This is similar to a real train, instead of slowing to a stop, it hits into a mountain side. The back of the train continues forward even though the front can not go anywhere. Since the water flow is restricted inside the pipe, a shock wave of incompressible water travels back down the pipe deflecting everything in its path. An unprotected transducer in the path of this monstrous wake is without question, going to sustain heavy damage. To understand the damage caused by the waterhammer forces, it is necessary to understand the principles behind the sensor.
Most pressure sensors utilize a rigid diaphragm as the primary sensing element.
The diaphragm deflects due to the pressure, and its deflection is transformed to an electrical output via various methods. The key component is the rigid diaphragm. The rigid diaphragm deflects only on the order of a thousandth of an inch. With a large wake of fluid hitting the sensor, it is no wonder the diaphragm is bent beyond its elastic limit and permanent damage is done. Remember that a snubber eliminates this effect and therefore should always be installed on every pressure system.