The Stovebolt Site Forums The Parking Lot Big Bolts alcohol evaporator

i bought a ex-air force 72' GMC 7500 wrecker and when i was working on it i found a bottle connected to the air compressor that says alcohol evaporator and was wondering what i am supposed to put in it

Does it have air brakes or tow trucks that have air brakes? I thought it was used to clear iced up airlines, but I'm not sure,
Scott

scroll down a bit here - most of the airbrake equipped military trucks had/have alcohol evaporators - you put alcohol in it [never beer] if you're going to be in freezing situations to avoid moisture in the lines icing, otherwise ignore it

Bill

it's hooked to the intake side of the compressor, and the purpose is to run evaporated alcohol vapors through the high pressure side, thru the lines, and eventually through all the air controls and tanks to keep condensed water from freezing.

that's about it.

Right, the evaporators were a way of keeping water/ice in your air lines from being as big of a problem.
Now most trucks use air dryers, often (or always?) the desiccant type, and not many use the evaporator any more.

But I too don't know much about them, other than I decided on the dryer and not the evaporator for my truck.

Grigg

evaporators are fine,and work very well, even with a compressor that has rings and valves that are in not so good shape. ya just gotta be smart enough to occaisionally drain your tanks.

dryers are fine, and work great when they are new, but, if any oil gets past the compressor, it coats the dessicant, so it work work properly. the first clue to that is when the spitter valve pops out oily water. another advantage to the evaporator is, there is no "spitter valve" to freeze open in very harse winters, which cause all the air to be drained out of the tanks, so the truck can't move, since the brakes are locked. every road service truck in the world has the brass fitting necessary to go around the dryer and make it useless, so the air can build up.

the evaporator will work fine, as long as you remember to add some alcohol / methanol in harse weather, and remember to occaisionally drain the air tanks. in fairness, the dryer is pretty much the preferred system, and works very well, until it fails. i guess i will leave it at that, since you just asked what the evaporator does.

I drove theses trucks when I was with in the ARMY. We used methanol in this system you have to remember to drain the air tanks when the truck is park for the day. Just check the filler tank and add when it is low until then no problem. Conprees air as it conpresses heats up that is where the water comes from the moisture comes from. Rust is going to be your biggest problem if you don't keep out the water.So drain your air tanks after you use the vehicle that will keep out the water. Good luck and watch for the water issue.

In prudoe bay ak, we use evaperators almost always. less trouble in the long run on the equipment we have

for most places where it REALLY gets cold, the evaporators are the weapon of choice. some folks forget alcohol / methanol mix with water and settles to the bottom of the tank eventually. that way, every time the brakes are applied or air operated windhield wiper, or control are operated, alcohol vapor is in the air. evap's are not affected by any oil that gets into the system either, and actually help the oil settle to the bottom of the tank.

i had a drier on both of my road tractors, but installed evaporator as well for those northern canada runs in the winter. i never had a freeze up problem. when i was a shop foreman for a local trucking company, we installed evaoprators on 181 trucks after a series of bendix driers failed during the winter. by the time 3 years had gone by, nearly every truck had the driers by-passed due to failures. we didn't bother to replace them. probably the newer generation of driers is better, but i have no experiance with them. i sure didn't care much for the old "dome top" bendix, with a 50% failure rate in 3 years. we also ran our trucks almost constantly too, and i suppose that is also a factor.

Methyl hydrate is what you use, and the rest is pretty much covered up there.