Not all steam traps can be reached with ultrasonic contact sensors. For safety and convenience reasons these traps are often overlooked during routine PM. To inspect hard-to-reach traps try using a laser-sighted parabolic transducer.
A parabola gathers ultrasound waves from a distant source and concentrates them onto a focal point. The result is fine-tuned directionality, at greater distances. By pointing the laser on the upstream or downstream side of the condensate trap, inspectors can hear if the trap is blowing through, plugged, closed, or cycling properly.