Nitrogen tank vs. On-Board Air?

[92yamaha]

Has anyone found a formula for calculating volume of gas given a temperature and pressure? I want to figure out how many times a 22 cubic foot nitrogen tank, at 2,000psi, will fill four 35x12.50xr16 tires from 12psi to 30psi.

I might be getting too technical here, but I just want to know how many times I can use this tank to fill my tires before dropping $180 on a tank and fill or $400 for a Viair 10007 continuous duty compressor.

 

[skunked]

Have you looked at this? https://www.powertank.com/full.chart.html

 

[kgblazerfive]

I think I have like $50 into my set up. Think I have filled like 50 tires or so over the last five or six years.

 

[Dabba]

PV = nRT

Pressure
Volume
n - amount of substance in moles (Can convert from grams using molecular weight)
R - Gas Constant. Just look up the number you need based on units you're using in the equation
Temp in Kelvin

Like you said, technical. But with basic algebra you can play with it and figure it out.

 

[dyeager535]

CO2 is typically referenced in pounds. 10lb tank, 20lb tank, etc.

Here is some data for you: http://www.uigi.com/co2_conv.html

Down and dirty, 175cu ft in a full 20lb tank.

Finding the cubic ft contained per tire, then dealing with the pressure difference? More math. Skunked linked you to the proper chart though. About 24 tires, if you use 20PSI as the increase on a 20lb Co2 tank, the most commonly found on Craigslist.

I personally would like to get my hands on a 10lb tank, but exchanging those is near impossible from what the local gas supplier tells me, it's just not a very common size. It would save space. I expect that if cost is a concern for you, the larger the tank, the less the refills cost per lb of CO2. It can be a significant difference with welding gases, but I assume people aren't running around with larger than 20lb CO2 tanks in their rigs.

BTW, $180 is ridiculous. I'm seeing 20lb'ers on Craigslist that are full, in cert, for $125. I picked mine up for $75. Out of cert, but with regulator and CO2. Cert cost me $15, but they just swap out the tank anyway.

 

[big dan]

I'll make it simpler, I have a small nitrogen tank (Hvac tech) that is around 40 cubic ft. I filled 4 36 " tires from 0 to 10 psi one time and it was empty. Don't remember the starting pressure as it wasn't full but it was at least half full probably more like 3/4.

I vote for a co2 tank or onboard air. Nitrogen is stored as a gas where co2 is a liquid so there will be more usable "air" with co2.

 

[runamok151]

Get a CO2 tank then ask your local FD where/ who refills their fire extinguishers.

 

[FOR MUD]

Here's where I got my tank.... http://www.aquariumplants.com/Aluminum-Co2-Cylinders-p/t.htm

I take it to a scuba shop to get filled. Cost about $15 - $20 to fill and they do it while I wait, takes about 4 min

 

[92yamaha]

Thank you everyone for your responses to this thread. Given the information here, I think I'll give the CO2 tank a shot. Worst-case, I have a portable 12v compressor that can top off the tires.

Thanks again all!