Combustion air control in an in-line flame arrestor

Claim 1

A flame arrestor and combustion air control combination, including, an elongated cylindrical firetube into which combustion is to be propagated, a hollow cylindrical core sealed by a first end to the entrance of the firetube, a removable base plate mounted on and sealing the second end of the core, a burner mounted on the base plate and within the core as a housing to propagate combustion into the firetube, an aperture through the wall of the cylindrical core through which combustion air flows to the burner, two spools of flame arrester screen mounted on the core, one on each side of the aperture, a sheath mounted about the two screen spools and sealed to the spool peripheries to limit combustion air flow to paths through both screens and down through the common aperture between the screens and into the cylindrical core, a sleeve positioned within the cylindrical core to establish the effective size of the aperture in the path of the combustion air, a linkage between the sleeve and the base plate powered by fluid pressure to increase the size of the aperture by movement of the sleeve, a spring connected between the sleeve and the core to generate a force urging the sleeve in a direction to reduce the size of the aperture, and a connection between the sleeve and the pressure of the fuel supplied the burner as power to actuate the linkage, whereby the quantity of fluid fuel supplied the burner has its pressure applied to position the sleeve in adjustment of the quantity of air supplied the burner through the aperture to propagate the combustion by the burner.