The reason I bought VTS 250s is, if you see a VTS 253, meaning its' specifically for CO2, ...
This is true, but there is more to it.
Actually, the current VTS250 model numbers for CO2 duty are below and their delivery ranges are given too:
VTS253A-320 ... 2 to 15 PSIG
VTS253B-320 ... 2 to 40 PSIG
VTS253C-320 ... 4 to 80 PSIG
VTS253D-320 ... 5 to 125 PSIG
Where the "320" means that it is for CO2 duty. The "A to D" means that they are A, B C and D models with differing delivery ranges. And, the VTS253 is the latest incarnation of the popular VTS250 series.
For reference, see the upper right corner on page 19 of the following Victor PDF: http://victortechnologies.com/IM_Upl...-2007_Feb2012/
Pages 10 and 11 in the same PDF also have some helpful identification information.
Page 25 in this other PDF has similar information: http://victortechnologies.com/IM_Upl...Regulators.pdf
BTW IMO, the VTS250 series of regulators are among the best ones for our use.