a/c equipment questions

[Shimmy1]

That's the point, Oxygen is an oxidizer, and the higher the pressure, the faster oxidation occurs, to the point where anything flammable, especially liquids, will self ignite from the heat of the oxidation. Oxygen creates it's own ignition source, violently. It's not a controlled risk, it's more like Russian Roulette.

Well said, Lantraxco. As a fire fighter, we learned right away the fire triangle. Fuel, air, heat. From the other posts, we know about pure O² properties as an oxidizer. My other point, I have never seen an oxygen regulator that doesn't have the words USE NO OIL somewhere on it, or the gauges.

 

[wastednights]

anybody ever try one of these? http://www.mile-x.com/mastercool-69110-automotive-a-c-recovery-system/

Yes Mike, I have one of these, it works very well, it replaced my Robinair unit that I had for 14 years

 

[Mike L]

Yes Mike, I have one of these, it works very well, it replaced my Robinair unit that I had for 14 years

right now I've got the Robinair 34788 on my truck. does it work the same way? hook it up and let it go? I tried to find a video on youtube but didn't have any luck.

 

[ohiofleet]

no I don't think it has a built in scale

 

[FSERVICE]

mike I do a lot of AC work on equipment.. most of the recovery machines work on the same idea, hook up it pumps liquid Freon out first then the vapor into the recovery cylinder, down to a vacuum.. when the first recovery machines came out they were BIG & expensive, now days they r still expensive but have gotten a lot smaller & more powerful. I have a buddy that bought that unit last fall & has had very good luck out of it so far.. if you have any questions ill b happy to ask him,

 

[caterpillarmech]

I have the Robinair one. It is simple enough to use and had it for ten years. Even with the bricks I work with, it still is very dependable. The one you listed Mike looks good, also had he recovery tank.

 

[biggav]

A quick question. What pressure does everyone go up to when looking for leaks.
I had trouble with a few machines lately where I show and the there is little no gas in the system. When I pressurise and try to find the leak I can't find anything. I have only been going up to 110 psi or there about as I don't know if it was good to put to much pressure in the low side. So what does everyone else do.
Cheers

 

[oarwhat]

From my basic welding class in college, I remember the instructor telling us just one drop of oil into the cylinder side of a regulator could be a deadly mistake. DO NOT use pure oxygen from a torch tank. I think they almost give cylinders of nitrogen away.

He's what happens when there is a drop of oil in a oxygen regulator. I replaced the high pressure gauge with one I had in the drawer. Obviously I must have used it to check hydraulic pressure before. I turned on the tank and it hit me right in the eye. Luckily for me not in the center of my eye and only bruised it. It almost blew it out of the threads. I've read just a piece of dirt can cause this. The best advice is to look away from the gauges EVERY time you turn them on. Every one stares at them when turning on.

 

[Mike L]

A quick question. What pressure does everyone go up to when looking for leaks.
I had trouble with a few machines lately where I show and the there is little no gas in the system. When I pressurise and try to find the leak I can't find anything. I have only been going up to 110 psi or there about as I don't know if it was good to put to much pressure in the low side. So what does everyone else do.
Cheers

I usually don't pressurize higher than 50 lbs and then use a lot of soapy water. I also unhook my nitrogen tank and check the shrader valve on the coupler for leaks. I had one leak there but had hell finding it cause I had the tank hooked up.

 

[caterpillarmech]

I go to 300 psi on the nitrogen charge. My tech teacher said it was fine. Ive seen high sides at 400 psi so why not. The pressure it what will find it quick. Had a hose leaking slightly on the low side that took a while to find. Nitrogen found it real quick.

 

[FSERVICE]

I go to 300 psi on the nitrogen charge. My tech teacher said it was fine. Ive seen high sides at 400 psi so why not. The pressure it what will find it quick. Had a hose leaking slightly on the low side that took a while to find. Nitrogen found it real quick.

X2... it wont hurt anything at that pressure!!

 

[repowerguy]

In the rough and tumble world of field work an air powered vac. works well,I know they're noisy but they're durable and won't leak oil if overturned. I have never used a scale only charged them to good gauge readings. Most of the beaters I worked on had no tag or were a Red Dot shop install so a scale was never on my radar. My old Mac gauges are 15 years old and still going, just don't use em much in my new job.

 

[lantraxco]

Yep, guy that used to do all my work had a scale and used it if the spec was handy, but all my stuff he did by the gauges and a pocket thermometer stuck in the outlet air flow. Never had any complaints

 

[Birken Vogt]

It's better if you have a thermocouple to measure superheat/subcool but use pressure alone if you have to...however if charge weight info is available and you have reason to suspect it is correct, then use it I say. I have seen some strange things happen when trying to charge by gauges alone, and then you have to be concerned about compressor floodback.

 

[wastednights]

I go to 300 psi on the nitrogen charge. My tech teacher said it was fine. Ive seen high sides at 400 psi so why not. The pressure it what will find it quick. Had a hose leaking slightly on the low side that took a while to find. Nitrogen found it real quick.

I always test with Nitrogen to 250Psi

 

[Joeyslushr]

I had one of those compressed air vac setups and it went to hell on me for some reason?? So I bought a 3.5 or 4 cfm Matco vac pump.....way better. Faster and pulls more vacuum. I've just got an old set of Matco gauges, a pail of hot water, a 30lb keg and a 60lb feed scale. Haven't had any complaints. Though hearing more about this nitrogen for leak tests makes me think I should at least try it...