Ever see an air compressor like this?

[TheEquineFencer]

Thanks for the links.

Anyone happy with powering a compressor with a VW engine is not too concerned with efficiency.

Those concerned with energy efficiency are those I would like to have as customers.

Frank

They were using the VW engine to drive the water pump for the dredge. The air comp was just an "accessory."

I wouldn't mind having a air comp that would put out enough air for two people down to about 20-30ft, but I don't want to spend $600 right now for the Gast 263. The Thompson T80 will run ok for one person down to about 15ft but if you're an airhog like me, you might run out of air working hard.

 

[Leveleer]

I would love to see the piston and rings (before and after installation. Also the seal for the rod.

You must have a really large rod length:stroke ratio ! I have heard that this is one of the (not so secret) secrets for the single cylinder extreme mileage vehicles. Godd on all engine, but difficult to implement.

Perhaps I can show some pictures later.
I am not prepared to reveal exactly how my crankcase works at the moment.
I'll just say that it is all bearings and the two cylinders are on the same axis and the piston rods are maintained concentric, therefore there is no side-load on the rod seals or the piston seals

 

[speed bump]

Thanks for the link. However, any loss is still a loss. I designed a lossless gate valve with built in actuator that I wil be using as soon as I get time to build it.
Of course my gate valve is more complicated and expensive then a check valve but performance is what matters to me.

Frank

What happens if your motor pops a breaker without a check valve?

Definitely cool that you are building a higher performance compressor but some of those performance killing items are in there for reliability/safety.

As far as the spring energized seals. Do you have any tricks for installing them.? We use them in our tools and it seems like they stretch really easily and don't return to shape.

 

[Leveleer]

They were using the VW engine to drive the water pump for the dredge. The air comp was just an "accessory."

I wouldn't mind having a air comp that would put out enough air for two people down to about 20-30ft, but I don't want to spend $600 right now for the Gast 263. The Thompson T80 will run ok for one person down to about 15ft but if you're an airhog like me, you might run out of air working hard.

When I was a kid, I was scuba diving in a rock pit and was down over 90 feet when my Voit regulator stopped supplying air. I reached back to flip the J valve on my twin 50 cubic foot tanks and found the reserve was empty
My unconscious body was pulled out and I was revived.

I hadn't thought about that in many years but this brought it back to me.

I'll think about a compressor design for this use and see what I can come up with.
Thanks,

Frank

 

[Leveleer]

What happens if your motor pops a breaker without a check valve?

Definitely cool that you are building a higher performance compressor but some of those performance killing items are in there for reliability/safety.

As far as the spring energized seals. Do you have any tricks for installing them.? We use them in our tools and it seems like they stretch really easily and don't return to shape.

What happens depends on the pressure, at least with my temporary setup.
If the pressure in the tank is greater then 35 PSI then the valve will close automatically, if not it will leak out.
This is because my current setup is temporary and the valve is operated by a double acting air cylinder controlled by 2 3 way solenoid valves. There is currently no spring.
I will be replacing this temporary valve with a new one I designed which incorporates the necessary spring to return the gate valve to the closed position when there is no voltage and insufficient pressure to overcome the valve sliding friction.

As far as spring energized U-cups are concerned, In the past I've used special tools to compress them during assembly. There might be some available for your application or if not perhaps one could be made?

Frank

 

[TheEquineFencer]

When I was a kid, I was scuba diving in a rock pit and was down over 90 feet when my Voit regulator stopped supplying air. I reached back to flip the J valve on my twin 50 cubic foot tanks and found the reserve was empty
My unconscious body was pulled out and I was revived.

I hadn't thought about that in many years but this brought it back to me.

I'll think about a compressor design for this use and see what I can come up with.
Thanks,

Frank

Thanks! And keep me in mind. I've looked at the T80, it appears pretty simple.

Trying to keep the air cool is another problem. Look at some Hookah systems, they use a small air tank to cool and hold the air from the pump. With your skills, you should be able to come up with something. They run the pump 100% of the time, it just blows off the excess air, it never cycles.

I'd sort of looked into it trying to use a crank from something else. Most are driven off the same pump they use for dredging.

Keep this in mind, this might be a way you can make yours unique. People running a Pacer or HF water pump, cannot run the air compressor off the engine.If you can design an adapter to, if nothing else, be able to run a belt driven compressor such as the T80 off the pull start end and still be able to pull start the engine, you'll make a fortune selling them. I met a guy on line a while back that did it with an old Brownie compressor on his dredge. He was an old, old school retired Master Machinist in his 70's that said he didn't have the desire to go in the business of making them.

 

[Leveleer]

Thanks! And keep me in mind. I've looked at the T80, it appears pretty simple.

Trying to keep the air cool is another problem. Look at some Hookah systems, they use a small air tank to cool and hold the air from the pump. With your skills, you should be able to come up with something. They run the pump 100% of the time, it just blows off the excess air, it never cycles.

I'd sort of looked into it trying to use a crank from something else. Most are driven off the same pump they use for dredging.

Keep this in mind, this might be a way you can make yours unique. People running a Pacer or HF water pump, cannot run the air compressor off the engine.If you can design an adapter to, if nothing else, be able to run a belt driven compressor such as the T80 off the pull start end and still be able to pull start the engine, you'll make a fortune selling them. I met a guy on line a while back that did it with an old Brownie compressor on his dredge. He was an old, old school retired Master Machinist in his 70's that said he didn't have the desire to go in the business of making them.

After thinking about it a bit more, I have concluded that between my current projects and my wife's "honey do's" there isn't sufficient time to work on this also.

Sorry,
Frank

 

[TheEquineFencer]

If you happen to do like I do, sit around and just mull over an idea, mull over how to build an adapter. and PM me your ideas. I'm going to pull a 5.5 Intek B&S engine with a pacer apart and take a look and see if there's a way to do it.

 

[Leveleer]

If you happen to do like I do, sit around and just mull over an idea, mull over how to build an adapter. and PM me your ideas. I'm going to pull a 5.5 Intek B&S engine with a pacer apart and take a look and see if there's a way to do it.

I try never to design anything that transmits torque through rubber belts and pulleys.
My current prototype direct direct drive compressor could conceivably be sandwiched between the engine and pump in a direct drive configuration.
If I equipped it with a small head on each end, it could easily put out 8 CFM @ 45PSI.
Would be kind of cool.
O.K. I mulled it over.

Frank

 

[PCMusicGuy]

What I see here is intriguing. As someone that is trapped in suburbs, I don't really have the space for a large enough compressor to give me the output I would want/need to do small blasting projects, running air sanders, etc. Those things are hundreds of pounds and nearly $1000 and always require at least 220~240V power.

I have found no options for a compressor that runs on a 110V (even 20 amp) circuit that can deliver more than about 5.5 CFM. I'd love to have something that could provide higher CFM on typical residential circuits as nothing exists that I found. Not saying it doesn't, I just haven't found it.

 

[Leveleer]

What I see here is intriguing. As someone that is trapped in suburbs, I don't really have the space for a large enough compressor to give me the output I would want/need to do small blasting projects, running air sanders, etc. Those things are hundreds of pounds and nearly $1000 and always require at least 220~240V power.

I have found no options for a compressor that runs on a 110V (even 20 amp) circuit that can deliver more than about 5.5 CFM. I'd love to have something that could provide higher CFM on typical residential circuits as nothing exists that I found. Not saying it doesn't, I just haven't found it.

I hear that
I found the same thing to be true last year which is one of the reasons I decided to design and build one.
I have concluded after quite a bit of testing that I can build an air compressor that produces 12 CFM and runs on a 115V motor.
However I was not looking very closely at cost while doing it.

Frank

 

[TheEquineFencer]

I hear that
I found the same thing to be true last year which is one of the reasons I decided to design and build one.
I have concluded after quite a bit of testing that I can build an air compressor that produces 12 CFM and runs on a 115V motor.
However I was not looking very closely at cost while doing it.

Frank

LOL.... spoken like a true innovator!

 

[Leveleer]

LOL.... spoken like a true innovator!

One of my fun projects from a while back.


Here is a video I made while evaluating my reed valve design.
It shows the unconstrained output reeds flowing at 15.9 CFM.

Frank

 

[TheEquineFencer]

One of my fun projects from a while back.


Here is a video I made while evaluating my reed valve design.
It shows the unconstrained output reeds flowing at 15.9 CFM.

Frank

When I saw your reed valves, it made me think about Bill Simpson and his pulse jet engines. He makes them with a bucket of salt water 3MM SS and battery. You sound as interesting as he is.

 

[Craptain]

When I saw your reed valves, it made me think about Bill Simpson and his pulse jet engines. He makes them with a bucket of salt water 3MM SS and battery. You sound as interesting as he is.

That is something on my bucket list. Though I have no idea what I would use it for.

Sent from my LG-D801 using Tapatalk

 

[Leveleer]

When I saw your reed valves, it made me think about Bill Simpson and his pulse jet engines. He makes them with a bucket of salt water 3MM SS and battery. You sound as interesting as he is.

I made a reed valve module for a local guy for this pulse jet he mounted on a bike.



Frank

 

[Leveleer]

I am finding that the most interesting aspect of my compressor project is understanding the dynamics of the air flow.
For example, when my compressor is pumping above 100 PSI, the 2nd stage output reed valves are only open for about 1/4 of the output stroke or less. This means that the flow is zero the rest of the time.
Therefore, the peak flowrate would have to be 8 times the average for that pressure which in my case is 12 * 8 = a whopping 96 CFM.
This might explain why my performance improves so much when eliminating the check valve and other flow restrictions.
Interesting!

 

[Craptain]

I am finding that the most interesting aspect of my compressor project is understanding the dynamics of the air flow.
For example, when my compressor is pumping above 100 PSI, the 2nd stage output reed valves are only open for about 1/4 of the output stroke or less. This means that the flow is zero the rest of the time.
Therefore, the peak flowrate would have to be 8 times the average for that pressure which in my case is 12 * 8 = a whopping 96 CFM.
This might explain why my performance improves so much when eliminating the check valve and other flow restrictions.
Interesting!

This makes some sense as the pressure from the pump has to exceed the pressure in the tank. I suspect that it is not over 100 psi it's just that it becomes more noticeable at that pressure.
I am curious as to how you are measuring airflow as that seems to be a variable thing depending on manufacturers and other things. Also how you are watching the valves. Do you have see through components?

I made a reed valve module for a local guy for this pulse jet he mounted on a bike.



Not sure I would want my *** that close to a jet engine. A real hot seat.

Frank

 

[KamiCrit]

Your setup looks pretty cool! I wonder if Ingersol Rand is watching?

 

[Leveleer]

This makes some sense as the pressure from the pump has to exceed the pressure in the tank. I suspect that it is not over 100 psi it's just that it becomes more noticeable at that pressure.
I am curious as to how you are measuring airflow as that seems to be a variable thing depending on manufacturers and other things. Also how you are watching the valves. Do you have see through components?

Since I designed the compressor, I know where the piston is at certain pressures.
I just used 100 PSI as an example. At 120 PSI the piston has to travel even further so the peak flow is even higher.
This phenomenon is no doubt true for all reciprocating compressors.
At the highest pressures the peak air flow could be well over 10 times the average flow rate.

I determine the CFM by measuring the time interval between different pressures while the pump is running while taking into account the air temperature and humidity. My humidity is always less then 25 percent.

Frank

 

[Leveleer]

Your setup looks pretty cool! I wonder if Ingersol Rand is watching?

Here is an example of IR engineering. Note the sharp right angle after the head. If one of my people had done something like this he would have had to sit through a lengthy lecture.

Mark me unimpressed with IR.

Frank

 

[TheEquineFencer]

Since I designed the compressor, I know where the piston is at certain pressures.
I just used 100 PSI as an example. At 120 PSI the piston has to travel even further so the peak flow is even higher.
This phenomenon is no doubt true for all reciprocating compressors.
At the highest pressures the peak air flow could be well over 10 times the average flow rate.

I determine the CFM by measuring the time interval between different pressures while the pump is running while taking into account the air temperature and humidity. My humidity is always less then 25 percent.

Frank

LOL, we know you're not in North Carolina....I'm about to die from the humidity in the shop right now...

 

[justanengineer]

I have found no options for a compressor that runs on a 110V (even 20 amp) circuit that can deliver more than about 5.5 CFM. I'd love to have something that could provide higher CFM on typical residential circuits as nothing exists that I found. Not saying it doesn't, I just haven't found it.

You probably can't find anything factory original bc you're in a niche of not having power but wanting to do work. If you can deal with only ~10 cfm, what you're looking for is a fairly easy build if you can find 1. a somewhat uncommonly large 110V motor (they go up to ~3 hp but are rare about 1.5-2 hp, American ponies not Chinese ponies btw ) and 2. an also somewhat uncommonly small industrial 2-stage compressor like a Quincy 310'ish compressor head. You'll want load-less starting on the head and maybe a soft-starter or hard breaker to keep the inrush current low. Again, you probably won't find that combination as a prebuilt factory compressor but its all commercially available standard components.

 

[Leveleer]

Check valves are restrictive. Look into larger thread size. 3/4" NPT flows about 30 CFM.

I am quite interested in the effect check valves have on the output of compressors. I don't know what a rating of 30CFM actually means when we are talking about the air flow from a reciprocating compressor to a tank.
The air flow from a compressor is actually not flowing at all most of the time and when it is flowing the rate is much much higher then the average rate.
For example, in a typical 2 stage setup the compressor might kick on at 150 PSI and off at 175. In this case, the air flow will only occur about 10 to 25 percent of the time. Thus the air flowing through the check valve when it is flowing would be much higher then 30 CFM.

I think this is very important and largely overlooked.

Frank

 

[pcmeiners]

To make sure you have no time to spare after you finsh the "to do list". Add a decent sized intercooler between the stages, you get at up to 15% more efficency, as you are removed a decent amount of water vapor before it gets to the second stage. As is most 2 stage compressor do not have a decent intercooler, wasting energy compressing water vapor and air which is already expanded due to temperature.

Typical two stage intercooler, reducing temperature little....

http://aetsjournal.com/ijampe_issue...f-Intercooler-In-Two-Stage-Reciprocating-.pdf

With a decent sized intercooler (with water removal devices), you can get up to 15% more efficiency.

http://constructionmanuals.tpub.com/14050/css/Intercoolers-204.htm

 

[Leveleer]

To make sure you have no time to spare after you finsh the "to do list". Add a decent sized intercooler between the stages, you get at up to 15% more efficency, as you are removed a decent amount of water vapor before it gets to the second stage. As is most 2 stage compressor do not have a decent intercooler, wasting energy compressing water vapor and air which is already expanded due to temperature.

Typical two stage intercooler, reducing temperature little....

http://aetsjournal.com/ijampe_issue...f-Intercooler-In-Two-Stage-Reciprocating-.pdf

With a decent sized intercooler (with water removal devices), you can get up to 15% more efficiency.

http://constructionmanuals.tpub.com/14050/css/Intercoolers-204.htm

Thanks for the suggestion.

In order to "gain up to 15% more efficiency" how much efficiency is lost due to the long winding flowpath through the heat exchanger during the time the air flow is in the most turbulent stage of high velocity short duration pulses? I don't know but I suspect it might be more then 15 percent.

I have designed a intercooler that doesn't restrict the flow but have yet to build it.

Frank

 

[pcmeiners]

On my compressor I have a 1" intake, with multiple (8) 3/4" tubes (in parallel), don't see how I could have much restriction, total length is approx the same as the original, but brings down the temp to ambient; if you used a air condition condenser with a small, long length tube, like many do, I would agree velocity and restriction would be an issue. The amount of water removed is considerable, all of which would have enter the second stage, fully expanded, requiring wasted power in compressing the vapor in the second stage. If you research further, any restrictions are figured in designs of compressor intercooler , so the 15% is not unrealistic with the proper designed cooler.

 

[Leveleer]

On my compressor I have a 1" intake, with multiple (8) 3/4" tubes (in parallel), don't see how I could have much restriction, total length is approx the same as the original, but brings down the temp to ambient; if you used a air condition condenser with a small, long length tube, like many do, I would agree velocity and restriction would be an issue. The amount of water removed is considerable, all of which would have enter the second stage, fully expanded, requiring wasted power in compressing the vapor in the second stage. If you research further, any restrictions are figured in designs of compressor intercooler , so the 15% is not unrealistic with the proper designed cooler.

What are you referring to as far as the 1" intake? Intake to the 2nd stage?

I agree 100 percent with the need for the intercooler but also feel that it negatively effects the overall efficiency because of the nature of the air flow through it. My own tests prove to my satisfaction that unless I normalize the flow first then the effect is significant.

Frank

 

[pcmeiners]

What are you referring to as far as the 1" intake? Intake to the 2nd stage?
Actually both ends of cooler are 1" .

 

[Leveleer]

When I first saw this compressor my immediate reaction was to mutter to myself, "OMG are you kidding me?".
It looked to me like Quincy had put the heads on backwards given the absurd plumbing layout.

To be fair, I looked at many compressors that day and wasn't impressed by any of them. I saw many with sharp right angle turns right from the 2nd stage head.

I decided that the Quincy was the worst so I bought it.
After I installed it in my machine shop and tested it, I was as underwhelmed as I expected to be.

Frank

 

[Leveleer]

I've been testing the CFM output of my latest compressor prototype prior to working on the cooling system.
I test it 2 ways:
1. Time to pressurize the tank to different pressures.
2. Pressure that is maintained while flowing out a specific orifice size.

It maintains around 40 PSI while air is blowing out a .125" orifice.
That calculates to about 10 SCFM.
I think is is pretty good for a 120V motor.
Once I get the water cooling going I expect it to be better.

Frank

 

[Leveleer]

I just tested my new Quincy QT-54 the same way I tested my custom made compressor and found that the Quincy tank gauge was reading almost 20 PSI higher then my reference gauge that I used to test my custom unit.
It took the Quincy 178 seconds to fill the 60 gallon tank to 90PSI on the reference gauge.
It takes my custom unit 19.5 seconds to fill a 5 gallon tank to 90 PSI on the same gauge.
Using the tank fill time formula gives me 3.25 CFM/HP for the Quincy and 6.1/HP for my custom.
I have yet to find any compressor that runs on 120V and can do what mine can do.

Frank

 

[MacMcMacmac]

So you've managed to home brew a compressor that's 50% more efficient than a Quincy?

Those morons will learn something about building compressors someday..

 

[Leveleer]

So you've managed to home brew a compressor that's 50% more efficient than a Quincy?

Those morons will learn something about building compressors someday..

The main difference is probably the highly efficient way I connect my compressor to the tank versus the highly inefficient way Quincy does it.

Frank

 

[bsaint]

I've been testing the CFM output of my latest compressor prototype prior to working on the cooling system.
I test it 2 ways:
1. Time to pressurize the tank to different pressures.
2. Pressure that is maintained while flowing out a specific orifice size.

It maintains around 40 PSI while air is blowing out a .125" orifice.
That calculates to about 10 SCFM.
I think is is pretty good for a 120V motor.
Once I get the water cooling going I expect it to be better.

Frank

10 cfm at 40 psi? That's pretty standard isn't it?

 

[Leveleer]

10 cfm at 40 psi? That's pretty standard isn't it?

I don't think so as it's also at least 10 CFM all the way up to the maximum pressure.

Frank

 

[Leveleer]

I stopped working on this compressor over a year ago but still use it occasionally. Although it performs quite well as far as air delivery is concerned, it is quite noisy with quite a bit of vibration.
I did recently design a new type of gate valve that I hope to make soon that will allow me to reconfigure the compressor so that both first and second stages are on the compression stroke at the same time.
An earlier iteration of the compressor which I set up as single stage opposed synchronized pistons was amazingly quiet and vibration free.
I plan on going back to that method but as a 2 stage. This will require buffering the output of the first stage.
It's a very interesting project.