Patent ID: 8360099

Claim:
A failure protection apparatus comprising: an air source providing air having an air pressure; a source of control fluid in fluid communication with the air source, wherein the air applies the air pressure to the source of control fluid to provide a control fluid having a predetermined control fluid pressure; a first valve in fluid communications with the air source and the source of control fluid, wherein the air pressure of the air provided to the first valve is the same air pressure as the air pressure applied to the source of control fluid, the first valve permitting fluid communication of the control fluid between a first fluid port and a second fluid port when the air pressure is at least a minimum air pressure and preventing fluid communication of the control fluid between the first fluid port and the second fluid port when the air pressure is below the minimum air pressure; a pressure control assembly in fluid communication with the second fluid port, the pressure control assembly containing a portion of the control fluid at the predetermined control fluid pressure, wherein the predetermined control fluid pressure is maintained when the air pressure changes from at least a minimum air pressure to below the minimum air pressure; a second valve in fluid communication with the air source, the second valve preventing communication of air between an air inlet and an air outlet when the air pressure from the air source is at least the minimum air pressure and permitting communication of air between the air inlet and the air outlet when the air pressure from the air source is below the minimum air pressure; a third valve in fluid communication with the air source, the third valve permitting communication of air to a third valve outlet when the air pressure from the air source is at least the minimum air pressure and preventing communication of air to the third valve outlet when the air pressure from the air source is below the minimum air pressure; a pressure container in fluid communication with the third valve outlet and having a pressure container air outlet, wherein the pressure container air outlet is in fluid communication with the air inlet of the second valve; and a warning device in fluid communication with the air outlet of the second valve and operable to emit sound when air is communicated from the air outlet.