Abstract: A pressure gauge shield for the pressure gauge on a pressurized fire extinguisher, which shield is formed integrally with the locking pin for the control valve for operating the fire extinguisher. The lock pin, which comprises a finger-hole loop connected to the valve assembly by a chain, has a pair of parallel prongs, one of which extends through aligned holes between the lever and valve housing to prevent operation of the lever, and the other acts to prevent the rotation of the lock pin when in its locking position so as to maintain the position of a semi-circular shield over the top of the pressure gauge also connected to the valve assembly. A breakable connection, such as of plastic cord, is provided to hold the lock pin it its locking position, which cord must be broken to withdraw the lock pin in order to operate the fire extinguisher.