We currently have a ht/lt pack that we look after. We have carried out a survey and noted that the prv's have not been piped to outside and have suggested that this be done asap. The pack is in a busy basement area, runs on r404a and holds approximately 140kg. It has two Henry valves rated at 24.8 bar. I need a simple calculation to work out the required pipe size to take the refrigerant away in the event of the valves venting. The run would be around 50-60 metres long. Any help/advice would be welcomed as all I've found is some pretty complicated equations!