Apparatus and method to mount sensors below a main valve of a fire hydrant

A main valve assembly of a fire hydrant, the main valve assembly comprising:

• a main valve including a drain valve and a main valve plate having a water-tight seal therebetween, the drain valve and main valve plate each including a first hole extending through a center thereof within the circumference of the groove and in axial alignment with each other to each receive a stem of a fire hydrant therethrough and a second hole extending therethrough between the groove and the respective first holes, the second hole of the drain valve being threaded to receive a compression fitting therein;
• and
• a bottom plate adjacent to a side of the main valve plate opposite to the side that forms a seal with the drain valve, the bottom plate including:
• a trench formed into the side facing the main valve plate;
• a groove formed around the trench to receive an O-ring therein that forms a water-tight chamber between the trench and the main valve plate;
• a hole extending through a center thereof to receive the stem therethrough, and
• at least one water characteristics sensor extending through a bottom surface of the trench and out of a side of the bottom plate opposite the side facing the main valve plate.

A method of mounting sensors in a water-proof area below a main valve of a fire hydrant, the method comprising:

• providing a first circumferential sealing means along an area adjacent to outer perimeters of a drain valve and a main valve plate of a main valve, the drain valve and the main valve plate each including a center hole formed therethrough and in axial alignment to receive a hydrant stem therethrough;
• forming a threaded hole through the drain valve within the circumference of the first sealing means;
• threading a compression fitting through the threaded hole in the drain valve, the compression fitting having a tube extending out of one end facing away from the main valve plate to provide outside pressure to an area within the circumferential sealing means between the drain valve and the main valve plate;
• forming a second hole through the main valve plate within the circumference of the first sealing means;
• providing a second circumferential sealing means along an area adjacent to outer perimeters of a bottom plate and a side of the main valve plate not facing the drain valve, the bottom plate including a trench formed therein within the circumference of the second sealing means, a center hole in axial alignment with the center holes of the drain valve and the main valve plate and extending through the trench to receive the hydrant stem therethrough, and at least one port hole extending through the surface of the trench to receive a respective sensor therein;
• threading a water characteristics sensor into the at least one port hole such that the sensor end extends outside the bottom plate, the sensor including wires extending from ends opposite the sensor end;
• feeding the wires extending from the at least one sensor through the second hole in the main valve plate and through the tube extending from the compression fitting;
• extending the fire hydrant stem through the center holes of the drain valve, main valve plate and the bottom plate;
• threading a lock nut onto the end of the stem extending through the bottom plate;
• and
• forming a third circumferential seal between the surface of the bottom plate and the lock nut to surround the stem.