A means is provided for separating the compressed air flowing in the instrument air path into a first path which provides actuating air to the controllable inlet valve and the controllable depressurizing valve, and a second path which provides {HEAD ~ a first source} of {TAIL ~ signal air} 
A means is provided for separating the compressed air flowing in the instrument air path into a first path which provides actuating air to the controllable inlet valve and the controllable depressurizing valve , and a second path which provides { HEAD ~ a first source } of { TAIL ~ signal air }
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