Guy,

I got the Kenmac KPR through a gas equipment supplier, and I bought it in brass because it was cheaper. Dry CO2 is not corrosive, so there is no reason not to use the cheapest material available. I didnt know that they made them in aluminium alloy, but I would expect brass to be the cheapest material of construction.

Jeremy

PS. My recollection is that the stainless steel regulators to the same spec cost over £250 at that time.