Abstract: The subject apparatus enables detecting changes in pressure of the fluid in a conduit from outside the conduit without disturbing the conduit or its function. The detection is made by sensing changes in diameter of the conduit caused by pressure changes, using a linear measurement electrical transducer. The transducer is mounted in a cylindrical sleeve which telescopes in a second sleeve which is externally threaded at both ends. A fixture is threaded onto one end with the sensing probe of the transducer extending through a hole in the fixture. An auxilliary sleeve is installed between the transducer support sleeve and the fixture, and also extends through the fixture and is forced toward the fixture by a compression spring between the transducer sleeve and auxilliary sleeve. A knurled knob is threaded onto the second sleeve and is used to adjust the position of the transducer along the axis of the sleeve.