Multi tank and compressor build for blasting

[conor1n]

Hello all,

I am currently trying to figure out the feasibility of setting up a compressed air system for some abrasive blasting.

My goal would be to be able to perform the following tasks (not concurrently). My aim is also to have a sustainable build, so I don't want to be labouring the motors/pumps too much. I want the system to be able to keep up. I really don't want to have to wait around for it to catch up after a period of time.

* Subframe blasting
* Possibly ladder frame chassis
* Car / Van underbody
* Smaller parts in a cabinet using dry shot.
* Vapour blasting using slurry in another cabinet

To start off, these are the types of tools I would plan on running:
* Blasting pot - 6-25 CFM requirement - 4 nozzles 2 to 3.5mm
* Blasting cabinet - 6-25 CFM requirement

What size is suitable if doing a subframe..... so that it's time efficient?

I have a figure in my head that I would like to achieve 20-30 CFM.. that's just finger in the air.

I currently own these compressors:
* Shamal 200 litre 3HP 220v with belt drive motor.
* SIP 50 litre 3HP 220v with direct drive.

I also have the following:
* A DIY air dryer - It seems decent as it removes a nice bit of water. I never noticed any moisture related issues when I painted my car with VOC paint. I would be happy to build another one with improvements on my first build. (I have since removed the quick connects on this for airflow reasons).
* A local friendly gas supplier is willing to give me a couple of 47kg gas tanks which are approximately 100 litres each. I am aware of the dangers of compressed air and I won't tamper with any of these vessels.

Some basically.. that's a total of 6HP and approximately 450 litres of capacity.

Thoughts:

I don't know how flow is calculated? And where FAD vs pump displacement comes into it. But the pump displacements of the two compressors above is 14 + 13.8 = 27.8 CFM.

Where does FAD come into it? Would the above numbers work for blasting?

Obviously there is the plumbing and wiring etc to be done.

* From research online, I would plan on plumbing the two propane tanks to the compressors. The idea would be to run the compressors with open and regulate after the receiver tanks.
* I would also add in the air dryer, and possibly another into the mix somewhere.
* Interested in thoughts on how to set up the motors. At a minimum, I wouldn't want them both kicking in at the same time. Is that best solved by using a time delay relay/switch? Do the switches on most pumps have a little delay trimmer switch? I saw online that you can get an alternating relay.. so each time the pressure drops the alternate motor will kick in, this will help with duty cycle and also help spread the wear evenly.
* For draining, I would like some kind of automated drains on the cooler and also the bottom of each compressor. I would plan on putting all this gear on a mezzanine so I could easily plumb all the various drains together and then run a line down to floor level which I could manually release or put a switched drain on it.

Interested in peoples thoughts, especially on the CFM side of things as this is something I don't know how to calculate etc. Actually can I ask a question.. is it the case that the pumps ultimately provide the CFM rating of the system.. and the tanks are just used to increase capacity to prevent overworking the pumps.

This was a long post... if you got this far, thank you for reading

 

[julianf]

The 47kg tanks -

There is only a single hole in them. So, if you have them the normal way up, I guess, they will gradually fill with water over time.

You would need to have them upside down maybe? But then you're sucking out any distillate with your air (which may be fine if your down stream dryer can handle it)

Just something to consider though. They sit upside down, but you would want them strapped to something also as they will be a bit unbalanced otherwise.

It would be technically possible to weld in another port and pressure test them but then you would have calor on your back for modifying "their" cylinders (which they charge more for in deposit than they cost to produce and then won't give back the deposit a lot of the time - but that's another conversation entirely!)

 

[conor1n]

Okay.. quick follow up on this, regarding CFM.

This calculator seems decent and easy to use. Do you guys reckon it's accurate?

After some estimated inputs, her is a FAD CFM calculation of my proposed system.

(I am not sure of the starting up PSI and time in seconds - but I suspect the system might be able to charge in 90 seconds with 6HP).

 

[conor1n]

The 47kg tanks -

There is only a single hole in them. So, if you have them the normal way up, I guess, they will gradually fill with water over time.

You would need to have them upside down maybe? But then you're sucking out any distillate with your air (which may be fine if your down stream dryer can handle it)

Just something to consider though. They sit upside down, but you would want them strapped to something also as they will be a bit unbalanced otherwise.

It would be technically possible to weld in another port and pressure test them but then you would have c**** on your back for modifying "their" cylinders (which they charge more for in deposit than they cost to produce and then won't give back the deposit a lot of the time - but that's another conversation entirely!)

Oh yes.. good points. I forgot to say.

I will mount them upside down and would secure them appropriately. I saw a guy online weld some legs onto them by welding to the bottom part and also use threaded rods to weld to the collar slots... so no welding the actual pressure vessel themselves.

The cylinders will be mine to do what I want (but still valid and sound). I'm not stealing them btw.

My intention would actually be have the bulk of the air dried before it hits the propane cylinders.. but I will still implement drainage at every point.

Thanks for your feedback.

 

[julianf]

Okay.. quick follow up on this, regarding CFM.

This calculator seems decent and easy to use. Do you guys reckon it's accurate?

After some estimated inputs, her is a FAD CFM calculation of my proposed system.

(I am not sure of the starting up PSI and time in seconds - but I suspect the system might be able to charge in 90 seconds with 6HP).

View attachment 426797

This page -

Air Consumption Chart - Hodge Clemco

Access detailed air consumption charts for blasting equipment. Ensure your operations are efficient with accurate data from Hodge Clemco.

www.hodgeclemco.co.uk

...has a slider for you to set your psi and then you can set the nozzle size and it will tell you the cfm.

Dont ask me what nozzle or psi you need though, as you have probably reached the limit of my understanding now!

 

[conor1n]

This page -

Air Consumption Chart - Hodge Clemco

Access detailed air consumption charts for blasting equipment. Ensure your operations are efficient with accurate data from Hodge Clemco.

www.hodgeclemco.co.uk

...has a slider for you to set your psi and then you can set the nozzle size and it will tell you the cfm.

Dont ask me what nozzle or psi you need though, as you have probably reached the limit of my understanding now!

Very useful, thank you.

 

[julianf]

The cylinders will be mine to do what I want (but still valid and sound). I'm not stealing them btw.

I don't know your situation but calor behave a bit like the waterboard. They reckon they own everything regardless of circumstance.

I'm not saying they do. Just that they think they do and will give you all sorts of threats if you draw their interest.

 

[conor1n]

I don't know your situation but c**** behave a bit like the waterboard. They reckon they own everything regardless of circumstance.

I'm not saying they do. Just that they think they do and will give you all sorts of threats if you draw their interest.

Ok, I hear you. The tanks aren't c****.

I only used that image as it was the first Google image result. I have removed it.

Would you mind removing the c**** name from your posts just to avoid any legal issues and confusion.

Thanks.

 

[MetalMonkey]

I don't know how flow is calculated? And where FAD vs pump displacement comes into it. But the pump displacements of the two compressors above is 14 + 13.8 = 27.8 CFM.

Where does FAD come into it? Would the above numbers work for blasting?

Interested in peoples thoughts, especially on the CFM side of things as this is something I don't know how to calculate etc. Actually can I ask a question.. is it the case that the pumps ultimately provide the CFM rating of the system.. and the tanks are just used to increase capacity to prevent overworking the pumps.

Short answer, ignore the CFM figures unless they state FAD, which for those compressors is going to be about 9 CFM each.
The extra tank capacity isn't really that important - with blasting you will go through that in a matter of a few seconds and then you will be relying on the pumps keeping up with demand.
Blasting is one of the most taxing things you can do for a home compressor setup. It is very air intensive.

If you are going to blast a few small parts occasionally in a cabinet, then you will probably get away with it - I have two 3hp belt drive compressors and they just about keep up with my cabinet, but I do need to stop periodically to give them a rest as they get mighty warm. If you run a small hobby cabinet with a smaller nozzle it should use less air, but you will take a lot longer to get things done. I suspect vapour blasting will be a bridge too far for that setup.

If you have a lot to do, you are going to need a bigger boat, or just send it out, which is probably going to work out a lot cheaper in the long run - those guys usually have road compressors and a serious set up.

Pressure pot should work well enough on that setup - @brightspark is your man for information on that, check out his previous posts.

The pressure cutoffs will usually be slightly different so the point at which the motors turn on and off will not be exactly the same, so it should naturally "stagger" the startup load. If not you can often tweak it.
Automatic drains are available, but a ball lever valve is cheap and easy as long as you get into the habit of draining it before you start and after you finish.

 

[CompoSimmonite]

If you have a lot to do, you are going to need a bigger boat, or just send it out, which is probably going to work out a lot cheaper in the long run - those guys usually have road compressors and a serious set up.

I was just going to say the same thing.

 

[brightspark]

even a 90cfm comp using a 6mm blast jet is about the minimum for doing under chassis etc car wheels and the likes i have one and a 28cfm pump setup using a 3.0mm jet

 

[conor1n]

Thanks for the advice all.

What compressor would you guys recommend if buying?

* Electric or petrol/diesel?
* Single phase vs three?
* How many HP?
* Displacement pump vs screw?
* Reservoir capacity?
* How many CFM (FAD / SCFM?)

I think I will buy a pressure pot and small cabinet to start off and see how I get on..

Thank you

 

[brightspark]

Thanks for the advice all.

What compressor would you guys recommend if buying?

* Electric or petrol/diesel?
* Single phase vs three?
* How many HP?
* Displacement pump vs screw?
* Reservoir capacity?
* How many CFM (FAD / SCFM?)

I think I will buy a pressure pot and small cabinet to start off and see how I get on..

Thank you

a couple of 14cfm comps linked will run a 3mm blast jet very well . dont buy direct drive you will soon kill it

 

[eddie49]

Plenty of earlier threads about this topic. E.g.:

These compressors sufficient for blasting?

This site seems to be the most knowledgeable on the subject. I'm sorry that its yet again a question on a subject that has been asked a million times all ready. But I really need advice before I throw down all this money. I am restoring a Beetle chassis for a buggy build, and will be chopping...

www.mig-welding.co.uk

compressor cant keep up sandblasting

good afternoon, i have just bought a sandblast cabinet to do parts of a camper im restoring, i have a,hydrovane 501 compressor but it can't keep up with the cabinet , i have it set at 120 but can only blast for around a minute before the pressure drops to around 40 so not enough to suck the...

www.mig-welding.co.uk

 

[bert]

For propper blasting we use a diesel road compressor. For cabinet blasting our 270l, 2x3hp 28cfm compressor does the job and keeps up with a 6mm tip

 

[AVI_8]

Do you have 3 phase? If you do on the second hand market big compressors are readily available for not a lot of money, they’re cheap because most of us don’t have 3 phase.
FAD is around 2/3 rds of SCFM as mentioned previously a couple of belt driven 3hp compressors will give you in the ballpark 20 CFM FAD, that’s what I’ve got as I don't have 3 phase if I did I’d have a big 7.5 hp thumper which could run for long periods of time without a problem.

 

[brightspark]

For propper blasting we use a diesel road compressor. For cabinet blasting our 270l, 2x3hp 28cfm compressor does the job and keeps up with a 6mm tip

i bet it doesnt keep it to 90psi if its a pressure pot will probably be a suction gun with a smaller air jet and the grit nozzle will; be 6.0mm

 

[bert]

Yes the cabinet is a suction gun with a 6mm deramic nozzle. Couldn't tell you what pressure it's at as the compressor if at the opposite end of the workshop now.

 

[conor1n]

a couple of 14cfm comps linked will run a 3mm blast jet very well . dont buy direct drive you will soon kill it

I will see how I get on with them. One belt drive and one direct. I'll see how I get on.

Plenty of earlier threads about this topic. E.g.:

These compressors sufficient for blasting?

This site seems to be the most knowledgeable on the subject. I'm sorry that its yet again a question on a subject that has been asked a million times all ready. But I really need advice before I throw down all this money. I am restoring a Beetle chassis for a buggy build, and will be chopping...

www.mig-welding.co.uk

compressor cant keep up sandblasting

good afternoon, i have just bought a sandblast cabinet to do parts of a camper im restoring, i have a,hydrovane 501 compressor but it can't keep up with the cabinet , i have it set at 120 but can only blast for around a minute before the pressure drops to around 40 so not enough to suck the...

www.mig-welding.co.uk

Thank you. I must admit i'm bad enough at searching .. any time I use various forum searches, they never seem to give me what I want.. I read both those threads .. interesting that one of them is in Ireland, too.. where my current operation is.

For propper blasting we use a diesel road compressor. For cabinet blasting our 270l, 2x3hp 28cfm compressor does the job and keeps up with a 6mm tip

If I get into it seriously, I am likely to go down a heavier route.

Do you have 3 phase? If you do on the second hand market big compressors are readily available for not a lot of money, they’re cheap because most of us don’t have 3 phase.
FAD is around 2/3 rds of SCFM as mentioned previously a couple of belt driven 3hp compressors will give you in the ballpark 20 CFM FAD, that’s what I’ve got as I don't have 3 phase if I did I’d have a big 7.5 hp thumper which could run for long periods of time without a problem.

I do have three phase and will investigate it. Sounds a good idea alright.. I wonder can I just get a pump + motor and mount them independently of tanks and just pipe the output of it to tanks, via drier.

 

[conor1n]

Out of curiosity ..

Has anybody ever used one of these blasters.. I see them in various stores and the idea seems novel but question their efficacy.