Air Systems: From CO₂ to HPA

In early recreational play, CO₂ was widely used because it was inexpensive and readily available. However, CO₂ exists as a liquid gas blend in typical paintball tank conditions, and its vapor pressure tracks closely to temperature. Rapid firing cools the tank and lines, causing pressure drops that translate into falling velocities and fluctuating shot to shot consistency. Liquid CO₂ entering the valve train could also cause erratic behavior and premature wear.

Compressed air, often referred to as HPA (High Pressure Air), replaced CO₂ as competitive rates of fire and accuracy demands increased. HPA offers stable, predictable pressure independent of ambient temperature within normal operating ranges. Tanks incorporate a primary regulator to step high storage pressure down to a safer intermediate output, while markers typically include a secondary inline regulator for final pressure tuning. This two stage regulation architecture dramatically improves consistency, especially under high cyclic loads.

As HPA adoption grew, the industry embraced standardized fill stations, burst disk protections, and routine inspection intervals. Composite wrapped cylinders lowered weight compared to steel, and hydrostatic testing schedules kept aging tanks within safety margins. The combined effect was transformative: markers could be tuned to precise velocities and maintain them across games, enabling tighter paint to barrel matching, faster loaders, and reliable electronic fire control without sacrificing safety.