rangerssuck wrote:
I have an unusual problem staring at me. I'm doing maintenance of an ice skating rink, and we have decided to replace the R22 with RS-45 as part of a general upgrade. The system was full of leaks and was constantly losing significant and costly amounts of R22.

This is a liquid overfeed system and as such, the refrigerant runs through the pipes under the ice surface. These pipes are buried in concrete and nobody knows how large they are. The people who installed this are long gone, and there is zero access to the piping after the large feed and return lines enter the concrete.

I need to determine how much refrigerant we need to buy. I have heard estimates ranging from 4000 pounds to 7000 pounds from various experts in the field. That extra 3000 pounds is almost $30,000, so it would be good to get a better feel for a real number. The refrigerant pipes in a typical rink are about 10 or 11 miles long (seriously), and are (sometimes) 5/8 OD thinwall steel, but that's a variable.

The R22 has been removed from the system - unfortunately, the quantity recovered really has no bearing on the actual capacity as there had been considerable leakage.

So, given that I have a system that's shut down and pumped out, and that I can isolate the rink floor pipes from the rest of the system and there are service valves accessible, does anyone know how I might determine the volume of these pipes?

How long does it take to pump that thing down? What's the temp of the ice
in an ice skating rink?