Azbil AUD300C1000 Series User manual

Thank you for purchasing an Azbil
Corporation product.
This manual contains information for
ensuring the correct use of this product.
It also provides necessary information
for installation, maintenance, and
troubleshooting.
This manual should be read by those who
design and maintain equipment that uses
this product. Be sure to keep this manual
nearby for handy reference.
AUD300C1000
Advanced Ultraviolet
Flame Detector
User’s Manual
No. CP-SP-1141E

NOTICE
Be sure that the user receives this manual before the product is used.
Copying or duplicating this user’s manual in part or in whole is forbidden.
The information and specifications in this manual are subject to change
without notice.
Considerable effort has been made to ensure that this manual is free from
inaccuracies and omissions. If you should find an error or omission, please
contact the azbil Group.
In no event is Azbil Corporation liable to anyone for any indirect, special or
consequential damages as a result of using this product.
© 2008–2016 Azbil Corporation All Rights Reserved.

i
Conventions Used in This Manual
The safety precautions explained in the following section aim to prevent injury to the operator and
others, and to prevent property damage.
WARNING
Warnings are indicated when mishandling this product might
result in death or serious injury.
 CAUTION
Cautions are indicated when mishandling this product might
result in minor injury to the user, or physical damage to the
product.
In describing the product, this manual uses the icons and conventions listed below.
Use caution when handling the product.
The indicated action is prohibited.
Always follow the indicated instructions.
Handling Precautions:
Handling Precautions indicate items that the user should pay attention to when handling
the AUD300C1000.
Note: Notes indicate information that might benefit the user.
(1), (2), (3): Numbers within parentheses indicate steps in a sequence or parts of an explanation.
This indicates the item or page that the user is requested to refer to.
>>: Indicates the result of an operation, details displayed on the personal computer or other
devices, or the state of the device after operation.

ii
Safety Precautions
WARNING
Use this device only in combination with Azbil Corporation’s burner controllers.
Make sure that this device does not detect ultraviolet rays other than those of the burner flame.
If it responds to other ultraviolet radiation, flame failure in the burner will not be detected.
As a result, the outflow of fuel will continue, causing a very serious explosion hazard.
Before removing, mounting, or wiring this device, be sure to turn off the power to the device
and all connected devices. Failure to do so may cause electric shock.
Before doing any wiring work, be sure to disconnect the power to prevent electrical shock.
To prevent explosion, carry out the pilot turndown test carefully. If this device detects a pilot
flame that is too small to ignite the main burner, the burner controller will not be able to
recognize flame failure of the main burner, allowing the outflow of fuel to continue, leading to
a serious explosion hazard.
If the pilot turndown test is carried out repeatedly, completely shut down all equipment each
time the test is finished, and completely discharge unburned gas or fuel that has accumulated
in the combustion chamber and flue. If unburned gas and oil are not discharged completely,
an explosion may occur.
Do not touch terminals F or G on this device or on the burner controller immediately after the
power to the burner controller has been turned OFF. There is a danger of electric shock because
terminals F and G retain a charge for up to 1 minute after the power has been turned off.
When measuring the voltage between terminal F and terminal G of this device in order to check
the wiring, do not touch any part of the terminals. Doing so may result in an electric shock.
Do not use this device with the cover removed. Doing so may result in an electric shock. If the
cover has been removed from this device, be sure to reattach it and tighten the four mounting
screws completely before use.

iii
CAUTION
This device is designed for both batch operation of the burner (at least one start and stop in a
24-hour period) and continuous operation (nonstop combustion for 24h or longer). It must be
used with a burner controller having a dynamic self-checking function.
Installation, wiring, inspection, adjustment, etc., should be carried out by a trained and
experienced technician with knowledge and technical skills related to combustion equipment
and flame safeguard control devices.
Do not install where the product will be exposed to any of the following:
•
Certain chemicals or corrosive gases (ammonia, sulfur, chlorine, ethylene compounds, acid, etc.).
•
Splashing water or excessive humidity
•
High temperatures
•
Prolonged vibration
If this device is operated in an atmosphere where there is steam, sooty smoke, oil mist, dust,
and/or organic solvents that interfere with ultraviolet rays, take appropriate corrective
measures.
When using multiple burners, mount this unit in a position where it can detect only the flame
of the burner to be monitored.
Carry out the wiring work in conformity with the specified standards.
Be sure to route the signal wires of this device separately from high-voltage ignition
transformer cables and power cables, and put them in a separate conduit.
After the wiring work is complete, be sure to check that there are no mistakes. Incorrect wiring
can cause damage or malfunction.
Only an experienced technician with knowledge and technical skills related to combustion
equipment and combustion safety should carry out the pilot turndown test.
Do not transport this device while it is mounted on the combustion equipment. Shock or
vibration during transport may cause it to malfunction. Before transporting, dismount it and
put it in its specially designed shipping box.
The service life of the tube unit and shutter unit components of this device is a maximum
of 3 years. To ensure operational safety, be sure to replace these units with new ones within
the service life period. For replacement, use the AUD Maintenance Kit (AUD60A1000), which
includes the tube and shutter units.

iv
The Role of This Manual
A total of 4 different manuals are available for the AUD300C1000, AUR300C. Read them as necessary for your spe-
cific requirements. If a manual you require is not available, contact the azbil Group or its dealer.
AUD300C1000 Advanced Ultraviolet Flame Detector
Manual No.CP-SP-1141E
This manual.
The manual describes the mounting, wiring, maintenance and inspection, and trouble-
shooting when the AUD300C is built-into the combustion equipment.
AUR300C Advanced Ultraviolet Burner Controller
Manual No.CP-SP-1142E
The personnel in charge of design, mounting, operation, and maintenance of the
combustion equipment using the AUR300C must read this manual.
The manual describes the mounting, wiring, trial-run adjustment, and mainte-
nance and inspection of the AUR300C.
AUR350C Advanced Ultraviolet Burner Controller with Communications
Manual No.CP-SP-1175E
Personnel in charge of design, mounting, operation, and maintenance of combus-
tion equipment using the AUR350C should read this manual.
It describes the mounting, wiring, trial-run adjustment, maintenance, inspection
of the AUR350C.
AUR450C Dynamic Self-Checking Burner Controller
Manual No. CP-SP-1264E
This manual should be read by personnel using the AUR450C for the first time,
those in charge of designing combustion equipment that uses the AUR450C or
designing the hardware for mounting the device in a control panel, and personnel
performing maintenance.
The manual gives an overview of the product, its mounting and wiring for con-
nection to other equipment, its operation, trial-run adjustment, maintenance and
inspection, and specifications.

v
Contents
Conventions Used in This Manual
Safety Precautions
The Role of This Manual
Chapter 1. OVERVIEW 1
 Overview 1
 Features 1
 Names of parts 1
 Model selection table 1
Chapter 2. MOUNTING 3
 What to know before installation 3
 Methods of monitoring burner flame 4
 Mounting position 4
 Mounting orientation 5
 Mounting of the monitoring pipe 6
 Mounting procedure 8
Chapter 3. WIRING 9
 Wiring diagram 9
 Wiring check 10
Chapter 4. ADJUSTMENT 11
 Before measuring the flame voltage 11
 Measuring the flame voltage 11
 Pilot turndown test 12
 Ignition spark response test 13
 Permanent mounting of monitoring pipe 13
 Final check 13
Chapter 5. TROUBLESHOOTING 14
 Troubleshooting procedure 14
Chapter 6. MAINTENANCE AND INSPECTION 15
 Periodic inspection 15
 Replacement of the shutter unit and tube unit using the AUD Maintenance Kit
(AUD60A1000) 16

vi
Chapter 7. SPECIFICATIONS 19
 Specifications 19
 External dimensions 20
Terms and Conditions

1
Chapter 1. OVERVIEW
■Overview
The AUD300C1000 Advanced Ultraviolet Flame Detector (hereafter this/the de-
vice) is designed to detect ultraviolet radiation from an oil or gas burner flame, for
use with both batch and continuous operation burners. The AUD300C1000 is used
in combination with a dedicated burner controller. By means of the built-in shutter,
any malfunction of the UV flame detector or burner controller is detected by the
start check and continuous self-checking function (Dynamic Self-Check), ensuring
highly reliable combustion safety control.
■Features
•Maintenance parts such as the tube unit and shutter unit can be handled as a
single unit. This ensures easy replacement and maintenance work.
•As for a flame sensor for the self-check, this unit is compact and lightweight. This
ensures free burner mounting.
•The operating ambient temperature is 100°C (up to 120°C during flame detec-
tion) and the protection structure is IP66. This ensures excellent environment-
proof performance.
•Because it can be mounted vertically and has a maximum wire length of 200m,
flexible installation is possible.
■Names of parts
●Main unit
■Model selection table
Model No. Lens type Additional
AUD300C1000 Standard None
AUD300C100D Inspection report
AUD300C100T Tropicalization treatment
AUD300C100Y Traceability certificate
AUD300C100DT Inspection report + tropicalization treatment
AUD300C100YT Traceability certificate + tropicalization treatment
AUD300C1100 Condenser None
AUD300C110D Inspection report
AUD300C110T Tropicalization treatment
AUD300C110Y Traceability certificate
AUD300C110DT Inspection report + tropicalization treatment
AUD300C110YT Traceability certificate + tropicalization treatment
Cover mounting screws (4)
AUD Maintenance Kit
AUD60A1000
Mounting nut
Cover
Lead wires
Flange unit: 81446924-001 or -101

2
Chapter 1. OVERVIEW
Certification
•UL: File No. MH27717
•CSA: Master Report LR 078402
•CE*: Gas Appliance Directive
0063BS1427 (with AUR450C_2_____and Q241A104)
0063CN6671 (with RX-R4_C_____)
RoHS Directive
*CE marking appears to comply with RoHS
Combined burner controller
Model Name
RX-R40, RX-R44, RX-R46 Burner Control Module
AUR300C, AUR350C Advanced Ultraviolet Burner Controller
AUR450C Dynamic Self-Checking Burner Controller
Maintenance/optional parts
Model Name
AUD60A1000 AUD Maintenance Kit *1
81446924-001 Flange unit (Standard type)
81446924-101 Flange unit (Condenser type)
81447495-001 Nut packing
81447509-001 Bushing 1×3/4
FSP136A100 Analog flame meter
*1 AUD60A1000 Maintenance Kit
The AUD Maintenance Kit incorporates the tube and shutter units (tube unit: AUD10,
shutter unit: AUD50), including expendables like the expiration date label*2and the
O-ring used for sealing between the flange and cover of the AUD.
*2 Expiration date label Position of the expiration date label
Terminal G (yellow lead wire)
Terminal F (blue lead wire)
Tube unit retaining screws (2)
Shutter unit
Thermolabel
Label
Tube unit
Terminal for shutter driver connection
(white lead wire)

3
Chapter 2. MOUNTING
WARNING
Before mounting or removing, be sure to turn off the power to this device and all connected
devices. Failure to do so may result in electric shock.
If this device is installed near a source of ultraviolet rays other than the burner flame or in an
atmosphere that interferes with UV rays, as described below, take sufficient countermeasures.
•
Near sources of ultraviolet rays, such as red-hot furnace walls (1371°C or more)
•
Near sources of gamma rays or x-rays, such as diffraction analyzers, electron microscopes, x-ray
machines, high-voltage vacuum switches, high-voltage capacitors, radioactive isotopes, etc.
•
In atmospheres that interfere with ultraviolet rays, due to steam, sooty smoke, oil mist, dust, etc.
Install the flame detector at an angle that does not allow the ignition spark to be detected.
Make sure that this device does not detect ultraviolet rays other than those of the burner flame.
If it responds to other ultraviolet radiation, flame failure in the burner will not be detected.
As a result, the outflow of fuel will continue, causing a very serious explosion hazard.
CAUTION
Install this device in accordance with the relevant laws and standards.
When discarding this product, dispose of it as industrial waste, following local regulations.
Installation, wiring, inspection, adjustment, etc., should be carried out by a trained and
experienced technician with knowledge and technical skills related to combustion equipment
and flame safeguard control devices.
If this device is operated in an atmosphere where there is steam, sooty smoke, oil mist, dust, and/
or organic solvents that interfere with ultraviolet rays, take appropriate corrective measures.
When using multiple burners, mount this unit in a position where it can detect only the flame of
the burner to be monitored.
Do not install where the product will be exposed to any of the following:
•
Certain chemicals or corrosive gases (ammonia, sulfur, chlorine, ethylene compounds, acid, etc.).
•
Splashing water or excessive humidity.
•
High temperatures
•
Prolonged vibration
Be sure to observe the ambient temperature indicated in the specifications. Failure to do so may
damage the device or cause faulty operation.
What to know before installation
•For proper installation of the device, thoroughly read the instruction manuals for
the burner, boiler, and other equipment provided by the combustion equipment
manufacturers. Make an appropriate installation plan according to those instruc-
tion manuals.
•
This device must monitor actual flames. Make the mounting position of the device
as close to the flame as possible unless that position affects the equipment layout
around the burner, the operating temperature, etc. The shorter the distance between
the device and the burner nozzle, the more ultraviolet radiation can be detected.
•Mount this device away from the ignition transformer. Mount the ignition trans-
former as close to the burner as possible, and be sure to ground the transformer.

4
Chapter 2. MOUNTING
Methods of monitoring burner flame
Monitoring of the pilot flame only (continuous, intermittent pilots)
The main burner must be reliably ignited even with the smallest pilot flame that
this device can detect. For this reason, throttle the pilot manual fuel valve so that
the main burner can be barely ignited. Under this condition, adjust the device so
that only the tip of the pilot flame is monitored. Adjust the device so that the moni-
tored area is as close to the tip of the flame as possible, and is also along the axis of
the pilot flame.
Monitoring of both pilot and main flames (continuous, intermittent pilots)
Adjust the device so that it monitors the area where the pilot and the main flames
overlap.
Monitoring of main flame only (interrupted pilot)
Adjust the device so that it monitors the part of the main flame that is the most
stable in any combustion condition (low fire, high fire, etc.). In special combustion
conditions, the use of two detectors is recommended in order to monitor the low
and high fire positions separately.
Separate monitoring of pilot and main flames (continuous, intermittent pilots)
Make sure that the detector monitoring the main flame cannot mistakenly detect
the pilot flame. If it detects the pilot flame when there is a flame failure of the main
burner, the flame failure will not be detected, and the fuel supply will not be shut off.
Monitoring if there are multiple burners in the same combustion chamber
Mount a UV sensor on each burner, making sure in each case that another burner’s
flame is not detected.
Note that there is an electrical discharge inside this device’s tube unit while a flame
is detected. Since ultraviolet rays are emitted from the tube due to this electrical dis-
charge, if multiple detectors are used, their position must be adjusted so that detec-
tors cannot detect ultraviolet rays emitted from the tube unit of other detectors.
Redundant system (redundant monitoring)
Redundant monitoring is recommended to avoid unnecessary shutoff as much as
possible and to ensure the reliability of the system. A redundant system can be made
if two pairs of this device plus a burner controller are used to monitor the flame of
one burner. If either flame detector does not output a flame signal or if there is a
false flame signal, an alarm will be generated, but combustion will continue.
If both burner controllers detect a flame failure at the same time, the combustion
system will be shut down. This kind of redundant system prevents unnecessary
shutoff caused by flame fluctuation or a malfunction of this device or of the burner
controller.
Mounting position
Taking the following items into account, determine the optimal mounting position.
Temperature
Mount this unit in a place where the ambient temperature during operation is
−20to +100°C (up to 120°C during flame detection).

5
Chapter 2. MOUNTING
Handling Precautions
•If the above temperature range is not observed, a malfunction of the tube unit
or shutter unit of this device, or unnecessary shutoff, may occur.
•When this unit is not being used to detect a flame, do not allow the ambient
temperature to exceed 100°C. While power is being supplied, an ambient
temperature over 100°C causes breakdown of the insulation on the internal
coil and, when the unit resumes operation (flame detection), faulty shutter op-
eration (failure to open).
•If the actual temperature is expected to be outside of the operating tempera-
ture range, provide a shielding plate between the combustion chamber and
this device, or use air purging or the like so that the temperature is within the
operating temperature range.
Vibration
Mount the device in a location where the acceleration is 4.9m/s2or less.
Handling Precautions
•Vibration may shorten the service life of the tube unit or shutter unit, or may
cause faulty operation or malfunction.
Outdoor use
Provide a roof, etc., to protect against rain.
Handling Precautions
•The surface of the case may change color due to sunshine or other causes.
However, this will not affect the functioning of the product.
Mounting orientation
Mount this device with the opening for the electrical wiring conduit facing down-
ward, aligned in a vertical plane.
Mounting pipe
Mounting nut
Conduit tube connection port
Front side
Vertical plane mounting
Do not tilt
OK
Do not mount
horizontally
Do not
mount upside-down

6
Chapter 2. MOUNTING
The allowable range of the mounting posture is that the upper limit is 90° (conduit
tube port becomes horizontal) and the lower limit is 45°.
Vertical
plane
Upper limit 90°
Lower limit 45°
Horizontal
plane
Side
90°
45°
Handling Precautions
•Mount this device so that it monitors the burner at an angle from above. If it
monitors the burner at an angle from below or from the same level, dust, soot,
etc., will accumulate on the monitoring window or in the monitoring pipe. This
may block the ultraviolet rays, preventing flame detection.
Mounting of the monitoring pipe
Monitoring pipe materials
Use a mounting pipe with a black inside wall. If the inside wall of the pipe has a
stainless steel or electroplated surface, ultraviolet rays will be reflected irregularly
inside the pipe, causing a malfunction.
Monitoring pipe size
To detect a large amount of ultraviolet radiation from the flame, this device’s light-
receiving surface must have a wide field of view. If the recommended flame voltage
of 2.0VDC cannot be ensured, change the monitoring pipe to a wider one so that
sufficient ultraviolet radiation is received.
•Use as large a monitoring pipe as possible. Connect the pipe to the device using a
reducer.
•Make the length of the monitoring pipe as short as possible. However, always
keep the operating ambient temperature within 100°C (up to 120°C during
flame detection).

7
Chapter 2. MOUNTING
Mounting space
Leave a sufficient space for easy maintenance, inspection, and service work.
Reducing socket AUD300C
Connection
nipple (1")
Weld this
part
Burner
Plate
Tapered monitoring hole *
Furnace wall
Air
*
Tees
Monitoring pipe, 1" or more (Use 2" to 3" pipe.)
* If the air purging is needed, tees are
used to supply the air.
Handling Precautions
•Mount this device so that it monitors the burner at an angle from above. If it
monitors the burner at an angle from below or from the same level, dust, soot,
etc., will accumulate on the monitoring window or in the monitoring pipe. This
may block the ultraviolet rays, preventing flame detection.
•Mount this device so that its monitoring orientation intersects the flame
axis at as small an angle as possible. This maximizes the overlap between the
flame and the area monitored by the device. Thus, the amount of detected ul-
traviolet rays also increases.
Flame surface area monitored is small.
Unburnt fuel
Flame surface area monitored is large and much ultraviolet radiation is detected.
Burner
Good sighting position
(low angle sighting)
Poor sighting position

8
Chapter 2. MOUNTING
Temporary welding for monitoring pipe positioning
(1) Preparing a monitoring pipe and making the mounting hole
Make the mounting hole at the selected location for the monitoring pipe. Cut
threads on one end of the monitoring pipe and cut it to the desired length,
making it as short as possible.
(2) Welding the monitoring pipe temporarily
Weld the monitoring pipe temporarily to the
plate of the combustion chamber of the
boiler, etc. Do not weld the monitoring pipe
completely at this time, because inspection
and adjustment are required for
successful flame detection.
(3) Carry out the air purging of the monitoring pipe.
The air purging of the inside of the monitoring pipe is useful to cool this unit
and keep the monitoring area clean.
In particular, if the ambient temperature of this unit exceeds 120°C, the cool-
ing, such as air purging is needed.
•If the inside of the furnace is a type of induction, make an air purging hole
in the monitoring pipe.
•If the forced type furnace is used, connect an air purging supply pipe.
Mounting procedure
When mounting the AUD300C on a monitoring pipe, proceed as follows:
Check item
File the monitoring pipe in advance to eliminate burrs and protrusions.
Mounting
(1) Hold the unit securely with one hand to prevent it from rotating.
(2) Tighten the mounting nut approximately 4 turns with the other hand until the
unit is held securely in place.
(3) Make sure the unit is properly aligned in the vertical plane when viewed from
the front. ( Mounting orientation (P.5))
Handling Precautions
•
Be sure the AUD300C is properly aligned vertically when seen from the
front. If not, the shutter in the shutter unit may be damaged or malfunction.
•If this unit is not mounted correctly, this may cause the shutter of the shut-
ter unit to be damaged or malfunction.
•File any burrs or protrusions from the monitoring pipe. If the packing in the
mounting nut is damaged, any chance of leakage may be caused.
•Do not use a tool such as pipe wrench when
tightening the mounting nut. Excessive
torque by a tool could damage the packing
and compromise the seal.
•Do not adjust the mounting pose by forcibly
holding the unit or wiring pipe. Failure to do so may damage the packing
and compromise the seal.
Plate
Monitoring pipe
Temporary
welds
Furnace wall
(refractories)

9
Chapter 3. WIRING
WARNING
Before doing any wiring work, be sure to disconnect the equipment power to prevent electrical
shock.
When measuring the voltage between terminal F and terminal G of this device in order to check
the wiring, do not touch any part of the terminals. Doing so may result in an electric shock.
CAUTION
Installation, wiring, inspection, adjustment, etc., should be carried out by a trained and
experienced technician with knowledge and technical skills related to combustion equipment
and flame safeguard control devices.
Be sure to route the signal wires of this device separately from high-voltage ignition transformer
cables and power cables, and put them in a separate conduit.
Wiring diagram
White
Shutter output
terminal
White
Yellow (G)
(F)
Blue
AUD300C
Run all wires connected to the burner controller through wiring conduits and con-
duit boxes. Also, be sure to route power wiring to the controller separately from
other power wires.
Handling Precautions
•Do not run the wiring to this device in the same wiring conduit as power
lines or high voltage cables from the ignition transformer.
•Put high-voltage ignition transformer cables and the ground wire in the
same conduit, and ground one end of the conduit. If an automotive spark
plug is used, pay special attention to wiring.
•If the surge from the ignition transformer adversely affects the detector,
ground both ends of the conduit between the detector and the burner
controller, or change the cable routing.

10
Chapter 3. WIRING
Wiring check
Before applying voltage to this device, check that the wiring is correct.
Steps
(1) In the relay box, disconnect the blue and yellow wires that come from the
AUD300C.
(2) Turn on the power to the burner controller.
(3) Measure the DC voltage between terminals F and G in the relay box using a
circuit tester or a digital voltage meter.
(4) Connect the + tester probe to terminal G (yellow wire) and the – tester probe
to terminal F (blue wire).
>> If the reading is between 160 and 220 V DC, the leads are connected cor-
rectly. If a negative voltage is measured, terminals F and G are reversed.
(5) Next, measure the DC voltage (shutter voltage) between terminals S1 and S2
(both wires are white).
Handling Precautions
•Terminals S1 and S2 do not have a specified polarity. When using a mul-
timeter, before measuring the shutter voltage, check the polarity using
a wide voltage range so that the needle does not go off the scale on the
minus side.
>> If the reading is between 15 and 24VDC, the leads are connected cor-
rectly.*If the meter indicates a constant voltage, either 24 or 0VDC, the
cause is probably a wiring mistake.
* If there is a flame, the shutter voltage fluctuates within the 0–24VDC range.
(6) In the relay box, reconnect the blue and yellow wires that come from the
AUD300C one minute or longer after the power to the burner controller has
been turned OFF.
Handling Precautions
•Terminals F and G retain an electrical charge for about 1 minute after the
power has been turned off. Within this time, touching terminal F or G may
result in electric shock.

11
Chapter 4. ADJUSTMENT
Before measuring the flame voltage
Before measuring the flame voltage, execute an operational check of this device
using the flame voltage output terminals of the burner controller.
Model No. Flame voltage output terminals
AUR300C
AUR350C
Terminal 9 (+)
Terminal10 (−)
AUR450C Positive terminal, Negative terminal
(1) Connect an analog flame meter (FSP136A100) to the flame voltage output ter-
minals of the burner controller.
(2) Light a lighter in front of the ultraviolet ray receiving part of this unit to check
that the voltage is output correctly.
Handling Precautions
•Before using fire, check that there is no flammable gas around this device.
Measuring the flame voltage
If there are both pilot and main flames, measure the voltage of each. Measure the
flame voltage for the maximum (high fire) and minimum (low fire) combustion.
(1) Mount this device on the monitoring pipe temporarily.
(2) Start burner combustion.
(3) To determine an optimal monitoring position, measure the flame voltage of
the burner controller with the analog flame meter (FSP136A100) while mov-
ing the monitoring pipe position little by little in order to find a position where
as highly stable voltage as possible is shown.
Recommended flame voltage Inspection item
The flame voltage must be stable at
2.0VDC or more.
(It may fluctuate in a range of 0.1–0.3V
synchronized with the shutter operation
of this device.)
•Is the flame properly monitored?
•Is the detector’s light-receiving lens clean?
•Is there accumulated soot, etc., in the
monitoring pipe?
Handling Precautions
•If the flame voltage exceeds 4V, install an orifice to limit the amount of ultra-
violet radiation. If the amount of ultraviolet radiation is too large, UV rays may
enter the tube unit due to diffuse reflection even when the shutter is closed,
causing a malfunction.

12
Chapter 4. ADJUSTMENT
Pilot turndown test
This test is intended to check that any pilot flame detected by this device will reli-
ably ignite the main burner, even if the gas pressure and air pressure have changed
to their worst possible conditions.
WARNING
To prevent explosion, carry out the pilot turndown test carefully. If this device detects a pilot
flame that is too small to ignite the main burner, the burner controller will not be able to
recognize flame failure of the main burner, allowing the outflow of fuel to continue, leading to a
serious explosion hazard.
If the pilot turndown test is carried out repeatedly, completely shut down all equipment each
time the test is finished, and completely discharge unburned gas or fuel that has accumulated
in the combustion chamber and flue. If unburned gas and oil are not discharged completely, an
explosion may occur.
CAUTION
Installation, wiring, inspection, adjustment, etc., should be carried out by a trained and
experienced technician who has knowledge and technical skills related to combustion
equipment and flame safeguard control devices.
Only an experienced technician who has knowledge and technical skills related to combustion
equipment and combustion safety should carry out the pilot turndown test.
For the pilot turndown test procedure, follow the user’s manual of the burner con-
troller used with this device or the instruction manual provided by the combustion
equipment manufacturer.