C7007A, C7008A, C7009A FLAME ROD HOLDER & FLAME ROD ASSEMBLIES
60-2024—06
4
Fig. 8. Flame rod installed in cool combustion area of
industrial burner.
Fig. 9. Suggested installation on ring type burner.
After selecting the best location (if burner manufacturer has
not provided a mounting place on burner), cut a hole large
enough for the correct size pipe (See dimensions, Figs. 1-4) in
burner faceplate or in the front of the boiler. Be sure to cut the
hole at approximately the angle needed to bring flame rod into
proper position to prove the flame.
Tack weld or temporarily cement a pipe into hole cut in burner
faceplate or boiler wall. If a flange is used, place over hole and
weld the pipe to the flange. Do not mount permanently until
checkout is complete.
Check out entire unit (see checkout section, page 6) to insure
that the flame rod is in proper position. Make this test under all
conditions of actual firing for the type of flame supervision that
will be used. In positioning the flame rod:
1.
Avoid bending the flame rod.
2.
Keep the flame rod as short as possible.
3.
Keep the flame rod at least 1/2 inch [12.7 mm] away
from hot refractory material.
When the flame rod has been properly positioned, weld or
cement the pipe and/or flange permanently. Mount and screw
the unit into the adapter pipe and tighten.
Connect the lead from the flame rod electrical connection to
the proper terminal on the flame safeguard control.
NOTE: Even with high temperature stainless steel used in
making grounding assemblies, the metal oxidizes
when it is exposed to temperatures exceeding 2000°
F [1093° C]. Where this deterioration cannot be
avoided, a scheduled replacement program should
be considered.
FLAME GROUNDING
The installer must provide an adequate electrical ground for
the pilot flame. The grounding surface in actual contact with
the flame must be at least four times greater than the area of
the portion of the flame rod in contact with the flame. The ratio
of ground to flame contact area with a raw gas pilot is usually
less than a factor of four. In situations where the ground area
available is inadequate, the ground area must be increased.
There are three proven methods for providing an adequate
grounding surface (area): a) the bomb fin assembly; b)
grounding rods threaded into the pilot nozzle; c) ground rods
welded to a collar.
The bomb fin assembly can be made by welding two sections
of high temperature stainless steel in the pattern illustrated in
Fig. 10-a. Then, this assembly is welded directly over the pilot
burner nozzle.
The threaded rod assembly is made by cutting a flame rod
into six or seven sections each about four inches in length.
The face of the pilot nozzle is to be tapped. The tappings
being located equidistant from each other around the
circumference of the nozzle (see Fig. 10-b). One end of the
four inch flame rod sections is threaded and screwed in place
as shown in Fig. 10-b.
The welded rod assembly is made by cutting a flame rod into
sections as described in the threaded rod assembly. The
flame rod sections are then welded to a high temperature
stainless steel collar as illustrated in Fig. 10-c. The assembly
is then welded in place over the pilot nozzle.
If the flame rod is used to prove only the main flame, the flame
contact area with the combustion chamber walls is generally
adequate for grounding. In some situations, it may be
necessary to provide a grounding target. A stainless steel fin
or rod assembly similar to those illustrated in Fig. 10 should
make an effective target.
In all cases, make sure the grounding area is securely
connected to ground.
WIRING
CAUTION
Disconnect power supply before making wiring
connections to prevent possible equipment
damage or electrical shock.
All wiring must conform to applicable codes.
FLAME ROD
M1845
COOL
COMBUSTION
AREA
PILOT
BOSS
C7009A
FLAME ROD
ASSEMBLY
TOP
VIEW
C7008A
FLAME ROD
ASSEMBLY
BURNER
RING
M1836
PILOT
SIDE
VIEW
