Patent Number: 
Section: claims

1. A gas supply apparatus comprising:an operating valve actuator that is placed in a piping for letting at least gas in a plant flow and that operates a valve main body by the gas flowing in the piping;a first electromagnetic valve that is placed in the piping and that opens or closes a flow of the gas to the operating valve actuator; anda gas supply source that supplies the first electromagnetic valve with the gas,wherein a gas discharge line of the first electromagnetic valve has a switching valve and has a second electromagnetic valve placed between the switching valve and the gas supply source,wherein the switching valve switches between a gas discharge from the first electromagnetic valve and a gas supply to the first electromagnetic valve,wherein the switching valve is switched to connect the piping in which the first electromagnetic valve is placed to the gas supply source so as to supply the first electromagnetic valve with the gas when a power source is lost,wherein at the time of a normal operation, the second electromagnetic valve opens a gas discharge line side and closes a switching valve side, andwherein the second electromagnetic valve opens the switching valve side and closes the gas discharge line side when the power source is lost. 2. The gas supply apparatus according to claim 1,wherein the operating valve actuator is for operating any one of an air-perated valve, a safety valve, a relief valve, and a safety relief valve. 3. The gas supply apparatus according to claim 1,wherein the gas supply source is connected to the piping via a third electromagnetic valve or a manual valve, the third electromagnetic valve being driven by a power source different in kind from the first electromagnetic valve. 4. The gas supply apparatus according to claim 3,wherein the third electromagnetic valve has at least a direct current power source as a power source, andwherein the third electromagnetic valve is driven by using the direct current power source as a driving source to thereby supply the first electromagnetic valve with the gas from the gas supply source when the power source is lost. 5. The gas supply apparatus according to claim 3,wherein the third electromagnetic valve is constructed of a single switching valve or a plurality of switching valves among three switching valves which have power sources of an alternating current power source or a direct current power source, a direct current power source, and a manual force, respectively, andwherein the electromagnetic valve having the direct current power source as a driving source is driven or a manual valve is operated to thereby supply the first electromagnetic valve with the gas from the gas supply source when the power source is lost. 6. The gas supply apparatus according to claim 4,wherein the direct current power source is a battery. 7. The gas supply apparatus according to claim 1,wherein a piping on a gas supply source side of the switching valve has an isolation valve placed in the piping, the isolation valve preventing a leak to a gas supply side of the switching valve. 8. The gas supply apparatus according to claim 1,wherein the gas supply source is a bomb in which any one of air, nitrogen, and carbon dioxide is stored.