Patent ID: 9212963
Filing Date: 2015-12-15
Classification: G01L

Abstract:
1. A pressure detector that has a water inlet and a pressure sensor for sensing the pressure of water in said inlet, said inlet including a channel that carries water toward and away from said pressure sensor, wherein said water in said channel can freeze when the ambient temperature falls below the water freezing temperature, wherein: said channel includes narrow and wide channel portions lying in series, with said narrow channel portion lying closer to said pressure sensor than does said wide channel portion, said channel including channel walls that have inside surfaces that form said channels and outside surfaces exposed to the ambient temperature; said narrow channel portion is of smaller cross-sectional area than said wide channel portion; and said channel includes a third channel portion lying opposite said wide channel portion and connected in series with said narrow channel portion, with said third channel portion being narrower than said narrow channel portion; whereby to cause water in said narrow channel portion to freeze and act as a plug before water in said wide channel portion freezes.