Out Of My Comfort Zone

[NozSpark]

A publican that I've done some work for in the past asked me to have at an aircon unit that wasn't working correctly. I said that I don't normally do them but I could have a look and if there was something I could do I would but that I might not be able to do anything.

So I get there and its in the cellar... It's a big old 3 phase unit fed from a switch fuse (3036). When you turn it on it operates for 20 seconds or so and then turns off....after another minuite it turns back on and the sequence repeats (ish)

So I checked out the contactor and thermostat and they were both ok... the power was being knocked off by the compressor unit so I go and have a look...

A quick check of the compressor and I can't see anything... I had just turned around to get something out of my tool bag... I was thinking of shorting out the klixon (but hadn't yet) and there was a bit of a bang and a massive spray cloud...... Yes the PRV had activated... FFS I'd just had my head in there...

One thing I know know is that it wasn't short on pressure

I've left it with him.... It'll need a new system IMHO

 

[kme]

To the best of my knowledge, the coolant shouldn`t vent to air - even in fault condition. There is a high pressure limit control on the condenser; which should isolate the system.

If its an old unit, the refrigerant can be very, VERY bad for you, if you breathe it in!!!!!!!!!

 

[NozSpark]

He had a slightly smaller one to the side... Quite old units, look nothing like modern ones, the top cover had a 12" hole on it and the terminal cover was missing..

This one had the cover missing off the rotary isolator because they'd obviously replaced the switch mechanism and the shaft is a different design to the switch

The coolant seemed to come from a union on the compressor... It looked larger than it needed to be

And yes.... I took several steps backwards as I'm sure it's a very old type of coolant

 

[binky]

old coolant is Freon, the stuff that puts holes in the ozone layer, it's actually very inert, so shouldn't do you any harm, hence it floats to the high atmosphere and causes problems. If Freon was dnagerous i would be dead a long time ago, we used to use it for cleaning hydraulic components, and because it evaporates quickly, it was good for a ' water fight' that left everyone dry in seconds.... :innocent

 

[Sidewinder]

Freon is an asphyxiant though in confined spaces.

So it can be lethal.

Mind so can oxygen, you can die from oxygen poisoning too!!!

 

[kerching]

Freon is an asphyxiant though in confined spaces.

So it can be lethal.

Mind so can oxygen, you can die from oxygen poisoning too!!!

Common misconception ......divers have oxygen cylinders on their backs. WRONG!

If you breath pure oxygen at a depth greater than about 6 m you have a fricking good chance of being dead within minutes. The richest mix we usually carry is about 80% ....and even that takes a lot of managing

Just saying

 

[Sidewinder]

No Kerch, I am NOT wrong.

You go into a confined space and fill it with Freon, and you can't exit the space, you will die of asphyxiation.

You cannot get any oxygen to respire from Freon, if you breath pure Freon, your body cannot get any oxygen, thus you will die.

IF you breath 100% oxygen, at all times in a confined space it will kill you, just the same as asphyxiation will kill you, even at atmospheric pressure.

I never said anything about divers & oxygen cylinders, I KNOW that divers do not carry oxygen cylinders.

If you go into medical stuff, there patients are not given 100% pure oxygen to breath at all times, else it WILL kill them, they have an enriched oxygen supply via the mask, but NOT pure, and IF the pressure is too high in the mask, well, you know the score.

The human body is not designed to take excesses of anything above it's normal environment.

 

[Andy™]

snakey - i think he was referring to pure oxygen tanks being used by divers...

 

[steptoe]

^^

+1

I think he was also referring to the fact pure oxygen can kill you

divers dont have 'oxygen' tanks

they have air tanks,

but, what do I know,,,,,,  :C

 

[Marvo]

Older air con units will be R22 which was considered an 'intermediate gas' which wasn't too bad for the environment and only recently taken off the market (it's still freely and legally available where I am). Nonetheless it shouldn't be vented to atmosphere, it should be recovered and if it was being discharged from the unit then it's because of a leak, it definitely won't be a safety valve. R22 is generally fairly harmless in mediocre concentrations but as pointed out it is an asphyxiant in large quantities and enclosed spaces. Problem with freon is you don't experience the choking feeling you normally get with lack of oxygen you just experience dizziness and disorientation which means it will kill you without you suffering distress, it's sometimes used as a method of suicide or euthanasia because of this. 

It can also be a problem when there's naked flames around, when freon burns it makes phosgene which is highly toxic and used to be called 'mustard gas' when it was used as a chemical warfare agent. Usually where there's a freon leak there's also atomised oil released which can be worse for health, the oil can be very acidic.

I'm actually surprised that UK sparkies are allowed to even remove the covers from HVACR equipment without an FGas certificate. I'd probably recommend you avoid this type of equipment to be honest.

 

[Blue Duck]

^^^ AFAIK were not. We repair most appliances but not fridges / AC units.

 

[NozSpark]

I definately wouldn't touch anything on the coolant side, but IMHO isolator switches and fans etc are fair game

 

[Andy™]

I definately wouldn't touch anything on the coolant side, but IMHO isolator switches and fans etc are fair game

+1

 

[Sidewinder]

I definately wouldn't touch anything on the coolant side, but IMHO isolator switches and fans etc are fair game

AFAIK you can do anything as long as it is not likely to release refrigerant gas into the atmosphere, legally, you should ensure that your business insurance covers you though for your own piece of mind, most electrical contractor policies would not.

 

[Marvo]

Where I am you wouldn't be allowed to work on anything past the point of power connection, even fans and connection cabling between the indoor and outdoor units are considered an integral part of the refrigeration system.

 

[Sidewinder]

The thing is Marvo, fridgies over here are useless sparks, and in fact most are dangerous with wiring!

They have no idea bout BS7671 let alone the other electrical requirements.

As far as the gas side goes, it is sealed, so unless you disturb a gas connection then you are fine, and in fact over here most of the gas switches are connected via Schrader valves, so you can change them without loss of gas, so thus you don't need an FGas Cert.

This has reminded me to check our insurance for chiller, air-con electrical though, mind, I would argue it is machinery, thus we are covered!

 

[Marvo]

The thing is Marvo, fridgies over here are useless sparks, and in fact most are dangerous with wiring!

They have no idea bout BS7671 let alone the other electrical requirements......

I couldn't agree more and not just in the UK unfortunately this is a sign of the times globally. There was a time when fridge mechanics were as capable of wiring and electrical fault finding of control systems as any sparky but not so much nowadays when true apprenticeships are all but gone. Across the board >40% of refrigeration faults are electrical related and there's always been a strong crossover of trades and electrical knowledge in the HVAC industry.  

 

[Sidewinder]

The thing is Canoe, they are also not capable of researching and understanding the requirements themselves, unless it seems they post on an Internet Forum, and get the answer spoon fed to them.

 

[kerching]

@ snakey post #8............

!misinterpretation of my post......what I MEANT to say was that. "It is a common misconception that Divers carry Oxygen cylinders on their back". When in fact most of the time it is air in the tanks

I know only too well about Pulmonary oxygen toxicity , OTUs, hypoxia and Hyperoxia., partial Pressures etc etc

I lost a good mate due to switching to too rich an Oxygen mix at a bit too deep a depth....he convulsed, lost his Reg and drowned!

This is the trouble with t'internet, it is open widely to misinterpretation.......and as i tend to wander off at the drop of a spacemans helmet my posts sometimes have little or no connection with the original!

Sorry for the misunderstanding

Just digressing

 

[Marvo]

I also have a strong refrigeration background and still work on some local ammonia plants that are owned by local fishing industry business. We also design and install SCADA systems for commercial and industrial coldchain monitoring. I have some HMI and BMS experience but fairly limited but I think you need a solid knowledge of other systems especially when they are integrated in order to design efficiently and elegantly even if working on them isn't your core business.