Exploding Fridges

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Exploding Fridges

Did anyone else notice the news story (Daily Mail 19th August) about the exploding fridge freezer? The fact that this isn't the first instance seems to have gone unnoticed and the story had a non-committal conclusion regarding the cause.

We don't know the cause of this particular incident as yet, but earlier examples of exploding fridges have pointed to the pitting or corroded pipes at joints in the evaporator circuit, which resulted in refrigerant leaking at a slow rate through the insulation and into the fridge itself.

During the day, when the door is frequently opened allowing the leaked flammable hydrocarbons to exit the fridge and be diluted into the kitchen, this isn't really a problem.

But at night, when everyone is sleeping and the door remains firmly shut, this leaked highly flammable gas can build up in the fridge cabinet. As the cooling load reduces, so the thermostat switches off creating a spark and....kaboom!

An open front, dairy deck style fridge freezer is left in the corner of your kitchen.

Now I'm not suggesting that every domestic fridge freezer is in imminent danger of exploding but it does highlight a real issue with using hydrocarbon refrigerants. Let's not forget that certain people in our industry, and many green lobbyists with no specialist knowledge of our industry, are actively lobbying government to rapidly phase out HFCs completely. They are telling civil servants that it is perfectly safe to use hydrocarbons in split system air conditioners.

Can you imagine the potential if these were used widely and suffered a similar leakage issue? Picture an office with a split system that has been slowly leaking away while the normal occupant has been away over the weekend. The amount of refrigerant involved could easily build up above the explosive limit threshold. When the unlucky office worker arrives on Monday morning, full of the joys of another working week ahead of them, they open the door, the automatic occupancy sensor switches on and....kaboom! Only this time the potential for large-scale damage is far more serious.

As yet we don't know the cause of this most recent incident but if hydrocarbons are found to be the cause, let us hope that those politicians and civil servants looking to legislate against HFCs will pay heed before there are deaths to contend with.

Graeme Fox is an RAC contractor based in Dundee. He is a director at AREA (Air Conditioning & Refrigeration European Contractors` Association) and a Fellow of the Institute of Refrigeration.

Posted by Graeme Fox 21 August 2009 13:25:31 Categories: Fox's Tales

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Comments

By graham mcauley

21 August 2009 13:36:31

EXPLODING FRIDGE
By Fridge Repair Center
I have just had a fridge freezer explode with devastating results,
could the person from The Fridge Repair Center who wrote the above comments please contact me as your imput could be very useful graham.mcauley@tiscali.co.uk

By Neil Everitt

21 August 2009 13:35:31

Katie,

Would you care to contact me at your earliest convenience regarding your comment.

Neil Everitt
Editor
ACR News
020 8651 7100
neil@fav-house.com

By Fridge Repair Center

21 August 2009 13:34:31

These explosions are being caused by the refrigerant leaking from the fridge evaporator and the gas building up behind the rear wall in a 'bubble'. Sometimes the wall splits under the pressure and if you are VERY unfortunate there will be an electrical spark at roughly the same time before the gas has dissipated. We tested 35g of isobutane ignited in a fridge case with a gas cooker igniter and BOOM. Next fridge we get like that one will be going on Youtube

By Not Telling

21 August 2009 13:33:31

You need a concentration of 6.4 grams of R600a Refrigerant in a fridge with a 5 cubic ft capacity to reach the LEL (Lower Explosion Level).

The lowest charge in a domestic fridge is around 20 grams while the highest ammount legally that can be charged according to EN60335 is 150 grams.

The first refrigerators manufactured using hydrocarbon refrigerants was in 1992. If these leaks are coming through the foam then it must be the joint that is foamed into the installation prior to leak testing and charging.

Most manufacturers now use helium to leak test this joint before foaming to ensure no leaks. Not all do so, maybe it is the manufacturing process that should be looked at.

By Colin Goode

21 August 2009 13:32:31

Following on from Tony Owens comments above I seem to remember that some time ago IMI / Marstair made HC versions of their split AC systems (& they may still do). These used considerably more HC refrigerant than a domestic refrigerator and if memory serves those Marstair systems were equipped with spark proof controls or controls mounted outside of the indoor / outdoor unit air streams to prevent any chance of ignition. So what's stopping domestic fridge manufacturers doing the same? Simples!
A potentially more serious domestic situation would be a mains gas hob or cooker leaking overnight which could be ignited the next morning by a half awake home owner with no sense of smell switching on a light switch or, a boiler on a timer in the kitchen firing up early the next morning. I suspect this would have far more serious consequences. My kitchen light switches are not spark proof and I have no mains gas sensors or alarms either & nor do I need them by law or regulation! I do have smoke alarms but by the time they go off the damage would have already been done & I would probably be half way the moon! Just another perspective.

By John Ellis

21 August 2009 13:31:31

Perhaps people should check their facts before dismissing other peoples opinions. I have seen 4 official reports into "fridge" explosions, all caused by leakage at the evaporator connection in the insulation finding its way through a cable entry into the compartment, where it accumulated until being ignited by the thermostat.As I recall the door was certainly blown off in most cases, quite spectacularly in at least one case.Reference to the MSDS indicates a flammable concentration of approximately 1.8 to 10.2% in air.Of course Hydrocarbons are heavier than air giving variable concentration in a space! As I recall the amount of vapour estimated to have been ignited in these 4 incidents was around 5g!! The charge in my domestic fridge is about 25g but I sleep well through the night and don't expect to be woken up!!

By John Wallis

21 August 2009 13:30:31

Fox tales, or fairy tales, or are they one and the thing?

Does Mr Fox, (Mr Fairy tales) know how much refrigerant is used in a domestic refrigerator?

By J W H

21 August 2009 13:29:31

Why don't the manufacturers add a very small amount of methyl mercaptan to the refrigerant so that any leaks will be immediately detectable by the smell.

This technology has been used to protect homes against natural gas for decades. Failure to incorporate this common approach in green freeze seems like negligence to me.

By Peter McCann

21 August 2009 13:28:31

I can't speak about split system air conditioners but as a one time development manager for a multinational refrigerator manufacturer I can certainly speak about the domestic refrigerator sector where the refrigeration circuit is hermetically sealed.

The relevant safety standard (EN60335-2-24) is very strict and in order to comply the refrigerator manufacturer needs to demonstrate, through laboratory simulation, that if a leak was to occur at a potential weak spot (i.e. a joint) that the upper or lower explosion limits of the refrigerant are not reached, or if they are reached, that all electrical components within the immediate vicinity are spark proof.

I would also emphasise that flammable refrigerants have been in production in domestic refrigerators since the mid 1990s and since then countless millions of refrigerators have been produced.

I would also point out that the quantity of flammable refrigerant contained in a typical domestic refrigerator, fridge-freezer or freezer is less than 80g.

By Simon Barnes

21 August 2009 13:27:31

If you can make 40g of R600a go 'kaboom' your telling porkies!

It barely has the energy to open the door lec refrigeration manufactured over 13 million fridges with R600a and not one went bang, let alone kaboom!

21 August 2009 13:26:31

This is a new story on an old theme I believe.

Quite a few years ago there were some major concerns when propane / methane / butane gases and their derivatives were first being used in commercial refrigeration applications.

The investigations that were made at the time, were concerning the flammable and explosive nature of the refrigerants when mixed with air. The conclusion of these investigations, I seem to recall, were that the problem of an explosion only occurred in a very specific concentration of say between 10 and 15% of the volume of the space concerned.

Above and below that concentration no ignition took place.

Because of the low risk potential in commercial air-conditioning applications, the use of these gases was allowed because the spaces were relatively large.

Since the relative volume of domestic refrigerator spaces are so small, the surest solution to this problem is therefore in the use of sealed electrical contacts, thus eliminating the potential ignition source.

Leaks will regretably always happen, even if we believe they should not.

Tony Owens.

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