OBA tank vs no tank: How long does it take to fill your tires?

[WSS]

Also, if it is faster; is the time saved worth the wear/heat of running the compressor continuously vs. letting it shut off between tires?

If you have compressor with a low duty cycle, it will help.

 

[jjvw]

Shuffle is step two. Get off the ground is step one.

Might as well add in some time for a cup of coffee.

 

[WSS]

Might as well add in some time for a cup of coffee.

Now you see what I’m talking about. I’ll post some pics of my coffee/tea/hot chocolate kit later.

 

[jjvw]

Now you see what I’m talking about. I’ll post some pics of my coffee/tea/hot chocolate kit later.

We already know it's something like this packed in next to the trail table saw...

 

[Brianj5600]

Here are my crazy justifications for carrying a 5 gallon tank on the trail. I leave home with 125 psi in the tank. My compressor is the same as the Smittybilt with out the chrome. The Speedmaster has a fairly high amp draw and and good flow rate.

https://www.speedmaster79.com/Speed...-4x4-Tyre-Deflator-4wd-Portable-Inflator-160L

1. sometimes my deflators drop pressure too low
2. sometimes someone in the group drops pressure too low
3. I have burped a tire
4. having a tank makes getting a bead reseated easier
5. humidity is bad in the southeast and the tank helps to keep moisture out of the tire

These things are easily and quickly fixed with an air tank.

I also connect the compressor through the tank when airing up. When going to next tire I leave the compressor running and the tank is usually around 65 psi to start the next tire. I have done my 35s to 27 psi and a buddies 37s to 34 psi with out turning the compressor off on different occasions and the thermo switch never tripped. I guess I didn't go over the duty cycle?

I don't know how having the tank affects the efficiency of the compressor. My thoughts are efficiency is better by reducing pressure waves. Pressing the valve core to let air out is painfully slow. I wonder if a less restrictive valve stem would help?

I am happy with it how it is and have no plans to change it. I don't want to have to fill CO2 bottles and usually mid pack airing up.

 

[jjvw]

...

1. sometimes my deflators drop pressure too low
2. sometimes someone in the group drops pressure too low
3. I have burped a tire
4. having a tank makes getting a bead reseated easier
5. humidity is bad in the southeast and the tank helps to keep moisture out of the tire

....

1. Irrelevant
2. Irrelevant
3. Irrelevant
4. Irrelevant
5. Plausible

 

[Apparition]

So here's my plan to test my system.

System notes:
I'm running the dual ARB instead of my Viair so the max pressure is only 150 psi.
The tank will start full as that's how it is when I finish a trail.

Target pressure range:
8 to 25 psi

1st method - I'll test both with and without the tank in the system. I'll pull all valve caps prior to testing so it's just moving from tire to tire airing them up. I think this will show a very minimal impact of the tank.

2nd method - I'll leave all the valve caps on which means I'll have to remove and reinstall them at each tire. This will give the compressor more time to fill the tank between tires and for me is more realistic of how I would fill after a trail. I'll do this both with and without the tank in the system. This will likely improve the impact of the tank but I'd guess it will still be negligible.

Any comments or critiques?

 

[mrblaine]

So here's my plan to test my system.

System notes:
I'm running the dual ARB instead of my Viair so the max pressure is only 150 psi.
The tank will start full as that's how it is when I finish a trail.

Target pressure range:
8 to 25 psi

1st method - I'll test both with and without the tank in the system. I'll pull all valve caps prior to testing so it's just moving from tire to tire airing them up. I think this will show a very minimal impact of the tank.

2nd method - I'll leave all the valve caps on which means I'll have to remove and reinstall them at each tire. This will give the compressor more time to fill the tank between tires and for me is more realistic of how I would fill after a trail. I'll do this both with and without the tank in the system. This will likely improve the impact of the tank but I'd guess it will still be negligible.

Any comments or critiques?

That will work just fine.

 

[mrblaine]

Something is not correct. A piston stroke does not give a specific amount of air (CFM?) on any air compressor, it varies considerably according to psi it is up against. The viair units I am currently using put out 3.53cfm@0psi and choke to 1.90cfm@100psi and down to 0.85@200psi

The lower end of a tire fill is faster due to less resistance via PSI. As a tire reaches it's desired PSI, the rate of fill is slower. That is why the stored air is used in pneumatic solutions. Not many run tankless. It is not efficient. I realize our OBA systems hardly qualify for an engineer, but it still falls under the laws of pneumatics.

So basically what you are saying is that due to the compression of the combustion gas mixture in a ICE, that the displacement is variable? Or in other words, a 4 liter Jeep motor is only 4 liters when the pistons are at the bottom?

The piston in the cylinder of a compressor has a diameter and it moves a certain distance which is the stroke. While you are absolutely correct that there is a slower rate of fill as the pressure rises, if we are using the compressor for the same job every time like filling a tire, that rate does not change. We are working about 30 psi into the tire. If we are filling balloons, that is going to be a different rate. But for the same job, the number of strokes does not change.

As for the laws of pneumatics, how do they apply to the trailer mounted compressors we use to run jackhammers?

 

[WSS]

So basically what you are saying is that due to the compression of the combustion gas mixture in a ICE, that the displacement is variable? Or in other words, a 4 liter Jeep motor is only 4 liters when the pistons are at the bottom?

The piston in the cylinder of a compressor has a diameter and it moves a certain distance which is the stroke. While you are absolutely correct that there is a slower rate of fill as the pressure rises, if we are using the compressor for the same job every time like filling a tire, that rate does not change. We are working about 30 psi into the tire. If we are filling balloons, that is going to be a different rate. But for the same job, the number of strokes does not change.

As for the laws of pneumatics, how do they apply to the trailer mounted compressors we use to run jackhammers?

Sure, to fill a tire from one set psi to another using the same compressor will be the same on that day, same place, same conditions. Weather, dew point, elevation ALL change the output. I have yet to find a compressor that produces the same volume through out it's life. I don't have a lot of experience, probably less than 100 compressors (not counting oba) varying from 15 to 100cfm so far.

As for your last question, I would have to do a little googling. I have never had a job that required a jack hammer. I did however have a job that ate up 1" impacts on a regular basis. I never could figure why, but screw compressors (cfm being equal) would shred the vanes (in the impacts) at about double the rate of rotary compressors. The efficiency of the system plays a big part in high CFM (trailer mounted??) systems. Dryers, coalescing filters, etc..

Pneumatic Engineers often make big $$ , but most work for companies. I prefer the unemployed life. It pays better and lately, the gov has really stepped up to keep me home.

 

[mrblaine]

Sure, to fill a tire from one set psi to another using the same compressor will be the same on that day, same place, same conditions. Weather, dew point, elevation ALL change the output. I have yet to find a compressor that produces the same volume through out it's life. I don't have a lot of experience, probably less than 100 compressors (not counting oba) varying from 15 to 100cfm so far.

As for your last question, I would have to do a little googling. I have never had a job that required a jack hammer. I did however have a job that ate up 1" impacts on a regular basis. I never could figure why, but screw compressors (cfm being equal) would shred the vanes (in the impacts) at about double the rate of rotary compressors. The efficiency of the system plays a big part in high CFM (trailer mounted??) systems. Dryers, coalescing filters, etc..

Pneumatic Engineers often make big $$ , but most work for companies. I prefer the unemployed life. It pays better and lately, the gov has really stepped up to keep me home.

Tow behind compressors for jack hammers don't have tanks. Now what?

Lets try and keep it in context though since that is all that matters.

 

[WSS]

I figured it would take a much larger tank than 2 gallons to impact the amount of time it takes me to fill my 4 35” tires from 8psi to 22. I chose to not bother with the hassle. If I could find a location for a larger tank it may be worth while.
Can always get one of these. I think they claim almost 9 cfm at 40 psi.


https://sherpa4x4.com/products/sherpa-12v-air-compressor-big-air

With 8.9 cfm at our max psi needs, skip the tank and enjoy the fast fills. That is over 4 times what my viair 444c puts out at needed pressure. That equals 4 times faster pumping air.

 

[WSS]

Tow behind compressors for jack hammers don't have tanks. Now what?

Lets try and keep it in context though since that is all that matters.

The "tow behind" ones I worked on did, looked more like oxy cylinders but longer. It is all about cfm to the tool needs. If it can produce the CFM and the tool can handle the higher air temps, a tank probably is not needed, but a dryer would be as there is no where for the moisture to accumulate except at the tool. Do jack hammers work good with water running through them? If so, skip the dryer too.

Last sentence was a bait you turkey! Ask a question (now what?) then suggest I stay on track. No trick or treat candy for you!

 

[Gollywomper]

With 8.9 cfm at our max psi needs, skip the tank and enjoy the fast fills. That is over 4 times what my viair 444c puts out at needed pressure. That equals 4 times faster pumping air.

Yes. Wish I would have seen these before I bought my viair. Oh well. I’m not in a hurry when airing up. Usually BSing with others any way while the tires fill.

 

[Viking Jeeper]

So here's my plan to test my system.

System notes:
I'm running the dual ARB instead of my Viair so the max pressure is only 150 psi.
The tank will start full as that's how it is when I finish a trail.

Target pressure range:
8 to 25 psi

1st method - I'll test both with and without the tank in the system. I'll pull all valve caps prior to testing so it's just moving from tire to tire airing them up. I think this will show a very minimal impact of the tank.

2nd method - I'll leave all the valve caps on which means I'll have to remove and reinstall them at each tire. This will give the compressor more time to fill the tank between tires and for me is more realistic of how I would fill after a trail. I'll do this both with and without the tank in the system. This will likely improve the impact of the tank but I'd guess it will still be negligible.

Any comments or critiques?

Sounds great, awaiting results, especially 2nd method.

 

[Apparition]

Sounds great, awaiting results, especially 2nd method.

Should be able to do it all tomorrow.

 

[Viking Jeeper]

If you get 26 inch wheels with your 37 inch tires there will be less volume so it will go faster. Just sayin.

 

[mrblaine]

The "tow behind" ones I worked on did, looked more like oxy cylinders but longer. It is all about cfm to the tool needs. If it can produce the CFM and the tool can handle the higher air temps, a tank probably is not needed, but a dryer would be as there is no where for the moisture to accumulate except at the tool. Do jack hammers work good with water running through them? If so, skip the dryer too.

Last sentence was a bait you turkey! Ask a question (now what?) then suggest I stay on track. No trick or treat candy for you!

It was bait since you don't yet understand how this works for OBA and tire filling.

 

[freedom_in_4low]

When the tank is at a higher pressure than the tire, it's helping.

When the tank is at equal pressure to the tire, it's slowing you down.

Just gotta figure out how much time you spend in each phase, and it will depend entirely on how big the tank is and how much pressure it starts with.

 

[Gollywomper]