degradation 27 see fig5 or a wearing away of the valve seat 72 78 to which it is attached typically the valve seat 72 78 is composed of a conductor and the strike face 86 92 of the valve 68 70 is composed of a conductor in such an embodiment the valve seat sensor 58 may be a sensor that measures conductivity between itself and another conductor such as an electrical resistivity sensor or a voltage sensor among other appropriate sensors as such in this embodiment the valve seat sensor 58 is encased at least partially in an insulator 59 and the sensor 58 and the insulator 59 are embedded in the valve seat 72 78 at a position such that when the valve seat 72 78 is not degraded as shown in fig4 or at least when the valve seat 72 78 is degraded to an acceptable level the valve seat sensor 58 does not contact the strike face 86 92 of the valve 68 70 and therefore cannot measure a conductivity therebetween and when the valve seat 72 78 is degraded to an undesirable level as shown in fig5 and indicated by degraded section 27 which is quickly followed by a degradation of the insulator 59 the valve seat sensor 58 contacts the valve seat 72 78 and measures a conductivity therebetween at such time the valve seat.