Normally closed selection valve device for fire extinguisher

The invention provides a normally closed selection valve device for a fire extinguisher. The device comprises a main valve body, wherein the main valve body is in up-down communication, an end cover is arranged at the top of the main valve body, a pneumatic valve and a fire extinguishing agent inlet are arranged on the outer side of the main valve body, the pneumatic valve is arranged on the upperside of the fire extinguishing agent inlet, the lower end of the main valve body is provided with a fire extinguishing agent outlet, the inner wall of the main valve body is provided with an upper convex ring and a lower convex ring which are the same in inner diameter, pistons corresponding to the inner diameter dimension of the upper convex ring and the lower convex ring are arranged in the main valve body, and compression springs are clamped between the pistons and the end cover. Compared with an existing selection valve device, the normally closed selection valve device for the fire extinguisher is simple in stru