Baso Y90AA-4210 Compression Coupling used to Control the Flow of Gas to a Pilot Burner.

• Material: Tip: Aluminum. Body: Brass.
• Maximum Temperature: Tip: 635F. Body: 750F.
• Ansi Code: Z21.20
• Orifice size: 0.10 inches
• Type of Gas: Natural and LP

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.