Questions about compressor/air tool usage...?

[The Z'eer]

This is the first time I've properly used an air tool via my Wolf Dakota, here's a couple of questions regarding this.

The tool in question was a Draper DA Sander, requirement of 4 CFM and operated at 70 PSi. Here, used with 40 grit for wood sanding.

This was connected via three 15 metre hoses to the Wolf 90 ltr Dakota in the garage.

I operated the sander for relatively long periods (15-20 mins) without a break. While running I noticed the RPM of the tool increase and decrease here and there. I figured this might be the compressor operating and thus increasing pressure and/or volume? Unfortunately I didn't have an inline regulator which would've helped monitor things.

The exhaust of the sander, expelled moisture at times. I thought this a little odd since the air initially travels through a copper pipe dog leg system and a DeVilbiss DVFR 3 to reduce moisture?

Eventually I'm intending to paint and the last thing I want is an increase/decrease in pressure as I've experienced from using the sander.

Also, why was a small amount of moisture apparent from the tool?

Thanks

 

[Hopefuldave]

Hot air holds a lot more moisture than cold, so probably everything upstream's hot (from the work going into compressing the air), then when it passes through the tool motor it decompresses and the temperature drops a fair bit (look up Boyle's gas laws) so the moisture condenses out. Did you get a bucketful of water out of the tank when you drained it, too?
I run a pair of water trap/driers in series, still get some water from air tool exhausts

Dave H. (the other one)

 

[The Z'eer]

Hot air holds a lot more moisture than cold, so probably everything upstream's hot (from the work going into compressing the air), then when it passes through the tool motor it decompresses and the temperature drops a fair bit (look up Boyle's gas laws) so the moisture condenses out. Did you get a bucketful of water out of the tank when you drained it, too?
I run a pair of water trap/driers in series, still get some water from air tool exhausts

Dave H. (the other one)

Firstly I drained the compressor, small amount of brown water, then one of the air traps (same amount of water) and finally the filter/regulator (same again)

I've never used the compressor for this kind of work before, the motor was very hot and the tank was pretty warm too. I suspect it'd been running continuously at times, sadly the work area is no where near the garage otherwise I'd of known for sure.

I did wonder if 45 meters worth of air line is responsible for increase/decrease in tool RPM and the moisture expelled from the tool ?

 

[optima21]

yeah the length of the hose wont help as the water vapour in the air is condensing into droplets and thats what you see. the air going into the hose is much warmer than it is going out. its how refrigerent driers work, by cooling the air. there will always be moisture in air so try and pick a day when there isnt as much humidity in the air.

 

[rcx132]

My DA tool would go up and down in RPM a lot. Eventually realised there was a tiny rpm dial by the trigger that I was inadvertantly touching!

A moisture trap will only traps water droplets. It won't trap evaporated moisture. If you're spray painting something important then a £10 inline water filter filled with dessicant works great.

 

[armalites]

I drain mine every time I use it and the water is always clean. I recently put an auto drain on mine. It works really well as it drains at full pressure and it can be configured for opening frequency and open time.

It cost about £16 on ebay, I had to get a couple of converter pieces as it 1/2" bsp. I ran hose out of the workshop, it's tucked in one of the raised sections of the metal profile so can't be seen and can't blast directly at someone.

 

[Hopefuldave]

My DA tool would go up and down in RPM a lot. Eventually realised there was a tiny rpm dial by the trigger that I was inadvertantly touching!

A moisture trap will only traps water droplets. It won't trap evaporated moisture. If you're spray painting something important then a £10 inline water filter filled with dessicant works great.

For the dessicant, supermarkets sell a crystal cat litter which I believe is close to pure silica gel - I've bought a 5 kg bag to try out...
I did request a MSDS for it, the makers are very reluctant to hand it out

Dave H. (the other one)

 

[rcx132]

With the cat litter how do you know when its used up though?

I spoke to a desiccant supplier and they said its going up in price because its an environmental problem and China is starting to regulate it. She also said that mineral desiccant is comparable in strength but has to be the right type. Mineral desiccant I think is cat litter.

I bought a small industrial dryer for £150 on eBay but not plumbed it in yet. But it just chills the air so won't get everything out. I avoided buying a commercial desiccant dryer as won't afford to replace the desiccant which doesn't last long and any eBay dryer will need its desiccant replacing.

 

[The Z'eer]

yeah the length of the hose wont help as the water vapour in the air is condensing into droplets and thats what you see. the air going into the hose is much warmer than it is going out. its how refrigerent driers work, by cooling the air. there will always be moisture in air so try and pick a day when there isnt as much humidity in the air.

So if I was to use a short hose, lets say less than ten meters the issue of moisture at the tool would be less so?

 

[optima21]

So if I was to use a short hose, lets say less than ten meters the issue of moisture at the tool would be less so?

the length of the hose doesnt make any difference to the amount of water in the air. if there is moisture in the air when it enters the hose, its still there when it leaves the hose. it may change its for from water vapor (which you can't see) to condensate (which you can see), as the water condenses as it cools.

think about it another way, in summer you cant see your breath as you breath as the surrounding air is warm. in winter you can see your breath as the surrounding air is cold. there is the same water content in the air, just in summer is vapor and in winter its liquid.

 

[The Z'eer]

My DA tool would go up and down in RPM a lot. Eventually realised there was a tiny rpm dial by the trigger that I was inadvertantly touching!

A moisture trap will only traps water droplets. It won't trap evaporated moisture. If you're spray painting something important then a £10 inline water filter filled with dessicant works great.

I'm pretty certain it's not the RPM lever on the tool.

I thought the idea of these inline filter/regulators was significantly reduce moisture?

 

[The Z'eer]

Ok, if

With the cat litter how do you know when its used up though?

I spoke to a desiccant supplier and they said its going up in price because its an environmental problem and China is starting to regulate it. She also said that mineral desiccant is comparable in strength but has to be the right type. Mineral desiccant I think is cat litter.

I bought a small industrial dryer for £150 on eBay but not plumbed it in yet. But it just chills the air so won't get everything out. I avoided buying a commercial desiccant dryer as won't afford to replace the desiccant which doesn't last long and any eBay dryer will need its desiccant replacing.

Is the dryer you purchased specifically for compressor usage/spray painting? I might need one of these too.

 

[rcx132]

Ok, if


Is the dryer you purchased specifically for compressor usage/spray painting? I might need one of these too.

Yep just look for compressed air dryer but you'll need to wait as they don't often come up at that price. Also be prepared to test it and take it back because i think most most dryers on eBay have done thousands of hours work and will be worn out. If @Hopefuldave is right about the cat litter then that might be a better option. I just got fed up with buying dessicant and wanted something that just switches on. Took me six months to find the dryer though!

 

[The Z'eer]

Yep just look for compressed air dryer but you'll need to wait as they don't often come up at that price. Also be prepared to test it and take it back because i think most most dryers on eBay have done thousands of hours work and will be worn out. If @Hopefuldave is right about the cat litter then that might be a better option. I just got fed up with buying dessicant and wanted something that just switches on. Took me six months to find the dryer though!

Oh dear, maybe I ought to bite the bullet and lay out. I think circa 500 sees a budget/small work load dryer.

 

[rcx132]

Oh dear, maybe I ought to bite the bullet and lay out. I think circa 500 sees a budget/small work load dryer.

If you have the money then its often worth buying new. Save the hassle of collection and having to service fix which is usually needed with anything second hand.

 

[MattF]

You can also make other additions to the drier. Hood's Franzinator thread should, eventually, be showing an easily made item for helping to remove moisture from compressed air.

 

[The Z'eer]

You can also make other additions to the drier. Hood's Franzinator thread should, eventually, be showing an easily made item for helping to remove moisture from compressed air.

Wonderful, I look forward to it

 

[winchman]

I avoided buying a commercial desiccant dryer as won't afford to replace the desiccant which doesn't last long and any eBay dryer will need its desiccant replacing.

Industrial desiccant dryers have a heat cycle to dry the dessicant should last 5+ years even then it will still work as long as it doesn't turn to dust, you may find a compressor company will sell you used dessican that would be fine for home use as they have to pay to get rid

 

[rcx132]

Industrial desiccant dryers have a heat cycle to dry the dessicant should last 5+ years even then it will still work as long as it doesn't turn to dust, you may find a compressor company will sell you used dessican that would be fine for home use as they have to pay to get rid

Thanks for clarifying.

Would you be the same Winchman that used to be on the Suzuki forums?

 

[winchman]

Think so I had an sj then a vit for many years mainly on difflock but occasionally on a few others