I know that the changes in using natural refrigerants has been on the agenda for a while now, but suprisingley the phasing in seems to have happened overnight. Even Fosters have started using HCs, and suprisingley CO 2 now seems to be the choice with the large plant and racks despite the Tescos disaster in Manchester some time back.

I had a call from a construction company that I used to deal with a couple of months back to assess the condition of a system in a disused supermarket that's been boarded up for almost 20 years. They wanted to know whether or not it was working or salvagable. I viisted the site and the system turned out to be a plant with parrallel compressors, which I was informed was a rack. There's also fire damage to the system from a spread of fire that had all but destroyed the control panel, and had dripped tar from the roof onto the compressors so I couldn't even see what make they were.

As I have never worked on such systems, I couldn't find out whether or not it was an ammonia, HCFC or CO 2 system, so I was reluctantant to even connect my guages just in case I was breaking any rules, and not knowing if a standard recovery machine would be suitable for ammonia or CO 2.

I informed the company that I would be back in touch when I had obtained more information about the plant and what type of medium it used. Then it would more than likely be scrapped and salvaged so the building can be dropped

After doing some research, it would seem that CO 2 can be vented into the atmosphere despite its GWP/TEWI of 1, I can't find any data on it within BSEN 375. Although I suuplemented my first 2078 refrigerant handling with ammonnia, I never have worked with it and I can't remember anything about it except its flammable and toxic.

Are there any regulations or supplememntary guidance notes that state that you have to recover CO 2, and that you can't vent it?

I know with HCs it is similar to the LPG regs and you can vent it out to an external lower point away from untrapped drains and any where else it can collect. But as CO 2 is innertly natural in the atmosphere just like Nitrogen. Is it just the general safety of its use regarding its high pressure and a well ventilated area to reduce the risk of aphyxiation that needs to be considered when venting it?