What size oxygen tank do I need for one day?

starlightdesigns · #1 2010-07-28, 10:18am

Hi,

Quick question here.

I am going to be doing a trunk show with demos all day on Saturday from 10 a.m. to 9 p.m. I have limited room to set up, so I don't want to take my really big tank. What size would be good for about 11 hours of intermittent torching?

I'll be using my bobcat.

kbinkster · #2 2010-07-28, 10:23am

How long does your big tank last? You can estimate an hourly usage by taking the size of your tank (a K tank is about 285 cubic feet) and dividing it by how many hours you can get out of it. Once you have that, you can multiply that hourly rate by however many hours you anticipate using it (always add a buffer to make sure you don't run out). Then, find a tank that holds that much.

starlightdesigns · #3 2010-07-28, 11:51am

The trouble is, I'm not sure what size tank I have. It stands about 5 ft. and is about 10" thick. When I was doing strictly tanked oxy, the tank would last me about a week, about 40 hours.

My oxygen supplier has five different sized tanks, the largest one is size 5 at 250 cubic ft. The next size down is Size 4 at 125 cubic ft. I probably have the larger one, but I am not sure.

If the tank I have is size 4, I can get size 2 for Saturday, which is 40 cubic feet. Cost $176.
If the tank I have is size 5, I can get size 3, which is 80 cubic ft. Cost is $247.

Neither is cheap. May be better to just refill the big one and lug it to the store. Sigh!

Howling Dog · #4 2010-07-28, 12:25pm

I've done some demonstration torching, and I used the smallest tank I could find. I don't know the numbers or the actual size, but the tank was under 3' tall with about an 8" diameter. It was something I could actually transport with ease. In my studio I use a 125cf according to the paperwork. In the beginning, I rented the tank for around $12 per month plus cost of oxy. Will your local welding store let you rent one?
Michelle

starlightdesigns · #5 2010-07-28, 12:32pm

There are two places in town that have tanks. One is a buy-only and the only is rent optional, but for a whole year, and he charges double for the oxygen. He says it's too much paperwork to rent for just a weekend.

The smallest tank available at the other place is $109 plus 15.99 filled, and it is 20 cubic ft tank. Would that be big enough????

kbinkster · #6 2010-07-28, 12:50pm

If you have the 250 CF (cubic feet) tank, then 40 hours use translates into about 6.25 CFH (cubic feet per hour). The Bobcat uses about 14-15 CFH for its largest neutral flame before distortion. That sounds about right (6.25 CFH) if you are running a small-medium sized flame. 20 cubic feet might last you a few hours. So, you're going to want something bigger than that. If they have something 70-80 CF range, that would cover about 11 hours at 6.25 CFH and give you a little buffer.

If you think that demos are going to be a regular thing for you, then you might consider renting a small tank or buying one. But, look at the size you would need to do what you want to do. If it is not that much smaller than the tank you have now (will be just as much of a hassle to handle), then you might want to stick with the tank you have.

Do you have a tank dolly? Those help a lot.

starlightdesigns · #7 2010-07-28, 12:59pm

Thank you, Kimberly! The local place does have a tank that is 80 cf, but it's expensive. I guess I'll go there tomorrow or Friday and either fill the tank I have (which has NOT run out, so I hate to fill it) OR get a smaller tank. I hate lugging that big one around, though, I can barely get it in my van. And yeah, I do have a handtruck that I use with it.

Thanks!