image
image
image


Flame Rods


PURPOSE

  • Positive flame indication in pilots(s) before the main burner gas is turned on.

ADVANTAGES

  • Allows discrete pilot flame indication.

  • Eliminates the non-discrete indication of optical scanners.

  • simplifies maintenance.

  • The flame rod is currently in world wide use in a variety of pilot/burner applications.

PHYSICAL CONFIGURATION

  • The flame rod consists of a center electrode and an outer metallic sheath.

  • The electrode is isolated from the outer sheath by an insulating material.

  • The end of the flame rod, in the flame path, has a special high temperature hermetic seal with a threaded adaptor which is connected to the center electrode.

  • A high temperature sensing rod is attached to the treaded adaptor.

  • The opposite end of the flame rod, outside the furnace/boiler, has flexible extension leads which connect to the center electrode and the outer sheath.

INSTRUMENTATION

  • The electrical instrument requirements consist of an excitation voltage (80-240 VAC, single phase) applied across the two flexible extension leads and current sensing ability.

  • In addition, relays and time delay capabilities are used to control the sequence between pilot and burner.

HOW DOES IT WORK?

  • The flame rod is positioned such that the high temperature sensing rod would be in contact with the pilot flame.

  • The flame creates an ionized "path" between the center electrode/rod and the electrical ground.

  • The excitation voltage induces a current flow across this "path".

  • This current is a stable, measurable signal which can then be used in the appropriate control scheme.

image
image