Compressor Hoses

[Patrick Fischer]

Went into the shop this morning and found that one of the compressor hoses had "ballooned" during the night. Didn't burst but it was close. This was one of those miserable poly hoses that never coil up right. Got me to thinking: I leave my compressor on and the valve at the compressor open so the system (6 outlets/connections in copper) is always pressurized. Do you folks de-pressurize your hoses at the end of the day? I'm definitely not going to leave a cheap hose under pressure (or even use them again) but I'm thinking that at the end of the day it would be easy to close the tank valve and bleed off the air in the rest of the system. Probably a smart thing too. Just curious what your practices are?

Patrick Fischer Olalla, WA

[Mortimer Schnerd, RN]

I leave the tank pressurized and the hose depressurized. I'm looking at what I consider the weakest link and removing it from the equation when it's not in use.

[Duane Bozarth]

Don't you have a single valve at the compressor outlet? I cut it off there at night routinely out of habit.

[RonB]

I usually leave the tank pressurized, or do an occasional draincock blow-out in the evening. However, you absolutely want to depressurize the hose and turn the compressor off at night. This is a good air compressor habit.

I grew up around a service station. We had one of those old high-capacity pumpers that served the garage and the pump lanes. One evening a hose in the garage area burst just inside of the quick-release fitting; but the metal fitting hung on. Before we figured out where the noise was coming from the flailing hose, with air fitting, had broken a window, shattered bottles and cleaned some small tools off of a bench. That big compressor would have kept that going forever. My dad was in the habit of shutting the compressor down at night; but if this had happend when we were gone it would have done some real damage.

RonB

[Mortimer Schnerd, RN]

No, it would have run until it used up its oil and/or it overheated. Then you would have seen the *real* damage.

[RonB]

Absolutely right. That is the other bad thing that can happen.

[Upscale]

pressurized.

My compressor is only 1hp with a 3 gallon hotdog tank, but I depressurize the tank every time I'm finished using it. Only takes 30 seconds. My theory is that pressure causes heat and forces moisture out of the air within the tank, which ends up sitting at the bottom of the take until it's drained. No pressure, less heat, less moisture, at least less moisture than I'd have otherwise.

[Pop]

Like most of the others, I leave the tank pressurized but dial down the pressure in the hose; gives 'em a longer life, too unless it's a rough area. IF the kids're around, I'll sometimes leave it at 20 lbs or a little less, for their footballs & pool toy blowups et al, but I still dial it all the way down after dinner. Keeping unused hose/s reeled (if you have one) is also a good idea. It shortens the flailing end just a bit, for a short period at least, giving you time to get out if you need to. Assuming you hear it go . I didn't. Never figured that one out; fittings were fine, but separated anyway. Near's I could tell it must've gotten oil on the connecting surfaces or something; never happened again. Didn't flail though; it was inside the reel so possibly reel pressure pulled it apart - I had had the tank empty just before that & was running 90+ at the time.

Just seems to make sense to drop the pressure when it's not being used; not much of a job to reset the pressure when I need it.

Pop

"Patrick Fischer" wrote in message news: [e-mail]...

[Mortimer Schnerd, RN]

Pressure and heat are directly related but pressure does not cause moisture to form out of the air. Actually, releasing the pressure will cause the temperature to drop, which causes the condensation of whatever water is present out of the compressed air. Open up a scuba tank full blast on a humid day and you'll end up with a block of ice where the valve used to be.

You want less moisture in your compressed air? Compress drier air to begin with. Scuba compressors get dry air with a more complicated scheme, through the use of intercoolers between the stages of compression (most shop compressors don't even have stages of compression) followed by filtration usually through activated alumina, along with frequent short purges of moisture during the compression cycle. But we don't have these features on our home copmpressors.

So if I'm working outside in humid air, I'll purge the entire tank later when I'm done working. If I'm working inside with dry air conditioned air, then I keep the tank pressurized and just purge the tank for a quick moment or two every now and then.

[Upscale]

Well, it's inside with relatively humid, non air conditioned air. Following your explanation, it sounds like I should be purging when I'm finished. The compressor is only used a couple of times a week at most so either way, I guess it's not a big concern.

[Oldun]

Play safe and depressurise the whole system. The amount of energy held in the tank and hoses means you have a potential bomb. Nobody, especially children can get hurt if there is no pressure.

It's too late after the accident has happened.

Patrick Fischer Olalla, WA

[Larry Jaques]

"Oh, no!" they screamed, terrified.

Do you feel that your cherished government should outlaw these "bombs" as they have your guns and the way-too-dangerous dado spindles on your table saws? Crikey!

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[Upscale]

Grow up!

[Bruce T]

I've spent more than 40 years around service stations/auto service centers. The Standard Operating Procedure is to turn off the power to the compressor when the place closes (when no one's around). It is also SOP to drain the water out of the tank periodically. If you're Florida, the drain interval should probably be daily. If you're in Arizona, maybe a week is appropriate. If you get more than a cup of water out of the tank, your drain interval is too long. If you have flexible hoses attached to your air system, you should install a gas valve (lever type) somewhere in the line before your flex hoses and turn it off when you turn off the power to the compressor (if they're close to each other, it makes it easy to do both at the same time). Leaving the compressor pressurized is fine--that's what they're designed for. None of this is rocket science. This is all just common sense.

BruceT

[Bruce T]

Why not play safe and depressurize the system permanently? That way nobody (especially CHILDREN) could EVER get hurt!!!!!

[RonB]

This has gone a little OT, but Oldun makes a damned good point. An air compressor or an air bubble can do a very good imitation of a bomb.

When I was in high school, many years ago, a classmate's father had a bubble filled at an area farm equipment dealer. On leaving the shop he turned around to say goodbye to the proprietor and apparently bumped the nipple against the door frame. The bottle exploded cutting him in two at about chest level. The proprietor was also badly injured. Government or not, I can tell you that air bubbles have come a long way since those days (1960's). This is also the reason that most reputable compressor shops won't even talk about welding a tank fitting.

If you think your air compressor is the most benign piece of equipment in your shop, think again.

RonB

[Edwin Pawlowski]

I saw that happen in the building where I work. A 15 hp compressor blew a line and it just ran and ran. I got tired of listening to it and walked over to that part of the building to see a haze lingering in the air that had a burn oil smell. I was able to find a breaker and shut it down.

Some compressors are built to run 24/7, but most home shop units are not.

[Edwin Pawlowski]

Our (commercial) tanks must be inspected every two years. They used to peek inside, tap on the wall and say "OK". No more. Now they use ultrasound to check. The good thing is that we don't even have to shut down to do it.

[Larry Jaques]

Bite me. (If I'm thought of as a kid, I might as well play the part.)

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