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WARNING
Explosion Hazard and Electrical Shock Hazard.
Can cause serious injury, death or property damage.
1. The C7027A, C7035A, C7044A and C7927 Flame
Detectors must be used with Honeywell flame
safeguard controls (primaries, programmers, and
burner management systems). Using with controls
not manufactured by Honeywell could result in
unsafe conditions.
2. Disconnect power supply before beginning
installation to prevent electrical shock or equipment
damage, more than one disconnect may be involved.
3. Read the installation instructions before starting the
installation.
4. All wiring must be NEC Class 1 (line voltage).
5. The flame detector must be positioned so that it
sights the flame and does not respond to the UV
radiation emitted by sparks generated by a spark
ignitor. The Q624A or Q652B Solid-State Ignitor may
be useful in difficult installations.
Basic Requirements For Ultraviolet
Detector Installations
All flames emit ultraviolet radiation, invisible to the human eye
but detected by the UV sensing tube. There are two important
factors in UV detector installation:
The detector must have a line-of-sight view of the flame.
The detector must not be exposed to other sources of
ultraviolet radiation, the most common being ignition spark.
Other sources are listed in the next section.
Because it is necessary for the detector to actually see the
flame, it is desirable to locate the detector as close to the flame
as physical arrangement and temperature restrictions permit.
Sighting requirements for different types of flame supervision
are:
1. Pilot flame only—Sighting must be along the axis of the
pilot flame. The smallest pilot flame that can be sighted
must be capable of igniting the main burner (see Pilot
Turndown Test, page 10).
2. Main flame only—Sighting must be at the most stable
part of the flame for all firing rates.
3. Pilot and main flame—Sighting must be at the junction of
both flames.
®
MINIPEEPER
Other Radiation Sources Sensed
By The UV Detector
Examples of radiation sources (other than flame) that could
actuate the detection system are:
1. Ultraviolet Sources:
a. Hot refractory above 2500°F (1371°C);
C7927 - 1800°F (982°C).
b. Spark.
c. Ignition transformers.
d. Welding arcs.
e. Lightning.
f.
Gas lasers.
g. Sun lamps.
h. Germicidal lamps.
In Addition for the C7927:
a. Solar Radiation
b. Bright incandescent or fluorescent artificial light.
c. Bright flashlight held close to the sensing tube.
2. Gamma Ray and X-ray Sources (The C7927 is immune
to x-ray):
a. Diffraction analyzers.
b. Electron microscopes.
c. Radiographic X-ray machines.
d. High voltage vacuum switches.
e. High voltage condensers.
f.
Radioisotopes.
Except under unusual circumstances, none of these sources
except hot refractory and ignition spark would be present in or
near the combustion chamber.
The UV detector may respond to hot refractory above 2500°F
(1371°C) [1800°F (982°C) for C7927] if the refractory surface
represents a significant percentage of the field of view of the
detector. If the temperature of the hot refractory causes the
flame relay (in the flame safeguard control) to pull in, re-
position the sight pipe so the detector views a cooler area of
the refractory.
Ignition spark is a source of ultraviolet radiation. When
installing the UV Flame Detector, make sure it does not
respond to ignition spark (see Ultraviolet Response Test,
page 11.)
For C7027A, C7035, and C7044A applications whose
response to ignition spark cannot be avoided, the Q624A or
Q652B Solid-State Ignition Transformer may eliminate the
ignition spark response. The Q624A or Q652B, when properly
installed, prevents C7027A, C7035A and C7044A ignition
spark response by alternately activating the spark generator
and the UV sensing tube.
5
ULTRAVIOLET FLAME DETECTORS
60-2026-16
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