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  1. #1
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    Red face Disastreous mishap



    I had a nasty experience last year.

    I was to replace a small hermetic compressor at a general store. It was a saturday with the place full of customers.

    The high side of the compressor was soldered in place and it was a capilary tube system. The new compressor had different conections so i decided to desolder the high side pipe from the condenser and make a new pipe from the condenser to the compressor. The pipe from the condenser was routed vertically from the condenser and there was the joint i planned to desolder. I recovered the refrigerant from the only conection at the low side of the system. I didnt get out as much refrigerant as i believed should be in the system. However i didnt linger more about it. As the event was to unfold that showed to be a disastrous failure.

    I'm sure some of you already are able to foresee what nex happened.

    I started to unsolder the vertical joint. Suddnely there was a powerful whoomm as the joint came apart and the refrigerant and oil bursted out up in the air. This happened instantly and the gas torch was of course still aimed at the joint with the result that the oil imidiately caught fire and transformed to a 3 metre high flamethrower which barely avoided my head.

    There was nothing i could do other than wait as the flames died out after some 5 second. But then the store was filled with nasty sticking smelling toxic white smoke and the 20 or so coustomers was shocked.

    The moral of this little mishap is to never ever desolder any joint before you have physicaly verified the absence of refrigerant under pressure in the pipe.

    This is especially valid in the instance that you unsolder a pipe between a compressor and a totally clogged cappilary tube with a condencer full of refrigerant and oil in between.



  2. #2
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    Re: Disastreous mishap

    Ooops.....

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    Re: Disastreous mishap

    Hi, SteinarN

    Quote Originally Posted by SteinarN View Post
    I
    The moral of this little mishap is to never ever desolder any joint before you have physicaly verified the absence of refrigerant under pressure in the pipe.
    ....and what stopped you to made a check

    ...sorry about your accident but still very ....shop full of customers and you with gas torch...you were lucky...

    Best regards, Josip

    It's impossible to make anything foolproof because fools are so ingenious...

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    No job is as important as to jeopardize the safety of you or those that you work with.

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    Re: Disastreous mishap

    An old colleague of mine once done the same.
    Condenser was on a 6hp twin comp unit, pipe must have been about 7/8ths and was still holding gas/oil. As the pipe blew apart oil ignited and burned the skin off the inside of his arm. A huge big scar to prove it as well.

    Moral of the story.... ALWAYS cut the pipe open before putting a torch near it.

    Chillin
    IF AT FIRST YOU DON`T SUCCEED.
    DESTROY ALL EVIDENCE THAT YOU TRIED!
    and go get a cuppa

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    Re: Disastreous mishap

    SteinarN,

    I hope all read and heed your great advise.

    I had a similar experience about 20 yrs ago.

    I was installing a new walk in cooler and equipment at a new Chile's in Atlanta. The condensing unit came sealed with copper caps on the suction and liquid lines. I decided to unsweat the caps versus cut them off after I de-pressurized the refrigeration circuit. What I didn't know was that the suction line stub had filled with oil, probably because the unit had been turned on its side. The oil sprayed out, caught on fire, and then caught the roof tar on fire.

    Luckily there was plenty of cardboard on the roof, due to new contruction, that I could use to snuff the fire out.

    I went home with this valuable lesson engraved in my mind forever.

    I also checked my shorts after I got home.
    Last edited by powell; 24-02-2008 at 12:54 AM.

  6. #6
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    Re: Disastreous mishap

    Quote Originally Posted by SteinarN View Post
    I had a nasty experience last year.



    The moral of this little mishap is to never ever desolder any joint before you have physicaly verified the absence of refrigerant under pressure in the pipe.

    This is especially valid in the instance that you unsolder a pipe between a compressor and a totally clogged cappilary tube with a condencer full of refrigerant and oil in between.

    I can understand exactly what happend, having done the same my self once about 20 years ago.
    Very valuable but painful lesson. I had removed a small comercial fridge to our workshop and was unbrazing the dryer. The resulting whoose of burning oil burnt my hand from thumb all the way up my arm.

    lesson learnt.

    taz.

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    Re: Disastreous mishap

    I sort of set a barn of staw alight once...was brazing in the dairy and the heat went up behind the corrugated clading and set the cobwebs alight, ran round to the other side to find a barn full of straw.

    Good job milking parlours have those big hoses for washing all the cow poo away.

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    Re: Disastreous mishap

    Sometimes the difference between a good day and a disaster is just one thought. When I first started ultralow service I got my first Sanyo unit with a low stage burnout. I recovered the Low stage charge and proceeded to unsolder the compressor. I didn't give a second thought to the two additional tubes by the suction port on the compressor. One blow torch fire, A shop full of smoke, and a load in my drawers later, I finally figured out what had happened. Sanyo runs the High stage compressor discharge through a loop in the bottom of the Low Stage compressor for an oil cooling circuit. I had looked at the refrigeration schematic but I hadn't really seen it or paid attention. God looks after fools and servicemen. No one was hurt, except for my pride, and BTW I cut all my joints now

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    Re: Disastreous mishap

    Quote Originally Posted by monkey spanners View Post
    I sort of set a barn of straw alight once...
    Kinda like "sort of pregnant"?
    Last edited by powell; 24-02-2008 at 01:29 AM.

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    Re: Disastreous mishap

    In the same vein, of unforeseen dangers, I would like to add one.
    "Just cut it off first" is still not necessarily safe procedure. You have to think of the pressure inside what you're cutting open and then decide how to approach the job.
    I was once fitting a new evap in a fridge. The pipe ends were pinched off. As I was cutting the pinched ends off, ready for install, I was happily chatting to my colleague and we were both rather shocked to see the end I was cutting off finally give way and shoot up into the ceiling.
    I only mention this as I never would have thought it would have been under that much pressure.
    It was all very "Laurel and Hardy" but it could have been very serious had I been pointing it at someone when the nitrogen popped the the end off the pipe I was cutting.

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    Re: Disastreous mishap

    I had a similar one when I was changing a heat exchanger on a swimming pool heat pump ( big manufacturer who will remain nameless). I was cutting the stubs off the new heat exchanger when the stub took off like a missile, just missing my mates head, and rattling its way around the plant room. The thing had no warning labels on it whatsoever. We got on the phone to the manufacturer straight away and had a moan about it, they said " yeah, your not the first person to complain about that, we must get round to putting labels on them" I doubt its happened, so be careful with these things.
    Also do you guys remember when the Samsung A/C units first come on to the scene about 10-11 years ago, they had a holding charge of refrigerant in the indoor units instead of nitrogen - nice!

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    Re: Disastreous mishap

    Quote Originally Posted by Andy AC View Post
    Also do you guys remember when the Samsung A/C units first come on to the scene about 10-11 years ago, they had a holding charge of refrigerant in the indoor units instead of nitrogen - nice!
    We had a couple of Carrier 50kw twin circuit condensing units last year that came with a 'Holding Charge' of R407C.. Alright, we recovered and then heated up the stub cap ends as they were only just long enough to peek out the side of the unit, but every time we did a braze joint we were choking on decomposing gas - it wasn't pleasant I can tell you.

    Missed that one on the Risk Assessmrent
    I'm back on the Pale

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    Re: Disastreous mishap

    It is nice to read that their are still so many Honest Engineers about. The only ones that don't make a mistake can't be doing anything!
    Or have learnt from the honest members from our profession. Personally the one lesson I never seem to learn which really pee's me off...
    How many others have done the same?
    Attach a Torr gauge to a line that still has positive pressure - result One duff Torr gauge and they are not cheap, mutter, mutter!
    Apparently there is a video doing the rounds ( I have yet to get my hands on it.) Showing a Engineer working in a stand alone plant room. It is in the corner of a car park. This is all filmed with site security cameras.
    Engineer fetches Oxy-Acetylene pack from vehicle.
    Engineer starts brazing.
    A puff of smoke and Engineer runs to vehicle for it's Fire Extinguisher.
    Engineer trains Extinguisher at source of smoke.
    Engineer empties extinguisher and throws it down in disgust.
    Engineer bows his head and walks away from fire.
    Which continues and plant room burns down.
    The moral of this is...
    WHEN APPLYING HEAT TO A SYSTEM CONTAINING SYNTHETIC OIL. GET A BIGGER FIRE EXTINGUISHER.
    AND HAVE IT WITH YOU BEFORE STARTING THE WORK!
    IF YOU DID NOT TREAT THE MINERAL OILS WITH RESPECT YOU SURELY DO THE NEWER STUFF.
    Grizzly

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    Re: Disastreous mishap

    surely not even Grump can beat this one....

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    Re: Disastreous mishap

    Quote Originally Posted by frank View Post
    We had a couple of Carrier 50kw twin circuit condensing units last year that came with a 'Holding Charge' of R407C.. Alright, we recovered and then heated up the stub cap ends as they were only just long enough to peek out the side of the unit, but every time we did a braze joint we were choking on decomposing gas - it wasn't pleasant I can tell you.

    Missed that one on the Risk Assessmrent
    A bit of a late addition this one. Talking of Carrier reminds me of when I used to work for the independent Carlyle / Carrier distributor Weathermaker (circa 1978). The MD was having a split installed in his office by one our dealers. All went well until the engineer brazed up the pipes on the outside of the building close to the wall. 20 mins later we could smell and see smoke coming from the roofline. Dealer's engineer panicked and started throwing cups of water in the wall hole to no avail. The MD's secretary rang the fire brigade who turned up 10 mins later. 6 guys came racing up the back stairs to the MD's office and prompty burried their axes in the MD's wood panelled wall to get at insulation which had caught fire and was smoldering away. After approx. 2hrs the MD's office was pretty much trashed, secretary in tears and dealer's engineer looking rather sheepish.
    Although fairly serious, we all thought is was a bit of a hoot. It's a storey that comes up every time a few of the old Carrier guys get together for a reunion.
    If in doubt read the instructions. If still in doubt follow them.

  16. #16
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    Re: Disastreous mishap

    Quote Originally Posted by Grizzly View Post
    Attach a Torr gauge to a line that still has positive pressure - result One duff Torr gauge and they are not cheap, mutter, mutter!
    You mean you haven't got a one way valve fitted yet to save your gauge?
    Brian - Newton Abbot, Devon, UK
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    Re: Disastreous mishap

    another late entry,but i did the same when fitting an oil balance line assembly on a VFV covered from head to toe in oil,i was lucky my jumping put touch out and had brazing glasses on but was still cleaning up by touch light many hours later!

    the only damaged was my pride and wallet after a number of jet washes to clean the side of the van off
    Paul


    "KEEP IT COOL"

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    Re: Disastreous mishap

    Had a accident myself about 18 years ago after degassing a fridge on the suction side only as no high side port available, so went to unbraze the copper service drier from the capillary line not knowing their was high gas pressure due to a blockage in capillary line and it exploded. All them little balls in the drier hit me in the face and i fell off me step ladder . As a result had pads on me eyes for a week and didnt know if i was gonna be able to see again. MY MISSES SAID I LOOKED LIKE THE FLY remember that film .So I always cut the lines never unsolder them now as you never know whats in them .

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    Re: Disastreous mishap

    Quote Originally Posted by Brian_UK View Post
    You mean you haven't got a one way valve fitted yet to save your gauge?
    Nah!
    The last time I had one of them was probably 5 years ago when last working. For the Senior Service Lads. Speak nicely to the fridge tiff, and anything is possible.
    If anyone knows if they are still available Would they post please.
    Do you know Brian?
    (I DIDN'T BLOW THAT 1 UP-- IT FAILED TO BOUNCE
    when it fell out my tool bag whilst doing the 1 handed
    cat ladder shuffle! )

    To everyone else nice threads guys!
    Its amazing how therapeutic realising that I am not the only 1 to of got it wrong occasionally. (Historically I mean !!!)
    Grizzly

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    Re: Disastreous mishap

    this thread is a classic...

    I've done the capillary tube holding back the high side pressure thing when I was a young fellow, soiled my pants.

    Also covered a site PC with about 5L of oil in a supermarket when I started in the supermarket game, another mechanic had condemned a copeland 4 cyl comp on a 4 comp rack which had been out for a few days, he had isolated the comp suction and disch and i arrived next day to change said comp. I sussed everything out and found suct svc valve frontseated, and noted oil weeping from the 1/4" access part of the valve, for some stupid reason I reached for the nearest spanner - 12" shifter and proceeded to "nip" up the weeping brass cap... cap let go (it was cracked) and shot a bucketload of oil all over me and the Microm Consultant alarm PC behind me.
    I tried to clean it all up but unfortunately i ruined the keyboard and oil was dribbling down rear of PC. After an hour or so, and a funny smell I lost the darn video card in the PC so I ended up spending all day sourcing and changing the video card and keyboard and all night changing the compressor i had turned up at 8am to change...
    ...and she said "give it to me you big fridgie"

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    Re: Disastreous mishap

    My boss has a really really good one, it's like Murphy was standing right next to him as it happened.

    He was my co-worker up untill 2 years ago, he's my service manager now.


    As he was working a friday, he was coming down with the flu, having a stiff neck, stiff joints and generally under the weather...

    Come saturday, our then service manager called him for a job, as he was the only guy close enough and with the experience to do the job... he was feeling under the weather, but it was a straightforward job, so he agreed...

    The job was to change a coiled pipe in pipe superfeed coil on a Howden WRV163.

    he got the acetylene/oxygene torch kit (30Kg) down to the engine room of the ship.

    Drained the pipes of pressure (or so he thought) and started unsoldering it...

    he was lucky and could sit down on an empty can of oil as he was working and got in a good position to unsolder it and rest the ace/oxy torch on his knees *BANG* he get's whacked in the side of his head... turned out one of the light fixtures were held up on one side by a piece of string that went over a HP pipe and then down to a guard rail right next to where he was heating the pipe, so he burned over the string and the light fixture swung down and smacked him on the head

    he got the light fixture out of the way and continued unsoldering... the pipes were allready depressurised, by him, what he didnt know was that the pipe inside the pipe had been blocked and that was why he was changing the superfeed...

    The pipes blew apart and he said there was a blue flame kind of hovering a little bit away from the pipe ends for a few seconds and then suddenly *WHOOOMP* the flame disappeared inside the pipe and a half second later *WHOOOOOOOOOOOO* the pipe was spewing white smoke

    HE ran up to the deck, and when the ventilation cleared the white smoke he called in a guy from a welding company to finish the job


    Me myself, I set fire to a hydraulic pump unit

    I was soldering on a provision plant that was located above a small hydraulic unit, there was some oil spill on the hydraulic unit, but there was paper that had soaked up the oil, so all was good (this was before all the certifications for using oxy/ace and where you were not held personally accountable if you seriously disregarded common sense )

    I was to solder a single joint, had lugged my 35 KG ace/oxy kit, and 10 kg N2 bottle all the way to the bow and down a few levels of the **** and got set up...

    I climbed up to the provision plant, lit up and started heating the joint, applied some solder (AG60 with flux) the flux dripped down and some seconds later I noticed my foot getting warm...

    The oil soaked paper on the hydraulic unit had caught fire and was licking up my feet... I jumped down and luckily was wea ring gloves so I threw the paper to the floor and started jumping on it

    I managed to put it out, but not before the ship had sounded a firealarm, and as the fire alarm moved to cover two zones, a general alarm...

    The cables to the hydraulic unit was charred and the leads were showing here and there, but the engineer just kinda snorted and said "nothing a bit of duct tape wont fix" and that was that


    the ship is russian now
    -Cheers-

    Tycho

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    Re: Disastreous mishap

    Had an electrician that thought he was a fridgey, was working on a rack with an experienced fridgey, they were repairing a stuff up by the sparky - he had pushed a contactor in on a 4 comp rack that was tripped out on HP and hydrauliced the end cap off the discharge header and lost the entire charge of the rack...

    Anyway as they finished repairing it and were putting the caps on any ball valves that had been opened or closed during the repair, the sparky takes aim at a 90 degree 1 & 5/8" check valve such as the one pictured below.



    Fridgey decides to check if all suction ball valves are open and proceeds to remove caps on valves and check their direction, sparky turns to fridgey and asks "do you want me to check this valve?", referring to the check valve which to him appeared the same as a ball valve. Now this was a loud plantroom and the fridgey misheard him and responded "yes, that is a check valve."

    So sparky grabs a 12" shifter and begins to unwind the cover that holds back the spring on the check valve, now most fridgies would realise that when its near impossible to unthread a fitting you suspect that pressure may be providing additional resistance, this does not go through the mind of a sparky who wishes he was a fridgey... next thing KABOOOOOOM, cap comes loose and punches sparky square in the chest (nearly kills him), knocks him over and spews discharge pressure and oil everywhere, once again dropping most of the charge in the rack.

    This just proves - electricians should have absolutely nothing to do with refrigeration systems. Incidentally that sparky did his refrig course after that, and is now a fulltime fridgey, but has a healthy respect for the equipment he now works on.
    Last edited by 750 Valve; 24-05-2008 at 04:16 AM.
    ...and she said "give it to me you big fridgie"

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    Re: Disastreous mishap

    Quote Originally Posted by 750 Valve View Post
    this does not go through the mind of a sparky who wishes he was a fridgey... next thing KABOOOOOOM, cap comes loose and punches sparky square in the chest (nearly kills him), knocks him over and spews discharge pressure and oil everywhere, once again dropping most of the charge in the rack.

    This just proves - electricians should have absolutely nothing to do with refrigeration systems. Incidentally that sparky did his refrig course after that, and is now a fulltime fridgey, but has a healthy respect for the equipment he now works on.
    If electricity don't kill the electrician, nothing couldn't kill him!
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    Re: Disastreous mishap

    i dont know what refrigerant was used but since it is a commercial system it is possible 500 or 502

    i have heard you can make phosgene gas from burning refrigerant witch can be very bad.


    also most systems are brazed not soldered.

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