Pressure Testing for R410a

Hi Folks
this question has come to light after a phone call yesterday from the Health & Safety Executive asking if we use a gauge manifold when pressure testing for R410a. Apparently an engineer has been killed when the glass window blew out of his manifold. My question is do people feed the pressure into the system to be tested through an R410a manifold or do you come straight of the nitrogen regulator?
Secondly how many engineers actually have a specific R410a manifold?

This is to give me an idea as to what is going on out in industry so we can make sure everybody knows how this procedure should be done for R410a. I have heard a couple of stories recently were engineers are pressure testing without a regulator, they come straight of the bottle and regulate the pressure with the gauge manifold valves.

Comments please

Ian

I think you should have a look here it was posted by someone a few days ago, on another thread.

mail@vgitraining.commail@vgitraining.com

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Originally Posted by Pooh

Hi Folks
this question has come to light after a phone call yesterday from the Health & Safety Executive asking if we use a gauge manifold when pressure testing for R410a. Apparently an engineer has been killed when the glass window blew out of his manifold. My question is do people feed the pressure into the system to be tested through an R410a manifold or do you come straight of the nitrogen regulator?
Secondly how many engineers actually have a specific R410a manifold?

This is to give me an idea as to what is going on out in industry so we can make sure everybody knows how this procedure should be done for R410a. I have heard a couple of stories recently were engineers are pressure testing without a regulator, they come straight of the bottle and regulate the pressure with the gauge manifold valves.

Comments please

Ian

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That’s an interesting thought, Ian.

I’ve been considering this for a while, now. I reality, the problem has always been there – it’s one of pressure integrity of test equipment.
It could just as easily arise on lower pressure threshold refrigerants and their dedicated gauges.
It just happens that the higher pressure with R410A have brought the issues to the fore because there is a temptation to use ordinary gauge and manifolds that were designed for use with other gases. Moreover, it was intended that R410A equipment should have a special larger service port to prevent the use of conventional manifolds. I see that it is possible to obtain a conversion fitting from quarter flare.

Someone has borrowed my EN 378, but from memory the tables in part 2 provide a minimum saturation temperature that may be converted to pressure to establish the allowable pressures etc. For heat pumps, I think that 53 degrees is significant. (?memory!). When converted to pressure for R410A this comes out at about 33 bar. However, whatever the values, this is the minimum but is often used as the test threshold. It can be higher.

My reasoning is, and anticipating the HSE’s thinking, the gauge manifold set that is put into circuit during the test becomes part of that circuit and must equal or exceed the same pressure integrity as the system.
Moreover, I believe that it should equal or exceed the stated strength pressure values for that system and a written safety assessment should describe this and state periods of use between safety testing of the equipment.
This puts the onus of responsibility straight back on, firstly the manifold manufacturers to ensure that their kit is fit for purpose and that they say so, secondly the employers to ensure that their safety assessments and equipment are up to date.

The real solution, I believe, is for the use of dedicated lines and gauges that are used for this purpose alone, not multi-purpose gauge manifolds.

For clarity, it’s sometimes helpful to look at the similar rules for lifting equipment, straps and ropes etc. They are described, regularly tested and clearly labelled.

As for piping straight from the regulator, I think that is to be discouraged – the regulator output gauges are not accurate enough at those pressures.

Health and safety rules are often ridiculed, but far preferable to this scenario.

Next question – Does this industry need official codes of practice?

.

Quote:

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Originally Posted by Argus

That’s an interesting thought, Ian.


Someone has borrowed my EN 378, but from memory the tables in part 2 provide a minimum saturation temperature that may be converted to pressure to establish the allowable pressures etc. For heat pumps, I think that 53 degrees is significant. (?memory!). When converted to pressure for R410A this comes out at about 33 bar. However, whatever the values, this is the minimum but is often used as the test threshold. It can be higher.

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Your memory serves you well:).
Its 55deg X 1.3 for strength testing and 55deg X 1.1
for leak testing.


taz.

If you are using a dedicated OFN regulator and R410A gauges for pressure/strength testing then there should not be any problems, as these items of equipment should be capable of working safely upto their maximun gauge pressure. The regulator screwed in to give maximum output cannot exceed the maximum shown on it's gauge.

A problem would however, arise if the OFN regulator could be set to provide a pressure in excess of the maximum working pressure of the R410A gauge manifold.

Frank
or a regulator was not used at all, the gauges on the R410a manifold we have in department are graduated to 54 bar which should mean they are safe for leak and strength testing.

Ian

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Originally Posted by Pooh

Frank
or a regulator was not used at all, the gauges on the R410a manifold we have in department are graduated to 54 bar which should mean they are safe for leak and strength testing.

Ian

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Ian

How can you not use a regulator to connect to a bottle of OFN? The OFN is filled to 300Bar?

I use a set of Yellow Jacket R410A gauges (which have a sight glass) And a regulator.
If i was being honest i'd also say i don't pressure test to 50+ bar as i dont trust the valves on the unit not to leak by. When they start sending out units with no gas in them things will change. Even the manufactures won't gaurantee the valves won't leak by!
If i were doing a vrf as opposed to small splits i'd test without the outdoor unit connected.
Also if an exploding gauge glass has killed someone, what is the likely effect of a cassette going pop above ones head as its tested? or a bit of pipe?
Well you did ask...

R410A requires special handling for safety and proper use in the systems it is used in .To use standard test gauges on this refrigerant is an absolute NO NO. For those who are interested if you Google Mitsubishi Electric - R410A you will find excellent information on this subject and highlights the salient points of EN378.

Monkey Spanners
suggest you look at EN378 and check what pressure you should be testing to.

As for how could you pressure test without a regulator I will try and find the home made adaptor I took of an engineer who worked for a company I was supervisor for.

Ian

Thankyou Pooh,

Will do. Still, what would happen if a cassette or such let go as it was tested?

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Originally Posted by monkey spanners

Thankyou Pooh,

Will do. Still, what would happen if a cassette or such let go as it was tested?

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There would be ahorrible splitting noise followed rapidly by the sound of escaping gas (and the distant scream from the technician:D)

I wouldn't expect any parts or bits to go flying through the air as the pipes/joints etc would rupture rather than explode.

I am prepared to get corrected here folks....

Folks
all equipment is designed to take the strength test pressures to check if any of the interconnecting pipework or joints are safe in the event of over pressurisation. Always read the manufacturers instructions to check what they say but most are built to take the En378 testing pressures. Just to confirm EN378 is not law it is only a standard however in the event of something going wrong and it goes to court as long as you have complied with the standard you should be OK if you have not then you are on your own.

The standards have been created to give us a bench mark to work to for our protection so why not comply with them.

And Brian yes it does tend to rupture and his and yes it does require clean underwear when it happens.

Ian

R410A should be tested as follows well accodring to my gas safe handling book from college,

Minimum allowable pressure for design and leak testing is 33.6 bar or 504psi.

Strength test pressure x1.3 allowable ps is 43.68bar or 655psi.

These are the guidelines we have been given on testing air and water cooled condensers, Air cooled test pressure is 35-43.3 bar, water cooled is 25 to 32.5 bar and the test pressure on the low side is 19 to 23.7 bar.

Hope this helps

Matt

Nice one Matt.

And as long as your service gauges are rated in excess of this pressure, then you should, by rights, be able to use them safely for pressure testing.

Accidents will always happen, and some items of equipment will always fail prematurely, no matter how careful we are.

I was one of those engineers who used guage line adapters on normal guages, 2 years ago i was hit in the face by my manifold sight glass while testing a system. Not pressure testing.

Luck would have it i had safety glasses on but no gloves, only injury burnt fingers and a cut cheek.

I never buy manifold sets now with sight glasses not even for standard refrigerants.

I have experienced the site glass go on a manifold when tesing a R410A unit that does not have a HP switch, but relies on thermistor and software. When in heating the small split just on working until hitting the isolator!

Ian, going back to your original point, it appears that the HSE is beginning to questioning the suitability of equipment and working practices.
They are obviously talking throughout the trade and I would be give some careful thought to my response.

There’s a fundamental point that has been overlooked which is crucial to this discussion when it is applied to small split or packaged systems and the like.

Most of these are designed and made in the Far East or are made else where by Far Eastern companies principally for the residential market.

The relevant international refrigeration safety manufacturing standard for this type of equipment is ISO 5149 and this standard has a pressure testing method specifically for small units such as split systems etc., intentionally made without pressure switches, which rely in the strength of the system walls.

It is quite an involved process and is referred to as the ‘Intrinsic Test’ and is described at some length in the standard.

Basically, it works like this: the manufacturer assesses if his unit is suitable for the intrinsic pressure test from the criteria laid down in the standard.
If it does, he carries out the test which simulates the worst case pressure scenario at the specified operating conditions. In short, he runs it with fans etc disabled so that it deliberately produces the highest pressures it is capable of under those running conditions.

BUT it only applies to the equipment as sold and unmodified - NOT to all the test equipment that you apply in the field.

The pressure integrity of sight glasses, manifolds and the like fitted externally to the equipment is outside the scope of this safety standard.

So while the unit may pass an intrinsic pressure test, test equipment may not.

When sight glass bull’s eyes and bits of gauges start flying around because you are cranking up the test pressure, you have to question the suitability of your own equipment……

If any member has access to a copy of ISO 5149, please check it.

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Argus
my point exactly, the problem is that there are a lot of guys out there using standard gauge manifolds designed for use with the standard refrigerants for testing R410A systems which as we know works at significantly higher pressures. I beleive that it is these manifolds that are failing and causing the injuries and fatalities which are being reported.
If on the other hand it is specifically designed R410A manifolds that are failing they are not by description FIT FOR PURPOSE which then moves the responsibility on to the manufacturer of the manifold.
Unfortunately there are a lot of people out there who have little or no training and they do not realise just how dangerous anything under pressure can be.
Firstly the adapters to convert 1/4 lines to 5/16 for connection to R410A systems should be banned, at least that would be a start.

Ian

If a nitrogen botle has 2000 lbs of pressure and your hoses are rated for 600-800 pounds burst. Never mind.... LOL

Quote:

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Originally Posted by Pooh

Argus
my point exactly, the problem is that there are a lot of guys out there using standard gauge manifolds designed for use with the standard refrigerants for testing R410A systems which as we know works at significantly higher pressures. I beleive that it is these manifolds that are failing and causing the injuries and fatalities which are being reported.
If on the other hand it is specifically designed R410A manifolds that are failing they are not by description FIT FOR PURPOSE which then moves the responsibility on to the manufacturer of the manifold.
Unfortunately there are a lot of people out there who have little or no training and they do not realise just how dangerous anything under pressure can be.
Firstly the adapters to convert 1/4 lines to 5/16 for connection to R410A systems should be banned, at least that would be a start.

Ian

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I have ben puting in r410 systems since 1999, I think the idea that some uses a r22 manifold set is ludicrous, the pressures won't read on most gauges as they are to high, and the test pressure necssary would kill your suction gauge. It is not an issue of making a law to change the port size, it is an issue of unqualified techs doing the work... Just my opinion though.

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Firstly the adapters to convert 1/4 lines to 5/16 for connection to R410A systems should be banned, at least that would be a start.

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Ian,

I can see your argument - however, don't forget that when pressure testing, vaccing etc you may need an adapter to convert your R410A service hose to 1/4 flare for connecting to OFN regulator or Torr gauge.

Quote:

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Originally Posted by Pooh

Folks
all equipment is designed to take the strength test pressures to check if any of the interconnecting pipework or joints are safe in the event of over pressurisation. Always read the manufacturers instructions to check what they say but most are built to take the En378 testing pressures. Just to confirm EN378 is not law it is only a standard however in the event of something going wrong and it goes to court as long as you have complied with the standard you should be OK if you have not then you are on your own.

The standards have been created to give us a bench mark to work to for our protection so why not comply with them.

And Brian yes it does tend to rupture and his and yes it does require clean underwear when it happens.

Ian

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Yes been there got the t-shirt

Takes me back to a point I made in another thread about 1/4 flares provided qas standard on all BC and BS boxes as well as certain units that cannot be changed to brazed connections.It pisses me off that after taking all the care to make sure refrigerants cannot be released to atmosphere this single small flare could fail ( possibly inadertantly caused by another Trade working in ceiling void )and result in massive losses of gas to atmosphere.

Quote:

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Originally Posted by monkey spanners

I use a set of Yellow Jacket R410A gauges (which have a sight glass) And a regulator.
..

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same here,althought i always try sticking to the 1.1 and 1.3 guide

an old thread


http://www.refrigeration-engineer.co...ead.php?t=8637

are these the new rigs everyone is selling? anyone got one?


and now i cant find the link grrrrrrrrrrrrrrrrrr

hello all

i have not read every reply but from recently completing my nvq @ college i know it is recommended to use r410a specific gauges without a sight glass. You can get sight glasses that connect to your yellow line if your worried about not putting liquid in when charging etc..
i use non sight glass manifould for testing specially when on daikin vrv we pressure test to around 41 barg

hope this helps

al

Why oh why do "engineers" insist on using the gauge manifolds for pressure testing?
As is correctly stated before, the high side of a system is tested to the pressure equiv' of 55C x 1.3..
Taking this into account some are using an item (manifold) which is bounced about in the back of a vehicle, dropped and generally abused. This item sometimes contains a sightglass which can act like a vehicle windscreen. In other words, it can get chipped and not be noticed until the chip becomes a crack. With a pressure of up to 44 bar behind it, it is a weak spot. You should be using an OFN regulator rated at 50 bar (750 psi) with two gauges on it. One for the cylinder contents, one for the outlet pressure, and a suitable high strength charging line direct from the regulator to the system.
Please don't use your manifolds.

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Originally Posted by pendlesteve

Please don't use your manifolds.

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I take it then that the manifold gauges sold by Yellow Jacket, ITE, Robinair etc. with sight glasses, are not rated upto the maximum pressure that is shown on the high side gauge??

Does anyone have any statistics of these 'sight glass' failures at below the maximum gauge pressure indication??

Has anyone ever been injured or killed??

.

I think that what Steve was saying was, "Don't use gauges and manifold sets for tasks that they were not specifically designed for".

Please correct me if I have it wrong, but the pressures encountered in everyday servicing situations are not those that are routinely used for the extremes of pressure testing, especially if you are working within the PED, that should be carried out under specified conditions and using equipment that is specified safe for the job and not used for anything else.

Service equipment is not test equipment.

.

Service gauges and hoses are no good for the pressure test as they are rated too low and though we all luv em they do get knocked about abit. There are too many weak points that can put yours and others lives at risk which in this risk averse world just won't do!
The ofn regulators are designed to work at the cylinders max pressure and give a controlled pressure output and release. They usually come with a steel braided hose as well so there is less chance of that bursting.
as usual though it is down to choice but use the ofn regulator to do the pressure testing and let the service gauges do their job safely.
See you all back here soon
Brit

I'm not convinced with the argument.

If the service gauges have a high side gauge that reads, say 50bar, then I would assume that the manufacturer (who would be liable if a failure happened) would make sure that the components, i.e. gauge lines, sight glass, manifold etc. would be capable of containing slightly more than 50bar.

I cannot see how anyone can state that you should not use the 'service gauges' for pressure testing when the pressure test pressure is less than the maximum shown on the gauge. ?????

I'm with Frank on this one.

i also agree with Franks comments, but would add that there may well be a more suitable rig arragememt for pressure testing new installations.

What this rig would comprise of, i am not sure.

Billy Ray

Ok if you have a brand new set og gauges then they will be rated at round 55bar for the high side gauge.
A brand new set of hoses without knicks or scuffs is also rated around 55bar.
The ofn cylinder could be charged at 230bar.
A suitably sized nitrogen regulator and high pressure hose will mean that you are not high prsure testing with a minimal safety margin of 5bar on "new" tools.
The service manifolds aren't often treated with the respect that they deserve so the hose could have a slight knick or the sight glass could have been knocked
There has already been problems with sight glasses in guages failing under pressure
Brit