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coolguy4
25-06-2017, 06:10 PM
I have been thinking about this for a long time. Are hydrocarbon refrigerants really as dangerous as people claim? I am thinking that there is no way that a small leak will ignite, especially since a unit specifically designed for a flammable gas should have sealed, spark free contacts. And it sustaining a flame is even more unlikely. Think about it- The most common place for a leak is the coils. If the outdoor coil leaks, there is plenty of airflow over the coil to disperse the flammable gas, even from a fairly large leak. I would think that even a leak on the outdoor coil without the system running would be pretty safe because there is likely to be a breeze to disperse the gas. Even if the gas did build up in the unit somehow ignited it with sealed contacts, when the unit started up, I would think that the airflow from the fan would reduce the concentration of the gas to the point of not supporting the flame for more than maybe 1-2 seconds. A possible solution to this problem is to ensure that the outdoor unit is at least a certain distance from the house. An indoor coil leak could be a bit more disastrous though. A small leak with the fan running probably is safe, but if the gas builds up inside the indoor unit with the fan off, a spark from something could ignite it. Another possible risk is if the indoor coil suddenly bursts and causes a very large gas release, no matter how well the gas is dispersed throughout the house, it could reach a high enough concentration to ignite explosively. How likely is it for an indoor coil to suddenly burst? I think that there are ways to safely use a hydrocarbon refrigerant in a home AC system, especially with small units like window AC systems. What do you think?

RANGER1
25-06-2017, 10:28 PM
I agree & you being from USA would be more aware than my area.
People cook with gas, heat with it, BBQ with it, have cars running off it.
As long as people are aware whats in it, mainly when carrying out repairs.
Usually you would hope they are designed correctly, have a very small refrigerant charge.
If it had a bigger charge I would think a bit harder, but sure there are restrictions for this purpose if followed anyway i assume).
It's the backyard guy you would have to worry about, converting things illegally & not following any safety regs.

I have a domestic fridge that states in instructions to open all windows if you hear hissing (leak).
I think it has as much as a cigarette lighter.

doormaster2008
30-06-2017, 03:39 PM
I personally will not work on systems containing it. You only need a shorting defrost heater or something similar to ignite it. What happens in a house thats closed up,especially at night and you get a leak. It only needs a spark from a fridge relay to ignite it. Potential bomb.

Rob White
30-06-2017, 04:50 PM
.

I was looking around an electrical shop that sells fridges and freezers the other
day and found a small domestic fridge on sale with 16 grammes of R600a inside.

The average size was 30 to 40 grammes of R600a.

I have (for training purposes) 6 disposable cigarette lighters and combined
they hold 46 grammes of butane.

There is more gas in the cigarette lighters than there is in the domestic fridge
and the small fridge has the same amount of gas as 2 lighters
but we are not afraid of the lighters are we???

Rob

.

coolguy4
30-06-2017, 05:20 PM
.

I was looking around an electrical shop that sells fridges and freezers the other
day and found a small domestic fridge on sale with 16 grammes of R600a inside.

The average size was 30 to 40 grammes of R600a.

I have (for training purposes) 6 disposable cigarette lighters and combined
they hold 46 grammes of butane.

There is more gas in the cigarette lighters than there is in the domestic fridge
and the small fridge has the same amount of gas as 2 lighters
but we are not afraid of the lighters are we???

Rob

.

I agree. Even if it did leak all the gas out and ignite, it's not like it would explode violently enough to seriously hurt you. It might make a small fireball that lasts maybe 1 second or blow the door open, but that's about it.

doormaster2008
30-06-2017, 06:27 PM
Yes,but what about commercial refrigeration where there can be 700grams or more.

coolguy4
30-06-2017, 06:40 PM
IF a large amount of the gas leaked out and ignited, that would be dangerous. But a sudden leak that large would probably be quite unlikely. However, if the system uses sealed relays and switches that can not ignite the gas, how could it ignite?

FaultCode
30-06-2017, 07:25 PM
IF a large amount of the gas leaked out and ignited, that would be dangerous. But a sudden leak that large would probably be quite unlikely. However, if the system uses sealed relays and switches that can not ignite the gas, how could it ignite?
Different scenario - leak from pipe through area with unsealed switches, shouldn't be , but....
Leak from plant into adjacent areas with unbunded drains, shouldn't be , but...

With commercial plant the vibration factor increases with the potential for pipe fracture. You do need to think about all of the worst case scenarios that can develope.

Used to look after a plant with 4 circuits containing 6kgs each; condenser fans would run at high speed if a leak was detected. Okay should be safe but what if there was an electrical failure, plant or mains, that prevents the fans from running. We now have say 5kg of flammable gas running across the compound into a 6" drain past a 3" natural gas meter. All good fun.

RANGER1
30-06-2017, 09:51 PM
Working here is probably out of the question!


http://www.santosglng.com/the-project.aspx

Rob White
01-07-2017, 06:37 PM
Different scenario - leak from pipe through area with unsealed switches, shouldn't be , but....
Leak from plant into adjacent areas with unbunded drains, shouldn't be , but...

With commercial plant the vibration factor increases with the potential for pipe fracture. You do need to think about all of the worst case scenarios that can develope.

Used to look after a plant with 4 circuits containing 6kgs each; condenser fans would run at high speed if a leak was detected. Okay should be safe but what if there was an electrical failure, plant or mains, that prevents the fans from running. We now have say 5kg of flammable gas running across the compound into a 6" drain past a 3" natural gas meter. All good fun.

I agree with all the what if's,
what if I went to a caravan park and bought
a 60Kg cylinder of propane, drive to a garage and fill the
car with 70ltrs of petrol, then pull into a McDonalds carpark
and light a cigarette??

Lot of what if's

Rob

.

FaultCode
01-07-2017, 08:02 PM
So very true Rob, I suppose we just have to be vigilant.

There is a private garage near me in direct line of sight which contains 2 x 47kg + 1 x 13kg of propane amongst all of the combustible materials. (For line of sight read line of fire ;) )

hookster
01-07-2017, 08:57 PM
.

There is more gas in the cigarette lighters than there is in the domestic fridge
and the small fridge has the same amount of gas as 2 lighters
but we are not afraid of the lighters are we???
Rob

.

Then we get a scenario like the Grenfell tower fire which actually began with a domestic refrigerator. Your pocket lighter does not have a power source connected to it. Sit inside a flammable plastic box covered in HC blown foam.

The attitude that a small amount of something is not dangerous is the actual danger!

Rob White
02-07-2017, 12:33 PM
Then we get a scenario like the Grenfell tower fire which actually began with a domestic refrigerator. Your pocket lighter does not have a power source connected to it. Sit inside a flammable plastic box covered in HC blown foam.

The attitude that a small amount of something is not dangerous is the actual danger!

.

Possible I agree :)

I'm not denying that they are not an issue
and the situation with the London tower block
is an extremely extreme example of a worst case
Scenario coming to pass.

But if we stand back a little and view the individual
events that led to that tragedy, the fridge catching
fire was the first of a series of events that if any one of
them had been prevented, it would have never happened.

If we banned flammable refrigerants because of the London
Tower fire, we should have banned petrol and diesel in vehicles
because of that tragic tunnel fire in the Alps some years back.

I have no answers and don't think for one moment I am belittling
the tragedy that has happened.............. As I said I don't have the
answers........

:)

I'm not afraid of flammables so I don't view them in the
same way but I'm not saying I'm not open to the risks.

Regards
Rob

.

Josip
04-07-2017, 12:58 PM
Hi all,

last decade I have been working mostly on petrochemical plants .... a lot of very flammable substances around plus a lot of hydrocarbon refrigerants ... R290, R1270, etc in my refrigeration units ...

We cannot neglect danger when working with such dangerous materials/substances ... for example: we are drinking water and without water we cannot survive so it is "not dangerous" ... then again it can be extremely dangerous .... high pressure super-heated vapor with sudden relief can cut us in halves and kill within second or by mistake step under shower with high temperature water will burn our skin and kill us ... anyhow we are using water in both states but with great precaution ... so must be with everything ...

There are a lot of safety rules when dealing with anything dangerous or "non dangerous" (like water ;)) and we have to follow them to assure safe use of anything to prevent loss of people or goods ...


Unfortunately, something (extremely dangerous) what we cannot avoid is a human factor ...
read my sig ...



Best regards, Josip

cadwaladr
04-07-2017, 05:28 PM
With anything flammable you should have safeguards built in that's common sense,I remember going back to the original 2078 gas certification when the volumes of carrying propane etc in a closed service vehicle and how it's stored in a compound,but some service vehicles I witness estate cars?,But Joe public can go and buy large bottles of propane then put a few litres of petrol in a plastic can put them in his car the list goes on,thank heaven for certified training and let's all abide by it and if we see/witness the regs being flouted report it!!!