Potter BVL – Lever Type Bleeder Valve used as a test valve for pressure operated devices on wet pipe sprinkler systems that have excess pressure, or dry pipe sprinkler systems. The BVL should be installed in-line with the pressure device. It provides a convenient means for removal or testing the pressure-actuated device without affecting the pressure in the system. Closing the valve (moving the valve handle perpendicular to the 1/2? pipeline) shuts off the water or air from the supply and opens a small orifice (pin-hole) to exhaust the pressure between the valve and the pressure device. This should provide a low-pressure actuation of the pressure device, testing its operation.