Honeywell 800 Series Manual page 10

HONEYWELL MODEL 700/800 SIGNAL PROCESSOR AND VIEWING HEAD
With no flame signal present, the green LED will flash one
pulse per second in step with the self-checking signal. The
viewing head is sending back an ID pulse; this is part of
the self-checking system. When a flame is present, the
green LED will flash at a rate proportional to the flame
signal, except when the pulses are interrupted once per
second for the self-check pulse arrival at the viewing head.
The pulse rate of the green LED flashes can be used for
aiming the viewing head.
NOTE: The LED indicators are provided for alignment
and troubleshooting only. Reinstall cover with
gasket correctly in place at all times, and ensure
that connector coupling is tightened securely.
This gasket and cover must be installed properly
to maintain IP67 rating.
Viewing Head Mounting and
Sighting
Mounting is 1/2-in. NPT (F) for all viewing head models
with a 1/4-in. NPT (F) purge air connection. Before
beginning installation, determine the best location for
mounting the viewing head based upon the following
factors:
Viewing Head Mounting Block
The S70X viewing heads are held firmly in place in their
mounting blocks by two zinc-plated steel latches. The
S80X viewing head is secured in its mounting block by a
friction twist-lock. Refer to the ACCESSORIES section for
part numbers.
Pressure
The S70X viewing head lens will withstand 50 psi (3.4 bar)
while the S80X lens will withstand 90 psi (6.2 bar),
provided the compression ring on the purge air adapter is
tightened properly. If the lens assembly is exposed to
greater pressures through the sight pipe, then an isolation
unit must be used. Honeywell isolation units with purge
air entrance are available as accessories; ISO-UNIT, ISO-
UNITSS, ISO-UNITHPGT. Each has a quartz window, two
1-in. NPTF connections and a 1/2-in. NPTF purge port.
Temperature
The case temperature of the viewing head housing must
not exceed 185°F (85°C) while the standard Delrin
mounting block must not exceed 180°F (82°C)
continuous service. Care should be taken to ensure the
case housing and mounting block temperatures do not
exceed these values.
Purge air will help reduce conducted heat through the
sight pipe and flange. A heat insulating Ultem
replacement viewing head mounting block is available for
both the S70X/S80X models (part numbers 700UA and
800UA) with a continuous service rating of 320°F (160°C)
as well a 1/2-in. NPTM Ultem nipple (part number R-518-
13) or an Ultem locking coupler adapter (R-518-PT13 or
R-518-PT13L) to reduce the conducted heat, but direct
radiation can cause the housing case temperature to
exceed limits. If the ambient heat (direct radiation) is
excessive, then an air cooling canister with vortex cooler
should be considered or alternately a fiber optic extension.
The extension uses a fiber optic cable assembly between
66-2069EP—08
the sight pipe and the viewing head, allowing the viewing
head to be placed further away from the heat source. Refer
to the Fiber Optic Manual 69-2683 or contact your
distributor or the factory for assistance with fiber optic
selection and pricing.
Purge Air
Use a flexible air supply line, to allow for repositioning of
the viewing head and sight pipe until a final and
permanent position has been decided. A continuous flow
of air must be maintained in order to reduce the
conducted heat and to keep the sight pipe and viewing
head lens free of dirt and debris. Air required is about 5
SCFM (0.13 Nm3 /min) delivered at 1 in. (25mm) above
the maximum pressure as measured at the "Y" or "T"
section of the purge air connection for each viewing head.
The air supply must be clean, free of oils and water, and
preferably cool. In order to electrically isolate the viewing
head, the purge air line should be installed using an
insulating material, such as a rubber hose, in between the
purge air line and the viewing head.
Vibration
Do not install the viewing head where it could be subject to
high vibration. Provide an anti-vibration mount if
excessive vibrations are present.
Clearance
Make sure there will be sufficient room to remove the
viewing head housing for servicing.
Viewing Head Mounting
Honeywell offers a range of swivel mounts, both pipe
thread or flange mounting for use with sight pipes or
direct wind box mounting. See "Accessories" on page 11.
or the Honeywell website for further details.
Viewing Head Sighting
The sighting of the viewing head should be parallel to the
center line of the burner in the direction of the flame. If
used, the sight pipe should be mounted as close to the
center line as possible so as to sight along the flame
rather than across the flame. Doing so will ensure
continuous flame detection under changing load
conditions. See Fig. 16, 17 and 18.
Utilizing a sighting or the sight pipe aimed at the root of
the flame (where the turbulent combustion air mixes with
the flame) is a good starting point for optimizing the
sighting. Where practical, using a swivel mount to "zero-
in" on the highest signal will assure maximum
performance. The optimum scanner location is parallel to
the burner center line. The use of a swivel mount allows for
line of sight adjustment, where practical to use.
Examples of viewing head installation with and without a
swivel mount are shown in Fig. 14 and Fig. 15. If using a
sight pipe, its diameter should be large enough to allow a
reasonable field of view, and to allow for adjustment of the
swivel mount angle.
In some instances, it may be beneficial to use two sets of
setpoints for Flame On, Flame Off and gain. The two-
channel capability (primary and alternate viewing head
settings) is ONLY possible when using the P531 or P532
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