The NV400 Tri-Action direct acting Pressure/Vacuum Relief Valve orBreather Valve is a special relief valve specifically designed for tankprotection.

It is fitted with a 2" (50mm) BSP threaded base and the outlet isvented to the atmosphere. The NV400 Tri-Action valve is usedextensively on bulk storage tanks, the valve prevents the buildup ofexcessive pressure or vacuum which can unbalance the system or damagethe storage vessel.