Corrosion sensor

In a corrosion sensor having a housing means carrying an electrical switch means that has an actuator means normally held in one switch operating position thereof by a corrosion sensing member of said housing means and moving to another switch operating position thereof when said corrosion sensing member ruptures through the corrosion thereof caused by being exposed to a corrosive area, said corrosion sensing member also comprising a seal member for normally sealing said switch means from said corrosive area until said corrosion sensing member ruptures, said housing means having a chamber therein containing said switch means, said housing means having an end provided with an opening leading to said chamber, said corrosion sensing member spanning said opening to seal said chamber from said corrosive area, the improvement comprising a flexible diaphragm carried by said housing means in stacked engaging relation with said corrosion sensing member and also spanning said opening immediately adjacent said corrosion sensing member and intermediate said corrosion sensing member and said switch means to seal said chamber from said corrosive area when said corrosion sensing member ruptures.