Options for better compressed air

[conor1n]

Hi guys

So i'm slowly getting ready to start paint my car...

My current compressor is an SIP TN3/50 i.e. 3 HP - 50 Litre - Direct Drive - 9.5 CFM Free Air Delivery.. I don't think it's a bad spec tbh given the extra bit of power (V motor) compared to similar ones.

I made one mistake.. I focused on the CFM value, but the 50 Litre capacity is a little low for spray painting I think.. My Devilbliss FLG-05 (LVLP) calls for about 9.5 CFM (Which I assume is FAD, as the displacement of the piston is immaterial to a gun, right?). My current compressor is 9.5.. would this be adequate or not because I thought I read something about losing some CFM in the hose?

Anyway.. I have some choices: (What would you do?)

1. Buy a new compressor - Unsure as to what to get, This SIP one looks good < https://www.iedepot.ie/sip-px3-200-air-compressor-clone/ >
2. Buy a pre-owned compressor - I've just come across this one. It's hard to know what CFM it is.. < https://www.donedeal.ie/tools-for-sale/fini-air-compressor/30660541 >
3. Buy a receiver tank only and plum it into my existing compressor - considering my unit is 3HP, this might not be a bad shout - I know I could drop another few quid on plumbing fittings - I can get a 200 Litre tank here for €357 EURO.. < https://compressedaircentre.com/product/210lt-horizontal-air-receiver-200-ls-2/ >

Two things I struggle with:

1. I see two guys near me paint with what I think are HVLP on 200 litre tanks with probably around only 10 CFM FAD... I can't see it being more than 10 CFM as they are single phase motors and not a tandem setup, which are required for more than 10 CFM FAD. Am I over thinking the CFM requirement and is tank capacity more important?
2. What figures effect the FAD CFM of a compressor, Is it not largely down to the size of the outlet from the receiver tank to the hose/tool. I mean, if I add another tank to my TN3/50, while, sure I get 250 litre capacity, will the CFM still be 9.5 FAD or what? Can you increase the FAD by using higher flow fittings..?

As an aside, I finished my air dryer/cooler the other day - one of the connections was leaking but I think that was my fault.. I need to mount it now and start running some air through it to see how much moisture it draws.

 

[carbon]

Buy another compressor and join the outlets together will increase the output cfm. Don’t add a second receiver to the one you have as refill times will increase and you won’t increase the output cfm.

If you intend to use 2k with an air fed mask then you will need approx 10 cfm just for the mask

 

[bricol]

I'm bemused why you've got PTFE tape in and around your compression fittings . . .

 

[Barking Mat]

Have you got three phase ? First question.

You need a suitable compressor, and big air tank.

 

[Lewis_RX8]

I had a good read of the paint system part of the forum guides when I was painting my rusty wings, Didn't use a comp I just spray cans but it has a section for air systems.

Reducing Water in a DIY Compressed Air Supply

How water droplets in the air supply can cause microblisters in paint, and ways to remove water without spending too much money.

www.mig-welding.co.uk

 

[Barking Mat]

I'm bemused why you've got PTFE tape in and around your compression fittings . . .

Nowt wrong with that in my books.

Educate me forum.

 

[MetalMonkey]

You are unlikely to be spraying continuously for any length of time, so a lot really depends on the job you are doing with it.

If you want more capacity you could look for some old HGV air brake tanks as another option - a couple of those would double your capacity, and can often be picked up cheap if you ask about.

Those direct drive compressors are very noisy - if you did decide to change your compressor I would suggest you go belt drive and as big as you can on your supply.

The FAD of the compressor is dependant on the pump that is fitted to it and the speed it runs at.
Using high flow fittings etc won't magically give you more than the compressor is rated to deliver - but it may remove restrictions which could cause you to get less.

Adding an extra tank isn't going to change what the compressor is pushing out, it just gives you more capacity - the flip side of that is it will take longer to charge up to pressure though.
That is assuming it is done sensibly of course - obviously if you pipe the extra tanks through a straw then, yes it would cause a restriction.

It all depends on what you want, FAD or receiver capacity, and what you are trying to do with it - spray a panel at a time or an entire truck in one go..

 

[brightspark]

Nowt wrong with that in my books.

Educate me forum.

its totaly pointless putting it on the threads on compression fittings. its the olive it seals on. not even needed on the olives to be honest unless they wont seal properly

 

[MetalMonkey]

Nowt wrong with that in my books.

Educate me forum.

Compression fittings seal against the olive - PTFE tape on the threads is redundant as they aren't doing any of the sealing.
Sometimes you can use some around the olive if its a bit knackered, but in theory it is not needed at all.

 

[Barking Mat]

its totaly pointless putting it on the threads on compression fittings. its the olive it seals on. not even needed on the olives to be honest unless they wont seal properly

We don't have olives over here on compressor fitting.

 

[Barking Mat]

We don't have olives over here on compressor fitting.

We do have olives, but we eat them.

 

[Barking Mat]

You're talking about rigid lines.

I'm not.

Haven't got any rigid lines, not that posh...

 

[voipio]

Nowt wrong with that in my books.

Educate me forum.

The seal is formed between the pipe and the olive, and between the olive and the body of the fitting. No need for PTFE tape. The threads have nothing to do with the seal. They only serve hold the above items in place, in compression, in order to maintain the seal.

 

[Barking Mat]

The seal is formed between the pipe and the olive, and between the olive and the body of the fitting. No need for PTFE tape. The threads have nothing to do with the seal. They only serve hold the above items in place, in compression, in order to maintain the seal.

Yeah, sorry, I'm on a completely different wavelength I missed any olives being involved.

I'm thinking threaded fittings, ignore me, as usual.

 

[AVI_8]

Your compressor is not ideal, it will be working flat out to spray a car, and you will probably have to wait a few times for it to catch up if the specifications you have posted match up, if you’re going to be using an air fed mask you’ll need 2 times that fad

 

[conor1n]

Hello all,

Thanks for the feedback thus far. Just to answer some of the points above.

(I also just read that compressors are an easy thing to underbuy, and boy did I what..? )

1. Single phase only please.
2. I put PTFE on the olives as I saw somewhere that it could help. I understand the theory of not needing them, but I thought it cheap insurance. I didn't want to have to realise there was a leak. (Inexperienced).
3. Ok, makes sense that I could add another compressor in line with the other increase CFM. Good shout.
4. Yes direct drive is loud, LMAO - I don't think you ever need to tell an owner of a DD compressor that
5. I'm probably still a little confused about the metrics of compressor power and tank capacity relating to FAD CFM. - can somebody explain to me how @RaceDiagnostics setup supports his FLG5 and Air Fed mask? It looks a little small based on what i'm reading... I have seen him do amazing jobs, which confuses me a lot.

 

[Turbo]

I had 2 small 25ltr direct drive compressors both running into a 47kg propane tank as a receiver. The extra tank allows the air more time to cool down & let more moisture out. It was surprising how much water I could drain from the big tank compared to the tanks on the compressors!
I could spray using that setup though I've never tried a whole car, just a panel or 2.

I've now got a big direct drive unit & it has more air & a lot quieter too!

You don't mention what spray gun you have. HVLP uses a lot less paint than a traditional gun but is quite hungry on air. There are LVLP guns out now & are quite easy on both paint & air but can be difficult to get a decent finish.

If you are using an air fed helmet you could get a compressor just to feed that.

If you do use 2 compressors you should adjust the pressure switch on 1 so that they don't try to start at the same time & overload your power supply.

 

[conor1n]

Can somebody also please explain to me how some compressors have larger FAD than others. Is it just a case that the outlet from compressor to tool is larger than smaller compressors? Because I can't see how this might be possible if that is not the case?

I am having trouble reasoning about it. I mean, imagine a garden hose... you can increase the amount of water flowing through by either increasing the pressure of the underlying system. Or just make the pipe larger in diameter. Larger pipe means more water can flow, but if the pressure of the system remains the same, surely the pressure of the water flowing is lower due to the wider pipe?

It's just not computing.

 

[conor1n]

I had 2 small 25ltr direct drive compressors both running into a 47kg propane tank as a receiver. The extra tank allows the air more time to cool down & let more moisture out. It was surprising how much water I could drain from the big tank compared to the tanks on the compressors!
I could spray using that setup though I've never tried a whole car, just a panel or 2.

I've now got a big direct drive unit & it has more air & a lot quieter too!

You don't mention what spray gun you have. HVLP uses a lot less paint than a traditional gun but is quite hungry on air. There are LVLP guns out now & are quite easy on both paint & air but can be difficult to get a decent finish.

If you are using an air fed helmet you could get a compressor just to feed that.

If you do use 2 compressors you should adjust the pressure switch on 1 so that they don't try to start at the same time & overload your power supply.

I did mention it in my OP. I am using Devilbliss FLG-05 which I believe to be LVLP. I was advised by the famous Gunman to get LVLP.

Good shout on the alternate timing of startup of motors, I have seen tandem units do that.

What compressor have you now?

 

[carbon]

With an approx air requirement of 9.8 cfm for an flg5 it’s not lvlp it’s hvlp. Some lvlp sprayguns have an air requirement below 6 cfm.

If the compressor has a regulator attached I wouldn’t use that, it’s much better to connect a hose to one end of the receiver then on to an external regulator. The hose and regulator ideally needs to be 1/2” for less restriction.

Larger fad is created with a larger pump that’s why adding a second receiver on its own doesn’t increase the fad