Liquid and gas pressure scan valves might look similar, but inside, they’re built for very different challenges—corrosion, viscosity, and condensation can turn a “universal” valve into a failed test. Here’s how to pick the right one.

Liquid valves need:

· Anti-clogging designs: Their internal pathways are wider (≥1mm) to handle viscosity (e.g., oil vs. water).

· Chemical resistance: Wetted parts in 316L stainless steel or PTFE prevent corrosion from acids, fuels, or coolants.

· Venting options: A bleed valve lets you purge air bubbles (which skew liquid pressure readings).

Best for: Hydraulic systems, fuel lines, coolant loops, or chemical processing tests.

Gas valves prioritize:

· Leak-tight seals (Viton or metal-to-metal) to prevent pressure loss—critical for gases like helium or hydrogen.

· Low internal volume: Smaller pathways (0.5–0.8mm) minimize dead space where gas can stagnate.

· Condensation protection: Heated manifolds stop moisture from forming in humid gas tests (e.g., HVAC airflow).

Best for: Pneumatic systems, exhaust gases, compressed air, or fuel vapor tests.

The danger of “multi-purpose” valves:
A valve marketed for both often compromises—liquid-focused ones leak gas, gas ones clog with liquids. Spend the extra $200–$500 for a dedicated valve instead of risking test data.

Need to test both? Look for systems with quick-swap manifolds (e.g., swap liquid to gas in <5 minutes) instead of buying two full valves.

What fluid are you testing? Share, and we’ll recommend specific valve features.