The air compressors at gas stations around here are all standalone devices, usually put there and maintained by a third party. They cost about a buck (in quarters) these days - no more free air around here. By the looks of some of them I doubt they drain the water very often, if at all. And, I am pretty sure they have no water/air separators on them because when I have pressed in the center of the air chuck it was like pumping a spray bottle filled with water. Might be a needless worry, but I won't put that into my tires.
Acceptable tire psi loss per month?
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Originally Posted By: DoiInthanon
Moisture in air is a function of psychometric properties and independent of the type of compressor.
"Psychometric?" Really?
Psychometric: The design of psychological tests to measure intelligence, aptitude and personality; and the analysis and interpretation of their results.
So ... are you saying that we are imagining the water?
Moisture in air is a function of psychometric properties and independent of the type of compressor.
"Psychometric?" Really?
Psychometric: The design of psychological tests to measure intelligence, aptitude and personality; and the analysis and interpretation of their results.
So ... are you saying that we are imagining the water?
Oops. Left out the r. psychrometric Good catch. Thanks
Originally Posted By: DoiInthanon
Oops. Left out the r. psychrometric Good catch. Thanks
Thanks. That makes it much clearer:
Oops. Left out the r. psychrometric Good catch. Thanks
Thanks. That makes it much clearer:
Kestas
Staff member
Originally Posted By: user52165
Originally Posted By: Kestas
Originally Posted By: DBMaster
I get a small bit of exercise and am at least putting DRY air into the tires. Have you ever seen how much water sprays out of your average gas station "air" hose?
I disagree. Air in = air out, in both cases. Gas station compressor air doesn't somewhow concentrate the water from the air, nor does the bicycle pump somehow remove water from the air.
Unless a water separator is used or the tank is emptied very often (probably daily for a high use item) thru the drain valve, water will collect in the tank and be transferred out with the air. This is one way air tools may be damaged unless oiled.
Even in a dry climate like San Diego, I still have to be very careful. The process is compressing the air will squeeze the water out of air. Takes much less time in high humidity air.
I too have noticed this phenomenon of visible water coming from the compressor. But I don't understand it. Both systems ingest the same air and humidity. How can a compressor magically introduce more water into the output stream than a bicycle pump? I'm looking at this as a steady state mass flow exercise.
Originally Posted By: Kestas
Originally Posted By: DBMaster
I get a small bit of exercise and am at least putting DRY air into the tires. Have you ever seen how much water sprays out of your average gas station "air" hose?
I disagree. Air in = air out, in both cases. Gas station compressor air doesn't somewhow concentrate the water from the air, nor does the bicycle pump somehow remove water from the air.
Unless a water separator is used or the tank is emptied very often (probably daily for a high use item) thru the drain valve, water will collect in the tank and be transferred out with the air. This is one way air tools may be damaged unless oiled.
Even in a dry climate like San Diego, I still have to be very careful. The process is compressing the air will squeeze the water out of air. Takes much less time in high humidity air.
I too have noticed this phenomenon of visible water coming from the compressor. But I don't understand it. Both systems ingest the same air and humidity. How can a compressor magically introduce more water into the output stream than a bicycle pump? I'm looking at this as a steady state mass flow exercise.
Kestas, what you're likely seeing in compressors that have a lot of water coming out is a lack of proper maintenance - i.e. draining the water out of the tank frequently, at least daily. Yes, there is a certain percentage of water in the atmosphere at any given location, regardless of it being a bicycle pump, an electric portable unit, or an actual compressor with a tank. The tank compressor, however, will accumulate a staggering amount of water if you allow it to do so.
I don't see water coming out of my compressor at home simply because I ensure it's as dry as possible as often as possible. I hate using anyone else's air compressor because most people don't bother draining the stupid things. If you check a body shop, aside from drying attachments and devices, I bet they're getting the water out of those tanks very frequently.
I don't see water coming out of my compressor at home simply because I ensure it's as dry as possible as often as possible. I hate using anyone else's air compressor because most people don't bother draining the stupid things. If you check a body shop, aside from drying attachments and devices, I bet they're getting the water out of those tanks very frequently.
Kestas
Staff member
I can appreciate that water accumulates in compressor tanks. I have one, and it was a problem painting cars with my sprayer. The problem is water separates from the air and becomes visible. You drain the tank and the problem is minimized.
The previous posts stress the problem with visible water. I'm still wrestling with the "bicycle pump is better than air compressor" idea. It goes against everything I've learned in class about steady state mass flow. Humidity in equals humidity out. How does an air compressor inject more water into a tire than a bicycle pump if they're both drawing from the same atmosphere? Show me the thermodynamics that apply in this case.
The previous posts stress the problem with visible water. I'm still wrestling with the "bicycle pump is better than air compressor" idea. It goes against everything I've learned in class about steady state mass flow. Humidity in equals humidity out. How does an air compressor inject more water into a tire than a bicycle pump if they're both drawing from the same atmosphere? Show me the thermodynamics that apply in this case.
1. I don't know how fast a tire has to leak to detect where the leak is coming from by using a bubble solution. I would wonder if the tires are leaking from the rim, but you could also check the valve.
2. I agree that the big compressor should not inject more water into the tires than a bicycle pump. In fact, since some air can cool between use, and you could even drain excess water, it may inject less-- presuming a similar dew point when the pumping is done.
3. I don't think your problem is water. If it somehow were, it would be reversible when the tire cools. I think you have leaks. Your point is to be able to cite an authority as to how much pressure loss is acceptable, and use that to get whoever warrants your vehicle to re-mount the tires and to check for other leaks.
2. I agree that the big compressor should not inject more water into the tires than a bicycle pump. In fact, since some air can cool between use, and you could even drain excess water, it may inject less-- presuming a similar dew point when the pumping is done.
3. I don't think your problem is water. If it somehow were, it would be reversible when the tire cools. I think you have leaks. Your point is to be able to cite an authority as to how much pressure loss is acceptable, and use that to get whoever warrants your vehicle to re-mount the tires and to check for other leaks.
The last time I had a "rim leak" was in 1981 on my 1972 Pontiac and it was due to a rusted bead area on the rim. After that, ANY low pressure situation was found to be caused be an easily detectable puncture in the tire. That is just my experience, though.
I think there has been more than enough discussion about the water in gas station air compressors. No doubt, a manual pump will also compress water vapor into water. Unlike the gas station machines, though, there is no accumulation sitting in a tank due to utter failure to maintain equipment.
That being said, I still think it is better to blow water into your tires than drive on them chronically low on air pressure. We are, after all, BITOGER's and that makes us compulsive by nature. Regardless of how you fill your tires, maintaining the air pressure is far more than the majority of vehicle owners do.
I think there has been more than enough discussion about the water in gas station air compressors. No doubt, a manual pump will also compress water vapor into water. Unlike the gas station machines, though, there is no accumulation sitting in a tank due to utter failure to maintain equipment.
That being said, I still think it is better to blow water into your tires than drive on them chronically low on air pressure. We are, after all, BITOGER's and that makes us compulsive by nature. Regardless of how you fill your tires, maintaining the air pressure is far more than the majority of vehicle owners do.
Originally Posted By: Kestas
I'm still wrestling with the "bicycle pump is better than air compressor" idea.
The problem, I suggest, would be that the air compressor itself is more of a closed system and operates with higher pressure differential over longer periods. Yes, a bicycle pump can achieve some pretty high pressures, but the system is much more dynamic than it is in the air compressor tank. There, too, the water accumulation is ongoing, saturating the compressed air. I've always noted that when using a compressor with too much moisture in it, you always seem to get a "burst" of it at the beginning, which is what concerns me with tires. Little top ups are common, as opposed to completely removing the tire from the rim and remounting it, with all the compressed air involved in that.
And I admit that it is very perplexing, too. After all, if an air compressor is sucking in an air/water mixture from the atmosphere and it compresses it, yet a whole bunch remains in the compressor tank (having to be drained out periodically), shouldn't the air coming out of the compressor be drier than the air going in? After all, water will accumulate until it fills the compressor. Air won't continue to accumulate until it bursts.
I'm still wrestling with the "bicycle pump is better than air compressor" idea.
The problem, I suggest, would be that the air compressor itself is more of a closed system and operates with higher pressure differential over longer periods. Yes, a bicycle pump can achieve some pretty high pressures, but the system is much more dynamic than it is in the air compressor tank. There, too, the water accumulation is ongoing, saturating the compressed air. I've always noted that when using a compressor with too much moisture in it, you always seem to get a "burst" of it at the beginning, which is what concerns me with tires. Little top ups are common, as opposed to completely removing the tire from the rim and remounting it, with all the compressed air involved in that.
And I admit that it is very perplexing, too. After all, if an air compressor is sucking in an air/water mixture from the atmosphere and it compresses it, yet a whole bunch remains in the compressor tank (having to be drained out periodically), shouldn't the air coming out of the compressor be drier than the air going in? After all, water will accumulate until it fills the compressor. Air won't continue to accumulate until it bursts.
Man, this sure turned into an off-topic discussion, didn't it? I will never claim that a bicycle pump is the preferred means of filling car tires. It is just MY preferred method. It allows me to check my tires cold (or, what passes for cold in a Texas summer) and keeps up my activity level. I could easily buy one of those cheap HF compressors and save myself some effort. Even those need to be drained periodically, though. I borrowed one a few years ago to use with a brad gun to do some baseboard jobs. The guy never maintained it. I did him a favor and drained out about a cup of nasty, rust colored water.
I'll tell you what, a bicycle pump would be mighty handy on the side of the road if someone got a flat and found his spare a little low, or even a lot low.
I've mentioned this in other threads, but my home compressor does not get much use at all. If I get a drop or two of water out in a year, it's amazing. But, it maybe cycles two or three times a day. At my businesses, they cycle more in 15 minutes than mine do all year, so you can imagine the water.
@Kestas: I just thought of something, which may account for the paradox I pointed out in my last post. As you mentioned, a bicycle pump is a certain amount of air/water in and a certain amount of air/water out. I would doubt that any regular air compressor would have such "stroke efficiency" as it were. Additionally, the compressor motors do get warm and warm the air as it's going in. That's really noticeable in my businesses, where they get quite warm. As it cools off a bit, it condenses out.
I've mentioned this in other threads, but my home compressor does not get much use at all. If I get a drop or two of water out in a year, it's amazing. But, it maybe cycles two or three times a day. At my businesses, they cycle more in 15 minutes than mine do all year, so you can imagine the water.
@Kestas: I just thought of something, which may account for the paradox I pointed out in my last post. As you mentioned, a bicycle pump is a certain amount of air/water in and a certain amount of air/water out. I would doubt that any regular air compressor would have such "stroke efficiency" as it were. Additionally, the compressor motors do get warm and warm the air as it's going in. That's really noticeable in my businesses, where they get quite warm. As it cools off a bit, it condenses out.
Garak? Are you named for the DS9 character?
Actually, I used to be in Indian Princesses with my daughter, before PC took over and they changed the name. I had a flat once, on a camping trip, on a brand new Michelin Pilot and then my daughter got sick and I had to drive home in the dark from the boonies on the dinky spare. At least I kept my dinky spare at the proper pressure. After that I always took my tire plugging tools and pump on any trip. I ended up using it on one of the other dad's Dodge Durango. I was able to plug the tire without removing it - gotta love ground clearance at times. Someone loaned us an air tank, but it didn't have enough air in it so we alternated filling that huge tire with my bicycle pump. Fine in a pinch, but what a workout!
I'm pretty sure most people (non-BITOGers) never check that dinky spare. Mine have historically lost about 10-15 psi during the six months I go between checks. It's a PITA, I know. On both of my cars I have had to take the spare completely out to access the valve.
I now have one of those higher volume versions made for mountain bikes. If you're going to manual route use a big barreled pump!
Actually, I used to be in Indian Princesses with my daughter, before PC took over and they changed the name. I had a flat once, on a camping trip, on a brand new Michelin Pilot and then my daughter got sick and I had to drive home in the dark from the boonies on the dinky spare. At least I kept my dinky spare at the proper pressure. After that I always took my tire plugging tools and pump on any trip. I ended up using it on one of the other dad's Dodge Durango. I was able to plug the tire without removing it - gotta love ground clearance at times. Someone loaned us an air tank, but it didn't have enough air in it so we alternated filling that huge tire with my bicycle pump. Fine in a pinch, but what a workout!
I'm pretty sure most people (non-BITOGers) never check that dinky spare. Mine have historically lost about 10-15 psi during the six months I go between checks. It's a PITA, I know. On both of my cars I have had to take the spare completely out to access the valve.
I now have one of those higher volume versions made for mountain bikes. If you're going to manual route use a big barreled pump!
Gast 120v compressor (great compressor but $$) with filter/water separator.
Then I have my large compressor and a couple 12v compressors. I'd probably have a stroke trying to wind up a bicycle pump...whew...
Motorcycle... also a 12v compressor and a CO2 air kit
Then I have my large compressor and a couple 12v compressors. I'd probably have a stroke trying to wind up a bicycle pump...whew...
Motorcycle... also a 12v compressor and a CO2 air kit
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Even with the junky Goodyear Wrangler Radials on my truck, the only time I have had to add air was due to either a nail or significant temperature change over a period of months. The most I've ever been down was about 5 psi and that was due to a nail.
Originally Posted By: DBMaster
Garak? Are you named for the DS9 character?
Yes, I am. And I, like many other people, have neglected spare tires on occasion. I've gone the route of carrying a bicycle pump or a 12V compressor, depending upon the decade and how much money I had.
Garak? Are you named for the DS9 character?
Yes, I am. And I, like many other people, have neglected spare tires on occasion. I've gone the route of carrying a bicycle pump or a 12V compressor, depending upon the decade and how much money I had.
Thanks for the spare tire reminder....
They did a good job on that show for sure!
@supton: Yep, I had to run over a nail somewhere this weekend, too. The G's TPMS is extremely sensitive, too. I had only lost maybe three pounds before it kicked in.
@supton: Yep, I had to run over a nail somewhere this weekend, too. The G's TPMS is extremely sensitive, too. I had only lost maybe three pounds before it kicked in.
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