Thread: Air Water Trap - Filter for Spray Gun

Hello All,

The local mob that I bought the Unimig plasma cutter filter from recommended that I mount the filter on a trolley as close as possible to the plasma cutter itself. While I sort the connections out for the plasma cutter filter I went to Super Cheap and grabbed one of the Blackridge Air Inline Water Traps
Blackridge Air Inline Water Trap | Supercheap Auto for $22.19.

The Blackridge water trap is a temporary measure and it worked well. I just laid a couple of coats of varnish on the bench tops and it produced a much better finish than before. I will see how it comes up tomorrow when it is dry. So far so good!

Kind regards
Lionel

Originally Posted by Lionelgee

Hello All,

I bought a UNIMIG Plasma Cutter Air Filter for the intended purpose of protecting my plasma cutter. Would this filter be able to be used on the air line for a spray gun for spraying automotive spray paint and furniture finishes such as clear oil-based varnish? As, in would the Unimig plasma cutter filter take too much air pressure out of the system for a spray gun to work properly?

The filter is still in its box so I have not tried it yet. Unimig Plasma Cutter Air Filter Plasma Cutter Air Filter | UNIMIG Welding Supplies

I saw online that there are small water traps that can be fitted inline just before the spray gun itself. Also there are mammoth sized water traps and filters that sit between the compressor and the spray line that start at $300.

For example, the small water trap fitted just before the spray gun Beduan Water Oil Separator Filter, 1/4" NPT Male and Female Thread Spray Gun Filters Air Line Compressor Fitting （Pack of 2）https://www.amazon.com/Beduan-Sepera...dp/B07N73LGVD/. Or a similar product that can be bought from Supercheap Auto and the like, auto parts stores.

I already have a water trap on the compressor itself. However, when I was using the air nozzle to blow clean some emery paper I noticed the paper was getting darker through it getting damp. This dampness would be carrying through into my spray gun too. Not an ideal situation at all!

Kind Regards
Lionel

Go the toilet paper filter !!!! Yeah, better still will be to run some drops across your shed



i need to do this someday in my shed again

A water trap will remove larger droplets of water but the air coming through can still be moist.

Air can only carry a certain amount of moisture but it depends on it's temperature, cool air can carry less. It's known as the dew point.
Industrial dryers chill the compressed air to below its dew point, the water drops out then the air is warmed before it leaves the dryer. As long as the air doesn't drop below the temperature it was chilled to, no more moisture drops out.

With a delivery system in a factory you take compressed air from the top of the large diameter main pipe, then turn 180degrees down to where it's needed. Drain legs (if needed) come from the bottom of the main pipe. The main pipe should be at a slight angle so any water is guided to a drain leg
I've been in the pneumatics industry for over 30 years and have never seen anything like the layout below and don't understand what would be achieved by the pipework (apart from generating business for the company that sold the pipe & fittings )




Using a large receiver can get moisture to drop out of the air initially as it's cooler than the incoming air. Remember to drain the receiver regularly though.
I went to use a small Junair silent compressor at a company I worked at and thought I'd drain the receiver....about 5 litres of rusty water were removed ! It had been used for a long term test on some pneumatic equipment then put back into stock.

A standard pneumatic filter regulator has stationary blades inside that spin the incoming airflow, water droplets are thrown to the inside surface of the bowl and can be manually drained out as it builds up (some have semi or fully automatic drains). They don't 'dry' the air.

You can buy in-line dryers but.....they are quite large, very expensive and restrict airflow.

I use a small compressor for spraying and don't get water coming through (more by luck than judgement) but it will depend on ambient temperature and other factors.

Colin

Originally Posted by gromit

A water trap will remove larger droplets of water but the air coming through can still be moist.

Air can only carry a certain amount of moisture but it depends on it's temperature, cool air can carry less. It's known as the dew point.
Industrial dryers chill the compressed air to below its dew point, the water drops out then the air is warmed before it leaves the dryer. As long as the air doesn't drop below the temperature it was chilled to, no more moisture drops out.

With a delivery system in a factory you take compressed air from the top of the large diameter main pipe, then turn 180degrees down to where it's needed. Drain legs (if needed) come from the bottom of the main pipe. The main pipe should be at a slight angle so any water is guided to a drain leg
I've been in the pneumatics industry for over 30 years and have never seen anything like the layout below and don't understand what would be achieved by the pipework (apart from generating business for the company that sold the pipe & fittings )




Using a large receiver can get moisture to drop out of the air initially as it's cooler than the incoming air. Remember to drain the receiver regularly though.
I went to use a small Junair silent compressor at a company I worked at and thought I'd drain the receiver....about 5 litres of rusty water were removed ! It had been used for a long term test on some pneumatic equipment then put back into stock.

A standard pneumatic filter regulator has stationary blades inside that spin the incoming airflow, water droplets are thrown to the inside surface of the bowl and can be manually drained out as it builds up (some have semi or fully automatic drains). They don't 'dry' the air.

You can buy in-line dryers but.....they are quite large, very expensive and restrict airflow.

I use a small compressor for spraying and don't get water coming through (more by luck than judgement) but it will depend on ambient temperature and other factors.

Colin

Those drops work well. it gives you extra cooling effect over the length of the pipes. The moisture will collect at the bottom of the drops (there is a tap at the bottom of each drop to drain them), but your air take off is up high. I've rigged up similar in my shed in the past. You do collect quite a good amount of water in the drops.



You are thinking from an (expensive) industrial perspective. We are talking about tinkering DIY in our sheds. You could bang one up with some PVC pipe quite cheaply. I have built sandblasters and painted a lot of cars. You can EASILY get moisture through, especially in humid or cold weather. I have a 17CFM compressor, the biggest you can really run from a 15amp power point in a domestic type shed. They run hot and hard to keep up with modern spray guns .... you really need two of them to run the sandblaster.



I just did a 5second google search to find that picture ... Here we go, 30second google search. See how you can drain each drop, but the point you take the air from is towards the top, away from where condensed water will have collected.

When I was doing a bit of sand blasting, I used to run a coil of copper pipe in the air line ... that was in a bucket of ice. It certainly seemed to help cool the air and condense out moisture.

Hard working compressors make heaps and heaps of moisture.

seeya,
Shane L.

Originally Posted by DoubleChevron

You are thinking from an (expensive) industrial perspective. We are talking about tinkering DIY in our sheds.

I was making a point that a water trap doesn't remove moisture.

The pipework layout in the picture still doesn't make any sense to me at all.
The last air point will have the flow compromised due to friction through the length of the pipework. If water builds up in the first drop then air going past to the rest of the system is getting wetter.

Single larger pipe high up set at a slight downward angle, drain leg taken from the bottom of the pipe, air take offs taken from the top. Used in every factory or workshop I've ever visited, well that's not exactly true, some small factories have flexible pipe strung from the rafters !

Diagram below is for a factory but shows the principle. A ring main is best but probably not always practical in a workshop.




Colin

Originally Posted by gromit

I was making a point that a water trap doesn't remove moisture.

The pipework layout in the picture still doesn't make any sense to me at all.
The last air point will have the flow compromised due to friction through the length of the pipework. If water builds up in the first drop then air going past to the rest of the system is getting wetter.

Single larger pipe high up set at a slight downward angle, drain leg taken from the bottom of the pipe, air take offs taken from the top. Used in every factory or workshop I've ever visited, well that's not exactly true, some small factories have flexible pipe strung from the rafters !

Diagram below is for a factory but shows the principle. A ring main is best but probably not always practical in a workshop.




Colin

I know what you are saying, but the moisture does condense in the pipework. I'm surpised those drops don't have a drain point in the bottom of each line in your diagram. as water does condense in the drops. It probably isn't an issue with a big cool running 3 phase giant compressor rumbling away. Barely any heat generated means you have far, far less moisture to begin with.

I think you are saying any moisture that makes it to the drops, doesn't condense out either way if it makes it past the first drop with the drain it it? I'm guessing you are right, you appear to have a much better understanding of this than me.

remember we are talking reducing water in a hot running little compressor and trying to figure out a DIY way of reducing moisture for little to no cost. I have found the "drops" really do work to a certain extent. You can drain quite a bit of water from them. You are right though, the first drop usually has the majority of the condensed water in it

Originally Posted by DoubleChevron

... tinkering DIY in our sheds...in a bucket of ice...

Coil of copper running through the beer fridge? All those accumulating (at least in my case) CPU cooling fans thermal pasted to the copper?

Half joking aside, very interesting info from yourself and gromit

Originally Posted by DoubleChevron

I'm surprised those drops don't have a drain point in the bottom of each line in your diagram.

That's because any decent industrial system has a dryer after the compressor, the drain legs are probably always dry.

The long pipe runs in your diagram will cool the air until the pipework warms up I'm just not sure about the up & down pipe runs.
I don't use compressed air long enough to use anything other than a flexible pipe and don't get problems with moisture.

I'm in the process of assembling a big compressor for abrasive blasting. Large receiver & single piston compressor from a company I worked at (they purchased a screw compressor). The three phase motor was given away and a Chonda 7.5hp motor being fitted. Blow-off valve rather than turning engine on & off. I'll probably be using the air faster than the compressor can deliver it !
Hopefully the big receiver will cool the air a bit and moisture won't be a problem.


Colin