Extractive type Gas Detector
Model PD-12
Instruction Manual Keep this instruction manual where it is readily accessible.
 Thoroughly read this instruction manual before using the equipment so it can be usedsafely and correctly.
 This manual provides information concerning standard specifications. If the specificationsof your model are nonstandard, refer to the delivery specifications.

Instruction Manual No.
GAE-037-08
October 2021

 Nomenclature
See pages 5 to 8.

 Replacement of Sensor
Unit
See pages 30 and 32.

 Wiring and Connecting
Methods
See pages 13 to 15.

 Display and Operation in
Each ModeSee page 18.
Red flashing
Green flashing Maintenance Check andOperation Methods

 Troubleshooting
See pages 34 to 35.

See pages 20 to 33.

?

Table of Contents
1. Introduction ......................................................................................................................... 1
2. Precautions ......................................................................................................................... 2
3. Contents of Package .......................................................................................................... 4
4. External Dimensions and Nomenclature ............................................................................ 5
4-1. Main Unit...................................................................................................................... 5
4-2. Display and Control Blocks ......................................................................................... 6
4-3. Terminal Block ............................................................................................................. 7
4-4. Flow Diagram............................................................................................................... 8
5. Installation........................................................................................................................... 9
5-1. Installation Method ...................................................................................................... 9
5-2. Mounting of Optional items ........................................................................................ 12
6. Wiring Method .................................................................................................................. 13
6-1. Wiring Work ............................................................................................................... 13
6-2. Wiring and Connection .............................................................................................. 13
7. Precautions before Use .................................................................................................... 16
 In Case of Gas Leakage............................................................................................ 16
8. Display at Start-up (Initial Delay) ...................................................................................... 17
9. Display and Operation in Each Mode............................................................................... 18
10. Trouble Alarm ................................................................................................................. 19
11. Maintenance Check and Operation Method................................................................... 20
11-1. Daily Inspection and Periodical Inspection .............................................................. 20
11-2. Preparing Calibration Gas ....................................................................................... 22
11-3. Calibration Method ................................................................................................... 24
 Maintenance Mode .................................................................................................... 24
 Zero Adjustment ........................................................................................................ 25
 Span Fine-tuning ....................................................................................................... 26
 Span Rough Adjustment ............................................................................................ 27
 Full-scale and Alarm Set Value Display .................................................................... 28
 Test Mode .................................................................................................................. 29
11-4. Replacement of Sensor Unit .................................................................................... 30
11-5. Replacement of Pump Unit ...................................................................................... 32
11-6. Replacement of Filter with Flow Checker (FC-32) .................................................. 33
12. Troubleshooting .............................................................................................................. 34
13. Specifications.................................................................................................................. 36
13-1. Product Specifications ............................................................................................. 36
13-2. Explosion-proof Specifications ................................................................................ 38
14. Warranty ......................................................................................................................... 39
15. Life Expectancy .............................................................................................................. 40
16. Detection Principle ......................................................................................................... 41
16-1．Catalytic Combustion ............................................................................................. 41
16-2．Hot Wire Semiconductor ........................................................................................ 41
16-3．Thermal Conductivity ............................................................................................. 41
17. Glossary.......................................................................................................................... 42

1. Introduction
 Thank you for purchasing the PD-12 Extractive type Gas Detector.
 In order to ensure the correct and safe operation of this product, be sure to read thismanual before use.
 This product detects various types of gas including combustible gas in industrial facilities.
The product detects gas leakage at an early stage in industrial facilities (e.g., gas
production plants and depots, chemical plants, paint factories, and power plants), andoutputs the gas concentration value in analog signal form while displaying the gas
concentration value.
If the gas concentration reaches a preset alarm level, the red ALARM indicator will flash
and turn ON an external contact output, thus helping to prevent disasters such as
explosion accidents and fires.
 Following PD-12s are available, according to the gas sensor incorporated.

Model

Detection Principle

PD-12A

Hot-wire Semiconductor sensor

PD-12B

Catalytic Combustion sensor

PD-12C

Thermal Conductivity sensor

 Maintenance and inspection are indispensable to the reliable performance of the Gas
Detection/Alarm System. Be sure to perform the maintenance checks described in thismanual.

Explanation of Symbols
The following symbols are used to indicate and classify precautions in this manual.

DANGER

Indicates information that, if not heeded, is likely to result in death orserious injury.

WARNING

Indicates information that, if not heeded, could possibly result in death orserious injury.

CAUTION

Indicates information that, if not heeded, could result in minor injury, or
damage to the product.

MEMO

Indicates advice on handling the product.

12. Precautions
 Read this manual completely and be sure you understand the information provided herein
before attempting to use the product.
 Abide by all applicable laws and regulations when using this product.

WARNING Do not open when energized.
 Do not open when an explosive atmosphere may be present. Do not disassemble the product or modify the construction or electric circuits of the
product. Otherwise, the explosion-proof construction of the product may be adversely
affected. Be sure to ground the product to prevent electric shocks.
 If there is a gas leak alarm, take the necessary measures in accordance with yourcompany's regulations.
 The cable entry device and blanking elements shall be of certified in type of explosion
protection flameproof enclosure ‘’db’’, suitable for the condition of use and correctly
installed.
 Unused apertures shall be closed with suitable certified blanking elements.
 Avoid using the product in an environment where it will be exposed to organic solvents
such as aromatic hydrocarbon or halogen hydrocarbon for extended periods. It may
affect polymeric materials.
 To avoid the buildup of a static charge, do not rub the surface of the product with a dry
cloth.
 Use a conductor with a cross-sectional area at least 4mm2 for grounding the unit.

2

CAUTION
 All necessary work for the product including wiring and installation should be carried out
by suitably trained personnel in accordance with applicable code of practice.
 Inspection, maintenance and repair of the equipment should be carried out by suitablytrained personnel in accordance with applicable code of practice.
 Do not install the product in places or near places where silicone sealant or gas is used.
Otherwise, the performance of the product may be adversely affected.

 Do not use the Detector continuously over a long period of time in an environment that
contains organic solvents, such as aromatic hydrocarbons and halogen hydrocarbons.
 Be sure to provide a protective cover (optional) if the product is installed outdoors.
 Use the product in accordance with applicable laws and regulations.
 Fastener type M4 x 16 and M8 x 25 shall have a yield stress factor of min. 450 N/mm2.

Special Condition for Safe Use If used in an ATEX hazardous area, an ATEX-certified cable gland or any devices (Ex db
IIB+H2 Gb or Ex db IIC Gb) must be usedaccording to EN IEC 60079-0:2018 and EN
60079-1:2014.
 If used in an IECEx hazardous area, an IECEx-certified cable gland or any devices (Exdb IIB+H2 Gb or Ex db IIC Gb) must be used according to IEC 60079-0:2017 Ed. 7 andIEC 60079-1:2014 Ed. 7.
 Cable entry requirements for cable gland or any devices<Thread type >Thread size:

G3/4 or PF3/4

Pitch:

1.81mmMinimum depth of engagement : 11 mm
Minimumthread engagement:

6 threads

Tolerance class: Class B
Enclosure material: Aluminum alloy
Thickness of enclosure wall: 3mm (min)The measuring function of gas detector for explosion protection in accordance with
Annex II clauses 1.5.5, 1.5.6 and 1.5.7 of the Directive 2014/34/EU, is not covered inthis certificate.

The customer shall contact the manufacturer for flame path information in order to carryout inspection, repair or adjustment of flameproof joint.

Fastener type M4 x 16 and M8 x 25 shall have a yield stress factor of min. 450 N/mm2.

3

3. Contents of Package
 The product is provided with the following items. Make sure that none of these items is
missing.
 Although the product is packed and shipped with the utmost care, contact your New
Cosmos representative if there should be any damage or missing items.
Accessories

Optional items

Detector headGas collector PF-N3 (see note 1)
Flow checker FC-32 (see note 2)
Four M6 screws
Two Joints
Hexagon wrench: 1pc
Instruction Manual (see note 3)
MJ-1 Magnetic Stick: 1pc

Protective cover (see note 4)
Auto drain AD-40 (see note 5)

Note: 1. It is put on the tip of sampling hose in order to drain rain drop / water splash.
Do not use the collector when the sampling is made in ducts, furnaces and closed
cabinet.
2. Specifications of the Flow checker FC-32 vary according to the requirement.
Refer the specification sheets for the details.
3. Instruction Manual is provided for each order.
4. It is used when the detector is installed outdoor.
5. The Auto drain is designed to automatically discard the accumulated moisture fromgas sampling hose from pits / furnaces.

WARNING Do not use the magnetic stick for any purposes other than the operation of this product.
 Keep in mind that when the magnetic stick attracts magnetic objects, tools, iron pieces,
etc., your hands may become pinched and injured.
 Do not touch the magnet if you are allergic to metal, otherwise your skin may becomechapped or reddened.
 Generally speaking, magnets break easily and the corrosion of the magnet progresses
from the fracture location. Fragments of the magnet may also get in your eyes or injure
your skin.
 The components of the magnetic stick may melt into water. Do not drink water exposed tothe magnetic stick.
 Keep the magnetic stick away from electronic medical devices, such as cardiac
pacemakers, or the magnetic stick may obstruct the normal operation of the device.

CAUTION Keep the magnetic stick away from magnetic tapes, floppy disks, and prepaid cards.
Otherwise, they may become magnetized and the information that they hold may be lost.
 Keep the magnetic stick away from high-precision devices, such as personal computers
and watches. Otherwise, they may malfunction.

44. External Dimensions and Nomenclature
4-1. Main Unit

(Dimensions are in mm)

NumberName

Description

1

Casing cover2

Casing3

Sensor unit

Incorporates a gas sensor.

4

Pump unit

Draws sample gas and exhaust it.

5

Ground terminal

Used when grounding the frame.

6

State display
indicator

Indicates the power supply state (green), alarm state (red), andtrouble state (yellow).

7

Control block

Insert the magnetic stick to control or set the product.

8

Display block

Displays the gas concentration and set values.
Install appropriate cable gland. See the “Special Condition for Safe
Use”
<Thread type >9Cable entry

Thread size:

G3/4 or PF3/4

Pitch:

1.81mmMinimum depth of engagement : 11 mm
Minimumthread engagement:

6 threads

Tolerance class: Class B
Enclosure material: Aluminum alloy
Thickness of enclosure wall: 3mm (min)10

Gas inlet

Inlet for sampled gas. (Size : R/c 1/4 )11

Gas outlet
Bolt with hexagon
socketFlow checker
FC-32

Exhaust outlet for sampled gas. (Size : R/c 1/4 )Used for securing the casing cover. Use a hexagon wrench with anominal diameter of 6 mm.

1213Prevents dust from entering the gas inlet. (Size R/c 1/4)
5

4-2. Display and Control Blocks
7)

6)

3)

1)
5)

4)

2)

8)
Magnetic switches(Insert the magnetic stick to operate the magnetic switches.)
NumberName

Description

1

MODE switch

Makes adjustments and settings or cancels the operationof the product.

2

ENTER switch

Enters settings or completes the control of the product.

3

UP switch

Makes adjustments and settings or increases set values
and other values.

4

DOWN switch

Decreases set values and other values.

Number
5

Name
Display block

Description
Displays the concentration of gas and set values.

State display indicator
NumberName

Description

6

POWER indicator

A green lamp to display the power supply state.

7

ALARM indicator

A red lamp to display the alarm state.

8

TROUBLE indicator

A yellow lamp to display the trouble state.

6

4-3. Terminal Block
Terminal Block

Sensor Connector
Terminal Block

Ground terminal

O ringNumberName

Description

1

24 V (+)

Power supply voltage (positive)

2

GND

Power supply voltage and analog signal(negative) common

3

Signal4- to 20-mA analog signal

4

F

Flow trouble output*(Rated load: 30mA at 30
VDC, resistance load)

5

ZA (TA)

6

ZC (TC)ZA, ZC :External alarm contact(TA, TC : External trouble alarm contact)

Ground terminal

Used to ground the frame.

*When flow decreases. (Open collector. Normally ON. When trouble / no power supply
OFF). The flow trouble output is optional function.
MEMO

Either external gas alarm contact or external trouble alarm contact is equippedon the detector. Refer the specification sheets for the details.
74-4. Flow Diagram

Flow
checker
FC-32

Power Analog Flow
Signal Trouble

External
Alarm

Main components and functions
1) Sensor: Converts gas concentration detected to an electrical signal.
One from the catalytic combustion sensor, Hot-wire semiconductor
Sensor or Thermal conductivity sensor is on the detector.
2) Flow sensor: Give the low flow signal when the flow decreased.
(It’s optional function)

3) Pump: Draw the sample gas through sampling pipe from the detection point.

4) AMP: Converts sensor output to an electrical signal. It also provides thepower to the sensor and the other devices composed.

5) Terminal block : Terminal block for external connection
Refer 6. Wiring Method for the details.

85. Installation
5-1. Installation Method

WARNING Do not open when energized.
 Do not open when an explosive atmosphere may be present. Do not disassemble the product or modify the construction or electric circuits of the product.
Otherwise, the explosion-proof construction of the product may be adversely affected. The cable entry device and blanking elements shall be of certified in type of explosion
protection flameproof enclosure ‘’db’’, suitable for the condition of use and correctly
installed.
 Unused apertures shall be closed with suitable certified blanking elements.

CAUTION Be careful not to damage the gas detector when installing it. Otherwise, the explosion-proof
performance of the gas detector will be lost.
 Use appropriate piping material considering type of gas to be detected.
 Maximum length of the piping should be less than 20m. Pay attention that the responsetime of the detector shall be delayed when the length of the piping is longer due to transport
time of sampled gas. And the length of the piping should be as short as possible when thetype of gas to be detected is highly absorbent gases.
 Do not install the product in the following places.
- Places where the ambient temperature exceeds the operating temperature range (10C
to 50C).
- Places where condensation occurs, or water is directly sprayed.
- Places subject to corrosive gas.
- Places where are in direct sunshine.
- Places close to equipment that generates high frequencies or a magnetic field.
- Places where silicone sealant is used or likely to be used.
- Places where silicone gas is used or likely to be used.
 Do not install the gas detector or tip of sampling pipe where vapor which contains silicone,or the sensor may be adversely affected.
 Install the gas detector in places where it can be maintained and inspected with ease.
 Install the gas detector in places free from vibration.
 Install the gas detector in places free from sudden temperature changes.
 Keep the gas detector free from impacts.
 When installing the gas detector outdoors, be sure to install the protective cover (optional).
 Install Auto drain (option) when the gas sampling is made near the outlet of steam or where
likely to suck the water.
 The pressure of gas inlet port should be ±1kPa and the pressure of outlet port should beless than 1kPa.
 Fastener type M4 x 16 and M8 x 25 shall have a yield stress factor of min. 450 N/mm2.

91) Locate the tip of the gas sampling pipe to be appropriate for the specific gravity of thegas to be detected. It must also be placed in a location where the target gases are likely
to accumulate.
Installing Height
Type of gas
Gas heavier than air(Example: LPG)
Gas almost the same as
air in specific gravity(Example: Carbon
monoxide)
Gas lighter than air(Example: City gas andhydrogen)

Installing height
A maximum of 10 cm above thefloor.
(Height to the sensor guard tip)

Remarks
Keep a space of approximately
7 cm from the sensor guard tip
for ease of maintenance andinspection.

75 to 150 cm above the floor.
(Height to the sensor guard tip)

Decide the height by considering
the specific gravity and mounting
environment.

Near the ceiling

Decide the height by consideringarrangements for ease ofmaintenance (e.g., a scaffold).

2) Install the gas detector in places where it can be maintained and inspected with ease.
Followings are locations where leaked gas may accumulate and appropriate locations
for installation of gas detectors.

Flow checker FC-32

Gas collector

CAUTION
 Place the tip of sampling pipe above water level.

3) Mount the main unit to the wall with the M6 screws that are provided with the product. It isnecessary to open the casing cover at the time of wiring and replacing the sensor. Install
the gas detector in places where the cover opening angle can be more than 90 degree.
Be sure to install the protective cover (optional) when mounting the main unit outdoors.
(Refer to 5-2 Mounting of Optional items for details of optional products.
10

(Dimensions are in mm)

11

5-2. Mounting of Optional items
Protective CoverProtective cover(231)

Flow checker FC-32

(168)

(294)

M3 screw (2 place)Gas collector

Sampling pipe

(Dimensions are in mm)

CAUTION Secure the casing cover with M3 screws if strong winds are expected.

Auto drain AD-40
Auto drain(AD-40)12

6. Wiring Method6-1. Wiring Work Be sure to provide explosion-proof wiring if the product is to be used in hazardous places.

WARNING The cable entry device and blanking elements shall be of certified in type of explosion
protection flameproof enclosure ‘’db’’, suitable for the condition of use and correctly
installed.
 Unused apertures shall be closed with suitable certified blanking elements.

CAUTION All necessary work for the product including wiring and installation should be carriedout by suitably trained personnel in accordance with applicable code of practice.
 Inspection, maintenance and repair of the equipment should be carried out by suitablytrained personnel in accordance with applicable code of practice.

Special Condition for Safe Use If used in an ATEX hazardous area, an ATEX-certified cable gland or any devices (Exdb IIB+H2 Gb or Ex db IIC Gb) must be usedaccording to EN IEC 60079-0:2018 andEN 60079-1:2014.
 If used in an IECEx hazardous area, an IECEx-certified cable gland or any devices(Ex db IIB+H2 Gb or Ex db IIC Gb) must be used according to IEC 60079-0:2017 Ed. 7
and IEC 60079-1:2014 Ed. 7.
Cable Work
 Use a shielded cable, such as CVV-S with a thickness of 1.25 to 2.00 mm2. Lay all cables
in protective tubes, such as metal conduits or carbon steel pipes, or other protective
structure, such as a metal / concrete duct.
 All joints should be connected with necessary couplings, fittings & etc. in accordance withapplicable code of practice.

6-2. Wiring and Connection

WARNING Before opening the casing cover of the gas detector, be sure to turn off the productand all devices (e.g., indicator unit and signal converter) connected to the product.
 If the power is turned ON, the power supply may become a source of ignition.
 Be sure to ground the product to prevent electric shocks.

CAUTION Wire the connecting terminals correctly.
 Separate connection cables from power lines as far as possible.
13Connecting Power Supply and Signal Wires Provide dedicated breakers, if needed, to lines that are connected to peripheral devices,such as indicator units and signal converters.
 Use a dedicated cable, such as CVV-S (with a thickness of 1.25 to 2.00 mm2).
 Make sure that the power supplied to the product is within the specified voltage range.
 Make sure that the load resistance of the signal line, including the resistance of the wire, is
300 ohm or less.
Power

MEMO

24V DC If the main unit is grounded on the power supply side, do not connect a shielded cableto the ground terminal (E) in the gas detector, or otherwise two-point grounding will result.
Connection Example with Power Supply Side Grounded
ＣＶＶＳケーブル
CVVS cable

PD-12
1

24V(+)

2

GND

3

Signal44F

5

ZA(TA)

6

ZC(TC)(＋) Power(－) 24V DC(－) Indicator(＋) unit

External alarm
deviceShieldGroundConnection method of external ground Use a conductor with a cross-sectional area at least 4mm2 for grounding the unit.
 Place a plain flat washer between the case and the terminal.

14

System Configuration Example
Single detector connected
to indicator unit

Multiple detectors monitored
togetherDetector

Detector

Indicator unit

PD-12

V3

PD-12
Security
management system

PD-12
S-500

GAS
VISION

PD-12
Comprehensive gas
detection/alarm system

PD-12

 For details, refer to the Instruction Manual of each device.

Typical Connection Procedure1)

Prepare a power supply that can provide 24 V DC.
(Do not turn on the power supply before wiring the main unit.)

2)

Loosen the hexagon socket bolts on the four corners of the main unit using theprovided hexagon wrench with a nominal diameter of 6 mm, and open the casing
cover of the main unit.

3)

Loosen and remove the screws on the terminal block.

4)

Connect the positive side of the power supply to the 24 V+ terminal.

5)

Connect the negative side of the power supply to the GND terminal.

6)

Check that the power supply cords are securely connected to the terminals. This
completes the power supply preparations.

7)

Wire the analog signal and external contact terminals, if required.

8)

Tighten the hexagon socket bolts (tightening torque : 0.8 – 2.4 N・m) on the four
corners of the main unit and close the casing cover of the main unit.

CAUTION When closing the casing cover, make sure that the power supply cord, harness, andO-ring are not caught by the casing cover.

15

7. Precautions before Use

CAUTION Before turning ON any of the devices (e.g., indicator unit, signal converter) connected tothe product, recheck that all of the connections are correct. Make sure that the gas
detector and indicator unit or signal converter, in particular, are connected properly.

 In Case of Gas Leakage

DANGER Without panicking, check that there is no fire around the product. Do not touch any
electric switches under any conditions. Sparks from turning electric switches ON or OFF
may cause ignition.
 Do not open when an explosive atmosphere may be present.

WARNING If there is a gas leak alarm, take the necessary measures specified by your company.
 If a gas leak occurs indoors, open the windows and doors to ventilate the room.
 Check the gas leakage location and promptly take the necessary measures.

16

8. Display at Start-up (Initial Delay)

CAUTION Check that there is no gas around the product before starting the product.
 If the sensor output is not stable, the external contact point may operate after the initialdelay. Release the interlock of the external equipment if necessary.
 During the initial delay, the analog signal fixed at 4 mA will be output and the external
contact will not operate.

MEMO

 The magnetic stick is not operable during the initial delay.
 The initial delay lasts approximately 30 seconds after the power is turned ON.

1)

When the power supply is turned ON, all of the indicator lamps (green, red, and yellow
lamps) and the display block are lit.

2)

While the indicator lamps (green, red, and yellow lamps) are lit, the following items will
be lit for approximately 1 second each.
Software version number (of the main unit)
Full scale
Example [] ppm
When the full-scale value is 2000 ppm.
Alarm set value
Example [] ppm
When the alarm set value is 500 ppm.

3)

Then the POWER indicator (green lamp) will be flashed for approximately 25 seconds.

4)

When the POWER indicator (green lamp) is lit, the start-up of the main unit iscompleted and the main unit will be in gas monitor mode.

* Make sure that the flow volume of the flow checker is more than 0.5 L/min.

MEMO If the sensor unit has not been turned ON for a long time after the product is shipped fromfactory, it may take some time for the sensor output to stabilize.
 If needed, turn ON the product for approximately one week, and make the zeroadjustment and span adjustment. Refer to 11.3 Calibration Method for the adjustments.
17

9. Display and Operation in Each Mode
In excess of alarm set value
At start-up(Initial delay)
Green lamp
flashes

Maintenance mode

Gas monitor
mode

Green
lamp isON

Test modeRed
lamp
flashes

Gas monitor
mode

Red lamp
Green flashes
lamp isON

Test mode
Red lamp
flashes

Green lamp
is ON

Contents
of display
[

]

[

]

The valueaccording to gas
concentration isdisplayed.
The value
gradually
approaches
zero.

Gas
concentration isdisplayed.

Analogsignal4 to 20 mA

Fixed at 4 mA

Gas
concentration
value is output.

Test value is
outputGas
concentration
value isoutput.

Test value is
output.

Contact
operation

Does notoperate (OFF).

Operates (ON).

Operates (ON).

Does notoperate(OFF).

Does notoperate(OFF).

18[Set
concentration]
A full-scale testfrom 10% to110% is possible.

[Gas
concentration]

Displayedalternately[Test value]

Displayedalternately

10. Trouble Alarm
 The product has a self-inspection function, and the trouble alarm will operate if a problem
occurs.
 The product will inform the user of the problem details with the display shown in thefollowing table when the trouble alarm operates.
 When the trouble alarm is generated, the analog signal will be approximately 0.9 mA or
below.
Screendisplay

Troubleindicator

Problemdetails

Probable cause

RemedyYellowlamp
flashes

Power supply
voltage droperror

The power supply voltage
is low.

Check the power supply
voltage.

Yellowlamp
flashesSensor error

The sensor connector is
disconnected or thesensor wire has broken.

Check that the sensor
connector is securely
connected.
If a sensor connector
failure or broken wire haspossibly occurred,
contact your local
representative.

Lamp isOFF

Zero-point
adjustment
error

There is gas in theambient air.

After checking theambient air, make thezero adjustment again.

Lamp isOFF(F and gas
concentration
are displayedalternately)

Yellowlamp
flashesSpanadjustment
error

Low flow
volume error

The gas concentration
applied for adjustment iswrong.

After checking the typeand concentration of gas,
make a span adjustment
again.
If the type andconcentration of gas issuitable, make spanrough adjustment.

Possible clog or dirty
filter element of FC-32.

Replace filter element of
FC-32.

Possible clog in thesampling pipe.

Clean the clogged pipe.

* The flow trouble alarm is optional function.
 If a screen other than the above is displayed, refer to the Troubleshooting section. If the
product does not reset to normal operation after taking the measures shown in the table orif the problem is not listed in the table, contact your local representative.
 If the product goes into any unintended mode during adjustment or setting, cease
operating the product and contact your local representative..

1911. Maintenance Check and Operation Method11-1. Daily Inspection and Periodical Inspection
 Daily inspections are conducted by the user, while periodical inspections are conductedby your local representative.
Frequency

Checking item

Contents of inspection
・The status of lamp (green POWER indicator)
is lit.
・The concentration display of the gas
concentration indicator.
・Corrosion of the gas detector.
・Corrosion of mounting screw. If a failure isfound, replace the parts.

Daily
inspection

At least once
per month・Confirm the flow volume. Check the flow
volume by reading the scale on the flow
checker. It is normal if the flow volume ismore than 0.5L/min. If the volume is lessthan 0.5L/min., check the following possible
clog and other causes that may decrease theflow volume before replacing the pump for
sample draw.

Visualinspection

・Clogged sampling tip / gas collector.
・Clogged sampling pipe
・Clogged or dirty filter.

20

Frequency

Checking item

Contents of inspection
・Apply inspection gas to the gas detector andcheck the operation of the alarm.
・Remove the upper cup of the flow checker
and connect a gas bag as below, and apply
inspection gas.

Daily
inspection

Minimumintervals of 2
to 3 months

Alarm operation
check with realgas

Periodical
inspection

At least once
per year

Consult your local representative。

Periodical Inspections
In order to maintain the reliability of the gas detection/alarm system, it is extremely important
to conduct maintenance and inspections.
Moreover, it is necessary to use actual gas (combustible gas or poisonous gas), to carefully
conduct inspection and calibration. It is highly recommended that you consider periodical
inspections under a maintenance contract with your local representative.

21

11-2. Preparing Calibration Gas
 Calibration gas is used for actual gas inspection.
 The following example shows how to prepare 0.72 vol% (40%LEL) isobutane as areference gas.
With a standard gas cylinder

0.72 vol% isobutane
air balanceStandard gas cylinder

Gasbag・ Use a urethane gasbag. Leave for about 30 minutes after drawing the gas and bringhumidity in the bag close to the ambient condition before use.

22

With no calibration gas cylinder Use the Gas Calibration Kit (optional item) and a pure gas cylinder of isobutane at
99 vol% or more, and dilute the isobutane with air to produce 0.72 vol% (40%LEL)
calibration gas.
Memo

The calibration gas can be used to check the alarm function. Check the concentration
using Gas Detector XP-3310Ⅱ or a similar device before using the gas for calibration.
●

DANGER

Make sure that there are no flammables nearby whenhandling flammable gas with a concentration over LEL (lower
explosive limit).
vinyl tube

(1) Drawing raw gas
Connect a gas bag to an isobutane 99vol% cylinderand draw a little more than you actually need.
Bend back the hose and pinch with a pinch cockpure gas cylinder(Keep it upright.)

so the gas does not leak from the bag.

①

(2) Drawing a fixed amount of raw gas
Connect a 10ml syringe to a gas bag and draw 7.2ml

gas bag with raw
gas

7.2ml of raw
gas

of raw gas. (Draw a little more than you actually needsyringethen discharge the excess.)pull(3) Transferring raw gas into a quantitative pump②

Connect a syringe to the inlet of a quantitative pumpthen pull out the pump’s piston. Raw gas in the syringe
syringeis sucked into the pump. Remove the syringe and pull
the piston all the way out (100ml).
(4) Making diluted gas

quantitativepump

Connect an empty gasbag to the outlet of the quantitative③

pump then push in the pump’s piston.

airMove the piston back and forth 9 times to add air inorder to make diluted gas.
quantitative
pump

Memo
If you take 7.2ml of raw gas and move the quantitative pump’s
piston back and forth 10 times (a back-and-force motion:
100ml),
7.2ml/(100ml×10)=0.0072
0.72vol% diluted gas is made.
Isobutane’s lower explosive limit (LEL) is 1.8vol%.
0.72/1.8×100=40.0
40%LEL diluted gas is made.

23

gas bag withdiluted gas④

11-3. Calibration Method
 Maintenance Mode

CAUTION While in maintenance mode, the external contact does not operate when theconcentration of gas reaches or exceeds the alarm set value. The product inmaintenance mode maintains the current status while the display shows [].
This mode is canceled by repeating the same operation(1 to 4), turning the product OFF,or waiting 8 hours.

1) While in gas monitor mode, press the MODE switch of the main unit first. Then press theUP switch with the magnetic stick within approximately 2 seconds.
2) The main unit displays
first, followed by(The product is ready to work but nothing has been operated.).

3) Press the UP or DOWN switch of the main unit with the magnetic stick and adjust thevalue to.

4) Press the ENTER switch of the main unit.

Gas concentration

5) When the above items are displayed alternately, the product has been set tomaintenance mode.
6) Upon completion of this mode, the product will automatically return to gas monitor
mode.
7) While

is displayed, the maintenance mode is being executed.

8) This mode will be canceled by repeating the same operation (1 to 4 above), turning the
product OFF, or waiting for 8 hours.
Carefully handle and make settings with the magnetic stick because the magnet is very
powerful. For details, refer to 3. Contents of Package.

24

 Zero Adjustment
 The external contact may operate. Therefore, set the product to maintenance mode if
needed.

MEMO

Conduct the zero adjustment in a place where there is no ambient gas.

1) While in gas monitor mode, press the MODE switch of the main unit first. Then press theUP switch with the magnetic stick within approximately 2 seconds.
2) The main unit displays
first, followed by.
(The product is ready to work but nothing has been operated.)

3) Press the UP or DOWN switch of the main unit with the magnetic stick and adjust thevalue to.

4) Press the ENTER switch of the main unit.
5) After pressing the ENTER,↓↓

When the above items are displayed, the zero adjustment is completed.
6) Upon completion of the zero adjustment, the product will automatically return to gas
monitor mode.
 If an error is displayed, refer to 10. Trouble Alarm.
 Carefully handle and make settings with the magnetic stick because the magnet isvery powerful. For details, refer to 3. Contents of Package.

25

 Span Fine-tuning
MEMO

Be sure to conduct the zero adjustment before performing span fine-tuning.

CAUTION The external contact may operate during span fine-tuning. Set the product tomaintenance mode or release the interlocks of the external devices if needed before
performing span fine-tuning.
 Only your local representative’s maintenance service members or personnel who havecompleted a maintenance seminar can perform fine-tuning.

1) Apply calibration gas corresponding to the equipment.

Calibration gas

To gas detector2) Sufficiently stabilize the gas.
3) While in gas monitor mode, press the MODE switch of the main unit first. Then press theUP switch with the magnetic stick within approximately 2 seconds.
4) The main unit displays
first, followed by.
(The product has completed starting but nothing has been operated.)5) Example: After zero adjustment,

will be displayed.

6) Press the UP or DOWN switch of the main unit with the magnetic stick and adjust thevalue to7) Press the ENTER switch of the main unit.
8) The main unit displays

first, followed by the present gas concentration.

9) Press the UP or DOWN switch of the main unit with the magnetic stick, and adjust thedisplay of the main unit to the actual span gas concentration.
10) Press the ENTER switch.
11) The span fine-tuning is completed whenis displayed.

12) Upon completion of the span fine-tuning, the product will automatically return to gas
monitor mode.
13) Remove the gasbag.
 Perform span rough adjustment if
oris displayed.
 If an error is displayed, refer to 10. Trouble Alarm.
 Carefully handle and make settings with the magnetic stick because the magnet isvery powerful. For details, refer to 3. Contents of Package.
26

 Span Rough Adjustment
 Perform span rough adjustment if

oris displayed.

CAUTION The external contact may operate during span rough adjustment.
Before performing span rough adjustment, set the product to maintenance mode orrelease the interlocks of the external devices if needed.
 Only your local representative’s maintenance service members or personnel who havecompleted a maintenance seminar can perform span rough adjustment.

1) Apply calibration gas corresponding to the equipment.
2) Sufficiently stabilize the gas.
3) While in gas monitor mode, press the MODE switch of the main unit first. Then press theUP switch with the magnetic stick within approximately 2 seconds.
4) The main unit displays
first, and displays.
(The product is ready to work but nothing has been operated.)
Example: After zero adjustment,
will be displayed.
5) Press the UP or DOWN switch of the main unit with the magnetic stick and adjust thevalue to.
6) Press the ENTER switch of the main unit.
7) The main unit displays

first, and displays the present gas concentration.

8) Press the UP or DOWN switch of the main unit with the magnetic stick, and adjust thedisplay of the main unit close to the actual span gas concentration.
9) Press the ENTER switch.
10) The span rough adjustment is completed whenis displayed.

11) On completion of the span rough adjustment, the product will automatically return to gas
monitor mode.
12) Remove the gasbag.
MEMO

Precise adjustment is not performed only by span rough adjustment. Performspan fine-tuning after span rough adjustment.

 If an error is displayed, refer to 10. Trouble Alarm.
 Carefully handle and make settings with the magnetic stick because the magnet isvery powerful. For details, refer to 3. Contents of Package.

27

 Full-scale and Alarm Set Value Display
 The full-scale and alarm set values are only displayed. They cannot be changed.
1) While in gas monitor mode, press the MODE switch of the main unit first. Then press theUP switch with the magnetic stick within approximately 2 seconds.
2) The main unit displays
first, and displays(The product is ready to work but nothing has been operated.)
Example: After zero adjustment,
will be displayed.

.

3) Press the UP or DOWN switch of the main unit with the magnetic stick and adjust thevalue to.
4) Press the ENTER switch of the main unit.

↓↓
Full scale↓↓
Alarm set value5) When the above items are displayed in sequence and repeatedly, the user can checkthe full-scale and alarm set values.
6) After the full-scale and alarm set values are displayed, the product will automatically
return to gas monitor mode.
 Carefully handle and make settings with the magnetic stick because the magnet isvery powerful. For details, refer to 3. Contents of Package.

28

 Test Mode Test values are adjusted and used for tests in this mode.

CAUTION The external contact may operate while the product is in test mode.
Before setting the product to test mode, set the product to maintenance mode or release
the interlocks of the external devices if needed.

1) While in gas monitor mode, press the MODE switch of the main unit first. Then press theUP switch with the magnetic stick within approximately 2 seconds.
2) The main unit displays
first, and displays(The product is ready to work but nothing has been operated.)
Example: After zero adjustment,
will be displayed.

.

3) Press the UP or DOWN switch of the main unit with the magnetic stick and adjust thevalue to.

4) Press the ENTER switch of the main unit.
↓
Test value5) When the above items are displayed, the test operation of the product in a concentration
range from 10% to 110% of the full scale is possible.
The test operation of the product is possible in a concentration range from 200 to 2200
ppm if the full scale of the product is 2000 ppm.
The test operation of the product is possible in a concentration range from 10%LEL to
110%LEL if the full scale of the product is 100%LEL.
6) Press the UP or DOWN switch of the main unit and set the desired concentration for the
test. Then the test will start.
If the setting is outside the operating range,orwill be displayed.
7) To quit the test mode, press the ENTER or MODE switch.
8) When the test is finished with the ENTER switch pressed, the tested value will be saved.
When the test is finished with the MODE switch, the previously saved value will remain.
 Carefully handle and make settings with the magnetic stick because the magnet isvery powerful. For details, refer to 3. Contents of Package.

29

11-4. Replacement of Sensor UnitWARNING Do not open when energized.
 Do not open when an explosive atmosphere may be present. Be sure to turn OFF the indicator unit or signal converter before replacing a sensor unit.
Otherwise, they may become a source of ignition.
 Do not damage the surface of the joints of detector enclosure, or the explosion proof
performance of the detector may be adversely affected.

CAUTION It may be necessary to rewrite the setting data of the detector according to the sensor tobe replaced. Only your local representative’s maintenance service members or personnel
who have completed a maintenance seminar can replace the sensor unit.
 Be sure to handle the sensor unit with care. Do not drop or throw the sensor unit.
Otherwise, the sensor wire may be disconnected or a sensor may be damaged.
 The external contact may operate when replacing the sensor unit if the sensor output is
not stable. Release the interlocks of the external devices if needed.
 When removing or mounting the sensor unit, do not twist the harness of the sensor
connector.
 When closing the casing cover, make sure that the power supply cord, harness, or O-ringis not caught by the casing cover.

30

Pump unit: 5), 10)Sensor unit fixing screws: 6), 7)
Sensor unit fixing plate: 6), 7)

Movement of pump unit:5), 10)Sensor connector: 3), 8), 9)
Sensor unit: 6), 7)
Sensor box: 7)* Set the groove on the sensor
unit to the dent on the sensor

Pump unit fixing screws: 4), 10)box and fix the sensor
unit.:7)

1) Turn OFF the power supply connected to the product.
2) Loosen the bolt with a hexagon socket on each of the four corners of the main unit withthe provided hexagon wrench with a nominal diameter of 6 mm, and open the casing
cover of the main unit.(See “4-1. Main unit”)
3) Disconnect the sensor connector.
4) Loosen the 4 pump unit fixing screws.
5) Pull the pump unit and slide it to left.
6) Remove 2 sensor fixing screws and remove sensor unit fixing plate and sensor unit.
7) Fix new sensor unit and sensor unit fixing plate and tighten the screws removed.
* Set the groove on the sensor unit to the dent of the sensor box when fixing the sensor
unit.
8) Connect the sensor connector to the sensor.
9) Check that the sensor connector is connected securely.
10) Place the pump unit where it was and fix it with the screws.
11) Tighten the bolt with a hexagon socket on each of the four corners of the main unit withthe provided hexagon wrench with a nominal diameter of 6 mm, and close the casing
cover of the main unit. (See “4-1. Main unit”)
12) Turn ON the power supply connected to the product.
13) When the sensor unit has been replaced, it is necessary to make zero adjustment andspan adjustment after keeping the product turned ON for approximately one week tostabilize the sensor output.
14) Be sure to make zero adjustment first, followed by span adjustment.
15) If an error is displayed, refer to 10. Trouble Alarm.
31

MEMO
 It is possible to replace the sensor unit without removing tube connected to thepump unit.
 Return the used sensor unit to your local representative.

11-5. Replacement of Pump UnitWARNING Do not open when energized.
 Do not open when an explosive atmosphere may be present.
 Be sure to turn OFF the indicator unit or signal converter before replacing a sensor
unit. Otherwise, they may become a source of ignition.
 Do not damage the surface of the joints of detector enclosure, or the explosion proof
performance of the detector may be adversely affected.

CAUTION After replacing the pump unit, make sure that all of the wirings and piping connections
are correctly connected.

Pump fixing screw: 4), 6)
Pump unit: 5), 6)

Pipes: 3), 7)

1） Turn OFF the power supply connected to the product.
1) Loosen the bolt with a hexagon socket on each of the four corners of the main unit withthe provided hexagon wrench with a nominal diameter of 6 mm, and open the casing
cover of the main unit.(See “4-1. Main unit”)
2) Disconnect the 2 pipes connected to the pump unit.
3) Loosen the 3 pump unit fixing screws.
4) Remove the pump unit.
5) Fix a new pump unit with 3 pump unit fixing screws.
6) Connect the 2 pips to the pump unit.
327) Tighten the bolt with a hexagon socket on each of the four corners of the main unit withthe provided hexagon wrench with a nominal diameter of 6 mm, and close the casing
cover of the main unit. (See “4-1. Main unit”)
8) Turn ON the power supply connected to the detector.
9) Check the sample air flow rate with the filter with flow checker (FC-32) and confirm thatthe flow is more than 0.5 liter /min.

11-6. Replacement of Filter with Flow Checker (FC-32)
Filter should be clogged if the flow rate returns to normal value (0.5 liter / min.) when thefilter in the flow checker is removed. Please replace the filter when it is necessary.
1)
2)
3)
4)

Remove the bottom cup of the flow checker after loosening fastener ring.
Pull the filter downward and remove it.
Put a new filter and fix it as it was.
Confirm that the flow rate of the flow checker is more than 0.5 liter / min.

FilterFastener ring

Bottom cup

33

12. Troubleshooting Before requesting repairs, refer to the following table. Consult your New Cosmos
representative if the product does not return to normal after taking the corresponding
remedies shown below or if the defective condition is not found in the table.
 If the product goes into an unintended mode at the adjustment or setting stage, stop
operating the product immediately and consult the system administrator.
Defective condition
The green power lamp is
not lit.

Probable cause

RemedyIncorrect wiring
connection.

Check and redo thewiring.

Low-voltage state

Check the power supply
voltage.

Reference page
P. 13
Wiring andConnection

Check that the sensor
connector is connected
securely.
The yellow lamp to
indicate an error is flashedand the error code isdisplayed.

The sensor unit isdefective, the connector
is disconnected, or thesensor wires are broken.

If there is a possibility
that the sensor isdefective or sensor
wires are broken,
contact your local
representative.

P. 13 Wiring andConnection

Check that a possibilityof clogged gas inlet,
sampling pipe and filter.

P. 33
Replacement ofFilter with Flow
Checker

The product is inmaintenance mode.

Return the product togas monitor mode.

P. 24
MaintenanceMode

The product is inmaintenance mode.

Return the product togas monitor mode.

Incorrect wiring
connection.

Check and reconnect thewiring.

The alarm point setting
is wrong.

Check the alarm setting.

The analog signal does
not change

The product is in test
mode.

Return the product togas monitor mode

A value andare flashing alternately.

The sensor output ishigh.

The concentration of gas
is in excess of the fullscale. Check theambient environment.

※
Clogged gas inlet,
sampling pipe or filter.
The detected gas
concentration andare flashingalternately.

There is no alarm contact
output.

34

P. 24
Maintenance
mode
P. 13
Wiring andConnection
P. 28
Full-scale andAlarm Set Value
DisplayP. 29
Test mode

Defective condition
A value andflashing alternately.

Probable causeare

The sensor output is low.

No adjustment or setting ispossible.

The product is operated
during the initial delay
time.

※

The flow trouble indication is optional function.

35

RemedyConduct zeroadjustment after
checking that the airaround the product is notcontaminated with gas.
Operate the productafter the 30-second
initial delay time.

Reference page
P. 25
Zero adjustment
Ｐ. 17
Display at Start-up(Initial Delay)

13. Specifications
13-1. Product Specifications
Model
Corresponding
sensor type
Sampling method
Detection gas

PD-12
PD-12A : Hot wire semiconductor sensor
PD-12B : Catalytic combustion sensor
PD-12C : Thermal conductivity sensor
Extractive
Depends on the specifications.

Detection range
Gas concentration
display
Alarm set value

Depends on the specifications.

Alarm accuracy

 Combustible gas: 25% of alarm set value under identical conditions.
 Toxic gas: 30% of alarm set value under identical conditions.

Alarm delay

 Combustible gas: Within 30 seconds with gas concentration that is 1.6
times as high as the level of alarm set concentration.
 Toxic gas: Within 60 seconds with gas concentration that is 1.6 times ashigh as the level of alarm set concentration.

Warning display

 Gas alarm (one stage only):
Red LED lamp flashes
 Trouble alarm (sensor disconnection, sensor zero drop, Flow decrease(It’s optional function), power supply voltage error, or internal EEPROM
communication error):
Yellow LED lamp flashes

External output

Gas concentration analog signal
 4 to 20 mA DC (common to the negative side of power supply)
 0.9 mA DC or less at the time of Trouble alarm.
 Make sure that the load resistance of the analog signal is less than
300 ohm including the wiring resistance.

Four-digit digital LED display
Depend on the specifications.

When flow decrease (It’s optional function.)Flow decrease alarm when the flow rate is less than 0.3 liter / min.
No contact output (Open collector) non-latching
Normally ON, when trouble OFF, when no power OFF (Max. rating : 30V
DC 30mA)
External alarm output (standard) or external trouble output
External alarm output (1 stage only)
1a no-voltage contact output/Non-latching
Rated load: 0.5 A at 250 VAC or 0.5 A at 30 VDC (resistance load)
External trouble output
1a no-voltage contact output/Non-latching
Rated load: 0.5 A at 250 VAC or 0.5 A at 30 VDC (resistance load)
Equipment orProtective System
Directive 2014/34/EU
intended for use in
Potentially Explosive SI 2016 No.1107
Atmospheres

36

Approvals

EU-Type Examination Certificate (CML 17ATEX1160):
2776
II 2G Ex db IIB+H2 T4 Gb
UKEx Examination certificate (CML 21UKEX1886):
2503
II 2G Ex db IIB+H2 T4 Gb
IECEx (IECEx CML 17.0080): Ex db IIB+H2 T4 Gb
EMC : EN61000-6-4:2007+A1:2011, EN 50270:2015 Type 2
Performance testing: The measuring function of the PD-12 gas detector for
explosion protection in accordance with Annex II clauses 1.5.5, 1.5.6 and1.5.7 of the Directive 2014/34/EU, is not covered in this certificate.

Harmonised/Design
ated standards

EN IEC 60079-0:2018
EN 60079-1:2014
IEC 60079-0:2017 Ed. 7
IEC 60079-1:2014-06 Ed. 7

Degree of protection IP65 (interior)
Applicable cable
Cable outer diameter 10.5 to 14.5 mm
 In case of a 6-conductor cable (for power supply, gas concentration analog
signal, flow decrease, and gas alarm or trouble alarm contact): CVV-S
2
2
1.25 mm or 2.0 mm
Operatingtemperature andhumidity ranges

 Temperature: 10C to 50C Humidity 10% to 90% (0 to 50C).
(No radical temperature or humidity changes and no condensation)

Power supply

24 VDC (18 to 30 VDC)

Size

133 (W) x 229 (H) x 132 (D) mm (excluding protruding parts)

Power consumption 11 W max.
Mass
Mounting method

Approx. 5.2 kg
Wall mounting

The above specifications are subject to change without notice.
If your specifications are nonstandard, refer to the delivery specifications.

37

13-2. Explosion-proof Specifications
Product nameGas Detector (Extractive Type)

Explosion-proof

EU-Type Examination Certificate (CML 17ATEX1160):
II 2G Ex db IIB+H2 T4 Gb
UKEx Examination certificate (CML 21UKEX1886):
II 2G Ex db IIB+H2 T4 Gb
IECEx (IECEx CML 17.0080):Ex db IIB+H2 T4 Gb

Ambient temperature-10C to +50CPower supply: 24 VDC (18 to 30VDC) 0.35A (max.)External output : 4-20mA DC
External contacts (1 place) : Rated load 250VAC 0.5A / 30VDC 0.5A
Flow rate: 2.2 l/min (max.)

Rating* The table above shows the specifications needed to retain explosion-proof characteristics of the productand differs from the actual product specifications as a gas detector. Refer to 13.1. "ProductSpecifications" for specifications of thegas detector.

<External makings (for explosion-proof model)>Rating label for CE/UKCA marking model

NameplateWarning label(Dimensionsare in mm)

Harmonised/Designated standards:
EN IEC 60079-0:2018
EN 60079-1:2014
IEC 60079-0:2017 Ed. 7
IEC 60079-1:2014-06 Ed. 7

38

14. Warranty
New Cosmos Electric Company Limited (New Cosmos) offers the following as the sole andexclusive limited warranty available to the customer.
This warranty is in lieu of, and customer waives, all other warranties of any kind or nature,
expressed or implied, including without limitation, any warranty for merchantability or fitness
for a particular purpose. The remedies set forth herein are exclusive.
New Cosmos warrants to the original purchaser and no other person or entity (the customer)that the gas detection product supplied by New Cosmos shall be free from defects inmaterials and workmanship for a period of one (1) year from the date of purchase. This
warranty does not include consumables, such as fuses, filters, etc. Certain otheraccessories not specifically listed here may have different warranty periods.
After examination of an allegedly defective product returned to New Cosmos, with freight
prepaid, should the product fail to conform to this warranty, the customer’s only remedy and
New Cosmos’s only obligation shall be, at New Cosmos’s sole option, replacement or repairof such non-conforming product or refund of the original purchase price of the
non-conforming product. In no event will New Cosmos be liable for any other special,incidental or consequential damages or losses of any kind whatsoever, including but notlimited to, loss of anticipated profits and any other loss caused by reason of non-operation of
the product.
This warranty is valid only if the product is maintained and used in accordance with New
Cosmos’s instructions and/or recommendations. New Cosmos shall be released from all
obligations under this warranty in the event repairs or modifications are made by persons
other than its own or authorized service personnel or if the warranty claim results fromphysical abuse or misuse of the product.

39

15. Life Expectancy
 The period of designed life expectancy of the product under standard environmental
conditions is approximately five years after the date of purchase.
The period of designed life expectancy after the expiration of the warranty period is arough standard on the condition that the product is used with specified gas calibration
performed. New Cosmos, however, does not guarantee the specified period of designed
life expectancy. The product may become unusable before the next calibration is
performed.
 The life of the hot wire semiconductor-type sensor incorporated in the PD-12A isapproximately five years after the date of purchase.
The sensor may not detect gas correctly with the lapse of approximately five years.
Replace the sensor at intervals of approximately five years. The life of the sensor is
specified on the condition that the sensor is serviced properly and that the sensor is not
exposed to high-density gas or toxic gas. New Cosmos, however, does not guarantee thespecified life of the sensor.
 The life of the catalytic combustion-type sensor incorporated in the PD-12B isapproximately three years after the date of purchase.
The sensor may not detect gas correctly with the lapse of approximately three years.
Replace the sensor at intervals of approximately three years. The life of the sensor is
specified on the condition that the sensor is serviced properly and that the sensor is not
exposed to high-density gas or toxic gas. New Cosmos, however, does not guarantee thespecified life of the sensor.
 The life of the thermal conductivity sensor incorporated in the PD-12C is approximately
five years after the date of purchase.
The sensor may not detect gas correctly with the lapse of approximately five years.
Replace the sensor at intervals of approximately five years. The life of the sensor is
specified on the condition that the sensor is serviced properly and that the sensor is not
exposed to high-density gas or toxic gas. New Cosmos, however, does not guarantee thespecified life of the sensor.

40

16. Detection Principle
16-1．Catalytic Combustion
・Catalytic combustion occurs on the catalyst even at a gas concentration below the lower
limit of combustion due to the operation of the catalyst applied to the platinum coil. The
electrical resistance of the platinum coil increases because of the rise in the temperature
at this point. This difference is extracted as deviation voltage in the bridge circuit.
Detection of combustible gases is possible up to the lower explosion limit (LEL).

16-2．Hot Wire Semiconductor
・A small amount of metal oxide semiconductor is deposited on a platinum coil, then theplatinum coil is heated to a high temperature. When combustible gases react with oxygen
absorbed on the surface of the semiconductor, free electrons increase in thesemiconductor. As a result, the resistance of the semiconductor decreases. This
resistance change is read as differential voltage using a bridge circuit for gas detection
purpose. This type of sensor is very sensitive and thus suitable for low concentration gas
detection.

16-3．Thermal Conductivity
・As compared to when only air is present around the sensor, the heat dissipation state ofthe detection piece (heated to around 150℃) to which an inert substance is applied andsintered on a platinum wire varies with the increase or decrease in the thermal
conductivity of the gas, and the temperature of the detection piece changes. Thisdifference is almost proportional to the gas concentration, and therefore, the difference inthe resistance of the platinum wire can be extracted as deviation voltage of the bridge
circuit.
Although only gases whose thermal conductivity is different from air can be measured, it
is possible to detect high-concentration gases between 0% and 100% by volume.

41

17. Glossary
Indicator / Alarm unit:

A unit that receives signals from the gas detector andindicates gas concentration and alarms.

Detector:

A unit that detects gas concentration and converts it toelectric signals.

Backup power source device: A device that supplies power to the gas detector, indicator /alarm unit in order to maintain its performance during a power
failure.
Flow meter:

A meter to measure air flow in gas sampling pipe.

Gas collector:

A gas collecting probe that enhances gas collection efficiency
and blocks water and dust.

Diffusion type:

A method to detect gas by utilizing convection and diffusionof gas.

Explosion proof construction: A totally enclosed structure. When an explosive gas explodes
in a container, the container can resist the pressure andprevent the ignition of explosive gases outside of it.
Preset alarm value:

A preset value for the alarm to go off when gas concentration
reaches a certain value.

Gas to be detected:

Gas that is detected and indicated which sets off an alarm.

Detection range:

Range of gas’s concentration that can be indicated and set
off an alarm.

Alarm accuracy:

Difference between the preset alarm value and gas
concentration when an alarm actually occurs or as thepercentage of the difference compared to the preset alarm
value.

Response time:

Time it takes from when the gas detector is exposed to a gas
with a concentration higher (lower) than the preset alarm
value until an alarm goes off.

Temperature range:

Range of temperature where the equipment can perform its
functions.

Maintenance and inspections: Work to guarantee that the equipment perform its required
functions.
Calibration gas:Gas used to calibrate scales of the equipment.

Peak hold:A function to constantly update and hold the peak value of
input signals.

Hazardous area:

An area in a plant or facility with a hazardous atmosphere
where explosive gases may mix with air and explode or starta fire. An area where gas may be present.

Non-hazardous area:

An area where electric equipment that has no potential tocreate a hazardous atmosphere.

Hazardous atmosphere:

Atmosphere within the explosive limit where explosive gas
and air are mixed.

42

LEL:

Lower Explosive Limit. The lowest concentration of
flammable gas that will explode when mixed with air andignited.

(Quoted from gas detection terms and detector tube gas meter terms used by the Industrial
Gas Detector Alarm Association.)

43

MEMO

44

Manual Revision History
Edition No.

Date

Revisions

GAE-037-00

June 201100

GAE-037-01

March 201201

GAE-037-02

May 2013

02

GAE-037-03

August 201703

GAE-037-04

February 201904

GAE-037-05

October 201905

GAE-037-06

January 202006

GAE-037-07

May 2021

07

GAE-037-08
October 2021
08
Additional copies of this Instruction Manual are available.
Contact the following address for ordering information.

Authorized representative:

Manufacturer:
NEW COSMOS ELECTRIC CO., LTD.
2-5-4 Mitsuya-naka, Yodogawa-ku
Osaka 532-0036, Japan
URL: http://www.newcosmos-global.com