Pneumatic pressure probe

A pneumatic pressure probe operable with a source of pressurized air and an air pressure sensor comprising

• a housing defining therewithin a pressure chamber having an inlet port connectable to the pressurized air source and an outlet source connectable to the air pressure sensor;
• a piston having an axial bore which is in communication with said pressure chamber and through which air flows, a proximal end of said piston being received in said pressure chamber and a distal end of said piston extending out from said housing;
• a sensing head associated with said distal end of said piston and comprising a transparent sensing membrane, an interior channel which is in communication with said axial bore of said piston and having at least one air outlet port for air flowing through said probe to exit;
• said proximal end of said piston having an end surface responsive to a pressure differential between said distal and said proximal ends of said piston created by air flowing through said probe to resiliently bias so as to urge said piston towards a fully extended position;
• said axial bore of the piston being of a diameter sufficiently small to maintain said pressure differential substantially constant;
• and
• light emitting means mounted in the housing, said light emitting means in use emitting light which is visible through said transparent sensing membrane.

A pneumatic pressure probe operable with a source of pressurized air and an air pressure sensor comprising

• a housing defining therewithin a pressure chamber having an inlet port connectable to an air source and an outlet port connectable to a sensor;
• a piston having an axial bore which is in communication with said pressure chamber and through which air flows, a proximal end of said piston being received in said pressure chamber and a distal end of said piston extending out from said housing;
• a sensing head associated with said distal end of said piston and comprising a transparent sensing membrane, an interior channel which is in communication with said axial bore of said piston and having at least one outlet port for air flowing through said probe to exit;
• light emitting means mounted in said housing, said light emitting means in use emitting light which is variable through said transparent sensing membrane;
• and
• means for resiliently biasing said piston towards a fully extended start position such that when said probe is in use said piston is forced back into said housing against said resilient biasing.