Automotive pressure tests range from checking tire pressure (simple) to mapping fuel injector flow (hyper-precise). The accuracy class of your pressure scan valve needs to match the job—too low, and data is useless; too high, and you’re wasting money. Here’s the breakdown.

Class 0.1% (±0.1% of full scale) is for:

· Critical engine tests: Fuel rail pressure (needs to measure 30–2,000 psi with <0.5 psi error) or turbocharger boost (where 1 psi 偏差 can hurt efficiency).

· Emissions testing: To meet EPA standards, exhaust pressure measurements must be dead accurate.

Class 0.25% works for:

· Brake system tests: Hydraulic pressure in brake lines (0–2,500 psi) tolerates slightly more error.

· HVAC airflow: Measuring cabin pressure differences (0–10 psi) doesn’t need pinpoint precision.

Class 0.5% is fine for:

· Routine checks: Tire pressure (30–50 psi) or coolant system pressure (15–30 psi) where ±0.25 psi error is acceptable.

· Prototyping: Early-stage part tests where you’re just looking for trends, not exact numbers.

Don’t forget turndown ratio:
A valve with 0–1,000 psi range and 0.1% class is less accurate at 100 psi (±1 psi error) than a 0–200 psi valve with the same class (±0.2 psi error). Match the range to your test pressure (e.g., 0–300 psi for most automotive systems).

Need help calculating the right class for your test? Share the pressure range and acceptable error, and we’ll do the math.