A pneumatic gas cylinder valve actuator that clamps to the threads on gas cylinder normally used for threading on a protective cap and is so designed that air pressure up to 100 psi admitted to the internal piston chamber in the valve actuator opens the gas cylinder valve while compressing the springs under the pistons in the internal piston chambers so that when air pressure is cut off the springs return the gas cylinder valve to the closed position; a torque indicator on top of the valve actuator shows proper positioning of the valve actuator clamp to adjust the closing torque exerted by the springs under the pistons to about 70 inch pounds.