1/8" Compression Coupling Fitting w/ .010" Orifice

The Y90 inlet fitting controls the flow of gas to a pilot burner. The orifice hole size and counterbore/coining, along with the applied gas pressure, determine flame size and characteristics.

Pilot burner inlet fittings consist of an inlet tip (containing the orifice holes) and a threaded inlet body allowing connection of the pilot line. The orifice holes are used to direct and control the flow of gas to a pilot burner. The inlet fitting positions the orifice holes in relation to the pilot burner's aeration opening and pilot tip.

The majority of inlet fittings Johnson Controls manufactures have two orifice holes offset at an angle. In an inlet fitting with counterbore/coining, the pilot gas streams intersect. The turbulence caused by this intersection provides better gas and air mixing for combustion. Figure 1 illustrates the counterbore/coining of an orifice. The two holes are drilled at 90° to the counterbore/coining surface. The gas flow rate and pattern is dependent upon the gas pressure, drill size, counterbore, and wall thickness (or web) of the inlet tip.