# Internal Pressure Change in Cylinder Question

1. Aug 21, 2013

### oilman

1. The problem statement, all variables and given/known data

I have a section of carbon steel pipe that was used to transport crude oil. The inside diameter is 24-inches. A blind flange and plumber's plug are being used to seal the pipe off. The length of the sealed section is 160-feet. Two 10 pound blocks of dry ice were placed inside the pipe to remove the flammable vapors. No vent or bleeder valve was used. The inside temperature of the pipe was approximately 100-degrees. How much, if any, would the sublimation of the two 10 pound dry ice blocks increase the internal pressure of the pipe over a two hour period?

I don't have any idea of where to start this problem...

2. Aug 21, 2013

### SteamKing

Staff Emeritus
You can figure how much the pressure would increase if all of the dry ice sublimed by using the perfect gas law,
PV = nRT

If you want to know how much it increases in 2 hours, you'll have to find some formula which describes the rate at which dry ice sublimes, given the ambient temperature.

Given the large volume enclosed by 160 feet of 24" pipe, the increase in internal pressure is going to be small.