compressors (sigh)....hot air = water problems

[paulioq]

gday I'd like to introduce my self I'm paul, long time reader first time poster and I had an idea I wanted to throw out there to see what others thought.

am having water issues like many others have and have found some information on here valuable and some that doesn't work in the hot humid climate we have here in sunny austrailia for e.g. enclousers are a no no as I built one from a hoop frame that hangs of the wall over the compressor and I sew'd a sound curtin to go around it leaving it 2 inches of the floor and wall for air movment as well as manifolding all 3 intakes together to a pipe that goes out side the enclouser with a silencer filter on it.

well good in concept but it actually made the enclouser to hot and started to produce high amounts of water but had that under control with a water trap I made( I got the idea of here) out of 2 meters of inch pipe with outlet of top for regulator and inlet 300mm of bottom and a 1/4 ball valve on bottom to release the water. this worked great but not with the enclouser as I learnt some more and found out you cant drop moisture from hot air. and when I sand blast or use air tools with heavy demand needs I am getting moisture out the exhaust and it blocks the tip on my deadman when blasting. the heat also made the motor cut out on thermal over load one time so it was off with the sound curtin but found out manifolding the inlet and a quality silencer filter actually did more for the sound then the curtin did.

but I was still getting water in lines and learning some more I found that to much negative preasure on the inlet can also make the compressor work to hard adding heat and compounding the moisture isuue so now have 3 smaller individual silencer filters installed and have made the compressor even quieter woo hoo( just using a db app on my smart phone)

now to my idea I wanted to sugest I have scene that in a lot of ideas for moisture removal it involves adding meters of larger diameter pipe into the system to allow the air to have time to cool and slowing the flow rate down to let the moisture drop out of suspension.

my idea is to add an air conditioning condesor I would modify from a car to use as a radiator to cool the air mounting it infront of the cooling wheel(big pully) on the cage. this would split the flow into the fins to let it cool of with more surface area to contact the air that pipe alone provides. and also the added benefits of cooling fins.

now I am wondering would I be beter of cooling the air from the pump to the tank to cool general temps in the tank or from the tank to the regulator to let the incomeing air to blend down with cool air in the tank and then to water trap regulator.

befor people start saying "you cant do that" I am a very competent home enginer enthusiast with a work shop that isn't missing much to do your average home jobs like rebuilding cars from the ground up or building ramjet engines from old truck turbos, what else is a bogan ment to do on a sunday afternoon I ask you. also I work in water treatment and some reverse osmosis machines create 1200 psi operating preassure so material selection and jointing methods is all under control. even if there is a point of failure there is no explosion that a lot of people sugest happens like when homer pours the milk into cearal on an episode of the simpsons once. it will just rupture and realese preassure, also car ac systems work in the 400psi range and my compressor shuts of at 8 bar so there is a safety factor of 4 and braizing copper pipe is proven to 25 bar. with out being rude can post be kept to the concept of the idea and not the execution.

cheers for reading and am looking forward to your feed back on the idea as there are some smart people on this forum because I have found the ozzie forums contain more talk about beer drinking and eating prawns, not theres anything wrong with that.

 

[Bill Edwards]

Well, while reading your post I was thinking of using a car inter cooler, but it seems you've already thought of that. I think it would do the job quite well. The other option is a coil of copper pipe.
I would install it between the compressor and the receiver. This is where most systems cool the air, and it is probably the most effective as you're working where the air is the hottest, and you'll get more air in the receiver. I think it'll also mean that you'll get more water condensing in the receiver, but I'm sure that can easily be drained off.

If you use the fan on the compressor to cool the air then you'll have the disadvantage of then having hotter air blowing over the compressor so it could end up running hotter. I really don't know whether this would be a big problem (i.e how much hotter the air will be after going through the inter cooler), but it is something to bear in mind.
I would actually be tempted to run a bigger, separate fan for the inter cooler which may be more effective anyway, though you could always try it using the compressor fan first.

 

[paulioq]

i am leaning towards between the pump and receiver my self. I was looking at an old intercooler kicking around here that gave me the idea but they cant handle the preasure, trying to get one to hold 30 psi can be an issue and you need a quality big doller unit to do that the cheap ebay ones are only good for a bar also they handle big cfm not real good for heat exchange, a water to air intercooler is tiny compared to air to air and works superbly.

I was thinking it might need a thermo fan using a 12v supply mounted on it then there would be constant air flow over the pump even when not running but the extra moisture in the tank is easy fixed with a automatic timed solenoid which I'm already waiting for to turn up, gees I luv that cheap **** on ebay from china it just the same crap they sell for 3 times the price in your shop just need to wait a fortnight for delivery.

but I wanted to keep the installation clean and can always add a fan later if need'd, I was wanting to stay away from the "running copper pipe" idea even though i do luv working with copper, nothing like beating out your own junctions and branchs on copper waste stacks but because firstly copper is to expensive in austrailia, jobs can ofton be done out of stainless for cheaper and secondly the concept of meters of coiled pipe on the ground sounds a bit hill billy to me just like the young fella across the road showed me his engine swap and the first thing I scene was a single wire just running over the rocker cover and I stoped looking there befor I found more **** work to pick the crap out off. but the concept of the radiator vs coil pipe is the same i.e to add contact surface area time for more effective heat exchange.

if any one is going to do this make sure you get a single pass condenser or modify it to suit because it could hydraulicly lock and u tube(not the website)

 

[optima21]

in the uk I used to have problems, but have cured them by using a water filter housing filled with sillica gel dessicant

http://retrorides.proboards.com/thread/158023/air-dryer-compressed

 

[rtbcomp]

If you're in a hot climate cooling the inlet air with ambient temperature air won't achieve much.

As mentioned, I'd be inclined to add an after cooler (or a bigger one if you've already got one) on the delivery pipe between the pump and the tank. Making it fan assisted might help. You'll get more heat out of hot air, and when it expands into the tank it will cool slightly.

Condesation occurs more readily at high pressures.

Does your pump cope easily with demand, ie does it stop and start as you work rather than running continuously? If so consider increasing the cut-off pressure. The higher pressure will generate a higher temperature, the higher temperature will dissipate more heat through the aftercooler, there will be a bigger pressure drop at the regulator and consequently even more cooling/condensing.

If you compressor isn't coping consider installing an additional one.

You could try evaporative cooling, ie drizzle some water over the tank

You could also try a refrigeration unit to cool the air, but I guess this would be more expensive than another compressor.

 

[paulioq]

I looked into that and am still thinking of doing it for a final step specialy if I buy a plasma cutter, i go look at one in the welding shop each time i go in for something else (havent convinced myself I need it to cut car panals with yet) but I looked into the holding capacity of dessicant and compared to the amount of water that use to come out the exhast of my die grinder I estimated I'd be drying it out daily. then I found one on ebay for $175 and thought the diy route was no cheaper and just more work. but I was looking at stainless housings the plastic ones can handle the preasure but distort with preasure and can be absolute ******** to undo the housing to the point I have told customers that I could destroy the housing after breaking the suppklied spanner they come with and useing stilsons then cracked it befor its undone. they give me night mares to the point i wake up in the middle of the night in a cold sweet waiveing my hands infront of me saying no no water filter housing no.

 

[MattF]

Sounds like your best method is probably going to be implementing several things to address the problem, rather than looking for a single cure-all. Expansion chambers with indirect or slightly convoluted in/out air paths, (those were originally implemented on steam systems, I believe, so their attributes are obviously handy for moist air compressor output too), desiccant driers, fan assisted coolers, (basically a large car style radiator with a fan blowing constantly through them), etc. will all add up, and can be done tidily. Plus, with the copper radiator/cooler, there's no reason to go horizontal and just coil the stuff on the floor. You could quite easily build a grid on the wall and have a moisture collection chamber and drain at the bottom. You could easily enough run a secondary water pipe along/around it for coolant water flow too, or connect large heatsinks etc. to the grid in suitable locations

 

[paulioq]

all it has at the moment is the finned pipe between the pump and reciever tank I guess this is an after cooler, intercooler goes between vein air compressor and motor but that's a supply and demand situation no storage, will both do the same job of cooling charged air befor its used.

your right to say that ambient temperature is a pipe dream but thought the stop start cycles would be enough to keep it at a modest temperature my concept was to use the air draw of the compressor fan to also draw the air through the condenser I put my hand on the cage infront of it and was surprised at how much air it actually drew.with a fan I could run it continues or controlled with a relay from the preasure switch but 2 fans inline running together usually interupt the flow of each other so will probably use the relay to actually turn the thermo off when the compressor comes on. car thermos usually only turn on in no air flow situations like at the lights and interrupt natural air flow because they actually draw air slower then you can push it through at speed so they turn off because natural air flow keeps a cooling system cooler then the thermo's do. but will use the k.i.s.s method of working and try it with out first. couldn't see much use to run a fan when theres no flow through the condenser because when the compressor cycles the hot air will also stop being delivered and has a chance to loose heat adaquitly between cycles. I plan on doing test after I set it up with a heat temp gun after I do it to see how effective it is. no use doing something if you cant measure it to see if its an improvement

it only runs continuesly when I am blasting but dependant on what media. fine grade it will cycle with a smaller tip if I use some thing course like crushed glass just runs flat out with the larger tip, also need to run higher preasure then the pot blaster booklet recommends to remove anything quickly and effectively but the down side is you use air quicker but it is designed for free air delivery so shouldn't be an issue. its a 17cfm three cylinder piston pump with a 100l tank the biggest I can run on our standard power supply. installing three phase to a domestic residance didn't seem practical or fisable for the cost of it and as for these little pot blasters I don't know how they can recommend that they will run on 12 cfm minimum. yes they will spit sand but I doubt it would even reach the job with a 2 piston 12cfm

 

[rtbcomp]

I don't think the standard aftercooler is much good. I made a serpentine one out of copper pipe for one of my compressors which worked quite well. Several small bore pipes in parallel would be more effective than one larger bore pipe.

Another mod I did was to extend the air intake with some vacuum cleaner pipe, the original setup drew hot air from above the motor.

 

[paulioq]

matt your right it may need a few solutions and I will probably end up doing the air dryer with this crazy condenser idea of mine but with out it being to expensive. the condenser idea is going to be about $20 for a second hand one I scene localy on gumtree and a bit of pipe I have floating around the place. if I add a fan that will be + $100 by the time I get a thermo fan and 12v power supply capable of giving 20 amps, there bloody expensive. the coil of copper pipe will be about the same but wouldn't work as well as something actually designed to dissipate heat (its already a pipe with heat sinks on it don't need to add them). I can drizzle water over the tank for evap cooling but need to catch it and recirculate it and so does the cooling pipe idea. this all starts sounding to complicated with to many moveing parts, k.i.s.s. stands for "keep it simple stupid" because adding a condenser will work as good if not better then other ideas I have scene for the cost and if It works with out a electric fan well that's just one less mechanical item that at some point in time will fail and need fixing. aluminum disipaits heat very effectively and am going to see how it goes on its own i'll up date you all once I get a chance to do this mod to my compressor

 

[paulioq]

rtb thanks for the proof of concept to the idea. that's why I wanted to post it to see what some people thought of this and get some input into it.
I did have a longer intake and made a manifold but removed this like I said in my first post because I thought it may have caused the intake side to work to hard . I don't usually like doing major mods to items unless I'm sure there going to be an improvement because to be honest it was made by some one smarter then me and might be fine but maybe they live some where with a cooler climate then wher I am. just like the 350 chev engine works beutifull in America where it was designed with a cooler climate but they always run hot in austrailia and need over sized radiators to keep there temp in check

 

[rtbcomp]

How about fitting a supercharger to the inlet? An old car intercooler could be placed between supercharger (old vacuum cleaner) because the pressure won't be too great.

I was thinking at one time of using an old domestic freezer to cool the air, but I don't think it would be powerful enough.

 

[MattF]

One thing to check with the air con condenser is to make sure it has decent size bores. Small channels generally seem to clog like there's no tomorrow, for some reason. A bit of a wider bore works wonders. They usually tend to be piddly bores on those A/C rads, judging from the ones I've seen.

 

[paulioq]

If I did add a super charger it would just be to brag to my mates that my compressor has a super charger and theres doesn't hahaha is a sound idea but very often in water treatment you use what is called a feed pump/jacking pump to supply another pump to achieve the required preasure and flow rate and also to reduce the load on the second pump so it can concentrate on pumping and not sucking unfortunately any pump only does one thing well push or pull and from a scientific point of view for all caculations water and air is the same in volume just different in density. water turning in to steam expands 1800 times so if you compress 1800 litres of air you'll make about a litre. when you compress air it will always squeeze the water out of it. refigirateing the inlet air would be better done with an a/c system would need some thing with the evaporative cooler in the air stream. they start at 2500 I only paid 600 for this compressor what can I say I'm a tight ass

 

[500e]

Coiled pipe pulled out flat (not a good explanation) 2 \3 layers with a felt\wadding type of material between them water trickled down to keep them wet & air blown through, the evaporation will pull the temp down a fair amount, all this in a box.
Keeping the compressor as cold as possible will help too, so with the box on the - pressure side you may get a further benefit as the evaporated moisture could be at a lower temp than either compressor casing or ambient

 

[MattF]

what can I say I'm a tight ass

Have you seen how many of us Yorkshiremen are on this forum? Believe you me, you're in good company in that regard.

 

[rtbcomp]

You can save money by using old domestic stuff, like I said a vacuum cleaner, or maybe a hair dryer (on cold blow!) could supercharge the compressor.

if you compress 1800 litres of air you'll make about a litre - not quite sure what you mean here, the volume of air you end up with depends on the pressure, until it eventually liquifies.

 

[paulioq]

will only clog with water matt and I will install it with the cores horizontal so that it will push through to the tank with the out let being on the bottom on one side and inlet on the top of the other side to have equal flow through all cores and have a proper manifold set up, and the reason I want to use an a/c condenser is because of there small bores which will increase the surface area available to absorb heat, if the cores are bigger it will just fit less cores in the available space or require a bigger unit to work efectively. if the bores are to big you don't actually cool whats running in the middle of the core. high end intercoolers and radiators actually have an interfirance set up internally to make the flow tumble and mix through the core to eliminate this problem. I made an educated guess to use the a/c condenser because controlling temperature like air temp in a house a/c cooling or heating or operating temp of something mechanical is dependant of flow rate x volume of fluid movement x desired temp difference between inlet and out let of the radiator/condenser. in short you need to slow it down to give it time to put its heat into the cores if it moves to fast it wont have time to loose its heat. theres no such thing as adding cold theres only takeing heat. you get a natural a/c effect each time the sun rises and starts to heat every thing up its drawing the last of the heat out. ever noticed how it gets real cold real quick about 15 minutes befor the sun cracks the horizon.

 

[paulioq]

nice work matt well I feel at home now if I didn't befor.

rtb if theres 50% humidity in the air as gassious water when you compress the air 1800 times you will make about 500ml when compessing air your not compressing the water you litraly squeeze it out of the air because it takes a lot more preasure and energy input then what an air pump produces to compress water. have you ever noticed on a petrol water jeter how big the moter is compared to the preasure pump maybe like 6.5 hp required to produce preasure at 12L/m but a compressor will make 310l/m with a 2.5hp motor. different densitys mate. hope that clears it up.

super charging your compressor still gives you bragging rights in my book and I'm allabout repurposeing house hold items for my work shop just ask my missus what she thinks she might not agree

 

[paulioq]

sorry in the last post I ment to say compress 1800L of air in to a space of 1L you will make 500ml hope that helps