Multi tank and compressor build for blasting

[Erie Fred]

Surely it's the propane receivers that are out of the question? Surely adding two compressors in series is not out of the question and not a questionable practice... surely?

If you think these are in series, you really need to step back, and get some help setting your system up.

 

[Burdekin]

I hear you.. but.. i'm going to ease myself into this.. I understand you probably have industry experience from the tone of your post.

I don't plan on running these things 8 hours flat each day. Probably more like a few days a month really.. I do plan on getting insurance and am waiting to hear back from a broker. Will see what stipulations they come up with.

The reality is that you need to stretch some things going down the startup route.. it's not like I am being reckless and I won't be bringing people in to do the work.. so while this will be a business.. the day to day will be very similar to my own personal workshop.

Realistically it’s a sensible approach, see how it goes first and you can always expand.

 

[conor1n]

If you think these are in series, you really need to step back, and get some help setting your system up.

You are right....that was a typo when composing my response.. I don't know why I said that.

My intention is to have a large diameter pipe, which I have been calling a "manifold pipe". The volume should be at least the sum of the pipes from each compressor.

Then into that manifold..I will have a pipe from each compressor..

Not what I made it sound like above.. I made it sound like I was connecting the output of one tank into the expansion port of another.

I'm not sure there is much difference between the two, only the latter would restrict the flow?

In any case.. I do have some drawings done up of what I had in mind, which are probably worth sharing.

As with most things.. especially dangerous, I always share my plans with people in the know.

Along the planning process, I just learn and design making various assumptions etc.. but before actually doing anything real, I always check first.

 

[conor1n]

pity u wernt local you could have had a go of my twin unit comp and pressure fed blast pot i use open or in a cabinet using a 2.5mm jet or the road tow comp @ 90cfm with the 6.0mm jet to give you the idea what its about and the capability

Awh that is a kind offer. I will get to a local business who makes this stuff for a demo one day.

 

[conor1n]

Here is the rough plan I drew out to previously to help visualise my plan and come up with a shopping list of parts.

The system is intended to be somewhat "modular" . So I can easily add or remove air receivers or a backup compressors for extra capacity.

What's not in the drawing is adding copper pipe driers between the compressor and manifold pipe. These would also be linked into the auto drain.

Does the gravity fed drain logic work?

Interested to hear what others think.

P.s. The intention is that this be housed in a sheltered cage / house out the back of unit, where few people go.

 

[Burdekin]

Your drains are all connected to all the vessels/lines so you’re pumping moisture around to everything. You don’t need a manifold, just connect the tanks together via a hose. If you have one of the receivers at the end of the line it will work best at dropping out the most water and then just take the air from in to feed the pressure pot. Having that much tank volume when you loose pressure when blasting you have a big volume to fill to keep the pressure up. Personally would drop one of the receivers.

 

[brightspark]

-to be honest its pointless adding extra tanks it takes twice as long to fill and if the comps cant keep up with the air required at the jet it drops in pressure and your back to square one. it takes a constant set supply pressure to get the ratio of air and blast media to run efficiently drops in pressure shoves more sand through and less cutting power

 

[henry Kadzielski]

I have to say something here. Blasting is about air volume at pressure. If you have a 'big job' then you need lots of air and grit to throw at that job otherwise it takes a long time.
Blast process, suction gun is OK but a pressure pot system is far faster, at least double. From the blasting book No2 (1/8")nozzle at 100psi requires 26cfm at the 100 psi. No3 (3/16) nozzle requires 57cfm at 100psi. The blasting speed from a No2 to a No3, the No3 is twice as fast blasting wise. The air consumption will drop slightly when you introduce grit as the grit takes up space in the air stream. Why 100psi? General industrial blasting efficiency / performance is measured at 100psi. For every 1psi above 100psi the blasting speed increases by 1.5% for the same grit consumption. So at 120psi your effective speed would be 30% faster using the same amount of grit. The converse is also true, for every 1psi under 100psi the speed drops by 1.5%.
I have in the workshop a 11kw screw compressor which does about 65/70cfm at 110psi and it has a 100% duty cycle, which is what you need for blasting, tank size as has been mentioned before is not very important, as when you need air you need air simples. For site work I have a 300cfm diesel which will run No6 (3/8") nozzle.
In short can you do what you want, yes, will it be efficient, no, and if you are looking to do this as a business then definetly no. I have done what you are trying to do, did it work well sort of, would I go back definetly not. As it takes so long to do what is required with what you have, you can't charge for all that time it takes to do it. No one wants to wait, especially if they are watching you do it.
We haven't mentioned the moisture in the system and what is actually required to get it out before the blast nozzle yet

 

[brightspark]

We haven't mentioned the moisture in the system and what is actually required to get it out before the blast nozzle yet

i only have a water seperator on the mobile pot what i do is connect it all up fill the pot with grit and start the comp. turn on the air supply and run it without the grit going through till the air gets warm then you see the water separating in the filter after a few minutes it dries up . when the system is running hot just start blasting water isnt a problem and it will run all day

 

[conor1n]

I have to say something here. Blasting is about air volume at pressure. If you have a 'big job' then you need lots of air and grit to throw at that job otherwise it takes a long time.
Blast process, suction gun is OK but a pressure pot system is far faster, at least double. From the blasting book No2 (1/8")nozzle at 100psi requires 26cfm at the 100 psi. No3 (3/16) nozzle requires 57cfm at 100psi. The blasting speed from a No2 to a No3, the No3 is twice as fast blasting wise. The air consumption will drop slightly when you introduce grit as the grit takes up space in the air stream. Why 100psi? General industrial blasting efficiency / performance is measured at 100psi. For every 1psi above 100psi the blasting speed increases by 1.5% for the same grit consumption. So at 120psi your effective speed would be 30% faster using the same amount of grit. The converse is also true, for every 1psi under 100psi the speed drops by 1.5%.
I have in the workshop a 11kw screw compressor which does about 65/70cfm at 110psi and it has a 100% duty cycle, which is what you need for blasting, tank size as has been mentioned before is not very important, as when you need air you need air simples. For site work I have a 300cfm diesel which will run No6 (3/8") nozzle.
In short can you do what you want, yes, will it be efficient, no, and if you are looking to do this as a business then definetly no. I have done what you are trying to do, did it work well sort of, would I go back definetly not. As it takes so long to do what is required with what you have, you can't charge for all that time it takes to do it. No one wants to wait, especially if they are watching you do it.
We haven't mentioned the moisture in the system and what is actually required to get it out before the blast nozzle yet

Thanks henry for your input, I appreciate it. I think a number of key points have been missed by you along the way. I am aware of the shortcomings of my system..but it will be enough to get started and try the process out etc. Time isn't a massive constraint starting off.. but if the business proves itself to be viable I will happily invest further.

I mentioned previously that I will use some DIY copper pipe dryer type systems.. I know these are not ideal but will get me started.. the one I currently have worked well for when I was spraying my car.

I'm not sure why you went the inefficient route etc.. but perhaps you were starting out too :/

Admittedly I have been proven wrong on the capacity thing.. looks like volume of stored air doesn't really matter for blasting.

I must make this point again though.. it feels like a lot of people have perhaps forgotten what it's like to start something new. You get a basic setup to get the ball rolling and the work hard to maximise it's value.. then invest in upgrades when it makes sense. I feel like if I came on here and said I was going to get into blasting and was about to spend 20k on a professional setup then some of you would be telling me to slow down and start with a basic setup to see how the business develops. A lot of successful businesses have started out in sub par conditions and gone on to blossom. I am not trying to sound bitter, but that needs to be said I think.

@henry Kadzielski thanks for your input though.. it sounds like you do know a lot about the business.

 

[conor1n]

Your drains are all connected to all the vessels/lines so you’re pumping moisture around to everything. You don’t need a manifold, just connect the tanks together via a hose. If you have one of the receivers at the end of the line it will work best at dropping out the most water and then just take the air from in to feed the pressure pot. Having that much tank volume when you loose pressure when blasting you have a big volume to fill to keep the pressure up. Personally would drop one of the receivers.

Ok, interesting.. I wasn't sure that was a valid setup. I think the only place it's an issue is at the bottom of manifold?

Interesting for dropping one of the receivers. I always thought the receivers operated as a buffer to help provide volume when the pump kicks in. Perhaps that works for tooling that isn't as intensive as blasting?

-to be honest its pointless adding extra tanks it takes twice as long to fill and if the comps cant keep up with the air required at the jet it drops in pressure and your back to square one. it takes a constant set supply pressure to get the ratio of air and blast media to run efficiently drops in pressure shoves more sand through and less cutting power

Ok makes sense. Thanks for clarifying.

 

[DanZac]

I must make this point again though.. it feels like a lot of people have perhaps forgotten what it's like to start something new. You get a basic setup to get the ball rolling and the work hard to maximise it's value.. then invest in upgrades when it makes sense. I feel like if I came on here and said I was going to get into blasting and was about to spend 20k on a professional setup then some of you would be telling me to slow down and start with a basic setup to see how the business develops. A lot of successful businesses have started out in sub par conditions and gone on to blossom. I am not trying to sound bitter, but that needs to be said I think.

But if your starting from nothing, which it sounds like you are, and your looking to make it into a buisiness venture in the future, then surely your better off starting from a good place than wasting time and money on something that others have found doesn't work very well?

 

[conor1n]

But if your starting from nothing, which it sounds like you are, and your looking to make it into a buisiness venture in the future, then surely your better off starting from a good place than wasting time and money on something that others have found doesn't work very well?

Well not really. I already have two 3HP compressors with 250litre capacity...

Adding a pressure pot for less than €200 allows me to start blasting stuff off metal. Remember this isn't a sand blasting business per se. The idea is to get a car in and strip it back and do blasting + painting etc .. so the blasting will only be a few days a month. If the blasting is 4 instead of 1 then that is something I can live with for the first project or two.

I will happily invest in a screw or road unit if things look positive.

I would like to highlight that I am not disagreeing with what anybody is saying about my current setups suitability.. I'm just choosing to see how far it can be stretched or how bad it actually is. I have zero doubt that the ideal setup will streets ahead of what I have now.

 

[conor1n]

Another point which has been sitting in the back of my mind is electric efficiency..

My two current compressors are likely to be very expensive to run.. and if I start to labour them into multiple jobs.. I could end up paying a nice bit to power company which could be used for a better setup.

It's a balancing act and something I am looking at.

 

[Erie Fred]

"Over Here" the little that I know of the ASME unfired pressure codes,
Every tank must have it's own pressure relief valve.
I don't see that in your drawing.

 

[conor1n]

"Over Here" the little that I know of the ASME unfired pressure codes,
Every tank must have it's own pressure relief valve.
I don't see that in your drawing.

Ahh the drawing was a personal one really and I hadn't intended sharing that version.

The two compressors to the left (50 + 200) have relief valves installed already. The two receivers have them in the 4 way unions is that acceptable?

 

[Erie Fred]

Ahh the drawing was a personal one really and I hadn't intended sharing that version.

The two compressors to the left (50 + 200) have relief valves installed already. The two receivers have them in the 4 way unions is that acceptable?

I see that now.

I don't know, but I know that the boiler & pressure codes were written in blood.
You would have to consider every situation, instead just follow the code.

I see your putting the relief valves where water can rust them shut.
Blowing the water in the bottom will cause the water to get blown up inside the tank negating the speed reduction for the water to settle out, and then go right out the out pipe.

Put the air in/out tees at the top, along with the pressure relief valves.
Only put the tank drain on the bottom.

 

[conor1n]

I see that now.

I don't know, but I know that the boiler & pressure codes were written in blood.
You would have to consider every situation, instead just follow the code.

I see your putting the relief valves where water can rust them shut.
Blowing the water in the bottom will cause the water to get blown up inside the tank negating the speed reduction for the water to settle out, and then go right out the out pipe.

Put the air in/out tees at the top, along with the pressure relief valves.
Only put the tank drain on the bottom.

OK that make sense. The reason for the singe union at bottom was to avoid having to weld in a bung.

Honestly at this stage it feels like those receivers are surplus to requirements and I really don't want to start messing about.


I have learned a lot from this thread so far.

I might very well end up making smokers out of those cylinders yet LMAO.

 

[conor1n]

OK.. so I have been browsing. Second hand market for screw compressors seems buoyant enough... there is a business near me who sells tested, serviced and warranted screws.

I didn't realise you could get decent CFM screws for reasonable money..including 100% duty cycle to boot.

The plan is still to use my two current compressors to do my first project (a friend)..and see how it goes. I am expecting it to be slow enough.. but if the project is a success and I can acquire new customers I know I can get a screw compressor turned around for me relatively easily and quickly.

One of the main reasons I'm reluctant to splurge on the compressor is I have a few other accessories to buy such as 360 degree nozzles for cavities and a fee other bits here and there.

 

[henry Kadzielski]

I'm not sure why you went the inefficient route etc.. but perhaps you were starting out too :/

Admittedly I have been proven wrong on the capacity thing.. looks like volume of stored air doesn't really matter for blasting.

Let me first clarify, I am not saying what you are doing is wrong, or that it won't work, it will but be slow. The reason I know this is that I have done the same. I have a compressor, I have a blast pot, connect the to two together and away we go. Sadly I found that it didn't work, on a number of fronts. Similarly the other problem I had was why it didn't work the way I was expecting. Over time and some hard knocks I learnt a bit. Even when I bought a 7.5kw screw for my first blasting job. I went to school, I could add up so what could go wrong. I thought I had it sorted, I didn't realise how wrong I was. It was painfully slow, but we all have to learn. Also no one is going to tell you exactly what you need because there isn't that many people out there that actually know. If you hear from someone who actually knows it seems way over the top, they are pulling your leg. However from some who thinks they know or has boggied something up and it sortof works for them will tell you this is all you need. It works for them, however it may not work for you.
We all started some where and if we continued we moved on to bigger and better things. When we look back we then realise 'WHAT THE F!!K WAS I THINKING'