Guest Post by Steve Massey
As Document L of the building regulations continues to be tightened for both new and existing dwellings, Argon gas filling will become a standard process in sealed unit production.
BS EN 1279 is now mandatory for all sealed unit manufacturers and clearly defines the rules for gas filling compliance. EN1279 part 3 states : units must be within -5%/+10% of a specified single gas concentration and must have a leakage rate of less than 1% per year, over a 10-year period. It is reasonable to take 90% as the concentration level for Argon, because this is the level that all WER windows are calculated at.
As part of our EN1279 part 6 compliance responsibilities, we have to undertake daily testing of our gas production. We are required to log and record the concentration levels for a minimum of 3 random units per day from the Argon batch. We actually test many more to check that all our systems are working correctly. This ensures that our customers will not be faced with a huge product recall due to either illegal or unfit for purpose products. Ask Toyota what their current recall issue is going to cost them.
Our calibrated external Sparklike Gas test machine gives instant readings of Argon content. We can test a unit that is in-situ glazed, as easily as testing units from our production. We would recommend that any window company buying gas filled sealed units asks their sealed unit supplier for the following:
• To visit their factory and view their gas production and testing systems
• Examine their EN1279 part 3 pass report
• To bring their in house gas testing machine to site and test the gas content of random units
• Repeat these actions regularly to ensure that they maintain quality.
We welcome window companies with any doubts about their products to bring a unit to our factory for a confidential Argon concentration test. We think that the peace of mind would be worth the trip.
Regards
Steve Massey
Regency Glass Ltd
www.regencyglass.co.uk
www.sparklike.com
Tags: argon gas filling, argon gas windows, BS EN 1279, regency glass, Sparklike Gas Testing Machine
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I have to say I am a little surprised that this post has recieved no attention . I read on a previous post about the loss of gas from a unit and was very interested to hear more. Does the gas testing highlight particular brands of sealant , spacer or specification that would set alarm bells ringing?
Response Kevin Ahern
Gas testing with the Sparklike gas tester simply highlights the gas content of a sealed unit.
Rather than it being a particular brand of sealant, spacer bar system or other component, the presence of Argon to sufficient volumes (90%) is wholly dependent on the sealed unit manufacturer being competent and conciencious enough produce quality gas filled units.
There are many issues that are not understood or assessed properly when gas filling is incorporated into sealed unit production.
Gas loss during production between the point when the unit is gas filled (no matter which equipment introduces the gas) and the point when the unit is finally completely sealed can be up to 30%. This means that the unit at point of production has potentially lost enough gas to render the Argon filling pointless.
If a sealed unit company does not have the relevent piece of equipment, such as the Sparklike test machine, to randomly test their production, they have absolutely no idea whether the products they are making have gas in them.
It takes longer and more processes are involved to manufacture a gas filled sealed unit that meets all criteria of EN1279 and thus are suitable for WER applications. Quality is the issue. Poor concentrations and high gas leakage rates are a direct result of low standards of production quality coupled with a lack of understanding of heavy gas dynamics.
Steve Massey
Many thanks Steve
I must admit I may have missed the thrust of your original post, but I was getting the impression that purely having compliance with EN 1279 pt 3 may not in fact be a guarantee of having properly filled units. Would it be fair to say that units certified to this standard would generally have a proper fill of argon?
Kevin
Hi Kevin
EN 1279 part 3 is the gas concentration and leakage test. Unfortunately, passing the test does not mean that on-going production will have the correct amount of Argon or the allowed leakage rate per annum.
Getting Argon into the sealed unit to a concentration of around 90% is not difficult. I would say that most sensor controlled machines available in the market today can do this. The main problems are keeping the gas within the units both before final sealing and post production when in situ.
We have a dual probe off-line, sensor controlled gas filling machine and an on-line gas press. We have passed EN 1279 part 3 through BSI on both pieces of equipment.
It is possible to manufacture a sealed unit to pass a test. It is then possible to continue producing gas filled units in a more ‘conventional’ format and those units may or may not pass the test.
e.g.
On visiting several sealed unit companies over the years to ascertain the best method for single seal hotmelt units to pass the EN1279 part 3 test, different approaches were undertaken to create a sealed unit that would stand the best chance of passing:
1. make the unit as per usual and gas fill and seal up.
2. select the glass to be the largest tolerance within the production control manual, making sure their are no shells in the glass. Then cut the spacer tube to the smallest tolerance within the manual. This gives the greatest sealant depth. Then, before inserting the corner keys, extrude sealant into the spacer tube and push the key into the tube. Do this to all four corners. This can be tricky as desiccant has to be put inside the tube at some point and the sealant is over 170 degrees C. The gas will be introduced to the cavity via a hole drilled through the middle of one of the lengths of spacer. On sealing, the unit was sealed by going round the corners without stopping. This is extremely diffcult. The whole unit is sealed thus except for the small area, say 2cm, where the gas hole is. Then gas fill until machine stops. Plug and seal the final hole remelting the adjacent sealant to avoid any cold joins.
3. Do the same as 2 above but apply aluminium foil tape over the corner key area before selaing to help prevent gas loss and also use silicone plugs in the gas hole to seal over. This plug is then removed to introduce the gas; this gives little area for the gas to leak out of during gas filling and final sealing.
All three sets were sent for testing and all three came back as failures. Interestingly, the concentration levels of 2 and 3 were still within the -5%/+10% specified levels but all failed on the maximum gas loss of 1% per annum criteria.
Undertaking the time consuming and costly methods as in 2 & 3 still ended up in a fail result. Meaning that more conventional methods as in 1 above, had no chance and indeed gave the worst results.
I accept that the sample selection was not scientific in the true sense but would say that they were above and beyond normal criteria in that the best units were chosen and not randomly selected. The actual test was a full EN1279 part 3 test carried out at an authorised laboratory.
As you can see, passing the test is difficult. Our method includes dual sealing with a sealant and not sticky tape. This process requires a higher investment in equipment and a quality management system. We have been BSI Kitemarked for nearly 20-years and are audited under this scheme annually. Daily, we undertake random gas testing of post production units to ensure that everything is working fine.
In conclusion, EN1279 part 3 pass is a start, continuous in-house testing under EN1279 part 6 is a must and random on-site testing of gas filled units will demonstrate compliance in the field.
Regards
Steve Massey