NAXJA Forums -::- North American XJ Association  

Go Back   NAXJA Forums -::- North American XJ Association > NAXJA Unibody Jeep Technical Forums > Jeep Cherokee XJ (1984 - 2001) > Modified Tech Discussion
HOME Member FAQ Sponsor Info Rules Bylaws E-Mail

Modified Tech Discussion Forum for Tech related discussion for Modified XJ's and MJ's.

Reply
 
Thread Tools Display Modes
  #16  
Old February 4th, 2019, 13:28
denverd1's Avatar
denverd1 denverd1 is offline
NAXJA Member
 
Join Date: Dec 2013
Location: Tyler, TX
Posts: 541
Re: Air tank volume question

what about going to welding supply store and getting a bottle with 800 psi of air in it? thinking the 5 pound will do plenty for what I'm trying to do. air up tires, maybe run air tools. The bottle is about $50, refills are $5.
__________________
Chili Pepper '98
4.5" lift, locked on both ends, 33s
10K winch and a lot of skinny pedal
Reply With Quote
  #17  
Old February 4th, 2019, 15:51
Trouble Trouble is offline
NAXJA Forum User
 
Join Date: Dec 2007
Location: So. Cal.
Posts: 404
Re: Air tank volume question

Air tank at 800 psi wont do much , maybe 3-4 tires. plus there is no protection for the valve or regulator unless the supplier has some kind of shield. My scuba tank is a 88 cu @ 3500 psi

Ive seen bad things happen to scuba tanks when they fall over and loose a valve. Also some states have certain laws on transporting an air pressure vessel.



CO2 fill ups are about 10-15 bucks around here, prices fluctuate but have been pretty low around here. you can build your own setup and use a fixed regulator for a little over $100, plus it will most likely be DOT certified so you dont get sued when in an accident and your air tank becomes a rocket.
Reply With Quote
  #18  
Old February 4th, 2019, 17:36
denverd1's Avatar
denverd1 denverd1 is offline
NAXJA Member
 
Join Date: Dec 2013
Location: Tyler, TX
Posts: 541
Re: Air tank volume question

Quote:
Originally Posted by Trouble View Post
Air tank at 800 psi wont do much , maybe 3-4 tires. plus there is no protection for the valve or regulator unless the supplier has some kind of shield. My scuba tank is a 88 cu @ 3500 psi



Ive seen bad things happen to scuba tanks when they fall over and loose a valve. Also some states have certain laws on transporting an air pressure vessel.







CO2 fill ups are about 10-15 bucks around here, prices fluctuate but have been pretty low around here. you can build your own setup and use a fixed regulator for a little over $100, plus it will most likely be DOT certified so you dont get sued when in an accident and your air tank becomes a rocket.
I would of course have a regulator on it.... so you're saying there's not significantly more volume of air in a tank with that kind of pressure?

Sent from my SAMSUNG-SM-G930A using Tapatalk
__________________
Chili Pepper '98
4.5" lift, locked on both ends, 33s
10K winch and a lot of skinny pedal
Reply With Quote
  #19  
Old February 5th, 2019, 07:54
XJEEPER's Avatar
XJEEPER XJEEPER is offline
NAXJA Member # 13
 
Join Date: Aug 2002
Location: Wasatch Range
Posts: 8,985
Re: Air tank volume question

Quote:
Originally Posted by Nimrod View Post
This may be more appropriately posted in the Tools and Garages forum, but I figured it would get more views here. The moderators can always move it if so inclined.

I’m thinking of getting an air tank, not to mount up as part of an onboard air system, but just to bring along on the trail or leave at camp to fill tires faster than my portable compressor. Space is an issue, so I’m looking to go small. My question, specifically, is this: will a 2.5 gallon tank rated to 150 psi hold enough air to fill four 35x12.5x15 tires from 10 psi to 32 psi? I’m no math or physics whiz, and I haven’t been able to find the answer on line. If anybody has some practical experience or knowledge that can shed light on the question, please post up. Thanks.
I have a 2.5 gal tank plumbed inline with my Viair 450C (100% duty cycle) and it takes about 12-15 min to air up all four 295/75/16 tires from 15 -> 32lb street pressure at the end of the trail. The first tire airs up quickly, the other 3....less quickly. This setup has worked for me for 11+ years. It also powers my ARB lockers.

I typically run with a group and they run similar compressor setups, so it takes everyone approx the same amount of time to air up at the end of the trail.
I guess if the goal is to win the tire air-up race, then a big CO2 tank will earn you a trophy, or if you break enough on the trail to need air tools to facilitate the repairs, then a full CO2 tank will trump an electric compressor/tank setup.
__________________
Speak the Truth-Question with Boldness-Speak without fear.
Reply With Quote
  #20  
Old February 5th, 2019, 09:42
denverd1's Avatar
denverd1 denverd1 is offline
NAXJA Member
 
Join Date: Dec 2013
Location: Tyler, TX
Posts: 541
Re: Air tank volume question

Quote:
Originally Posted by XJEEPER View Post
I have a 2.5 gal tank plumbed inline with my Viair 450C (100% duty cycle) and it takes about 12-15 min to air up all four 295/75/16 tires from 15 -> 32lb street pressure at the end of the trail. The first tire airs up quickly, the other 3....less quickly. This setup has worked for me for 11+ years. It also powers my ARB lockers.

I typically run with a group and they run similar compressor setups, so it takes everyone approx the same amount of time to air up at the end of the trail.
I guess if the goal is to win the tire air-up race, then a big CO2 tank will earn you a trophy, or if you break enough on the trail to need air tools to facilitate the repairs, then a full CO2 tank will trump an electric compressor/tank setup.
that's pretty funny. the tire air-up race....

Actually, just see no reason to pay someone like powertank 5 bills for something I can do much cheaper. I carry a a small compressor with me for times when I roll a bead.

I trailer to and from the ride spot anyway, so I've already won your silly race. Rarely break, so don't think I'll need the tank or the tools, but we're all here to talk about jeeps, right?
__________________
Chili Pepper '98
4.5" lift, locked on both ends, 33s
10K winch and a lot of skinny pedal
Reply With Quote
  #21  
Old February 5th, 2019, 16:05
Trouble Trouble is offline
NAXJA Forum User
 
Join Date: Dec 2007
Location: So. Cal.
Posts: 404
Re: Air tank volume question

I have both smittybilt compressors small one and the big one in my shop right now so i did a little test.

tire: 35x12.50r15

small one from 15-30psi 2min 5 seconds. 0psi-30 psi: 4 min 58 sec
big one from 15-30psi 1 min 20 seconds. 0psi-30 psi:3min 15 sec

I also tested two of their deflators i had in stock. One is my personal one that has been modified and one is new out of box, along with an older currie ( like 20 years old)

stock 30psi-10psi: 42 seconds
modified 30psi-10psi: 33 seconds
currie 30psi -10psi: 40 seconds
Reply With Quote
  #22  
Old February 5th, 2019, 17:28
denverd1's Avatar
denverd1 denverd1 is offline
NAXJA Member
 
Join Date: Dec 2013
Location: Tyler, TX
Posts: 541
Re: Air tank volume question

The compressor and deflator shootout.

All good info, I suppose. Maybe need a new thread for it tho

Sent from my SAMSUNG-SM-G930A using Tapatalk
__________________
Chili Pepper '98
4.5" lift, locked on both ends, 33s
10K winch and a lot of skinny pedal
Reply With Quote
  #23  
Old February 5th, 2019, 17:56
Greenz's Avatar
Greenz Greenz is offline
NAXJA Member
 
Join Date: Nov 2005
Location: Oregon
Posts: 331
Re: Air tank volume question

Quote:
Originally Posted by Nimrod View Post
This may be more appropriately posted in the Tools and Garages forum, but I figured it would get more views here. The moderators can always move it if so inclined.

Iím thinking of getting an air tank, not to mount up as part of an onboard air system, but just to bring along on the trail or leave at camp to fill tires faster than my portable compressor. Space is an issue, so Iím looking to go small. My question, specifically, is this: will a 2.5 gallon tank rated to 150 psi hold enough air to fill four 35x12.5x15 tires from 10 psi to 32 psi? Iím no math or physics whiz, and I havenít been able to find the answer on line. If anybody has some practical experience or knowledge that can shed light on the question, please post up. Thanks.

No it wont.


I installed a 3 gallon tank coupled to ARB twin compressor 150psi. Bottom line is 3 gallons is practically nothing for filling tires. The only advantage of having a tank for filling tires is the compressor is partially recovering the tank between filling tires where as without a tank the compressor reaches 150 psi and shuts off before you can screw the valve cap back on. The tank will help some but the savings is just a few seconds per tire. Not really worth it.


If you are planning other uses like air tools, forget it. To blow out a filter, clean debris from a work area, fill inflatables, train horns, (lol) the tank will be useful.
Reply With Quote
  #24  
Old February 5th, 2019, 19:07
devildog0's Avatar
devildog0 devildog0 is offline
NAXJA Member
 
Join Date: Apr 2005
Location: Hunt County Texas
Posts: 609
Re: Air tank volume question

Quote:
Originally Posted by denverd1 View Post
I would of course have a regulator on it.... so you're saying there's not significantly more volume of air in a tank with that kind of pressure?

Sent from my SAMSUNG-SM-G930A using Tapatalk
No. Because CO2 is stored as a liquid and converts into a gas as you use it. This is why the tank needs to be mostly upright when being used.

800psi of atmospheric air is still just a gas.

A 20 lb CO2 tank has 20ish lbs of liquid CO2 in it. As you use the gas off the top the liquid CO2 converts to gasseous form and cylinder pressure stays around 800-1000 psi. Once your tank pressure needle starts coming down from that point you no longer have liquid in there and just gaseous CO2.

This is why CO2 tanks are so useful for onboard air, for a given tank size you get far more energy than something stored in the same size bottle as a gas.

FWIW we can use our 45 min SCOTT SCBA bottles to "power" our lift bags for emergency rescues. These bottles when full are at 4500psi. They dont last very long using them like that.

Sent from my SM-G892A using Tapatalk
__________________
1995 XJ Country/4.0L/AW4/231/UpCountry Suspension
2004 Suzuki DL650 VStrom/1978 Suzuki GS1000E/2003 Yamaha TW200
1982 Suzuki GS850G (barnfind project)
Reply With Quote
  #25  
Old February 6th, 2019, 11:23
denverd1's Avatar
denverd1 denverd1 is offline
NAXJA Member
 
Join Date: Dec 2013
Location: Tyler, TX
Posts: 541
Air tank volume question

Great

Sent from my SAMSUNG-SM-G930A using Tapatalk
__________________
Chili Pepper '98
4.5" lift, locked on both ends, 33s
10K winch and a lot of skinny pedal
Reply With Quote
  #26  
Old February 7th, 2019, 23:45
Greenspan's Avatar
Greenspan Greenspan is offline
NAXJA Member
 
Join Date: Aug 2016
Location: Los Angeles
Posts: 118
Air tank volume question

Previous Poster said a 35" tire has 3.47 ft^3 which is about 98L

A 2.5 gal tank is almost 9.5L so

9.5L * 150psi = X * 98L * 20psi

Where X is the number of tires you can fill from 10psi to 30psi (20psi)

X= 0.72 tires

So a 2.5gal tank would not work, you would need at least 16gal at 150psi


For the 10lb tank filled up with 800psi of air:

https://www.mathesongas.com/industri...Dimensions.pdf

Looks like a 10lb tank has 7.8L so

7.8L * 800psi = X * 98L * 20psi

X = 3.18

So you should be able to fill up three 35" tires from 10psi to 30psi using a 800psi 10lb tank of just air.


For the 10lb liquid CO2 tank, 10lb of CO2 = 103mol. Using PV=nRT (800psi * V = 103 * R * 60). V = 44L, so since its a liquid the small tank is equivalent to a 44L tank.

44L * 800psi = X * 98L * 20psi

X = 17.9 tires with the liquid CO2 at 800psi

*These are all spitball approximations

Last edited by Greenspan; February 8th, 2019 at 00:37.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Factory manual 92 xj two volume set 5150xj For Sale: Private Party Only. XJ ITEMS ONLY 1 October 23rd, 2010 21:44
gas tank vent valves & routing question for carb'd XJ tank - any help? JrTxJ OEM Tech Discussion 2 June 11th, 2009 11:08
Volume formula...am I right? LazarusMJ Advanced Fabrication and Engineering 11 November 20th, 2005 14:40
I need to know the volume of a 4.0 head gzweber Modified Tech Discussion 7 September 30th, 2004 22:30
High Volume Oil Pump Trail-XJ OEM Tech Discussion 2 March 26th, 2004 16:37


All times are GMT -7. The time now is 06:42.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
NAXJA and NAXJA logo's Copyright NAXJA. All content/images Copyright NAXJA 1999-2014