An optical flame-sensor includes an optical circulator, an optical-fiber cavity, and a first optical sensor. The optical circulator includes a first port, a second port, and a third port. The first port is configured to receive an optical signal. The second port is configured to output the optical signal received at the first port. The third port is configured to output the input to the second port. The optical-fiber cavity includes a cavity proximal-end optically coupled to the second port, and a mirror at a cavity distal-end, such that a cavity optical signal output by the optical-fiber cavity is the input to the second port. The first optical sensor is optically coupled to the third port to quantify the cavity optical signal.

A reflective pilot light viewer is disclosed. The reflective pilot light viewer has an attachment flange securable to a water heater tank by fasteners. The reflective pilot light viewer also has a viewing segment joined to the attachment flange and extending from the access outer panel at an approximate forty-five degree to fifty degree angle, the viewing segment having an upper portion which is a reflective surface. An access outer panel having the reflective pilot light viewer and a water heater having the reflective pilot light viewer are also disclosed.

Burner (10), in particular for a vehicle heater (12), having an orifice plate (14) separating an inner combustion region (16) from an outer region (18), wherein a photosensitive sensor (20) is arranged in the outer region (18), wherein at least two separate air inlet openings (22, 24, 26, 28) are being provided in the orifice plate (14), wherein one of the at least two air inlet openings (22, 24, 26, 28) is additionally formed as a light opening (28) which also allows light to pass from the inner combustion region (16) to the photosensitive sensor (20) that is arranged in the outer region (18), wherein the at least two air inlet openings (22, 24, 26, 28) are being shaped such that the same combustion air quantities flow into the internal combustion region (16) per unit time, respectively, and wherein the orifice plate (14) is transparent and/or the light opening (28) has a shape different from the air inlet openings (22, 24, 26) that are not formed as light opening such that an illumination area defined by the light opening (28) is larger than a reference illumination area defined by one of the at least two air inlet openings (22, 24, 26) that are not formed as light opening (28).

A viewport for a combustion zone includes an inner casing having a flange extending into the combustion zone. A first layer of ceramic fiber insulation is exterior to the inner casing. A middle casing includes two panes of quartz glass separated by traverse plates. A second layer of ceramic fiber insulation is exterior to the middle casing. An outer casing is positioned to the exterior of the second layer of insulation. The middle casing includes L-shaped ledges having third and fourth layers of ceramic insulation. The panes of glass are each positioned between layers of insulation and the insulation positioned in the L-shaped ledges. The viewport is modular enabling the separation of the first layer of insulation, the middle casing, the second layer of insulation and the outer casing from the combustion zone for maintenance or repair. The viewport minimizes heat migration to the outer casing during use.

A flame sensor apparatus includes a sensor assembly. The sensor assembly includes a photodiode for sensing characteristics of a flame. The photodiode outputs an electrical photocurrent. The sensor assembly includes an electrical assembly that is electrically remote from the sensor assembly. The sensor assembly includes an electric cable assembly extending from the sensor assembly to the electrical assembly. The electric cable assembly includes an electrical cable to electrically convey the photocurrent to the electrical assembly. At least the sensor assembly is configured and constructed to experience and continue to operate at a temperature at or greater than 200 C.

A pseudo flame detecting portion detects a presence of a pseudo flame due to disturbance light when a sensor output of a flame sensor is equal to or greater than a pseudo flame threshold value and detects an absence of pseudo flame when the sensor output is equal to or less than another pseudo flame threshold value. The combustion controlling portion monitors the pseudo flame detection result from the pseudo flame detecting portion before an ignition attempt in the combustion equipment and, when the pseudo flame detection result continuously indicates presence of pseudo flame for a first monitoring time, cancels the ignition attempt in the combustion equipment.

A flame detection adjusting portion adjusts a preset reference threshold value based on a sensor output indicating disturbance light obtained from a flame sensor before an ignition attempt in combustion equipment and outputs an obtained adjusted threshold value, and a combustion flame detecting portion detects a presence or an absence of a combustion flame in the combustion equipment based on the sensor output obtained from the flame sensor during combustion in the combustion equipment and an adjusted threshold value.

A flame scanner includes a lens barrel assembly defining a generally hollow body having a first end and a second end, and an opening formed in the first end, a lens positioned adjacent to the second end, and a fiber optic cable receivable through the opening in the first end, the fiber optic cable having a distal end. A field of view of the flame scanner is selectively adjustable by varying a position of the distal end of the fiber optic cable with respect to the lens.

The state of a flame in a gas turbine engine combustor is acoustically monitored using a dynamic pressure sensor within the combustor. A spectral pattern of a dynamic pressure sensor output signal from the sensor is compared with a characteristic frequency pattern that includes information about an acoustic pattern of the flame and information about acoustic signal canceling due to reflections within the combustor. The spectral pattern may also be compared with a characteristic frequency pattern including information about a flame-out condition in the combustor.

The state of a flame in a subject combustor of a gas turbine engine is acoustically monitored using a dynamic pressure sensor within the subject combustor and one or more additional sensors in nearby combustors. Dynamic pressure sensor output signals from the sensors are cross correlated to identify acoustic oscillations generated by a flame in the subject combustor and received by the sensors. The cross correlation may be constrained by a maximum time delay between correlated components of the signals, based on physical characteristics.