Uniweld does not recommend that CO2 be used for purging or pressure testing an A/C&R system because it may from carbonic acid within the system, causing premature equipment failure. The Sludge Sucker® Kit options include a choice of high or low-pressure regulators for Nitrogen or CO2 [with optional F36 adaptor] and various carrying stands depending tank size. All Sludge Sucker® Kits include the handy Sludge Blaster® for quickly unclogging drain pipes.