Life Expectancy of 50lb CO2 tank with Rosco Coldflow.

[gafflover87]

So Im trying to figure out how many 50lb CO2 tanks I might need for an upcoming production while using the Rosco Coldflow. I only need it for maybe 10 minutes during each show, and I have a 7 performance run, with 6 dress / tech rehearsals.

The rosco website says one bottle is enough is enough for up to 2 hours of continuous use. Considering I will have to charge the cold flow for each performance and wont necessarilly let it run non-stop, Im not sure their number fits my needs.


Any thoughts, insights, or suggestions?

 

[derekleffew]

Where are you getting the CO2? Can't you rent multiple tanks (in this case, probably two) and return unopened ones for a full refund?

 

[tyler.martin]

This can vary quite a lot. It depends on how long between you pre-chill and use the effect. While the unit is pre-chilling it is quite loud and sounds like a Fire Extinguisher going off, so we had to chill it during intermission, and then use it about half an hour later for a 5 minute effect, which took about half a tank, as we were getting 2 shows out of a 50lb tank. The more hot fog you pump through it, the more CO2 it takes to chill the unit back down. The other issue we had was the Solenoid kept freezing open because we insulated the lines so much. If you dont insulate the line from the unit to the tank, the liquid sublimates, and turns into gas faster, then you use more liquid.

We ended up renting syphon tanks from Praxair, and just getting them rotationally filled. I dont know the tank rental cost. But it was 15 dollars or so to get the tanks filled with Food Grade Liquid CO2. Another cost saver for us was getting our Production Driver to pick up the tanks, but he also has his Dangerous Goods Transportation licence.

 

[Les]

You don't need any special license or placards to transport Co2. But do make sure to transport it in a non-enclosed space.

 

[Traitor800]

If you dont insulate the line from the unit to the tank, the liquid sublimates, and turns into gas faster, then you use more liquid.

Just for the Record, a liquid can't sublimate. Sublimation is what happens when a substance skips the liquid phase and goes straight from solid to gas.

To the OP, skip the 50lb siphon tanks and go with a dewars tank. They're harder to move around but much more stable once you get them into place. They also last a lot longer when doing these kind of effects. I used one in a show last fall with a similar fogger and we ran it for 3-5 min a show and the tank easily lasted for 15 shows.

 

[gafflover87]

Where are you getting the CO2? Can't you rent multiple tanks (in this case, probably two) and return unopened ones for a full refund?

We have thought about renting multiple, and they are very cheap. Our college has an agreement with Airgas, so we do not get charged for tank delivery. Im just hoping to estimate the amount of gas needed because I will need to use a purchaase order. I can pay for refills with my Company card though, so that helps in figuringthing out.