air vs. nitrogen
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bclapham
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- Nov 5, 2001
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air is 20% oxygen and some moisture too. Both are bad for the shock when put under extreme pressures and temps. nitrogen is inert, i used argon also.
some people believe you can get away with just dry compressed air, i cant believe the bladder would permeate O2, so it might be OK.
some people believe you can get away with just dry compressed air, i cant believe the bladder would permeate O2, so it might be OK.
bike_rider250
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- May 6, 2005
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i used compressed air for mine but would like to use nitrogen, but does my dealer have it?
wornknobby
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- Feb 5, 2004
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how did the argon work? does it behave the same way as nitrogen? please give details :nod: :nod:
Moisture content of the air is the big concern. If the air is clean and dry, it will act the same as the nitrogen fill.
Oxygen can be an accelerant, if the conditions exist, as bedell stated...but there is no interaction of the oil and air, also, the air is still just air, and not pure oxygen. It's just dry air.
Filling from an air compressor that doesn't have the proper equipment mounted is a big mistake. Off-the-shelf filters won't do the job.
Oxygen can be an accelerant, if the conditions exist, as bedell stated...but there is no interaction of the oil and air, also, the air is still just air, and not pure oxygen. It's just dry air.
Filling from an air compressor that doesn't have the proper equipment mounted is a big mistake. Off-the-shelf filters won't do the job.
Speedfreek
Member
- Nov 3, 2003
- 153
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What is a ballpark cost for a nitrogen tank and regulator ? Would the regulator I use for my argon/co2 tank (for my mig welder) be capable of doing the job ?
Air filtration is not cheap.
First thing to consider is that your compressor creates floods of water each time it's operated. Open up the petcok at the bottom of the tank and see what I'm talking about...rusty, dirty, water.
The water is collected from the natural humdity in the air, and at certain temps, it will recondence into water form.
The head (or high pressure side) or the compressor creates huge amounts of heat while compressing the atmosphere. By simply reducing the temperature of the compressed air by 20 deg f you can effectively reduce the water carrying ability of the air by 50%. Which means that the once water vapor filled air cannot hold the water when the air temp is reduced.
One easy way to reduce this air temp and turn the gas back to water vapor, is to run a line from your compressor head (already compressed and heading to the receiver tank) to a location near the compressor. If you run this air line through say 10ft of copper line coil mounted on the wall next to the compressor (or an old, clean, radiator for that matter), the temp of the air leaving the head is cooled down lots before it reaches the tank. At this point, there is air with LOTS of water in it entering the tank.
Now, you have a tank full of air and water...you now need an automatic drain that will expell the water you created by cooling the air down.
At this point you have effectvely goten rid of 90% of any water that once existed in your air as a gas.
A good drain with an automatic water release (to a hose ran outside the shop or to a storm drain) will run you about (10 SCFM ~$130 )
(50 SCFM ~$210)
Now that 90% of the water is gone, you are in a better shape to fill anything than the guy with a raw compressor. But to get the remaining 10% water out, you need an effective coalescing filtration system.
You can get a filter that will clean the air of particulate and oil, as well as remove the remaining water vapor, for about $200 wo/ additional auto drain, $300 w/ additional auto drain. (drains are electronically timed for auto release of water...you can also do this with the load line of the compressor for free)
Try pricing a regulator set-up and a tank of Nitrogen.
Also, the air set-up can be used on EVERYTHING that uses air. Tires and shocks included.
The air set-up also means that, if you lube regularly, your air tools will last almost indefinately. Dirty, wet air is what kills air tools of all sorts.
First thing to consider is that your compressor creates floods of water each time it's operated. Open up the petcok at the bottom of the tank and see what I'm talking about...rusty, dirty, water.
The water is collected from the natural humdity in the air, and at certain temps, it will recondence into water form.
The head (or high pressure side) or the compressor creates huge amounts of heat while compressing the atmosphere. By simply reducing the temperature of the compressed air by 20 deg f you can effectively reduce the water carrying ability of the air by 50%. Which means that the once water vapor filled air cannot hold the water when the air temp is reduced.
One easy way to reduce this air temp and turn the gas back to water vapor, is to run a line from your compressor head (already compressed and heading to the receiver tank) to a location near the compressor. If you run this air line through say 10ft of copper line coil mounted on the wall next to the compressor (or an old, clean, radiator for that matter), the temp of the air leaving the head is cooled down lots before it reaches the tank. At this point, there is air with LOTS of water in it entering the tank.
Now, you have a tank full of air and water...you now need an automatic drain that will expell the water you created by cooling the air down.
At this point you have effectvely goten rid of 90% of any water that once existed in your air as a gas.
A good drain with an automatic water release (to a hose ran outside the shop or to a storm drain) will run you about (10 SCFM ~$130 )
(50 SCFM ~$210)
Now that 90% of the water is gone, you are in a better shape to fill anything than the guy with a raw compressor. But to get the remaining 10% water out, you need an effective coalescing filtration system.
You can get a filter that will clean the air of particulate and oil, as well as remove the remaining water vapor, for about $200 wo/ additional auto drain, $300 w/ additional auto drain. (drains are electronically timed for auto release of water...you can also do this with the load line of the compressor for free)
Try pricing a regulator set-up and a tank of Nitrogen.
Also, the air set-up can be used on EVERYTHING that uses air. Tires and shocks included.
The air set-up also means that, if you lube regularly, your air tools will last almost indefinately. Dirty, wet air is what kills air tools of all sorts.
BadgerMan
Mi. Trail Riders
- Jan 1, 2001
- 2,479
- 10
I paid < $150.00 for my small nitrogen bottle, regulator, high pressure hose, and associated fittings. The volume required to fill a shock is very small. I have done probably thirty charges with my setup and the bottle is still nearly full.
Before I acquired the bottle, I pressurized my shock with a MTB shock pump. I went for an entire season with no ill effects.
Before I acquired the bottle, I pressurized my shock with a MTB shock pump. I went for an entire season with no ill effects.
Fox (Fox Shox) makes a mini high pressure pump for its line of bicycle suspension. The one I bought goes up to 300 psi. I live in a desert area with very low humidity and it works fine for all my shocks. Cost on fleabay: $20. Cost to have each of my nitro reservoirs charged on my bikes
20 each.
The pump has long-since paid for itself. :cool:
By the way, I was an Aircraft Pneudraulics Specialist for 10 years on the Air Force. We used compressed air and nitro in alot of high pressure situations. Pressure rise with temp rise was a tad higher with compressed air, but not much more than it was with nitro. The real issue was the moisture, which can cause corrosion. Even then, the corrosion was usually minor. You have to remember, some of these components stay on an aircraft for up to 20 years before rebuild, and corrosion can become a problem in that kind of timeframe.
20 each. The pump has long-since paid for itself. :cool:
By the way, I was an Aircraft Pneudraulics Specialist for 10 years on the Air Force. We used compressed air and nitro in alot of high pressure situations. Pressure rise with temp rise was a tad higher with compressed air, but not much more than it was with nitro. The real issue was the moisture, which can cause corrosion. Even then, the corrosion was usually minor. You have to remember, some of these components stay on an aircraft for up to 20 years before rebuild, and corrosion can become a problem in that kind of timeframe.
Those handpumps still introduce water into a shock. Not a good thing.
bedell99
~SPONSOR~
- May 3, 2000
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I don't really know why this is such a big deal. It cost's $10.00 to go to a shop and have it filled with nitrogen and not have to worry about the ill effect. The reason why MTB's don't have to use nitrogen is the shochs rarely get to see the temps that a motocross shock does. Next time you guys are riding hard take off your glove and feel you shock. It gets hot, real hot and to take the chance of having moisture in there is not good, because if it flashes to steam you can cause it to blow. Most of us don't really have to worry about this though because we either ride slow or don't ride long enough to really heat up the shock enough. If you want to test this out, pick the most hottest/humid day of the year, release the nitrogen out of your shock, fill it up with air and go out for 2 hours and ride hard. I mean really heat that sucker up then tell me what happens.
Erik
Erik
dirt bike dave
Sponsoring Member
- May 3, 2000
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I think the main purpose of the pressurized bladder is to put some pressure on the oil so that it does not foam.
No doubt nitrogen is superior to air in theory, but nobody is going to be able to tell the difference in shock performance with air or nitrogen in the bladder at the same psi. As far as safety concerns - I think the advantages of nitrogen are largely theoretical. I mean you have 2 gallons of gas between your legs - you are going to worry about a few cubic inches of air? As for the moisture in air ruining the bladder or the shock body - maybe in a few decades. Catostrophic failure while riding is highly unlikely.
BTW, at 175 psi, water is going to have to get pretty hot to turn into steam... at 14 psi it takes 250 degrees to boil water. What's the boiling point at 175 psi? 400 degrees? 500 degrees? Your shock is going to fade into total uselessness way before the moisture in the bladder turns to steam.
I've only used air once, but if I was on a tight budget or it was terribly inconvenient to get my shock filled with nitrogen, I would not sweat it if I had to use air.
No doubt nitrogen is superior to air in theory, but nobody is going to be able to tell the difference in shock performance with air or nitrogen in the bladder at the same psi. As far as safety concerns - I think the advantages of nitrogen are largely theoretical. I mean you have 2 gallons of gas between your legs - you are going to worry about a few cubic inches of air? As for the moisture in air ruining the bladder or the shock body - maybe in a few decades. Catostrophic failure while riding is highly unlikely.
BTW, at 175 psi, water is going to have to get pretty hot to turn into steam... at 14 psi it takes 250 degrees to boil water. What's the boiling point at 175 psi? 400 degrees? 500 degrees? Your shock is going to fade into total uselessness way before the moisture in the bladder turns to steam.
I've only used air once, but if I was on a tight budget or it was terribly inconvenient to get my shock filled with nitrogen, I would not sweat it if I had to use air.
we build machines with pressure reservoirs. the manual says:
only use nitrogene to avoid risk of explosion!
I don't think that the risk of using air is very high on shocks but I have nitrogene and use it. :nod:
http://www.supercross-online.de/Z/susp.htm
only use nitrogene to avoid risk of explosion!
I don't think that the risk of using air is very high on shocks but I have nitrogene and use it. :nod:
http://www.supercross-online.de/Z/susp.htm
Nothing happens.bedell99 said:
I have been using air in my shocks for 3 years. Motocross, harescrambles, 120+ mile days in WV trail riding at speed.
Carmichael may be able to blow up a shock with a whiff of steam in it but I doubt I ever heat one up enough to cause an issue.
Out of curiousity, if a shock seal goes bad, doesn't air enter when the fluid leaks out? I have run across several people riding with leaking shocks over the years, are they at increased risk for explosions? Also, if a shock is not completely bled, does it contain enough air to create a concern?
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dirt bike dave
Sponsoring Member
- May 3, 2000
- 5,348
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What about forks? The air is an integral part of the system and not even separated from the oil by a bladder. I'll bet the air gets pretty compressed when you bottom out, and it is mixing with the fumes from the oil! And those fork tubes are a lot thinner walls and more exposed to crash damage than a shock body. Sounds like a recipe for a BOMB. (cue Hindenburg announcer) Ohh, the humanity...
No doubt the moisture from the air probably wrecks havoc on the inside of your fork tubes, rots your springs, etc...
No doubt the moisture from the air probably wrecks havoc on the inside of your fork tubes, rots your springs, etc...
BadgerMan
Mi. Trail Riders
- Jan 1, 2001
- 2,479
- 10
kawamaha said:
I think they may be worried that someone will use oxygen from a bottle.
I don’t see “air” causing a shock to “explode” as a very likely scenario. It seems to me that the bladder would burst long before the reservoir would split or fracture. Regardless, I set the pressure in my shocks at 170psi. Some older shocks required 250psi or more. Never saw one of those explode. MTB shocks run high pressures too. Air is 70% nitrogen anyway so the small amount of water in the air could cause an increase but not enough to change the performance of the unit and certainly not enough to cause it to fail.
I think corrosion is the main reason for the dry charge of nitrogen, which is a pretty cheap source of “moisture free pressure”. However, worst case would be corrosion of the inside of the reservoir cap since the charge is contained to the bladder.
I ran air from a pump in my YZF for an entire season of racing and trail riding….I even went fast a couple times! I serviced the shock three times that year and never saw any corrosion of the end cap.
I ended up getting a tank of nitrogen because it is easier than stroking a little pump a hundred times and I also service shocks for other people on occasion………some who would not be comfortable with running plain old air.
Nitrogen is the best choice, especially if you don’t service your shock regularly. Air will work in a pinch.
dirt bike dave
Sponsoring Member
- May 3, 2000
- 5,348
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James said:
My only concern would be the air in the shock oil from teh bad seal would cause the oil to foam and the damping would fade, which might cause a crash. I guess if the poor shock performance causes a crash into something expolsive, you are at increased risk for explosions . :)
FWIW, shock bodies are aluminum. This is a metal that does not spark when struck. The cylinder is small, strong and the walls are thick compared to, say, a compressed air tank like you have in your garage. The shock is also well protected within the frame of the motorcycle.
In theory, nitrogen may offer more consistancy during a temp change, less corrosion to the interior of the shock and bladder, and less risk of explosion. In practice, it is more expensive and less convenient and unlikely to offer any noticeable improvement for our application (bladder contained within a reservoir).
dirt bike dave said:
Dave, I think the theory is that forks don't get as hot as a shock body, so the air/moisture concern is less.
Badger, I found this neat compressor at sears that you set at 175 and it has auto shut off...no pumping.
Now that I have quit fiddling with valving and stuff so much, I could probably take the shock in for nitrogen. I don't service other peoples shocks because air may have an adverse effect and I don't want to take that chance with other people's stuff.
LOLdirt bike dave said:
I was coming at it from the angle of air being more of an accelerant than nitrogen (as mentioned above by Jaybird I think). I have been lucky enough thus far to not have crashes that result in explosions. That would make for am interesting ride report though :)
