1：
Used for water circuits such as gas water heaters, with water flowing in the direction of the arrow.
2：
Positive opening pressure: ≤ 0.02MPa
3：
No seepage or deformation for 1 minute under 1.75MPA water pressure
4：
Reverse water supply: Apply negative pressure of 65 ± 15KPa in the forward direction, observe for 5s, and the pressure change is less than 0.05KPa
