but my concern is the last flared joints connected to the outdoor unit. Most manufactures say pressure test without connecting to the condensing unit, but what about the last connection?

On split A/C the units are pre-charged with refrigerant but I’m not sure weather the service connection valves would withstand back leakage if I crank the OFN up to high, I still need to test the last connections?

Anyone know what the safe leak test pressure on R410a should be?

Can I test the evap and pipework while connected to the outdoor unit?

If someone could mail me method statement for pressure testing Daikin R410 split system would be greatly appreciated or any other manufacture for that matter as we install most makes.

Cheers
mrchatts@aol.com

[stan1488]

flared brass plugs cheers

[mrchatts]

flared brass plugs cheers

Thanks for the quick reply Stan; if that’s common practice I could use them, anyone else with the pressure test issues?

[norcool]

Hey,first off all I use new Cu pipes,soft copper seem to be useless after 2 years if you
use it for flare nuts,It should be new and really softend.Next ,the saturation pressure
for R410 is high enough to get bobbles from dish soap+water.Use oil in the backhousing
of the flare nut before tightening.If you have 3/8-1/4 pipings its guite easy.Use right
force .have a nice day norcool

[Greg Alexander]

Hi, for R410a you should leak test at 650psi,
cheers

[mrchatts]

Hi, for R410a you should leak test at 650psi,
cheers

Thanks Greg, but can i do it connected to the pre-charged out door unit?

Daikin advise 41.5 Bar for 24hours. has anyone got method statement to say i can do this test connected? :confused:

Thx norcool i always oil my nuts lol :eek:

Frank can you help??

[Greg Alexander]

Hi, yes you can do it connected to the outdoor unit, make sure the flare nuts are not overtightened, use a torque wrench to manufacturers spec, its in the manual, the copper pipe will burst before the flare connection will. Make sure you only preesure test for a few minutes at that pressure then do a standing leak test around 140 psi for as long as you like!

cheers

[Gary]

I'm thinking the pre-charged unit would be irrelevant. The most likely component on the low side to burst would be the evaporator.

Consider what normal pressures might be on a completely assembled R410A system that is not running. Just sitting there on a warm day, the equalized pressure throughout the system might be 250-300 psi on a warm day, and possibly as high as 400 psi on a very hot day.

[Stuart]

Thanks Greg, but can i do it connected to the pre-charged out door unit?

Daikin advise 41.5 Bar for 24hours. has anyone got method statement to say i can do this test connected? :confused:

Thx norcool i always oil my nuts lol :eek:

Frank can you help??
Daikin recommend this pressure test for 24 hrs.......So leave it on for 24hrs
Mitsubishi also recommend a very similar test pressure for similar time frame.

There is no possibility of the nitrogen mixing with the pre-charged gas in the outdoor unit as the valves are shut, & if they weren't gas tight you would know one way or another.

410 is a safe gas to work with treat it with respect but don't be scared of it.

[BritCit_Juve]

Hi all

Just a word of caution when pressure testing the pipework on splits with OFN. It is assumed that when the valves are shut they are gas tight. Unfortunateky this isn't always the case as the valves are sealed by the refrigerant pressure and can in some instances be forced open when the pipework pressure is greater than the refrigerant pressure.
Its a case of to be sure remove the original charge and test or block the pipework while detached from the CU and test.

Have fun and take care
BritCit_Juve

[Stuart]

Hi all

Just a word of caution when pressure testing the pipework on splits with OFN. It is assumed that when the valves are shut they are gas tight. Unfortunateky this isn't always the case as the valves are sealed by the refrigerant pressure and can in some instances be forced open when the pipework pressure is greater than the refrigerant pressure.
Its a case of to be sure remove the original charge and test or block the pipework while detached from the CU and test.

Have fun and take care
BritCit_Juve

BritCit That is a possibility but unlikely as the valves are screwed shut using a mechanical operation. If the valve worked on a plunger method as in the taps on your sink then it would be more of a chance. After all how many units have you installed vacced then opened up to find there is no gas in there?
It can happen but more often than not it does not.

As for dissconnecting pressure testing then reconnecting.....Does anybody else see a problem with this.

It means that there is at least 1 (one) joint that hasn't been tested on the system. Also not to mention the extra work involved for no real reason.

It is best to pressure test with Nitrogen using the service valve.

This way ALL the joints are tested.

This is the only way a clerk of works on a site will pass the installation, all installations should be made to be fully leak free.

[chemi-cool]

24 hours at 41 bar?

They must be nuts and so everyone that follow these instructions.

The unit comes charged and pretested.
All you have to check is the flare connection at the out door and in door units.

That should not take more then 1/2 an hour.

May be the manufacturer doe's not trust his own pressure test at the factory and wants you to have all the responsibility?

If there is a leak in the evaporator or condensing unit, who's responsible is that?

Chemi :)

[freezy]

I normally pressure test with pipes connected but find some units will pass refrigerant when tightening flare nuts and some will pass nitrogen when testing. It drives me mad, especially when your alone on a high rise roof of a building site where the lifts are not yet operational and your van is parked 7 blocks away due to parking restrictions - more kit to lug.
With this said I now take great care when tightening nuts to keep the retaining spanner still and operate correct force as eratic movement seems to upset the valve and be the main cause. :)

[chemi-cool]

What came to my mind is that now with this new, high pressure refrigerant, I would expect the tools manufacturers to come out with a new double flaring tool. :rolleyes:

That will eliminate all leaks.

Chemi :)

[rbartlett]

What came to my mind is that now with this new, high pressure refrigerant, I would expect the tools manufacturers to come out with a new double flaring tool. :rolleyes:

That will eliminate all leaks.

Chemi :)

or go back to the old way of welding the connections..

cheers

richard

[capthummel]

I agree the factory is responsible for the pressure testing of the inside and outdoor unit. The test is mainly for the flare connections although I have experienced problems with the valves on the outdoor units being faulty and leaky from the factory so use caution.

24 hours at 41 bar?

They must be nuts and so everyone that follow these instructions.

The unit comes charged and pretested.
All you have to check is the flare connection at the out door and in door units.

That should not take more then 1/2 an hour.

May be the manufacturer doe's not trust his own pressure test at the factory and wants you to have all the responsibility?

If there is a leak in the evaporator or condensing unit, who's responsible is that?

Chemi :)

[The Viking]

Apples and pears guys, apples and pears.


You are discussing 2 issues here as if they were one.
After the installation there are 2 different tests to be carried out.
1. A strength test, the 40 odd Bar one.
2. A standing pressure test for leaks, the long one.

Normally you would carry out the strength test and then reduce the pressure for the leak test. These tests must, as far as I'm aware, be carried out for the whole system so no joints to be made up afterwards.

Here in UK, when the R410a first started to appear in splits some 5 years ago, it is true that most manufacturers were caught with their trousers down. They had used cheap and nasty valves in the units.
(If you put a claim in for warranty to reclaim/recharge after the valves had let OFN through, they would pay up after you said the valves weren't fit for purpose)

Nowadays, they all seems to have learnt the lesson and put better valves in.


P.S. I still would like to see anybody who actually leaves the pressure for 24 hrs on a split, especially in today's price beaten society.

[Grizzly]

Yet again the voice of common sense.
Well done viking.

Not so long ago I was talking to a young fridge engineer from another company.
He had been on a course where the lecturer. Said he must carry empty vacuumed out cylinders.
So that when he is left with the small amount of low pressure vapour in his gauge lines.
It can be purged into a virgin cylinder!!!!

Discuss!!
Grizzly

[Karl Hofmann]

Yet again the voice of common sense.
Well done viking.

Not so long ago I was talking to a young fridge engineer from another company.
He had been on a course where the lecturer. Said he must carry empty vacuumed out cylinders.
So that when he is left with the small amount of low pressure vapour in his gauge lines.
It can be purged into a virgin cylinder!!!!

Discuss!!
Grizzly

The lunatics have taken over the assylum....

Hey Viking... Nice to see you about, we wondered what had happened to you...

[chemi-cool]

Not so long ago I was talking to a young fridge engineer from another company.
He had been on a course where the lecturer. Said he must carry empty vacuumed out cylinders.
So that when he is left with the small amount of low pressure vapour in his gauge lines.
It can be purged into a virgin cylinder!!!!



It made me laugh.

Lecturers in colleges and university, are the people with the least experience in that field,

NO ONE IS SMARTER THEN US!!

Even that unexperienced lecturer forgot to think about the probability of using different types of refrigerants....

Stupidity is the only thing on earth that makes me mad

Welcome back Viking.

[sinewave]

Yes, welcome back Viking!


Glad to see your website back on-line too! :)

[The Viking]

Thank you all,
I'm pleased to see that I been missed.

@ Sinewave,
Slowly, it is coming back together again. It was hijacked by someone advertising Russian Ladies. At least it taught me to have an off-line backup and that I need to find another service provider.

Unfortunately work has been quite hectic of late and any time off has been claimed by the family...

[yoelyeve]

Hi I put leak lock on the flare male trad's and tighten until the copper starts turning together with the nut and never had problems .
After its connected to unit I use nitrogen to pressurize for 450 PSI for 3 hours release nitrogen and vacuum system add the charge for the line-set by weight open the valves and test unit

[Karl Hofmann]

It's great that you have been busy... Given recent times you can't help fearing the worst when someone goes AWOL...

Oddly enough, I was hijacked by a Russian lady because of my website....:D:D:D

[james10]

EN378 states that a refrigeration system must be strength tested @map x 1.3 map (refrigerant pressure @55 degrees C air cooled/45 degrees C water cooled in a temperate climate maximum 26 degrees C for us in the uk) for a minimum of one hour then leak tested @ map x 1.1 the pressures given by manufacturers are some where near the correct test pressures and given their test guidlines for pressure testing are to valadate warranty most would presume that the system and its components can withstand the stated pressures when tested in a complete state especially when dealing with split A/C. when dealing with water cooled evaporators you need to isolate the evaporator as normally the pressure ratings on the evaps are a lot less than EN378 test pressures

[capthummel]

Hi I put leak lock on the flare male trad's and tighten until the copper starts turning together with the nut and never had problems .
After its connected to unit I use nitrogen to pressurize for 450 PSI for 3 hours release nitrogen and vacuum system add the charge for the line-set by weight open the valves and test unit
I have had big problems with leak lock hiding problems that bite you in the ass down the line.

[R1976]

What's leak lock?

By the way, I currently have 3 Sanyo gas fired heat pumps and 1 Mitsubishi water cooled VRF on pressure test for 48 hours. Hopefully vacing them tomorrow.;)

[capthummel]

Hi, yes you can do it connected to the outdoor unit, make sure the flare nuts are not overtightened, use a torque wrench to manufacturers spec, its in the manual, the copper pipe will burst before the flare connection will. Make sure you only preesure test for a few minutes at that pressure then do a standing leak test around 140 psi for as long as you like!

cheers
I have had many leaks from screwed up threads on the nut side that have passed leak testing and vacuum that leak after releasing refrigerant. The problem is usually a half thread at the very bottom of the nut now I re flare as a standard good flare from the factory or not it is the easiest way to relieve what has become a standard head ache at least from fujitsu. Also I think fujitsu's toque values are BS.

[capthummel]

What's leak lock?

By the way, I currently have 3 Sanyo gas fired heat pumps and 1 Mitsubishi water cooled VRF on pressure test for 48 hours. Hopefully vacing them tomorrow.;)
Leak lock is a refrigerant sealant some asshole told me was great all it does is hide leaks. Just dealt with one that passed pressure test and everything including my electronic sniffer that shut down and needed a recharge in six months. I do not use that crap any more at all the 410a eats it off the threads the uh oh by by 410a. Don't use it ever.

[r0ss]

Sorry for going a bit off topic... but...

Why is there any need for flared nut joints anyway?

The old Daikin BS Boxes had flared nuts on them but we cut them away - now the new style boxes come pre-swaged so no need for that now.

We also did a 72 unit job recently with Mitsi shallow ducted units which is a brazed joint onto the unit rather than nuts. Im on a job now with 124 Daikin shallow ducted units but they have flared nuts which increase the chance of leaks.

Anyone shed any light on this?

[capthummel]

Sorry for going a bit off topic... but...

Why is there any need for flared nut joints anyway?

The old Daikin BS Boxes had flared nuts on them but we cut them away - now the new style boxes come pre-swaged so no need for that now.

We also did a 72 unit job recently with Mitsi shallow ducted units which is a brazed joint onto the unit rather than nuts. Im on a job now with 124 Daikin shallow ducted units but they have flared nuts which increase the chance of leaks.

Anyone shed any light on this?
Flare joints where the idea of some lazy engineer in an office probably trying to save time in the field just causing problems for us out there to deal with latter. Maritime industry they are not allowed. I hate them with a passion they have cost me plenty of lost time having to return to a job for a damn flare.

[AndrewB]

The subject of flared vs soldered often comes up where I work, I tend to agree with the older generation of fridgies that say solder doesn't leak.

As for LeakLock, I was always taught to believe that it is for people that can't do flares. A good Flare with oil on it is all you need.

[R1976]

If you look in the ends of the pipes on Mitsubishi VRF wall mounts and bc boxes there are strainers so if you cut the flare end off you have no strainer.

Also I have never had a flare nut leak after I have left a job, I believe leaky flares are for people who cannot tighten flare nuts:D.

Use oil on flared copper part.

[capthummel]

If you look in the ends of the pipes on Mitsubishi VRF wall mounts and bc boxes there are strainers so if you cut the flare end off you have no strainer.

Also I have never had a flare nut leak after I have left a job, I believe leaky flares are for people who cannot tighten flare nuts:D.

Use oil on flared copper part.
I should send you some of the crap that they have been sending me never seen such junk. Crap copper flares with cracks oblong flares you name it. And I always use oil on my flares. I have also ran into missing threads all the way behind the flare unseen even had them pass a leak test and end up leaking latter down the line.

[R1976]

Do you use a concentric faring tool?

[still learning]

cut pipe, debur, file flat, fit nut, use concentric flare tool, oil back of flare, use torque wrench.
ptest to 35bar , bubble test flares, whilst ptest is on for 24 hours, and fit boots round flares, have a cuppa.
made a note to read dakin manual about 600psi test.

[SkyWalker]

the strength test should be 1.3x the MOP for the system, as said previous a leak test is the 24hr test, this can be 1x MOP, obviously you should increase pressures in stages using your ofn regulator NOT your gauge manifold, also if you install hitachi have a read in there manual, they say you must reclaim all refrigerant in the condensor before the test goes ahead.

apparently due to new f-gas regs all sytems will come OFN charged anyway, only a matter of time

[Peter_1]

Also I have never had a flare nut leak after I have left a job, I believe leaky flares are for people who cannot tighten flare nuts:D.
Use oil on flared copper part.
Same remark, if a flare is made good, then it stays good.

And...Leaklock is only to avoid that water enters between the copper and the nut and then can enter into the thread and damage it by freezing up. A flare must be tight without leaklock, it's only to prevent water infiltration.

It all depends with what sort of flaretool you make you flares.

[B G Scott]

It made me laugh.

Lecturers in colleges and university, are the people with the least experience in that field,

NO ONE IS SMARTER THEN US!!

Even that unexperienced lecturer forgot to think about the probability of using different types of refrigerants....

Stupidity is the only thing on earth that makes me mad

Welcome back Viking.
Those that "can" DO,
Those that "can't", TEACH
Those that "can't teach" TEACH TEACHERS.
I know it's an old quote in the teaching (profession)( I use this term lightly) but there is an element of truth in there!!

[lomb]

What sort of oil should one be using on r410a to oil the back of the flare(not fit surface)?I have tried to find a supply of a small amount of POE oil but cant. I persume i shouldnt use PAG oil for r134a systems? And if not why not as if not applyed to the fit surface of the flare it shouldnt enter the pipes and damage the unit.Do the manufacture torque values still apply when oiling the flare as persumably if wet one can apply a higer torque.

Also when making the flare some say to oil the fit surface,is this really required and do people then clean this off before torqueing up. Thanks
Thanks

[flyinkiwi]

Agree - Leak lock = You're a ****e Fridgie... or you're a sparky. :eek::D:eek:

Fujitsu General have issued a bulletin, stating that pressure testing with dry nitrogen is not to exceed 200psig - there have been incidences of nitrogen leaking into the OD unit.

This weakness in the valve is sometimes caused by the distortion of the valve body when the flare is tightened (yes, even with 2 spanners) - I've also struck a panasonic that was like this too.

[taz24]

.

This subject has been discussed for a few years now and it is still causing problems :D.

I was speaking to a manufacturer a few months back and he was confident that no valve
and flare would leak if used and done correctly.

When the final flare was fitted, using torque spanners the flare would never leak and after
the flare was fitted the service valve needs retightening to ensure that it is sealed.
The fitting of the flare and the stress that, that incurrs is what could cause the valve to pass.

So fit the flare correctly and then reseat the valve to ensure it does not pass, that in the words
of the manufacturer will garentee a correct fitting.

taz.

.

[lomb]

So is use of oil a good idea and if so should it only be on the back to let the shoulder of the flare not catch on the nut? Can a small dot of vac oil be used as it shouldnt enter the system?

[lomb]

Agree - Leak lock = You're a ****e Fridgie... or you're a sparky. :eek::D:eek:

Fujitsu General have issued a bulletin, stating that pressure testing with dry nitrogen is not to exceed 200psig - there have been incidences of nitrogen leaking into the OD unit.

This weakness in the valve is sometimes caused by the distortion of the valve body when the flare is tightened (yes, even with 2 spanners) - I've also struck a panasonic that was like this too.

If that is the case then whats the point in testing with OFN at all? Running pressures are 400-450 psi.

[flyinkiwi]

True - but if you have a rubbish flare, it's as likely to leak at 50psi as it is at 500.

[Sridhar1312]

Hi Guys & Girls

Hope someone can point me in the right direction.

I know the regulations for pressure testing pipework (EN378) but my concern is the last flared joints connected to the outdoor unit. Most manufactures say pressure test without connecting to the condensing unit, but what about the last connection?

On split A/C the units are pre-charged with refrigerant but I’m not sure weather the service connection valves would withstand back leakage if I crank the OFN up to high, I still need to test the last connections?

Anyone know what the safe leak test pressure on R410a should be?

Can I test the evap and pipework while connected to the outdoor unit?

If someone could mail me method statement for pressure testing Daikin R410 split system would be greatly appreciated or any other manufacture for that matter as we install most makes.

Cheers
mrchatts@aol.com
The correct pressure testing for R-410a is 600 PSI especially where ambient goes to 40 degree C.
Ideally it is always better to charge any split at site after duly pressure testing with dry nitrogen and vacuumizing, offcourse for high side 600 PSI excluding compressor and low side shall be 200 psig.
When you follow the above procedure the last connection also gets tested. But reasons best known most of the manufacturers send precharged and in many cases it is pressure tested and charged leading to failure of the system.

In India the failure rate of split AC is directly proportional to the quality of dealer technicians quality of brazing, pressure testing and vaccumizing.

[constantine]

hi there!
as far as i know daikin systems,the cu and indoor units are always pretested,they are suplied with correct length of piping as per the specification of the system itself,therefore theonly joints recomended are the flared joints unless otherwise.the easier way of testing these joints is only when the service valves are shut and flare joint connected to the system.i stand to be corrected on this.