Honeywell C7076D, C7076A Product Data
C7076A,D
Adjustable Sensitivity
Ultraviolet Flame Detectors
PRODUCT DATA
The C7076A and C7076D are identical except for their
housings. The C7076A is designed for standard installations
The explosion-proof housing used with the C7076D meets the
requirements for Division I, Class I, Groups C and D; and
Class II, Groups E, F, and G of the National Electrical Code
(NFPA70).
The C7076 features two sensitivity adjustments, each with a
400:1 dynamic range, and an integral flame signal meter jack
to facilitate precise sighting.
C7076A
C7076D
APPLICATION
The C7076 Adjustable Sensitivity Ultraviolet Flame Detector is
a solid-state, adjustable sensitivity, device for sensing the
ultraviolet radiation emanating from gas, oil and pulverized
coal flames. It is designed for burner management and flame
safety systems which require optimum sensitivity and/or flame
discrimination.
The flame detector is designed for use with Dynamic
Self-Check Ultraviolet Amplifiers R7476A and R7886 to
provide a closed-loop, self-checking circuit which insures the
integrity of both amplifier and flame detector. Improper
response to simulated flame loss results in a safety shutdown
and/or alarm.
FEATURES
• High level output permits long distance transmission
without special wiring.
• Solid state circuitry assures long life and stable
sensitivity over wide ranges of temperature and
voltage.
• Available in two versions:
— C7076A for use in standard installations.
— C7076D for use in installations requiring
explosion-proof packaging.
® U.S. Registered Trademark
Copyright © 2002 Honeywell • All Rights Reserved
Contents
Application ........................................................................ 1
Features ........................................................................... 1
Specifications ................................................................... 2
Ordering Information ........................................................ 2
Installation ........................................................................ 7
Wiring ............................................................................... 8
Troubleshooting ................................................................ 16
Service ............................................................................. 18
95-8269-1
C7076A,D ADJUSTABLE SENSITIVITY ULTRAVIOLET FLAME DETECTORS
SPECIFICATIONS
Models:
C7076A—Adjustable sensitivity flame detector packaged in
standard housing. Used with R7476A and R7886 Dynamic
Self-Check Ultraviolet Amplifiers.
Table 1. Electrical Ratings.
Line Voltage
(+10%, -15%) Frequency (Hz) Shutter Voltage
100 50/60 100 7 14
120 60 120 7 14
200 50/60 120 7 14
220/240 50/60 120 7 14
c
117
a
Supplied by the appropriate flame safeguard control operating at the designated line voltage.
b
Does not include shutter power, which is supplied by the flame safeguard control.
c
For applications in South Africa.
Temperature Ratings:
Maximum Aspirator Temperature (C7076A only): 225°F
(107°C).
Ambient Operating Temperatures:
C7076A: -40°F to +160°F (-40°C to +71°C).
NOTE: Derate ambient temperature 1°F for every 13°F of
aspirator temperature over 160°F.
C7076D: -40°F to +160°F (-40°C to +71°C).
Storage Temperature Range:
-60°F to +185°F (-51°C to +85°C).
Sensitivity Selection:
Remote Sensitivity Selection: External switch can be wired to
select the setting sensitivity control, either A or B.
External Selector Switch: Must rated for switching 20 mA at
48 Vdc.
Sensitivity Adjustment:
Range: 400 to 1.
Sensitivity Controls: Two, labeled A and B, on plug-in
electronics chassis. Each can be set independently and
locked to prevent drift due to vibration.
50 117 7 14
C7076D—Adjustable sensitivity flame detector packaged in
explosion-proof housing. Used with R7476A and R7886
Dynamic Self-Check Ultraviolet Amplifiers.
Electrical Ratings: See Table 1.
Maximum Power Consumption
a
Flame Signal Amplifiers:
R7476A or R7886 Dynamic Self-Check Ultraviolet Amplifier;
order separately.
Flame Signal:
Measured at flame current meter jack on C7076: 1.4 to 5.5
mA nominal.
Measured at flame current meter jack on R7476A amplifier:
2.5 to 5.5 mA nominal.
Measured at flame voltage meter jack on R7886 amplifier: 0.0
to 5.0 Vdc.
Shutter Frequency:
R7476A: 1.25 Hz nominal. Interrupts the line-of-sight of the
detector about 75 times per minute to provide
self-checking.
R7886: One test every 5 seconds to provide self-checking.
Pressure:
C7076A quartz viewing lens: 20 psig (138 kPa) maximum.
C7076D quartz viewing lens: 142 psig (981 kPa) maximum.
Watts VA
b
ORDERING INFORMATION
When purchasing replacement and modernization products from your TRADELINE® wholesaler or distributor, refer to the
TRADELINE® Catalog or price sheets for complete ordering number.
If you have additional questions, need further information, or would like to comment on our products or services, please write or
phone:
1. Your local Home and Building Control Sales Office (check white pages of your phone directory).
2. Home and Building Control Customer Relations
Honeywell, 1885 Douglas Drive North
Minneapolis, Minnesota 55422-4386
In Canada—Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Scarborough, Ontario M1V 4Z9.
International Sales and Service Offices in all principal cities of the world. Manufacturing in Australia, Canada, Finland, France,
Germany, Japan, Mexico, Netherlands, Spain, Taiwan, United Kingdom, U.S.A.
95-8269—1 2
C7076A,D ADJUSTABLE SENSITIVITY ULTRAVIOLET FLAME DETECTORS
Interchangeability:
Models C7076A and C7076D are not interchangeable with
other flame detector models; they must be used with either
the R7476A or R7886 Dynamic Self-Check Ultraviolet
Amplifier.
Wiring Connections:
C7076A: Terminal block in front compartment of housing;
wire-clamp type, removable screws (terminal lugs can be
used).
Conduit fitting: 7/8 in. opening in housing to accommodate
1/2 inch flexible conduit; fitting must be water-tight to
meet NEMA 4 standards.
C7076D: Terminal block in front compartment of housing;
wire-clamp type, removable screws (terminal lugs can be
used).
Conduit fitting: 1/2 in. NPT tapped opening in bottom of
housing to accommodate conduit.
Plug-in Electronics Chassis:
Field-replaceable; plugs into octal socket in housing. Contains
ultraviolet sensing tube, shutter assembly, power supply,
solid state circuitry, sensitivity adjustment controls and
flame current meter jack. Keyed to housing to ensure
proper orientation.
Air Flow Requirements (C7076A only):
Purge Air: 0.7 SCFM (3.3 ml/sec) is required to maintain 4 in.
(102 mm) of differential pressure from the aspirator inlet to
the combustion chamber. An air flow of 3 SCFM
(14 ml/sec) is recommended.
Seal-off Air: 5 psig (34.5 kPa) maximum combustion chamber
pressure.
Housing:
C7076A: Meets NEMA 4 standards (water-tight and dust-tight,
indoor and and outdoor).
Construction: Aluminum and cadmium-plated steel.
Color: Light blue.
Front compartment contains terminal block; rear
compartment contains electronic chassis.
C7076D: Meets NEMA 7 requirements (explosion-proof).
Construction: Cast aluminum alloy.
Color: Light blue.
Front compartment contains terminal block; rear
compartment contains electronic chassis.
Mounting:
C7076A: Aspirator has 1-in. NPT tapping for mounting onto
sight pipe, and 3/8 in. NPT tapping for connecting to the air
supply.
Detector mounts on aspirator by means of a removable
piano-type hinge.
C7076D: Detector has 1-in. NPT tapping for mounting onto
sight pipe and two 5/16-18 UNC tapped holes for attaching
a bracket for additional security.
For allowable mounting positions, see Fig. 1.
Weight:
C7076A: 6.6 lb (3 kg).
C7076D: 17.6 lb (8 kg).
Dimensions: See Fig. 2.
Accessories:
118367A Swivel Mount.
W136A Test Meter (includes 117053 meter connector plug).
117053 Meter Connector Plug (for older W136A models).
Replacement Parts:
C7076A:
191002B Plug-in Electronics Chassis (without UV sensing
tube).
190971E Coil and Shutter Assembly (for all models except
100V model).
190971F Coil and Shutter Assembly (for 100V model).
190998A Aspirator Assembly.
191205 Pin and Chain.
191055A Cover Assembly for 120 Vac models.
191055B Cover Assembly for 220/240 models.
191203-767 Hinge.
191053 Ultraviolet Sensing Tube.
191050 Viewing Lens.
190999 grommet, silicone rubber for viewing lens.
191054 Gasket, silicone-rubber seal for front and rear
cover plates.
C7076D:
191002R Plug-in Electronics Chassis (without UV sensing
tube).
190971E Coil and Shutter Assembly (for all models except
100V model).
190971F Coil and Shutter Assembly (for 100V model).
191053 Ultraviolet Sensing Tube.
191050 Viewing Lens.
24400152-001 Lens Kit (consists of quartz window gasket
and gasket seal).
Approvals:
C7076A:
Underwriters Laboratories Inc. Listed (120V models only):
File No. MP268, Guide No. MCCZ.
Canadian Standards Association (CSA) Certified (120V
models only): File No. LR1620.
Factory Mutual Approved: Report No. FM26980.
C7076D:
Underwriters Laboratories Inc. Listed: File No. E34649,
Guide No. ZTSZ.
Industrial Risk Insurers Approvable.
3 95-8269—1
C7076A,D ADJUSTABLE SENSITIVITY ULTRAVIOLET FLAME DETECTORS
SIGHT PIPE
ASPIRATOR
DETECTOR CANNOT BE
ROTATED IN THIS PLANE.
THE ASPIRATOR MUST BE ON TOP.
SIGHT PIPE
90
90
DETECTOR MAY
BE ROTATED 90 IN
EITHER DIRECTION
FROM HORIZONTAL
C7076A
90
90
ASPIRATOR
DETECTOR CANNOT BE
ROTATED IN THIS PLANE.
DETECTOR MAY
BE ROTATED 90 IN
EITHER DIRECTION
FROM HORIZONTAL
C7076D
Fig. 1. C7076 allowable mounting positions.
INSTALLATION
Planning the Installation
Proper flame detector application is the basis of a safe and
reliable flame safeguard installation. Refer to the burner
manufacturer instructions as well as to those included here.
Follow all instructions carefully.
Determine the Location
Before beginning the actual installation, estimate the best
location for mounting the detector based upon the following
factors:
Temperature
Install the flame detector where the surrounding temperature
will remain within the specified ambient operating temperature
ratings.
M20748
For the C7076A, to keep the detector temperature within
specifications, the aspirator temperature must not exceed
225°F (107°C). If the aspirator temperature will exceed
temperature ratings, the introduction of cooling-purging air will
be required.
Vibration
Do not install the detector where it could be subjected to
excessive vibration; it shortens the life of the electronic
components. Vibrations with a magnitude greater than 1g will
require an antivibration mount to cushion the detector.
Clearance
Make sure there will be enough room to swing out the detector
for servicing. Refer to Fig. 2 as applicable.
Radiation Sources Other Than Flame
Examples of radiation sources, other than flame, which could
actuate the detector system include:
95-8269—1 4
C7076A,D ADJUSTABLE SENSITIVITY ULTRAVIOLET FLAME DETECTORS
6
1 INCH NPT
2-1/4
(57)
1
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
5/16-18 UNC (3 PLCS)
X 0.47 (12) DEEP
2-1/4
(57)
4 (102)
4-25/32 (122)
1
1-1/16
(27)
(102)
3/8 INCH NPT
4
2-9/32
1-5/8
(19)
(58)
2-21/32
(68)
3/4 (19)
7-13/32 (188)
10-1/4 (261)
29/32 (22) OPENING FOR
1/2-INCH CONDUIT
1 (25)
7-19/32
(194)
1
C7076A
-23/32
(171)
1-31/32 (50)
3-15/16 (100)
15/16
(24)
25/32 (20)
1-9/16 (40)
C7076D
7-13/16 (198)
11-13/16 (300)
1-27/32
(47)
5-25/32
(147)
5-25/32 (147)
M20749A
Fig. 2. C7076 dimensions in in. (mm).
1. Ultraviolet sources:
a. Radiant surfaces above 2200°F (1200°C).
b. Sparks from ignition transformers and welding arcs.
c. Gas lasers.
d. Sun lamps.
e. High voltage condensers.
f. Radioisotopes.
Except under very unusual circumstances, none of these
sources, except a radiant surface or ignition spark, would be
present in or near the combustion chamber.
e. Germicidal lamps.
f. Incandescent lamps held close to the sensing tube
2. Gamma ray and X-Ray sources:
(filament above 2200°F [1200°C]).
The detector may respond to a radiant surface at a
temperature above 2200°F (1200°C) if both of these
conditions are present:
a. Diffraction analyzers.
b. Electron microscopes.
c. Radiographic x-ray machines.
• The detector sensitivity control is set at (or near) maximum,
and
d. High voltage vacuum switches.
5 95-8269—1
C7076A,D ADJUSTABLE SENSITIVITY ULTRAVIOLET FLAME DETECTORS
• the surface represents a significant percentage of the
detector field of view.
If the temperature or a radiant surface causes the flame relay
(in the flame safeguard control) to pull in, re-aim the sight pipe
so the detector views a cooler area, or decreases the
sensitivity of the detector.
Ignition spark is a rich source of ultraviolet radiation. When
installing the detector, make sure it does not respond to
ignition spark.
Single Burner Requirements
The detector must have an unobstructed view of the flame it is
supervising under all firing conditions. This implies a proper
sighting angle and the minimization of screening effects.
Sighting Angle
The first 30 percent of a flame (the root) radiates the most
intense ultraviolet energy. Low angle sighting permits the
detector to view a greater depth of the flame root, thus
reducing the effects of irregularities in the flame pattern. The
best sighting angle is nearly parallel to the axis of the flame,
as shown in Fig. 3.
DETECTOR IN GOOD
SIGHTING POSITION
(LOW ANGLE SIGHTING)
BURNER
NOZZLE
DETECTOR IN POOR
SIGHTING POSITION
Fig. 3. Detector sighting angle.
NOTE: When possible, it is desirable to tilt the detector and
sight pipe downward to prevent the buildup of soot in
the pipe or on the viewing lens.
FLAME DEPTH–
ANGLE VIEW
UNBURNED FUEL
FLAME DEPTH–
PERPENDICULAR VIEW
M1956
reaching the detector and may cause flame signal
deterioration resulting in a shutdown. The adverse affects of
screening may be minimized by proper burner adjustment,
increasing the detector viewing area (shorten sight pipe
and/or increase its diameter), and optimizing detector
sensitivity.
Multiburner-Multifuel Requirements
In addition to meeting the requirements for a single burner, a
multiburner installation also requires flame discrimination.
Flame discrimination may be defined as the location of all
flame detectors such that each detector responds only to the
flame(s) produced by the burner it is supervising.
MULTIBURNER REQUIREMENTS
In multiple burner systems, not every detector can be
positioned so that its line of sight does not intercept flames
from other burners. This situation occurs in front-fired boiler
furnaces having more than one row of burners, or in multilevel
opposed-fired furnaces where the burners face each other.
When planning such an installation, locate each flame
detector so that it has the best possible view of the first 30
percent closest to the burner nozzle (the flame root) it is
supervising, and the worst possible view of all other flames.
Fig. 4 illustrates a critical detector application problem that
requires flame discrimination. Flame discrimination is
accomplished for Detector A by repositioning it until the flame
relay (in the flame safeguard control) does not respond to
Flame B. Note that Detector A is aimed at the first 30 percent
of Flame A where the ultraviolet radiation is most intense. It
sights the tip of Flame B, but it is not aimed at the first 30
percent of Flame B where ultraviolet radiation is intense.
Detector A is repositioned to assure maximum response to
Flame A while rejecting Flame B. Similarly, Detector B is
positioned to assure maximum response to Flame B while
rejecting Flame A.
If the sensitivity control on a detector is set at its minimum
position and flame discrimination cannot be achieved, insert
an orifice plate in the sight pipe. An orifice of the proper
diameter will reduce the ultraviolet radiation reaching the
detector so that the sensitivity can be adjusted to effect flame
discrimination.
In most installations, the detector will need to respond to the
pilot flame alone, then to the pilot flame and main burner
flame together, and finally to the main burner flame alone. The
detector must meet all sighting requirements which apply.
1. Pilot flame alone—the smallest pilot flame that can be
detected must be capable of reliably lighting the main
burner.
2. Pilot and main burner flame together—the detector
must sight the junction of both flames.
3. Main burner flame alone—the detector must sight the
most stable part of the flame for all firing rates.
Screening Effects
Smoke, fuel mist, dirt and dust are masking agents that
absorb ultraviolet radiation from the flame. They create a
screen that reduces the amount of ultraviolet radiation
95-8269—1 6
DETECTOR A
FLAME A
FLAME B
DETECTOR B
M1957
Fig. 4. Example of flame discrimination problem
(opposed-fired burners).
C7076A,D ADJUSTABLE SENSITIVITY ULTRAVIOLET FLAME DETECTORS
MULTIFUEL REQUIREMENTS
Detectors supervising burners that alternately fire more than
one fuel may require a different sensitivity level for each fuel.
For example, a higher sensitivity is required to reliably sense
pulverized coal or No. 6 fuel oil in contrast to natural gas or to
No. 2 fuel oil. Reliable flame sensing and flame discrimination
may not be maintained simultaneously (without changing the
sensitivity setting) when alternating between two fuels.
The C7076 has two integral sensitivity adjustments that can
be remotely and automatically selected. The two sensitivity
adjustments can be chosen by means of the fuel selector
switch (refer to Remote Sensitivity Selection in the Installation
section). The sensitivity adjustments should be made for both
fuels as described in the section on multiburner requirements,
using one adjustment pot for each fuel.
Parallel Flame Detectors
Two C7076 detectors can be connected in parallel to the
same flame signal amplifier and still provide independent
sensitivity adjustment. This capability is particularly useful for
multiburner, multifuel applications.
Shifting flame patterns, commonly encountered on burners
with wide turndown ratios, may require parallel detectors to
prove the flame at the highest and lowest firing rates. In this
case, one detector supervises the pilot (interrupted) and both
detectors supervise supervise the main burner flame. During
the main burner run period, either detector is capable of
maintaining system operation.
In addition to assuring more reliable flame detection, parallel
detectors facilitate maintenance during burner operation.
Each detector can be removed in turn without shutting down
the supervised burner. However, a flame simulating failure
occurring in the flame signal amplifier or in either detector will
cause a shutdown.
Redundant Flame Detection System
Two C7076 detectors connected to two flame signal amplifiers
wired in parallel comprise a redundant flame detection
system. In addition to the features of parallel flame detectors,
a redundant system increases reliability and is therefore
recommended for critical burner applications. A flame failure,
flame signal loss, or flame simulating failure occurring in either
detector subsystem will cause an alarm (not a shutdown)
allowing corrective action to avert a shutdown.
When Installing this Product…
1. Read these instructions carefully. Failure to follow them
could damage the product or cause a hazardous
condition.
2. Check the ratings given in the instructions and on the
product to make sure the product is suitable for your
application.
3. Installer must be a trained, experienced flame
safeguard service technician.
4. All wiring must comply with applicable local electrical
codes, ordinances and regulations.
5. All wiring must be NEC Class 1 (line voltage).
6. Voltage and frequency of the power supply connected to
this detector must agree with the values marked on the
detector.
7. If an air supply is connected to the aspirator on the
C7076A, its pressure must equal or exceed that
required to seal off the detector from the combustion
chamber.
8. On multiburner installations, each detector must
respond only to the flame(s) produced by the burner it is
supervising.
9. Do not connect more than two detectors in parallel to a
single R7476A or R7886 Dynamic Self-Check
Ultraviolet Amplifier.
10. Perform all required adjustments and checkout tests
after installation is complete.
Selecting and Installing Sight Pipe
After you have determined the approximate location and
sighting angle, select the sight pipe. A black iron pipe is
recommended to provide reliable flame sensing. Stainless
steel and galvanized pipes have bright surfaces that initially
transmit ultraviolet radiation very well. However, their ability to
transmit ultraviolet radiation will decay when the bright
surfaces become dull with age or contamination, and flame
detection will become less reliable with time.
The aspirator on the faceplate of the C7076A, and the
faceplate on the C7076D, are tapped for a 1-inch NPT
threaded pipe. A larger pipe may be necessary to obtain
proper performance; an diameter other than 1 inch will require
a reducer coupling. The geometry of the sight pipe affects the
performance of the detector. If the flame signal is too small,
reduce the length or increase the diameter of the pipe to
increase the field of view of the detector. If a sight pipe longer
than 1 foot is required, use a 2-inch diameter pipe with the
reducer as close to the detector as possible.
INSTALLATION
WARNING
Electrical Shock Hazard.
Can cause serious injury, death or equipment
damage.
Disconnect power supply before beginning installation.
More than one disconnect may be necessary.
NOTE: Sight pipe couplings cannot be used with C7076D
due to the need to safeguard the integrity of the
explosion-proof quality of this model. The size of the
sight pipe for the C7076D, therefore, is restricted to
1-inch diameter.
Cut a hole of the proper diameter for the sight pipe in the
burner front or windbox at the selected location. The hole
should be at least 2 inches in diameter to allow adjustment of
the sighting angle. If register vanes interfere with the desired
line of sight, trim the interfering vane(s) to assure an
unobstructed view of the flame.
Cut the pipe to the desired length. Thread one end of the pipe
to fit the desired mating component; i.e., reducer coupling,
aspirator on the faceplate of the C7076A aspirator; or
7 95-8269—1
C7076A,D ADJUSTABLE SENSITIVITY ULTRAVIOLET FLAME DETECTORS
faceplate on the C7076D Detector. Insert the other end of the
pipe into the mounting hole, align it to the desired sighting
angle, and tack weld it in position.
NOTE: When initially mounting the pipe, tack weld it in place
to allow further sighting adjustments. Make sure the
tack weld will support the weight of the detector
when it is installed.
NOTE: When installing a C7076A Detector, a Honeywell
118367A Swivel Mount is recommended to facilitate
sighting the flame properly. For installation
instructions for the Swivel Mount, see form 60-0361.
Installing the C7076A Detector
Mounting the Aspirator
The aspirator on the faceplate of the C7076A Detector screws
directly onto the 1-inch NPT threaded pipe. Remove the
aspirator from the C7076A Detector by removing the hinge
pin. Use an adjustable wrench to tighten the aspirator onto the
pipe. For alternate mounting methods and further information
refer to Fig. 5.
Mounting the Detector
Mount the detector on the faceplate by placing the detector on
its hinge and re-inserting the hinge pin. Install 1/2 inch flexible
conduit to the detector as follows:
Loosen the four captive screws in the front coverplate (with
the viewing lens) and remove the plate.
Seal off of the sight pipe prevents hot gases from escaping
from a positive pressure combustion chamber when the
detector is swung open on its hinge for maintenance. Refer to
Fig. 9 for the minimum inlet pressure or air flow required to
seal off a sight pipe against a positive combustion chamber
pressure.
Fig. 10 shows a method of supplying a constant airflow to
purge the sight pipe, while also providing enough pressure to
seal off the sight pipe when needed.
Mounting the Faceplate
The faceplate of the C7076D Detector screws directly onto the
1-inch NPT threaded pipe (see Fig. 5). Screw the faceplate
onto the pipe; hand-tighten in place, making certain that the
four mounting holes in the faceplate are properly aligned to
allow the detector to be in the desired position when secured
to the faceplate.
Mounting the Detector
Mount the detector on the faceplate and fasten in place using
the four mounting screws supplied for this purpose. Do not
tighten the screws at this time, because the detector must still
be wired.
Obtain a piece of conduit that is not longer than 18 inches in
length and has 1/2-inch NPT threads at both ends. Screw this
piece of conduit into the threaded opening in the bottom of the
detector housing (see fig. 11). Install an approved seal box on
the other end of the piece of conduit and then complete the
conduit installation as required.
Install a flexible conduit fitting in the opening in the bottom of
the detector (Fig. 7). To meet NEMA 4 standards, use
watertight conduit and a watertight fitting (such as an Appleton
ST50 Liquid-Tight® Connector with an STG-50 Neoprene
O-ring and Steel Gasket Assembly). See Table 2 for other
applicable connectors.
Table 2. Applicable Watertight Connectors.
Manufacturer Coupling No. O-Ring No.
T&B 5232 5262
Efcor 11-50 LTG-1
Raco 3402 2452
Steel City LT-101 LR-531
Crouse Hines LT-50 SG-1
Connecting Air Supply (Optional)
Use a flexible air supply line which will allow repositioning of
the sight pipe until the permanent detector position has been
verified.
The aspirator air inlet can be plugged, left open, or connected
to a clean (oil/moisture-free) air supply. Use a 3/8 in. NPT
connector if aspirator air is used (see Fig. 5). The aspirator
allows air to flow through the sight pipe into the combustion
chamber to cool, clean and seal off the sight pipe. The airflow
eliminates the need for frequent lens cleaning. See Fig. 8 for
purge air requirements.
WIRING
WARNING
Electrical Shock Hazard.
Can cause serious injury, death or property
damage.
Disconnect all power before beginning wiring. More
than one disconnect may be involved.
1. All wiring must comply with applicable local electrical
codes, ordinances and regulations. Use NEC Class 1
wiring.
NOTE: The detector has color-coded and labeled,
plastic-insulated no. 18 leadwires, 8 ft (2.4 m) long,
rated for 221°F (105°C).
2. Keep the flame signal leadwires as short as possible
from the flame detector to the terminal strip or wiring
subbase. Capacitance increases with wire length,
reducing the signal strength. the maximum permissible
leadwire length depends on the type of leadwire and the
conduit type and diameter. The ultimate limiting factor in
flame signal leadwire length is the signal current or
voltage at the flame safeguard device. See Table 1.
95-8269—1 8
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