Relay pilot regulator

A relay point regulator for use in combination with a main regulator in a gas distribution system, the gas distribution system including an inlet conduit supplying gas at an inlet pressure and an outlet conduit for delivering gas at a reduced outlet pressure, the main regulator including a main valve controlling gas flow from the inlet conduit to the outlet conduit and thereby also controlling the outlet pressure, a main regulator diaphragm mechanically linked to the main valve and a loading chamber the loading pressure in which acts on the main regulator diaphragm wherein the loading pressure positions the main regulator diaphragm and the main valve, the relay pilot regulator comprising:

• (A) a housing defining
• (1) an inlet passage connected to the inlet conduit for supplying gas at the inlet pressure,
• (2) a load/unload passage intersecting the inlet passage adjacent the end thereof, the load/unload passage connected to the loading chamber of the main regulator,
• (3) an unload passage intersecting the load/unload passage adjacent the end thereof, the unload passage and the inlet passage being generally aligned with their ends juxtaposed and separated by the end of the load/unload passage,
• (4) a chamber connected to the outlet side of the main valve whereby the outlet pressure is supplied to the chamber, and wherein the unload passage also connected to the chamber;
• (B) an unloading valve comprising a tubular valve stem having radially protruding longitudinally extending fins and terminating at one end in a radially protruding valve disc, the unloading valve slideably mounted in the unload passage on its fins with its valve disc disposed at the end of the unload passage juxtaposed the end of the inlet passage and the other end of the valve stem extending into the chamber, the unloading valve slideable between a first closed position wherein its valve disc blocks flow through the unload passage and a second open position permitting flow through the unload passage between the fins of the tubular valve stem, the unloading valve spring biased to its closed position, and the tubular valve stem and the valve disc defining an axial opening therethrough;
• (C) a loading valve comprising a valve stem terminating at one end in a valve face, the valve stem slideably mounted in the axial opening defined through the unloading valve with its valve face facing the end of the inlet passage and the other end of the valve stem extending into the chamber beyond the end of the unloading valve stem, the loading valve slideable between a first closed position blocking the inlet passage and a second open position unblocking the inlet passage;
• (D) a relay pilot regulator diaphragm mounted in the chamber wherein the outlet pressure is applied thereto, the relay pilot regulator diaphragm spring biased against the outlet pressure for movement in response to changes in the outlet pressure;
• (E) a mechanical linkage comprising an L-shaped lever having first and second lever arms mounted to the housing at the intersection thereof, the lever being disposed in the chamber, and the free end of the first lever arm terminating in a ball captured in a slot defined near the end of the valve stem of the loading valve, the ball also sized to engage the end of the tubular valve stem of the unloading valve and the free end of the second lever arm pivotally carried by the relay pilot regulator,
• whereby movement of the relay pilot regulator diaphragm in response to changes in the outlet pressure pivots to L-shaped lever to
• (1) open the loading valve when the outlet pressure is below a given desired outlet pressure, thereby supplying gas at the inlet pressure to the loading chamber of te main regulator through the load/unload passage for acting on the main regulator diaphragm to open the main valve and increase the outlet pressure to the given desired outlet pressure,
• (2) close the loading valve when the outlet pressure is at or above the given desired outlet pressure,
• (3) open the unloading valve when the outlet pressure is above the given desired outlet pressure, thereby decreasing the pressure in the loading chamber by bleeding gas from the loading chamber through the load/unload passage and unload passage and causing the main regulator diaphragm to close the main valve and reduce the outlet pressure to the given desired pressure, and
• (4) close the unloading valve when the outlet pressure is at or below the given desired outlet pressure.