Although I have a CO2 cylinder I still use s30 cylinders, as it's a way of purging equipment that is out of reach of my main CO2 cylinder. I have been thinking of a way to refill the S30 cylinders from my main CO2 cylinder not only as a cost saving exercise , but my nearest shop is 35 miles away and postage makes the cost even more. It will not solve a lot of brewers problems, but it might be possible for generous owners of big cylinders to refill S30 cylinders for local S30 owners. I will give it my attention this weekend. Please no comments from all you Health and Safety guys.