PT2E-15916

Furnace Gas Monitor

SD-2500
Operating Manual(PT2E-159)(PT2-159)0Operating Precautions
This gas monitor is a gas detector that detects combustible gases in the air and triggers a gas alarm.
The gas detector is a safety unit, not an analyzer or densitometer which performs quantitative/qualitative
analysis/measurement for gases.
Please fully understand the following points before using it, so that it can be used properly.
1.

This gas monitor may be interfered by gases and vapors other than the gas to be detected.
Please note that the alarm may be triggered by interference. In addition, it may be fluctuated byenvironmental (temperature, humidity, etc.) changes in the installation site.

2.

The alarm must be set within a range where the performance of the gas monitor can be ensured.
In facilities compliant with the High Pressure Gas Safety Act, an alarm setting below our standard alarm
setpoint may trigger a false alarm.

3.

This is a safety unit, not a control unit.
The alarm contact output of the gas monitor must be used for an external alarm lamp/buzzer, while theanalog signal output must be used for an indicator or external recorder. If these outputs are used tocontrol other units, we shall not be responsible for any malfunctions.

4.

The gas sensing part of the gas detection sensor installed in this gas monitor is made of metal porous
sintered alloy permeated with an oxidation catalyst.
If silicon or sulfide compounds are accumulated on the surface of porous sintered alloy, the area of thegas sensing part becomes smaller, which may results in serious deterioration of its sensitivity.
For safety reasons, do not use the gas monitor under the presence of silicon or sulfide compounds
even though their amount is very small.

5.

For maintenance of the gas monitor, it must go through a regular maintenance, including replacement
and adjustment of the regular replacement parts as specified in the operating manual. In addition,
because this is a safety unit, it is recommended that a regular maintenance and a gas calibration are
performed every six months in accordance with the regulations.

-1-

SD-2500

<Contents>

0

1
1-1.
1-2.
1-3.
1-4.

Outline of the Product .............................................................................................. 1
Preface .................................................................................................................... 1
Purpose of use ........................................................................................................ 1
Definition of DANGER, WARNING, CAUTION, and NOTE ..................................... 2
Method of confirmation for Standards and Explosion proof specification................. 2

2
2-1.
2-2.
2-3.
2-4.

Important Notices on Safety .................................................................................... 3
Danger cases .......................................................................................................... 3
Warning cases ......................................................................................................... 3
Precautions ............................................................................................................. 4
Safety Information ................................................................................................... 4 4

3
3-1.
3-2.
3-3.

Product Components ............................................................................................... 6
Main unit and standard accessories ........................................................................ 6
Names and functions for each part .......................................................................... 7
Block diagram .......................................................................................................... 8

4
4-1.
4-2.
4-3.
4-4.
4-5.

How to Use .............................................................................................................. 9
Before using the gas monitor................................................................................... 9
Precautions for installation points ............................................................................ 9
Precautions for system designing ............................................................................ 10
How to install ........................................................................................................... 13
How to wire.............................................................................................................. 14

5
5-1.
5-2.
5-3.
5-4.
5-5.
5-6.

How to Operate ....................................................................................................... 19
Preparation for start-up............................................................................................ 19
Basic operating procedures ..................................................................................... 19
How to start the gas monitor.................................................................................... 20
Modes...................................................................................................................... 21
User mode ............................................................................................................... 22
How to exit............................................................................................................... 24

6
6-1.
6-2.
6-3.
6-4.

Operations and Functions ....................................................................................... 25
Gas alarm activation ................................................................................................ 25
Fault alarm activation .............................................................................................. 26
External output operation ........................................................................................ 27
Other functions ........................................................................................................ 28

7
7-1.
7-2.
7-3.
7-4.

Maintenance ............................................................................................................ 29
Maintenance intervals and items ............................................................................. 29
Regular maintenance mode .................................................................................... 31
Gas calibration method............................................................................................ 38
Parts replacement ................................................................................................... 40

8
8-1.
8-2.
8-3.

Storage, Relocation and Disposal ........................................................................... 41
Procedures to store the gas monitor or leave it for a long time ............................. 41
Procedures to relocate the gas monitor or use it again ........................................... 41
Disposal of products ................................................................................................ 41

9

Troubleshooting ....................................................................................................... 42

10
10-1.
10-2.
10-3.

Product Specifications ............................................................................................. 44
List of specifications ................................................................................................ 44
List of accessories ................................................................................................... 47
Detection principle ................................................................................................... 48

11

Definition of Terms ................................................................................................... 49

1 Outline of the Product1-1. Preface

1

Outline of the Product1-1. Preface
Thank you for choosing our furnace gas monitor SD-2500. Please check that the model number of the
product you purchased is included in the specifications on this manual.
This manual explains how to use the gas monitor and its specifications. It contains information required forusing the gas monitor properly. Not only the first-time users but also the users who have already used the
product must read and understand the operating manual to enhance the knowledge and experience before
using the gas monitor.
Product specifications may be abbreviated in this document as follows.
Japan Ex specification ： Japan specification
ATEX / IECEx specification ： Export specification

1-2. Purpose of use
 The gas monitor is a fixed type detector head that continuously detects combustible gases and that
performs the alarm activation when the gas concentration is over the setting value.
This gas monitor is a safety unit, not an analyzer or densitometer which performs quantitative/qualitative
analysis/measurement for gases. Please fully understand the features of the gas monitor before using it, sothat it can be used properly.
 The gas monitor detects abnormalities in the air caused by presence of gases or other reasons (leak) withthe built-in gas sensor. The concentrations of detected gases are displayed on the seven-segment LED.
 The gas monitor has a built-in alarm contact and can be used either as a gas alarm, fault alarm, or common(gas, fault) alarm.
 The gas monitor outputs gas concentration in 4 – 20 mA.

SD-2500-1-

1 Outline of the Product1-3. Definition of DANGER, WARNING, CAUTION, and NOTE

1-3. Definition of DANGER, WARNING, CAUTION, andNOTE
DANGERWARNINGCAUTION
NOTE

This message indicates that improper handling may cause serious
damage on life, health or assets.
This message indicates that improper handling may cause serious
damage on health or assets.
This message indicates that improper handling may cause minor
damage on health or assets.
This message indicates advice on handling.

1-4. Method of confirmation for Standards andExplosion proof specification
This instrument has some specification depends on standard and explosion proof certificate. Pleaseconfirm the detector specification before using. Please refer Declaration of Conformity that is at the end of
this manual if you have CE marking type.
You can confirm instrument specification to see name plate as follows.
Ex marking

Japan Ex certificate
CE marking

ATEX/IECEx, CE marking type name plateSD-2500

Japan Ex type name plate-2-2 Important Notices on Safety

2-1. Danger cases

2

Important Notices on
Safety2-1. Danger cases
DANGER<About explosion-proof> The window plate material is a polycarbonate resin. Do not use organic solvents and alkali types(liquid or vapor). It may cause the color and shape of the window plate to be changed.
 Do not open the lid when applying current.
 Do not attempt to repair the detector.
 For the lid, use hexagon socket head bolts specified by RIKEN KEIKI.
 Do not apply a strong force or shock to the window plate. The explosion-proof performances may be
deteriorated due to damages. The explosion protection conditions for the detector is "low (2J)"
possibility of mechanical damage.
 Do not repair the explosion-proof joint surface.

2-2. Warning cases
WARNING
Power supply
Before turning on the gas monitor, always check that the voltage is properly applied. Do not use an
unstable power supply because it may cause malfunctions.
Need of grounding circuit
Do not cut the grounding circuit or disconnect the wire from the grounding terminal.
Defects in protective functions
Before starting the gas monitor, check the protective functions for defects. When seeming defects arefound in the protective functions, such as protective grounding, do not start the gas monitor.
External connection
Before connecting the gas monitor to the external control circuit, securely connect it to a protective
grounding circuit.

-3-

SD-2500

2 Important Notices on Safety

2-3. Precautions

WARNING
Zero adjustment in the atmosphere
When the zero adjustment is performed in the atmosphere, check the atmosphere for freshness before
beginning the adjustment. If other gases exist, the adjustment cannot be performed properly, thus
leading to dangers when the gas leaks.
Response to a gas alarm
Issuance of a gas alarm indicates that there are extreme dangers. Take proper actions based on yourjudgment.

2-3. Precautions
CAUTION
Do not use a transceiver near the gas monitor.
Radio wave from a transceiver near the gas monitor or its cables may disturb indication reading. If atransceiver is used, it must be used in a place where it disturbs nothing.
To restart the gas monitor, wait for five seconds or more before doing it.
Restarting the gas monitor within five seconds may cause errors.
Do not use the external output of the gas monitor to control other units.
This is not a control unit. It is not allowed to use the external output of the gas monitor to control otherunits.
Do not disassemble/modify the gas monitor, or change the settings if not necessary.
Disassembling/Modifying the gas monitor will invalidate the warranty of the performance. Changing thesettings without understanding the specifications may cause alarm malfunctions. Please use the gas
monitor properly in accordance with the operating manual.
Avoid applying organic solvents and others to the window plate for a long time.
The window plate material is a polycarbonate resin. When organic solvents (liquid or highly-concentrated
vapor) and others are applied to the plate for a long time, its color and shape may be changed.
The zero adjustment in the furnace
After the furnace becomes the operating temperature, perform the zero adjustment carry out after one
hour.
Do not forget to perform a regular maintenance.
Since this is a safety unit, a regular maintenance must be performed to ensure safety. Continuing to use
the gas monitor without performing a maintenance will deteriorate the sensitivity of the sensor, thus
resulting in inaccurate gas detection.

SD-2500-4-

2 Important Notices on Safety

2-4. Safety Information

2-4. Safety Information
Necessary information for explosion proof construction of Model SD-2500.
<ATEX/IECEx Specification>
The Model SD-2500 is a fixed mount, continuous-monitoring detector head and provides a 4-20mA signal
which indicates the target gas reading for use by a gas monitoring controller, recording device, or
programmable controller.
There is one relay, and the relay is used for the gas alarm or the fail alarm.
Technical Data
(Protection Method)

Flameproof enclosure “d”(Certificate Numbers)

IECEx DEK 11.0040X
DEKRA 11ATEX0095 X(Group)II(Category)

2G(Type of Protection and Marking code)

Ex db IIC T3(Equipment Protection Level)

Gb(Ambient Temperature)-20C to +60C(Process Temperature)-20C to +160C(Electrical Data)

Supply voltage: 24 V dc (Typ.)
Output signal: 4 to 20 mA(Applicable Standard)

IEC 60079-0: 2017，IEC 60079-1: 2014
EN IEC 60079-0: 2018，EN 60079-1: 2014

(Manual Number)

PT2E-159

Installation

Hazardous Location(Zone 1)

Installation Diagram
Nonhazardous Location←→
Indicator

Gas Detector(SD ‐2500)＋＋－－
SignalCVVS Cable＋－
SignalContacts

Contacts-5-SD-2500

3 Product Components

3-1. Main unit and standard accessories

3

Product Components
3-1. Main unit and standard accessories<Main Unit> (including a cable gland)<Standard Accessories>






Operating manual
Dedicated handling lever (used for the wiring)
Dedicated control key
Flange gasket
Exhaust air direction nameplate

CAUTION
Use the supplied dedicated control key to operate the gas monitor. If products other than theseaccessories are used, key operations cannot be accepted properly.

SD-2500-6-

3 Product Components

3-2. Names and functions for each part3-2. Names and functions for each part

(5) Power lamp

(6) Alarm lamp

(7) Fault lamp(3) ▲ key(1) MENU/ESC key(8) Concentration
value display(4) ▼ key(2) SET key(1)

MENU/ESC key(2)

SET key

(3)
(4)

 key
 key

(5)

Power lamp

(6)

Alarm lamp

(7)

Fault lamp

(8)

Concentration value
display

Used to enter the maintenance mode.
It is also used to cancel in a specific mode.
It is used for value confirmation and so on in a specificmode.
Used to switch menus or change a value (UP).
Used to switch menus or change a value (DOWN).
Power lamp
Detection mode: It lights up in green.
Maintenance mode: It blinks in green.
Alarm lamp. It lights up in red when the alarm setpoint value
is reached.
Fault lamp. It lights up in yellow when an abnormality isdetected in the gas monitor.
Displays the gas concentration and so on.

-7-

SD-2500

3 Product Components

3-3. Block diagram

3-3. Block diagram<Electric Diagram>

Power supply part
POWER INPUT (24 VDC)
Display(POWER) (ALARM) (FAULT)

Alarm contact controller

Controller(CPU)

Gas alarm contact (ALARM)
Contact activation• De-energized(De-energized at a
normal environment)• ON-ALARM(Closed contact at an
alarm time)Seven-segment LED(four-digit)
Magnetic operation part
(MENU/ESC) (▲) (▼) (SET)

SensorTransmitter• 4 – 20 mA transmission

SD-2500-8-

4 How to Use

4-1. Before using the gas monitor

4

How to Use
4-1. Before using the gas monitor
Not only the first-time users but also the users who have already used the product must follow the operating
precautions.
Ignoring the precautions may damage the gas monitor, resulting in inaccurate gas detection.

4-2. Precautions for installation points
CAUTION
This is a precision device. Because the gas monitor may not provide the specified performance in someplaces (environments), check the environment in the installation point, and then take appropriate actions
if necessary.
Because the gas monitor plays an important role for safety and disaster prevention, as many units of thegas monitor as needed must be installed in appropriate points.
Because points where gases leak and remain easily are different depending on the types of gases andthe working areas, please decide carefully on installation points and the number of units to be installed.
Do not install the gas monitor in a place with vibrations or shocks.
The gas monitor consists of sensitive electronic parts. The gas monitor must be installed in a stable place
without vibrations or shocks and it cannot drop.
Do not install the gas monitor in a place exposed to water, oil or chemicals.
When selecting installation points, avoid a place where the gas monitor is exposed to water, oil orchemicals.
Install the gas monitor in a place with operating environment temperatures that meet the following
requirements:<Export Specification>
Main unit case part:The detector head must be installed in a stable place where the operating temperature is 0 to +50C and
do not change suddenly.
Gas sensor part: 0 to +160C<Japan Specification>
Main unit case part:The detector head must be installed in a stable place where the operating temperature is -20 to +60Cand do not change suddenly.
Gas sensor part: 0 to +160C-9-

SD-2500

4 How to Use

4-3. Precautions for system designing

Do not install the gas monitor in a place exposed to direct sunlight or sudden changes in the temperature.
When selecting installation points, avoid a place where it is exposed to direct sunlight or radiant heat
(infrared rays emitted from a high-temperature object), and where the temperature changes suddenly.
Condensation may be formed inside the gas monitor, or the gas monitor cannot adjust to sudden changes
in the temperature.
Keep the gas monitor (and its cables) away from noise source devices.
When selecting installation points, avoid a place where high-frequency/high-voltage devices exist.
Do not install the gas monitor in a place where maintenance of the gas monitor cannot be performed orwhere handling the gas monitor involves dangers.
Regular maintenance of the gas monitor must be performed.
Do not install the gas monitor in a place where the machinery must be stopped when maintenance isperformed in its inside, where parts of the machinery must be removed to perform maintenance, or where
the gas monitor cannot be removed because tubes or racks prevent access to it. Do not install the gas
monitor in a place where maintenance involves dangers, for example, near a high-voltage cable.
Do not install the gas monitor in machinery which is not properly grounded.
Before installing the gas monitor in machinery, the machinery must be grounded properly.
Do not install the gas monitor in a place where other gases exist around it.
The gas monitor must not be installed in a place where other gases exist around it.

4-3. Precautions for system designing
CAUTION
An unstable power supply and noise may cause malfunctions or false alarms.
The descriptions in this section must be reflected on the designing of a system using the gas monitor.
Using a stable power supply
The external output and alarm contact of the gas monitor may be activated when the power is turned on,when momentary blackout occurs, or when the system is being stabilized. In such cases, use a UPS, ortake appropriate actions on the receiving side of output signals.
The gas monitor must be provided with the following power supply.
Power supply
voltageAllowed time of
momentary blackout

Others24 VDC±10%: Terminal voltage of the gas monitor
Up to 10 milliseconds(To recover from the momentary
blackout for 10 milliseconds or more,restart the gas monitor.)
Do not use it with a power supply oflarge power load or high-frequency
noise.

Example of actions
To ensure continuous operation andactivation, install a UPS outside thegas monitor.
Example of actions
Use a line filter to avoid the noise
source if necessary.

Introducing protective measures against lightning
If cables are installed outside the factory/plant, or if internal cables are installed in the same duct as the cables
coming from outside the factory/plant, "lightning" will cause problems. Because lightning acts as a large emission
source while cables act as a receiving antenna, devices connected to the cables may be damaged.
Lightning cannot be prevented. Cables installed in a metal conduit or under the ground cannot becompletely protected from inductive lightning surge caused by lightning. Although complete elimination ofdisasters caused by lightning is impossible, the following protective measures can be taken.

Protection against
lightning

SD-2500

Take appropriate measures in accordance with the importance of the facilities
and the environment.
 Provide protection by a lightning arrester (cable arrester).
(Although inductive lightning surge can be transmitted through the cable, it is- 10 -

4 How to Use

Grounding

4-3. Precautions for system designing
prevented by installing a lightning arrester before the field devices and central
processing equipment. For information on how to use a lightning arrester,
please contact the manufacturer.)
In addition to lightning, there are more sources of surge noise. To protect units
from these noise sources, the units must be grounded.

* The lightning arrester has a circuit to remove a surge voltage which damages field devices, so that signals
may be attenuated. Before installing a lightning arrester, verify that it works properly.
Proper use of alarm contact
The alarm contact of the gas monitor is used to transmit signals to activate an external buzzer, an alarm
lamp or a rotating lamp. Do not use the gas monitor for controlling purpose (e.g., controlling the shutdown
valve.)CAUTIONThe b contact (break contact) under de-energized state may be opened momentarily by a physicalshock, such as external force.
When the b contact is selected for the alarm contact, take appropriate actions to prepare for a
momentary activation, for example, add signal delay operation (approximately one second) to thereceiving side of the b contact.

The specifications for the alarm contact of the gas monitor are based on the resistant load conditions. If
inductive load is used at the alarm contact, the following errors will occur easily because counterelectromotive force is generated at the contact.
 Deposition, defective insulation or defective contact at the relay contact
 Damage of any electric parts due to high-voltage generated inside the gas monitor
 Abnormal operations by an out-of-control CPU

CAUTION In principle, do not activate inductive load at the alarm contact of the gas monitor. (In particular, never
use the inductive load to activate a fluorescent lamp or motor.) If inductive load is activated, relay it with an external relay (contact amplification). However, because
the coil of an external relay also involves inductive load, select a relay at a lower voltage (100 VAC or
below), and then protect the contact of the gas monitor with an appropriate surge absorbing part, suchas a CR circuit.
If load is to be activated, appropriate measures must be taken to stabilize the operation of the gas monitor
and protect the alarm contact referring to the following information.
 Relay it with an external relay at a lower voltage of 100 VAC or below (contact amplification). At the sametime, the surge absorbing part SK1 suitable for the specifications must be attached to the external relay.
 In addition, the surge absorbing part SK2 must be attached to the loaded side of the external relay ifnecessary.
 It may be recommended that the surge absorbing part should be attached to the contact for certain loadconditions. It must be attached to an appropriate position by checking how the load is activated.

- 11 -

SD-2500

4 How to Use

4-3. Precautions for system designing

SD-2500(Low voltage relay)

SD-2500- 12 -

4 How to Use

4-4. How to install

4-4. How to install<Maintenance Space><How to fix the windscreen>

NOTE

Exhaust air

When performing maintenance,
installation/de-installation is required in
the direction shown below.
Do not cover installation flange by heatinsulator etc.

Installation flange

Exhaust air
direction nameplate

Windscreen

Bolt for fixing
the windscreen

Lid
Installation/de-installation direction

WARNING

Furnace wall

When the detector head is to be installed in a furnace,make sure that the exhaust air hits the windscreen where it
is installed.
Securely fix the windscreen with bolts for fixing it.
After the gas detector head is installed, affix the supplied"exhaust air direction nameplate" on the surface of the lid.

Space required to attach/detach a gas detector head
Recommendation 1000

<How to Install>
Main unit case
Windscreen

Lid

Housing(For M12)

A-A cross-section (Flange installation hole)
Reference line 2

Reference line 1

Ambient temperature to
the left of Reference Line
2 in the furnace (gassensor part):0-160℃(Length of part inserted into the furnace)

Ambient temperature to theright of Reference Line 1
outside of the furnace (mainunit case part):0-50℃

Welded all roundGas sensor part

GasketExternal cable inlet part for
power supply and signals

WARNING
Install at the place of
furnace wall where
sealing can be doneby gasket etc.

Installation flange
Furnace wall

Over 150

CAUTION

NOTE

When performing maintenance,
de-installation is required in the direction
shown above.
In case of installing conduit, use the flexible
conduit.

For higher accuracy measurement, set the gas sensor
part to the place where is over 150mm inside frominternal wall of furnace.

- 13 -

SD-2500

4 How to Use

4-5. How to wire

4-5. How to wire
CAUTION Be careful not to damage the internal electronic circuit when wiring. In addition, be careful not to apply
stresses on the gas monitor when (overweight) cables are installed.
 The power cables and signal cables must not be installed together with the motor power cables, etc.
When these cables must be installed together for unavoidable reasons, put the power cables andsignal cables in a metal conduit. The conduit must be connected to a grounding circuit.
 When stranded wires are used, prevent wires from contacting each other.
 Use the dedicated handling lever to wire.

<Recommended Cable>
3-wire (when the contact is not used)
5-wire (when the contact is used)

CVVS1.25 mm2 - 3-core
CVVS1.25 mm2 - 5-core<Parts. length table of outside conductor lead-in>
The parts for the external cable inlet are different from specifications. Use the appropriate parts, referringto the following lists.

Export Specification
Cable overall outer
diameter(mm)Rubber seal innerdiameter(mm)Washer innerdiameter(mm)Clamp innerdiameter(mm)From Φ9.6 to less than Φ10.5

Φ11

Φ12

Φ10.8

From Φ10.5 to less than Φ11.5

Φ12

Φ12

Φ11.8

From Φ11.5 to less than Φ12.5

Φ13

Φ14

Φ12.8

From Φ12.5 to less than Φ13.0

Φ13.5

Φ14

Φ13.8

Rubber seal innerdiameter(mm)Washer innerdiameter(mm)From Φ9.6 to less than Φ11.0

Φ11

Φ12

From Φ11.0 to less than Φ11.5

Φ12

Φ12

From Φ11.5 to less than Φ12.0

Φ12

Φ14

From Φ12.0 to less than Φ13.0

Φ13

Φ14

Φ13.0

Φ13.5

Φ14

Japan Specification
Cable overall outer
diameter(mm)SD-2500- 14 -

4 How to Use

4-5. How to wire

φ23

<Figure of Terminal Plate>

24 VDC

4 - 20mA

DC+

1- (Common)

2

Sig+

3

Contact

4

Contact

5

Groundingterminal<Specifications of Terminal Plate>Specifications of terminal plate Rated voltage: 250 VAC
 Rated current: 12 A
However, it depends on cables to be used.
Connection conditions
 Cables: 0.08 - 2.5 mm2
 Bare wire length: 8 - 9 mm
 Connecting tool: Dedicated handling lever (accessory)- 15 -

SD-2500

4 How to Use

4-5. How to wire

CAUTION
The specified bare wire length must be observed when the wire insulation is peeled off.
Improper clamping of the wire due to a shorter bare wire length may cause defective electric conduction
or heating.
Catching the wire insulation due to a shorter bare wire length may cause defective electric conduction or
heating.
Exposing the wire due to a longer bare wire length may cause defective insulation or a short circuit.
Be careful not to break up the wire.If the wire is broken up when inserted to the terminal, this may cause
defective insulation or heating.

8 - 9 mm

Compatible bar terminal
For a bar terminal, the following items are available.
 Bar terminal (ferrule): Model 216 Series (manufactured by WAGO)
 Crimping tool: Model VarioCrimp 4 (206-204) (manufactured by WAGO)

CAUTION
A bar terminal of the specified model must be used. Using other bar terminals invalidates the warranty ofthe performance.

<How to Connect to Terminal Plate>
When cables are connected to the connectors, use the dedicated lever or a flathead screwdriver to do it asshown below.

CAUTION
The right tools must be used.
In principal, one wire can be connected to one wiring hole.
When the wire is inserted into the driver slot by mistake, it does not contact the conductive part. This may
cause defective electric conduction or heating.
When the wire is inserted under the spring by mistake, it does not contact the conductive part. This may
cause defective electric conduction or heating.

NOTE<How to Use the Dedicated Handling Lever>Push the lever with your finger
to lower the spring in its inside.

While holding down the lever, insert the wire
into the (round) wiring hole until it reaches thedeepest point.

To check whether the wire is connected securely, pull the wire gently. (Do not pull the wire strongly.)

SD-2500- 16 -

4 How to Use

4-5. How to wire

<Attaching External Cable>
The way to attach the external cable is different from specifications. Attach the external cable appropriately,referring to the following information.
Export Specification
Attach the parts in the following order: cable grand, eccentric washer, washer, and rubber seal to thecable, then connect the cable into the main unit and screw the cable gland to tighten the rubber seal.
Japan Specification
Attach the parts in the following order: cable grand, washer, and rubber seal to the cable, then connect
the cable into the main unit and screw the cable gland to tighten the rubber seal.

Below 1.5mm（Japan Specification）

CAUTION

 Export Specification:
Ensure the tightening torque for the cable gland and seal plug to be 40 N･m or larger.
 Japan Specification:
Tighten a cable gland with a tool until a clearance between the cable gland and a main unit caseis below 1.5 mm.
 If it is difficult to tighten the cable gland, grease its screw part and then tighten it with the tool.

- 17 -

SD-2500

4 How to Use

4-5. How to wire

<Grounding>Connect the gas monitor to your grounding terminal with the external terminal.

WARNING
Before turning on the gas monitor, do not forget to connect it to a grounding terminal.
For stable operation of the gas monitor and safety, it must be connected to a grounding terminal. Do notconnect the grounding wire to a gas pipe.
The grounding must be made as D type grounding (below 100 Ω of grounding resistance).

<Wiring Example>
Connecting to the indicator

SD-2500
1 2 3 4 5
RM-593, etc.
+24 V
GND
Sig

Connecting to the upper unit (DCS, PLC)
SD-2500
1 2 3 4 5Power supply(24 VDC)

Relay terminal
plate

+
-

Upper unit
(DCS, PLC)+

SD-2500- 18 -

5 How to Operate

5-1. Preparation for start-up

5

How to Operate
5-1. Preparation for start-up
Before supplying power, read and understand the following precautions. Ignoring these precautions may
cause an electric shock or damage the gas monitor.
 Connect the gas monitor to a grounding circuit.
 Check that the wiring is connected to external device properly.
 Check that the power supply voltage is compliant with the specifications.
 Because the external contact may be activated during the adjustment, take measures to prevent anactivated contact from having influences on external device.

5-2. Basic operating procedures
Normally, the detection mode is activated after the power is turned on.

LED

MENU/ESCMENU/ESC

LED

LED

LED

LED

- 19 -

SD-2500

5 How to Operate

5-3. How to start the gas monitor

WARNING
When the gas monitor enters other mode from the detection mode while an alarm is activated, the alarmis reset.

5-3. How to start the gas monitor
 Before supplying power (24 VDC) to the gas monitor, check that the gas monitor is installed properly.
 Supply power (24 VDC) to the gas monitor (turn on the gas monitor).
 After the gas monitor completes the start-up, it enters the detection mode swiftly.

CAUTION Do not turn off the gas monitor during the initial clear. The gas monitor is reading the internal memory
during the initial clear.
 After the warm-up is completed, perform a gas calibration.

NOTE<<Start-up Operation Procedures>> (approximately 25 seconds for system check of the gas monitor and alarmdeactivation)
Power on -> Initial clear (approximately 25 seconds) -> Detection mode

LED

SD-2500- 20 -

5 How to Operate

5-4. Modes

5-4. Modes
Details on each mode are provided as follows.

CAUTION Do not change the settings if not necessary. Changing the settings without understanding thespecifications may cause malfunctions.

Mode
Detection
Mode
MaintenanceMode(User)

Item-

LED display
Gas
concentration

Details
Normal state

ROM/SUM Display

1-0

Zero Adjustment
Setting Display
Switch to maintenance
mode

1-1
1-2

Display the program version and others.
This is not typically used by the user.
Perform the zero adjustment.
Display various setting values.

1-3

Switch to the regular maintenance mode.

Test Mode

2-0

Zero Adjustment
Span Adjustment
Zero/Span Initialization

2-1
2-2
2-3

Environmental Setting

2-4

Display

2-5

Switch to factory mode
Switch to user mode

2-6
2-7

Perform various tests.
2-0.0 Gas Test
2-0.1 Alarm Test
2-0.2 Fault Test
2-0.3 LED Test
2-0.4 Memory Test
Perform the zero adjustment.
Perform the span adjustment.
Initialize zero/span values.
Used for various environmental settings.
2-4.0 Sensor Power Supply ON/OFF
2-4.1 INHIBIT Setting
2-4.2 Alarm Setpoint Setting
2-4.3 Alarm Delay Time Setting
2-4.4 Alarm Pattern Setting
2-4.5 Zero Suppression Pattern Setting
2-4.6 Zero Suppression Value Setting
2-4.7 Alarm Contact Specification Setting
2-4.8 Energized/De-energized Contact
Setting
2-4.9 Maintenance Mode External Output
Setting
2-4.A External Output Setting
2-4.B Alarm Test External Output Setting
2-4.C Sensor Operation Start Setting
2-4.D Password Setting
2-4.E Sensor Fault Alarm Pattern Setting
Display various electrical settings.
This is not typically used by the user.
Not used
Returns to the user mode.

Maintenance
Mode(Regularmaintenance)- 21 -

SD-2500

5 How to Operate

5-5. User mode

5-5. User mode
WARNING
After the adjustment is completed, never fail to press MENU/ESC key to return to the detection mode.
(If the gas monitor remains in the user mode, it automatically returns to the detection mode in ten hours.)

LED

Detection Mode
Press the MENU/ESC key forthree seconds.

User Mode
1-0. ROM/SUM Display
Display the program version andothers. This is not typically usedby the user.

1-1. Zero Adjustment
Perform the zero adjustment.

Zero Adjustment=> P231-2. Various Setting Display
Display various setting values.

Setting Display=> P241-3. Mode Switching
Switch to the maintenance mode.

See "Regular
maintenance mode".

To 1-0SD-2500- 22 -

5 How to Operate

5-5. User mode

<Zero Adjustment "1-1">This is used to perform the zero adjustment.
LED

NOTE

 If the zero calibration failed since the zero point was significantly fluctuated from around zero, it returns to
1-1 after FAIL rather than PASS is displayed. In this case, the zero adjustment has not been completed.

- 23 -

SD-2500

5 How to Operate

5-6. How to exit

<Setting Display "1-2">
Display various setting values.
LED

Press the SET key.

AL.:

The contact is activated
due to the gas alarm.
FAU.: The contact is activated
due to the fault alarm.
A. or F.: The contact is activated
due to the gas alarm or
the fault alarm.

5-6. How to exit
To turn off the gas monitor, turn off the power supply (24 VDC) to the gas monitor.

WARNING When the gas monitor is turned off, an alarm may be activated on the upper (central) system.
 Before turning off the gas monitor, INHIBIT (point skip) on the upper (central) system must be
activated. Decide whether the power can be turned off by checking the operation of the devices
connected to the external output or external contact output terminal of the gas monitor.

SD-2500- 24 -

6 Operations and Functions

6-1. Gas alarm activation

6

Operations and Functions
6-1. Gas alarm activation
Gas alarm: Activated when the concentration of detected gas reaches or exceeds the alarm setpoint value.
<<Auto-Reset>>

NOTE
The alarm setpoint is factory-set. Although the alarm delay time (standard: 2 seconds) works in the gas monitor
to prevent a false activation, it can be cancelled if not needed.

<Display Operation>
Gas Concentration Display
In case of over the detection range (Over Scale), "∩∩∩∩" is displayed on the LED.
Power Indicator Lamp (POWER: Green)
During operation, this lights up continuously.
Alarm Indicator Lamp (ALM: Red)
It lights up when the alarm setpoint value is reached to or exceeded.

<Contact Activation>
The contact is activated when the gas concentration reaches or exceeds the alarm setpoint value. (onlywhen the alarm is used)
The contact activation is reset automatically when the gas concentration drops below the alarm setpointvalue.

Concentration

Alarm setpoint

0
Time
Alarm lamp (ALM)
Alarm contact (terminal plate 4, 5)

Alarm delay time (2 seconds)- 25 -

SD-2500

6 Operations and Functions

6-2. Fault alarm activation<Response to Gas Alarm>
A gas concentration value exceeds the alarm setpoint
When a gas alarm is triggered, take actions in accordance with your management rules of gas alarm.
Normally, take the following actions.
 Check the reading of the gas monitor.

NOTE
If a gas leak is momentary, the reading may already have dropped when checking it. In addition, when thealarm is triggered by noise or other incidental conditions other than a gas, the reading may have already
dropped.
 Based on your management rules of gas alarm, no one can be allowed to access the monitored zone toensure safety.
 If the gas concentration display continues to be displayed, close the main valve of the gas, and then checkthat the gas concentration reading dropped.
 Access the gas leak point, equipped with a protective gear to avoid dangers caused by possibly remaining
gases, and check whether gases remain or not by using a portable gas detector.
 Check that the point is free from dangers, and take actions to fix the gas leak.

6-2. Fault alarm activation
A fault alarm is triggered when the gas monitor detects abnormalities. After a fault alarm is triggered, thefault lamp (yellow) lights up and an error message is displayed on the LED. Determine the causes and takeappropriate actions.
After the gas monitor is successfully returned from the fault, it restarts with the process normally performed
right after it is turned on (initial clear).
If the gas monitor has problems and is repeatedly malfunctioning, contact our overseas sales department or
local representatives immediately.

NOTE
For information on malfunctions (error messages), see "9. Troubleshooting".

SD-2500- 26 -

6 Operations and Functions

6-3. External output operation

6-3. External output operation
Signal Transmission System
Transmission Path
Transmission DistanceConnection Load Resistance1
Detection Mode (No Alarm)2
Detection Mode (Gas Alarm)
3
Initial Clear

4

Maintenance Mode

5

Alarm Test

6
7

Fault Alarm
INHIBIT

8Power OffElectric current transmission (non-isolated) 4 – 20 mA
CVVS
CVVS 1.25 mm2: Maximum 1 km
Below 300 Ω
4 - 20 mA (concentration output)
4 - 20 mA (concentration output)
Depending on the setting of the section 4.
2.5 mA setting: 2.5 mA
4 mA, HOLD, 4 - 20 mA setting: 4 mA
2.5 mA setting: 2.5 mA
4 mA setting: 4 mA
HOLD setting: The previous value retained
4-20 mA setting: 4 - 20 mA (concentration output)
Output ON setting: 4 - 20 mA (concentration output)
Output OFF setting: 4 mA
0.5 mA (Fixed)
Depending on the setting of the section 4.
2.5 mA setting: 2.5 mA
4 mA, HOLD, 4 - 20 mA setting: 4 mA
0 mA

Example of Gas Concentration and External Output
4 - 20 mA specification(Maintenance output: 2.5 mA setting)External output
22 mA
20 mA

Detection Mode
Maintenance Mode

4 mA
2.5 mA
Zero suppression0

Gas concentration
Full scale

CAUTION The 4 - 20 mA output is already adjusted. In case of over scale, an output will not exceed 22 mA.
 Output during INHIBIT or initial clear is based on 4 - 20 mA output setting in the maintenance mode.
In particular, when the gas monitor is started or the specification is changed, be careful about 4-20 mA
output setting. Understand how the gas monitor functions, and take actions, if necessary, so that thesignal receiver side can prepare to avoid false alarms.

- 27 -

SD-2500

6 Operations and Functions

6-4. Other functions

6-4. Other functions<Suppression Function>
The sensors used with the gas monitor are influenced by environmental changes (temperature, humidity,
and other characteristics) or interference gases (interference characteristics) in no small measure, which
affects the reading. Therefore, the reading might be fluctuated around zero even in a normal environment.
This function obscures influences by environmental changes and interference gases around zero that haveno meaning for your management rules of gas alarm. This function is used to hide (suppress) the fluctuationof the reading under the setting value, indicating zero.
<<Example>>
Suppression Disabled
A fluctuation around zero is displayed as the reading.

Suppression Enabled
A variation under the standard setting value = 2% LEL is
hidden with zero.
(Zero suppression)

NOTE In the maintenance mode, this function is disabled and the variation of the reading under the setting value isdisplayed.

CAUTIONA reading under zero is suppressed with the 10% FS suppression.
A reading that gets 10% FS or more under zero is displayed as "-0.0", which prevents an accurate gas
detection and needs the zero adjustment.

SD-2500- 28 -

7 Maintenance7-1. Maintenance intervals and items

7

MaintenanceThis is an important instrument for the purpose of safety.
To maintain the performance of the gas monitor and improve the reliability of safety, perform a regular
maintenance.

7-1. Maintenance intervals and items
 Daily maintenance:
Perform maintenance before beginning to work.
 Monthly maintenance: Perform maintenance on the alarm circuit (alarm test) once a month.
 Regular maintenance: Perform maintenance once or more for every six months to maintain theperformance as a safety unit.
Maintenance
itemPower Supply
Check
Concentration
Display Check

Alarm Test
Span
Adjustment
Gas Alarm
Check

Maintenance content
Check that the power lamp lights up.
Check that the concentration display
value is zero. When the reading isincorrect, perform the zeroadjustment (AIR adjustment) after
ensuring that no other gases exist
around it.
Check the alarm circuit by using thealarm test function.
Perform the sensitivity calibration byusing the calibration gas.
Check the gas alarm by using thecalibration gas.

Daily
maintenance

Monthly
maintenanceRegularmaintenance































<About Maintenance Services> We provide services on regular maintenance including span adjustment, other adjustments andmaintenance.
To make the calibration gas, dedicated tools, such as a gas cylinder of the specified concentration and gas
sampling bag must be used.
Our qualified service engineers have expertise and knowledge on the dedicated tools used for services,along with other products. To maintain the safety operation of the gas monitor, please use our maintenanceservice.
 The followings are typical maintenance services. For more information, please contact our overseas sales
department or local representative.

- 29 -

SD-2500

7 Maintenance7-1. Maintenance intervals and items

Main Services
Power Supply
Check

:

Concentration
Display Check:

Flow Rate
Check:

Filter Check:

Alarm Test:

Span
Adjustment
Gas Alarm
Check:Cleaning andRepair of theGas Monitor(visualdiagnosis)
Gas Monitor
Operation
Check
Replacement ofConsumable
Parts

:

SD-2500:

Checks the power supply voltage.
Verifies that the power lamp lights up.
(Verifies that relevant points can be identified on the system.)(When a UPS (uninterruptible power system) is used, checks the operation with the UPS.)
Verifies that the concentration display value is zero (or 20.9 vol% on the oxygen deficiency
meter) by using the zero gas.
Performs the zero adjustment (AIR adjustment) if the reading is incorrect.
Checks the flow rate indicator to find abnormalities.
Checks the flow rate by using an external flow meter to verify the correctness of the flow rate
indicator on the gas monitor. If the flow rate is incorrect, performs the flow rate adjustment.
Checks the dust filter for dust or clogging.
Replaces a dirty or clogged dust filter.
Inspects the alarm circuit by using the alarm test function.
• Checks the alarm lamps. (Checks each activation of ALM1 and ALM2.)• Checks the external alarm. (Checks the activation of the external alarm, such as a buzzer.)
Performs the sensitivity calibration by using the calibration gas.
Checks the gas alarm by using the calibration gas.
• Checks the alarm. (Checks the alarm activation when the alarm setpoint is reached.)• Checks the delay time. (Checks time to delay until the alarm is triggered.)• Checks the alarm lamps. (Checks each activation of ALM1 and ALM2.)• Checks the external alarm. (Checks the activation of external alarms, such as a buzzer andreset signal.)
Checks dust or damage on surface, cover, or internal parts of the gas monitor, clean andrepair such parts of the gas monitor.
Replaces parts which are cracked or damaged.

:

Uses the keys to check the operation of functions and parameters.

:

Replaces consumable parts, such as a sensor, filter and pump.

- 30 -

7 Maintenance7-2. Regular maintenance mode

7-2. Regular maintenance mode
WARNING
After the adjustment is completed, never fail to press MENU/ESC key to return to the detection mode.
(If the gas monitor remains in the regular maintenance mode, it automatically returns to the detection
mode in ten hours.)

Mode

Maintenance Mode
(Regularmaintenance)

Item

LED
display

Details

Test Mode

2-0

Zero Adjustment
Span Adjustment
Zero/Span
Initialization

2-1
2-2

Perform various tests.
2-0.0 Gas Test
2-0.1 Alarm Test
2-0.2 Fault Test
2-0.3 LED Test
2-0.4 Memory Test
Perform the zero adjustment.
Perform the span adjustment.

2-3

Initialize zero/span values.

Environmental
Setting

2-4

Display

2-5

Switch to factorymode
Switch to user
mode

Used for various environmental settings.
2-4.0 Sensor Power Supply ON/OFF
2-4.1 INHIBIT Setting
2-4.2 Alarm Setpoint Setting
2-4.3 Alarm Delay Time Setting
2-4.4 Alarm Pattern Setting
2-4.5 Zero Suppression Pattern Setting
2-4.6 Zero Suppression Value Setting
2-4.7 Alarm Contact Specification Setting
2-4.8 Energized/De-energized Contact Setting
2-4.9 Maintenance Mode External Output
Setting
2-4.A External Output Setting
2-4.B Alarm Test External Output Setting
2-4.C Sensor Operation Start Setting
2-4.D Password Setting
2-4.E Sensor Fault Alarm Pattern Setting
Display various electrical settings.
This is not typically used by the user.

2-6

Not used.

2-7

Returns to the user mode.

- 31 -

SD-2500

7 Maintenance7-2. Regular maintenance mode
LED

User ModeIn "1-3.", press the SET key.

Then press the SET key
again for three seconds.
Regular Maintenance Mode
2-0. Test Mode
Perform various tests.

Test Mode=> P332-1. Zero Adjustment
Perform the zeroadjustment.

Zero Adjustment=> P382-2. Span Adjustment
Perform the span
adjustment.

Span Adjustment=> P392-3. Zero/Span Initialization
Initialize the zero/span
adjustment after the sensor
is replaced.
2-4. Environmental Setting
Set various operations andfunctions.

Environmental
Setting=> P372-4.0 and 2-4.3 to 2-4.F arefactory-set. They are nottypically used by the user.

2-5. Various Electrical
Settings Display
Display various electricalsettings. This is not used by
the user.
2-6.
Enters the factory mode.
This is not used by the user.

2-7.
Returns to the user mode.

rET. is displayed.
Press the SET
key again to
return to the usermode.
To 2-0. Test Mode

SD-2500- 32 -

7 Maintenance7-2. Regular maintenance mode

<Alarm Test Mode "2-0">
LED

2-0
Press the SET key.

2-0.0 Gas Test

Gas Test=> P342-0.1 Alarm Test

Alarm Test=> P342-0.2 Fault Test

Fault Test=> P352-0.3 LED Test

LED Test=> P352-0.4 Memory Test

Memory Test=> P36

To 2-0.0

WARNING Before starting the alarm test (transmission test), provide a notification to the related sections so thatthey can prepare for false abnormalities (external output signals and alarm contact). After the test iscompleted, never fail to press MENU/ESC key to return to the detection mode. (If the gas monitor
remains in the alarm test mode, it automatically returns to the detection mode in ten hours.)
 In the alarm test mode, the gas concentration equal to the reading is output even in the maintenancemode depending on the setting. Take actions, if necessary, so that the signal receiver side canprepare to avoid false alarms.

- 33 -

SD-2500

7 Maintenance7-2. Regular maintenance mode

<Gas Test "2-0.0">
LED

2-0.0
Press the SET key.

Introduce the test gas andperform the gas test.

Stop introducing the test gas. Whenthe reading drops, press the
MENU/ESC key to cancel the test andto go back to the original state.
To 2-0.0

WARNING
Because the contact and gas concentration output can be activated by a gas test even in themaintenance mode depending on setting, be careful to perform the test.

<Alarm Test "2-0.1">
LED

2-0.1
Press the SET key.

Alarm Test ON/OFF(The used contact setting is "Alarm","Alarm or Fault")
Select either ON/OFF, and then press
the SET key.

▼

Perform the gas alarm test byincreasing or decreasing the readingwith the ▲ or ▼ key.
Press the MENU/ESC key to cancel thetest and to go back to the original state.
To 2-0.1

WARNING
Because the contact and gas concentration output can be activated by an alarm test even in themaintenance mode depending on setting, be careful to perform the test.
SD-2500- 34 -

7 Maintenance7-2. Regular maintenance mode

<Fault Alarm Test "2-0.2">
LED

2-0.2
Press the SET key.

Fault Test ON/OFF
Select either ON/OFF.
Switch ON and press the SET key toactivate the fault alarm.
Return to OFF and press the SET key
to cancel the fault alarm.
(Pressing the MENU/ESC key alsoenables to cancel the fault alarm andto go back to the original state.)

WARNING
Because the contact and gas concentration output can be activated by a fault alarm test even in themaintenance mode depending on setting, be careful to perform the test.

<LED Test "2-0.3">
LED

2-0.3
Press the SET key.

LED Test ON/OFF
Select either ON/OFF.
Switch ON and press the SET key toturn on the LEDs (POWER, ALM,
FAULT) and to display the gas
concentration of 8.8.8.8.
Return to OFF and press the SET key
to cancel the test.
(Pressing the MENU/ESC key alsoenables to cancel the test and to go
back to the original state.)- 35 -

SD-2500

7 Maintenance7-2. Regular maintenance mode

<Memory Test "2-0.4">
LED

2-0.4
Press the SET key.

When StA. is displayed, press the
SET key again.

When CAL. is displayed, the memory
diagnosis is performed.

When memory is correct as a result of
the diagnosis, PASS is displayed.
Press the SET key to go back to theoriginal state.

To 2-0.4

NOTE
When abnormalities are found in memory as a result of the diagnosis, PASS is not displayed. F-RA isdisplayed for the RAM fault, and F-RO is displayed for the ROM fault. For both the RAM fault and ROM fault,
F-RA and F-RO are displayed alternately.

SD-2500- 36 -

7 Maintenance7-2. Regular maintenance mode

<Environmental Setting "2-4">
Set various operations and functions in the environmental setting.
LED<<Environmental Setting 1>>
2-4. Environmental Setting
Press the SET key.

2-4.0
They are factory-set and not
typically used by the user.

2-4.1 INHIBIT Setting
Set Inhibit.
Select either ON/OFF, and thenpress the SET key to confirm
the selection.
When ON is selected, in thedetection mode InHI. and 0.0(gas concentration value) aredisplayed on the LED
alternately. As a result, an alarm
is not triggered to external
device.
Alarm Setpoint Setting=> P372-4.2 Alarm Setpoint Setting
Set the alarm setpoint.

2-4.3 to 2-4.E
They are factory-set and not
typically used by the user.
To 2-4.0<Alarm Setpoint Setting "2-4.2">
LED

2-4.2
Press the SET key.

Alarm Setpoint Setting
Change the value by pressing
the ▲ or ▼ key, and then press
the SET key to confirm thevalue. (Press the MENU/ESC
key to go back to the originalstate.)

Return to 2-4.2.

- 37 -

SD-2500

7 Maintenance7-3. Gas calibration method

7-3. Gas calibration method
Perform a gas calibration in each mode (zero adjustment mode and span adjustment mode) using thecalibration gas.
 Zero adjustment gas
 Span adjustment gas (collected in a gas sampling bag) Gas sampling bags

SD-2500 gas monitorGassampling
bag
for exhaust

OUT

IN

Gas calibration adapter

Needle valve

Flow meter<Zero Adjustment "2-1">

Gas
samplingbag

Pump
1.0 ± 0.2 L/min

This is used to perform the zero adjustment.
LED

2-1
Press the SET key.

Current Concentration Value Display
Press the SET key to perform thezero adjustment.

Under Zero Adjustment (CAL. is displayed)
Wait for a while until the adjustment iscompleted.

Zero Adjustment Completed
It automatically returns to 2-1 after
PASS is displayed.

Return to 2-1.
* If the zero adjustment failed, it
automatically returns to 2-1 after
FAIL is displayed.
Return to 2-1.

NOTE

 If the zero calibration failed since the zero point was significantly fluctuated from around zero, it returns to
2-1 after FAIL rather than PASS is displayed. In this case, the zero adjustment has not been completed.

SD-2500- 38 -

7 Maintenance7-3. Gas calibration method<Span Adjustment "2-2">This is used to perform the span adjustment.

CAUTION Before starting the span adjustment, provide the gas monitor with the span adjustment gas and wait
until the indicator is stabilized.

LED

2-2
Press the SET key.

Gas Introduction
Introduce a gas, and then press the SET
key when the reading is stabilized.
* In case of less than 10% F.S., thiscannot be set.

Span Adjustment
Because the reading will be fixed, adjust
the introduced gas concentration bypressing the ▲ or ▼ key.
Adjust the value, and then press the SET
key.

Span Adjustment Completed
It automatically returns to 2-2 after PASS
is displayed.

Return to 2-2.
* If the span adjustment failed, it
automatically returns to 2-2 after FAIL
is displayed.
Return to 2-2.

NOTE

 If the span adjustment failed since the reading was significantly fluctuated from the introduced gas
concentration, it returns to 2-2 after FAIL rather than PASS is displayed. In this case, the span adjustment
has not been completed.
Check if the correct concentration span adjustment gas has been provided and check the gas adjustment
tool for a gas leak. If there are mistakes, perform the span adjustment again.
If the span adjustment cannot be performed even when there is no mistake or after recalibration, the gas
sensor life might have expired. After turning off the power supply, please contact our overseas sales
department or local representatives.
After the span adjustment is completed, perform the zero adjustment at the operating temperature of thefurnace.

- 39 -

SD-2500

7 Maintenance7-4. Parts replacement

7-4. Parts replacement<Sensor Replacement>
Our service engineers need to replace the sensor and perform the gas calibration.
Please contact our overseas sales department or local representatives.

NOTE
The gas calibration using the standard gas is required after the sensor is replaced. Please request it to ouroverseas sales department or local representatives.

<Replacement of Regular Replacement Parts>
List of recommended regular replacement parts
No.
1
2

Item
O-ring(for the housing joint surface)
Rubber seal(for flange installation)

Maintenanceintervals

Replacement
intervals (year)

Quantity(pieces/unit)

1 year3 - 6 years

1

1 year3 - 6 years

1

NOTE

 The above replacement intervals are recommendation only. The intervals may change depending on theoperating conditions. These intervals do not mean the warranty periods either. The result of the regular
maintenance may determine when to replace the parts.

SD-2500- 40 -

8 Storage, Relocation and Disposal

8-1. Procedures to store the gas monitor or leave it for a long time

8

Storage, Relocation and
Disposal
8-1. Procedures to store the gas monitor or leave it fora long time
The gas monitor must be stored under the following environmental conditions.
 In a dark place under the normal temperature and humidity away from direct sunlight In a place where gases, solvents or vapors are not present

8-2. Procedures to relocate the gas monitor or use it
again
When the gas monitor is relocated, select a new place in accordance with "4-2. Precautions for installation
points" and "4-4. How to install".
For information on wiring, see "4-5. How to wire". The unpowered time must be minimized when the gas
monitor is relocated.

CAUTION When using a relocated or stopped/stored gas monitor again, do not forget to perform a gas
calibration. For information on readjustment including a gas calibration, please contact our overseas
sales department or local representatives.

8-3. Disposal of products
When the gas monitor is disposed of, it must be treated properly as an industrial waste in accordance withthe local regulations.

- 41 -

SD-2500

9 Troubleshooting

9 Troubleshooting

9

Troubleshooting
The Troubleshooting does not explain the causes of all the malfunctions which occur on the gas monitor.
This simply helps to find the causes of malfunctions which frequently occur. If the gas monitor shows asymptom which is not explained in this manual, or still has malfunctions even though remedial actions aretaken, please contact our overseas sales department or local representatives.

<Abnormalities on Unit>
Symptom/Display

The power
cannot be turnedon.

Abnormaloperations
Sensorabnormalities
E-1

Systemabnormalities
E-9

SD-2500

FAULT

-

-





Causes
The wiring is not correct.
The terminal plate isremoved.

Actions
Connect the wiring properly.
Connect the terminal plate properly.

Abnormalities/momentary
blackout of power supply
systemProvide the rated voltage.
Check the UPS, power supply line filter andinsulation transformer, and then take additional
measures.

Cable abnormalities (opencircuit/not connected/shortcircuit)Check the wiring of gas monitor and related
devices around it.

Disturbances by sudden
surge noise, etc.

Turn off and restart the gas monitor.
If such a symptom is observed frequently, takeappropriate measures to eliminate the noise.

The sensor is notconnected or improperly
connected.
Faults of the sensor
The rated voltage is not
supplied to the gas
monitor.
Abnormalities of ROM,
RAM, or EEPROM insideof the gas monitor- 42 -

Check if the sensor cable is securely fastened tothe terminal plate.
Replace the sensor with a new one.
Check the power supply, and supply the rated
voltage.
Please contact our overseas sales department
or local representatives.

9 Troubleshooting

9 Troubleshooting<Abnormalities of Readings>
Symptoms
The reading rises(drops) and it remainsso.

CausesDrifting of sensor
outputEnvironmental
changes
Disturbance bynoise

A gas alarm is triggered
despite of no gas leakand no otherabnormalities at thedetection point.

Slow response

Sudden change inthe environment

Deteriorated sensor
sensitivity

Actions
Perform the zero adjustment at the operating
temperature of the furnace.
When the sensor ambient temperature rises (or drops),the "zero point" drops (or rises), but this is not a
malfunction. Perform the zero adjustment at theoperating temperature.
Turn off and restart the gas monitor.
If such a symptom is observed frequently,
take appropriate measures to eliminate the noise.
When the environment (temperature, etc.) changes
suddenly, the gas monitor cannot adjust to it and isaffected by it.
In some cases, the gas monitor triggers an indication
alarm.
Because the gas monitor cannot be used under sudden
and frequent environmental changes, the user shouldtake some preventive actions to eliminate them.
Replace the sensor with a new one.

- 43 -

SD-2500

10 Product Specifications

10-1. List of specifications

10

Product Specifications
10-1. List of specifications<ATEX/IECEx Specification>
Detection principle
Detectable gas
Gas concentration
display
Measuring range
Resolution
Detection method
Alarm preset point
Power indication
OutputAlarm accuracy(under an identicalcondition)
Alarm-delay time
(under an identicalcondition)
Gas alarm typeGas alarm indication
Gas alarm action
Trouble alarm・Self
diagnosis
Trouble alarmindication
Trouble alarm action
Alarm contact
Contact capacity
Transmission
schemeSpecification oftransmission
Transmission cable
Transmission
distance
Power supply
Power consumption
Cabling port
SD-2500

Catalytic combustion method
NMP
LED(4digits・7segments)
0～100%LEL
0.5%LEL
Direct-insert method
25%LEL【Standard】
POWER lamp lighting(green)
Gas concentration signal
Alarm contact(Gas alarm or Trouble alarm or Gas・Alarm common alarm)Less than ±25%(against alarm preset point)
Less than 30sec(when introducing 1.6 times thicker gas than alarm preset point)
Single alarm(H)ALM lamp lighting(red)Auto-recover
System failure/Sensor failure
FAULT lamp lighting(yellow)/content display
Auto-recoverNo-voltage contact 1a or 1b
Non-exciting at normal(exciting at alarm) or exciting at normal(non-exciting at
alarm)
DC30V･0.5A(resistive load)
Three-wire analog transmission(in common with power supply<power supply,signal,common>)DC4～20mA(linear・load resistance less than 300Ω・resolution ability 200division)
CVVS worth of shield cable(1.25mm2)・3-core or 5-core(by using alarm contact)
Less than 1km
DC24V(DC20～26.4V)
MAX.3W
Flame proof packing method- 44 -

10 Product Specifications

10-1. List of specifications

Initial clear
Approx.25sec
OperatingSensor：0～+160℃(non-rapidly-vary)
temperature
Case：-20～+60℃(non-rapidly-vary)
Structure
Direct-insert type
Explosion-proof
Flame proof structure
structure
Explosion-proof
Ⅱ 2 G Ex db ⅡC T3 Gb(ATEX) / Ex db ⅡC T3 Gb(IECEx)
grade
Outer dimension
Approx.148(W)×167(H)×458(D)mm(protection excluding)
WeightApprox.4.6kg
Color
Munsell 7.5BG5/2* Specifications subject to changes without notice.

- 45 -

SD-2500

10 Product Specifications

10-1. List of specifications<Japan Ex Specification>
Detection principle
Detectable gas
Gas concentration
display
Measuring range
Resolution
Detection method
Alarm preset point
Power indication
OutputAlarm accuracy(under an identicalcondition)
Alarm-delay time
(under an identicalcondition)
Gas alarm typeGas alarm indication
Gas alarm action
Trouble alarm・Self
diagnosis
Trouble alarmindication
Trouble alarm action
Alarm contact
Contact capacity
Transmission
schemeSpecification oftransmission
Transmission cable
Transmission
distance
Power supply
Power consumption
Cabling port
Initial clear
Operatingtemperature
Structure
Explosion-proof
structure
Explosion-proof
grade
Outer dimension
WeightColor

SD-2500

Catalytic combustion method
NMP
LED(4digits・7segments)
0～100%LEL
0.5%LEL
Direct-insert method
25%LEL【Standard】
POWER lamp lighting(green)
Gas concentration signal
Alarm contact(Gas alarm or Trouble alarm or Gas・Alarm common alarm)Less than ±25%(against alarm preset point)
Less than 30sec(when introducing 1.6 times thicker gas than alarm preset point)
Single alarm(H)ALM lamp lighting(red)Auto-recover
System failure/Sensor failure
FAULT lamp lighting(yellow)/content display
Auto-recoverNo-voltage contact 1a or 1b
Non-exciting at normal(exciting at alarm) or exciting at normal(non-exciting at
alarm)
AC250V･0.5A/DC30V･0.5A(resistive load)
Three-wire analog transmission(in common with power supply<power supply,signal,common>)DC4～20mA(linear・load resistance less than 300Ω・resolution ability 200division)
CVVS worth of shield cable(1.25mm2)・3-core or 5-core(by using alarm contact)
Less than 1km
DC24V(DC20～26.4V)
MAX.3W
Flame proof packing method
Approx.25sec
Sensor：0～+160℃(non-rapidly-vary)Case：0～+50℃(non-rapidly-vary)
Direct-insert type
Flame proof structure
Ex dⅡC T3
Approx.148(W)×167(H)×458(D)mm(protection excluding)Approx.4.6kg
Munsell 7.5BG5/2* Specifications subject to changes without notice.

- 46 -

10 Product Specifications

10-2. List of accessories

10-2. List of accessories
 Operating manual ････････････････････････ 1sheet
 Dedicated handling lever ･････････････････ 1pce.
 Dedicated control key ････････････････････ Depends on ordered quantity of the unit.
1 pce.
1～10 units
2 pcs.
11～20 units
3 pcs.
21～50 units
51 units and above
4 pcs.
 Flange gasket ･･･････････････････････････ 1pce.
 Exhaust air direction nameplate ･･････････ 1pce.

- 47 -

SD-2500

10 Product Specifications

10-3. Detection principle

10-3. Detection principle
When a combustible gas burns on the surface of a highly active oxidation catalyst in catalytic combustion,
the contact burning-type sensor measures resultant temperature changes by measuring the resistancechanges in the heat-resistant alloy wire coil.
The sensor consists of two elements: A detecting element having a heat-resistant alloy wire coil with anultrafine particle oxidation catalyst sintered on it together with a carrier and a temperature-compensating
element with a mixture of gas-inert alumina and glass sintered on it.
When a combustible gas comes into contact with the surface of the detecting element with oxidation
catalyst sintered on it, the gas burns, causing the temperature to rise. In accordance with this temperaturechange, there occurs a change in the resistance of a heat-resistant alloy wire coil that constitutes theelement. These resistance values are approximately proportional to gas concentrations. From the changes
in the resistance values, potential differences are obtained using a bridge circuit and displayed as gas
concentrations on the meter.
[Structure][Principle]
A

Alumina
Oxidation catalyst

Heat-resistant alloy wire coil

C: Compensating
element

D: Detecting element

1.4 - 1.6 mm

X

Fixed
resistanceFixedresistanceYB

1.3 - 1.8 mm

Variable resistor for bridge
equilibrium adjustment
E
SW
VR

SwitchPower supply
Variable resistor for bridge
voltage adjustment

SD-2500- 48 -

M

11 Definition of Terms

11 Definition of Terms

11

Definition of Terms
Catalytic
combustion type
Initial clear
Full scale%LEL
Calibration
Zero suppression
Alarm delay time

SD-2500

This is a principle of the sensor installed in the detector head.
See "10-3. Detection principle" for details.
Output from the detector head fluctuates for a while after turning on the power.
This is a function to prevent triggering alarm during that time.
Maximum value of the detection range.
A unit which the lower explosive limit (LEL) of the combustible gas to be detected is
set to 100.
Adjusts the readings to the calibration gas concentration value by using thecalibration gas.
A function to cut off the specific drifting that the sensor has.
A function which temporarily suspends activation to prevent a false alarm caused
by noise from its outside.

- 49 -