Negative pressure test: -10 ~ -30kpa error is not greater than + 0.5KPa, LED digital display negative pressure.
Negative pressure output -10 ~ -30kpa + 0.5kpa, LED digital display negative pressure.
The negative pressure of the measuring system is maintained: within 1 minute, it shall not drift + 0.5kpa.
Duration of test: 60S, no more than 0.5KPa.