A handheld device according to an exemplary embodiment of this disclosure, among other possible things, includes an emergency stop valve including an inlet, at least one outlet, an exhaust, a main passage, and a stem passage. Air flows from the inlet to the outlet and from the outlet to the exhaust during normal operation of the handheld device, and the inlet is blocked and the air is exhausted through the exhaust during emergency operation of the handheld device. The handheld device includes a valve stem assembly received in the main passage, and the valve stem assembly includes a button and a cavity having a pocket. The handheld device also includes a locking stem including an end portion, and the locking stem is received in the stem passage and the end portion of the locking stem is received in the cavity of the valve stem assembly. The end portion of the locking stem is located in the cavity during normal operation of the handheld device when the valve stem assembly is in a first position to direct air to
