SNV gauge valves are designed as service valves with a very sturdy construction. SNV-ST are made in steel approved for low temperature operations, SVA-SS are stainless steel versions. SNV valves have internal backseating (metal to metal), enabling the spindle seal to be replaced while the valve is still under pressure. SNV is applicable to HCFC, non flammable HFC, R717 (Ammonia) and R744 (CO2).