Safety Precaution Thread when working with Phasechange cooling.

[jinu117]

Since there is a lot of tribal knowledge with no good compilation I decided to start on post to hopefully compile those into one thread. Whatever you can think of, please contribute and I will update this post to reflect it.
Thread will be updated with contributions.

1. Brazing Safety
   1. General Safety
      • Read the instruction of your tool. If there is conflict with guides here, than follow tool manufacturer's suggestion and let us know.
      • Look at the direction you will have to braze and see if there is any combustible parts on the line of torch. If there is, use some type of heatshielding material to prevent fire.
      • Tanks should not be subjected to shock. Find safe and secure place to store the tanks.
      • Work in well ventilated area. In case of leak, this helps making sure that local cloud of gas doesn't form. Which could be very explosive when ignited.
      • Prepare your work pieces in advance with consideration for ease of brazing. Harder the brazing angle is, more chances you will do something that is unsafe to make it work.
      • Keep emergency fire extinguisher handy in area near your brazing
      • Use proper attire that isn't likely to get caught with part brazing, or can hold melted solder in, or can burn easily (wool comes to mind). Use safety protection such as gloves, glasses, etc.
      • When possible, braze outdoors. Make sure the light level is bright enough to see the work, but dim enough to see the flame.
      • Always have someone else ready to take care of any accidents that can happen
   2. Mapp/Propane Torch
      • Always shut off the valve, switch after use.
      • Make sure there is no leak on joint. Soapy water can be used to test.
   3. Oxy Acetylene Torch
      • Always shut off both acetylene tank and oxygen tank after use.
      • Test each time you replace tanks for leaks and tight seals. Also test it weekly to make sure.
      • While in use, keep the acetylene tank ranch in the knob so you can do emergency cut off without having to search for it.
      • Please, please, spend money and buy the proper fitting flash back arrestor. Some can be attached on regulator side, some can be attached on torch side.
      • There was a debate on how to light the torch. My manufacturer's recommendation and what i do is crack it open on acetylene side first, light it up, than turn oxygen. The other way to cut off the flame.
      • Keep the tip clean. It not only helps with better flame for use, but also less chance of sudden cut off of flame when you get too close to work piece (which really shouldn't happen)
2. Combustible Refrigerant Safety
3. General Refrigerant Safety
   • Always put a cap back on when done using refrigerant. Your dog, your kid, or yourself can accidentally turn the valve and let refrigerant out. You can get frost bite, suffocate, or all together lose oxygen in your blood stream with any refrigerant.
4. Charging Safety and when you start up system.
   • When leak testing, only go up to weakest rated pressure of component you have. Use inert gas such as Nitrogen, Argon.
   • When charging the second stage of a cascade, always static charge. Since the temperature of the second stage is very low when running, and pressure is proportional to volume and temperature, when temperature increases, so will the pressure in the system. This means that while the pressure in the second stage may be fine when running, the pressure can rise to an unnacceptable level when the system warms up, creating a potentially dangerous situation. This goes double for 3rd, 4th, or Nth stages.
   • When starting up a system for the first time, make sure that if something explodes, catches fire, etc. that you have a way to turn it off quickly and try to put it where it can't damage anything. Test outdoors if you must.
   • On high pressurized gas, take it serious and always use at least high pressure cut off valves (hint, cascade and autocascade). Also nice to have will be high pressure relief valve below or around 400psi. Somewhere in discharge line for sure. --> If there is a good reason for exact location... please let us know.
   • Expansion tanks while useful in controling pressure if they are not properly constructed they will turn into a bomb. Please use appropirately constructed or commercial one.
5. Electrical Safety
   • Always refer to schematic diagrams before attempting to wire a compressor. If no schematic is available, and you are not 100% sure of the configuration, it is better to ask than to to hook it up wrong. The capacitors used in these systems can be fairly powerful, and can explode, releasing carcinogens and dangerous chemicals, if used incorrectly. Always insulate all connections. Heat shrink tubing is usually preferrable, but electrical tape and liquid electrical tape will also work. Make sure all mechanical connections are snug. It doesn't hurt to solder, even if you're using the appropriate connectors. Make sure the compressor housing is grounded to both the wall and the chassis if possible. Always use, at bare minimum, a thermal overload relay
   • Making a load tester out of a few resistors and attaching it to mains voltage is very dangerous. Especially that it is then frozen. Use an isolating transformer and a fused line. Better still use a low voltage supply (<50Vac).

[eshbach]

a few bits:

Charging Safety:

When charging the second stage of a cascade, always static charge. Since the temperature of the second stage is very low when running, and pressure is proportional to volume and temperature, when temperature increases, so will the pressure in the system. This means that while the pressure in the second stage may be fine when running, the pressure can rise to an unnacceptable level when the system warms up, creating a potentially dangerous situation. This goes double for 3rd, 4th, or Nth stages.

Electrical Safety:

Always refer to schematic diagrams before attempting to wire a compressor. If no schematic is available, and you are not 100% sure of the configuration, it is better to ask than to to hook it up wrong. The capacitors used in these systems can be fairly powerful, and can explode, releasing carcinogens and dangerous chemicals, if used incorrectly. Always insulate all connections. Heat shrink tubing is usually preferrable, but electrical tape and liquid electrical tape will also work. Make sure all mechanical connections are snug. It doesn't hurt to solder, even if you're using the appropriate connectors. Make sure the compressor housing is grounded to both the wall and the chassis if possible. Always use, at bare minimum, a thermal overload relay.

[SexyMF]

Making a load tester out of a few resistors and attaching it to mains voltage is very dangerous. Especially that it is then frozen. Use an isolating transformer and a fused line. Better still use a low voltage supply (<50Vac).

[QuikSilver]

Originally Posted by n00b 0f l337

And a bit from me.
When working with propane, always unhook any hoses, close your manifold and all other methods before leak testing with a lighter.
This is not a recommended method, but for those who do, be careful.

Remember, propane is dangerous in every form, don't be a fool and use it without taking every precatauion.

And alwys have a fire extinguisher when working with your torch or other.

You leak test with a lighter...? .....in a propane system.

[Xeon th MG Pony]

We do it with systems of near a 1000Liters of propane too, very effective way to check for obvious leaks

[Metaxas]

Isn't that a bit on the dangerous side? I mean pressurized propane can have the tendency to go BOOM if provoked into being pissed off...right?

[Xeon th MG Pony]

No, it becomes explosive when a gas could is formed, when it is even a moderate leak it makes a 10inch flame, worst you end up with is singed arm hair. but if it where in a sealed room (Suicide as is as it displaces air) and we waited for the room to fill just over a quarter THEN it would be dangerous.

Majourity however unles you are being stupidly careless it is very safe.

[star882]

When starting up a system for the first time, make sure that if something explodes, catches fire, etc. that you have a way to turn it off quickly and try to put it where it can't damage anything. Test outdoors if you must.

When possible, braze outdoors. Make sure the light level is bright enough to see the work, but dim enough to see the flame.

And remember: Always have someone else ready to take care of any accidents that can happen.

[martinjon666]

Good thread!

My 2 cents, use common sense, if it seems like a bad idea it probably is. Most accidents or mistakes could be avoided using common sense.

Jon

[the_new_guy]

sticky....

[Unknown_road]

I'm against leak finding with propane and a lighter! when you have a relative big leak and don't find it right away, a gas cloud can form and give a big rapid flame that can cause permanent injury. when gas is released into the air it is not spread troughout the room with the speed of light or anything. What's wrong with using soap anyway?

1 more thing for a flame to form out of a leak, the leak has to be pretty big small leaks don't release enough propane to form a flame so the whole method is useless anyway.

[Jack]

Shouldn't the soapy water test be under some general header?
What is a pressure should be used for the soapy water test? Around 1,5 bar(a)? Because if the pressure is too high, the soap gets blown away and won't bubble.

And for a leak test with a static charge, what pressure should you use then?
And how long should you test?

[Unknown_road]

If you blow away the soap you don't need soap to find the leak leak size determines if soap gets blown away mostly.

I would say leak test around 10bar or something.

[Jort]

Originally Posted by Jack

Shouldn't the soapy water test be under some general header?
What is a pressure should be used for the soapy water test? Around 1,5 bar(a)? Because if the pressure is too high, the soap gets blown away and won't bubble.

And for a leak test with a static charge, what pressure should you use then?
And how long should you test?

1.5bar is mutch too low like U_R saids, 7-10 bar should do the trick.

just let it stand for 1 night and your set,
i don't leaktest just vacuum and leave it 30min.

i trust my brazing skillz

[4everCS]

I use around 200-250 psig of nitrogen to leak test with soap and it works great.

[ak_47_boy]

It would be fine to leak test propane with a lighter, as long as there is not 85% air 15% propane in your setup... I do not know where the myth came from that fire can get into a propane tank and blow it up, there is NO air, it could POSSIBLY happen if a bbq tank was empty and the valve was left open for a while so air could get in. Flashback (BAD) happens when two tanks are conected at the same time to somthing (ex. oxy-actalene) inproperly. The oxygen being higher pressure goes into the acetalene tank.... Somthing like this happened about a mile away from me in a greenhouse, OMFG i felt that WHOA. Unfortunatly 2 people where killed . Just dont get and air fuel mix and you will be safe

[Xeon th MG Pony]

well the systems we work with they aren't inside all piping is out side

Secondly soap and water is whay we use if there is still any leaking even after passing the lighter test, usualy the lighter test finds any leaks with flares, and realy it's only the big leaks we are worried about, microscopic leaks no one bothers with, but in a refrigeration system it changes you want zerro leaks, so first flame to find any obvious leaks for your flares then soap and water to find any small leaks all ways do it out side where there isn't a whole ton of air flow but still a light breeze.

[jinu117]

Originally Posted by 4everCS

I use around 200-250 psig of nitrogen to leak test with soap and it works great.

Is your suction line rated for that?

[rockdude14]

when pressure testing if it doesnt leak immediatly what can happen at higher normall pressures

if somthing goes wrong does it just warp and develop a small leak
or can things burst

[jinu117]

need some help from you guys using combustible refrigerant... any information to keep this place safer?

[the_new_guy]

chain cylinders


work in ventilated place

[Xeon th MG Pony]

When dealing with flammables:

ALL WAYS work in ventilated areas, and all ways have a constant air flow!

Keep all flammable liquids 5 feet away from your torches when in use & make sure all solvents have completely evaporated and has had good air flow be-for starting any soldering with flame or brazing.

Don't sniff flammable liquids!!!! (Sadly this isn't a joke)

Keep a first aid Kit and an ABC Fire extinguisher around (A large thing of distilled water will work on any fire that does not involve Magnesium or other Alkali metals, if there is an Alkali metal involved DO NOT USE WATER it will explode!)

The best method to deal with an emergency is to not have it happen to begin with! So use that sophisticated unit in you head and think about what can go wrong be for you start after fixing the potential problems

[wdrzal]

propane tank that exploded last night. Always keep in mind propane contains a massive amount of chemical energy. Treat it with respect !!!!

here a link .click on the picture for 10 more pics.

http://www.local6.com/news/9208722/detail.html

[Xeon th MG Pony]

Looks like a BLEVI which is totally NOT APPLICABLE to our situation. It is a good indicate, how ever, of what one should expect if your house should catch fire and what you can expect from All your refrigerants.

[wdrzal]

I think you mean BLEVE ( boiling liquid expanding vapour explosion)