Single-Point Gas Alarm System
NV-120 series
Instruction Manual for Installation

Keep this manual for easy reference.
Prior to use, carefully read this manual as well as NV-120 series instruction manual for operation(separate document) for correct use.
This manual describes the standard model. If your unit has end-user-specific options, this manual will besuperseded by your delivery specifications.

Instruction Manual No.
GAE-153-03
September 2022

Related Manuals
The following documents have been prepared to guide your installation and use of this product.
(1) NV-120 series Instruction Manual for Installation (this document), No. GAE-153-xx
This document is intended for your supervisors and service personnel who are concerned with the
installation of this product. It also provides the following information to ensure correct installation of
the product:● Safety precautions● Unit dimensions and components and precautions for unpacking● Installation precautions
One manual is provided per order, not per unit.
(2) NV-120 series Instruction Manual for Operation, No. GAE-154-xx
This document is intended for your supervisors, operators and service personnel who are concernedwith the operation and maintenance of this product. It provides the following information to ensure
the safe use of the product:● Unit dimensions and components, power on/off, troubleshooting● Basic construction and component names/functions● Operation modes and on-screen menus● Maintenance procedure and consumable replacement
One manual is provided per order, not per unit.
(3) NV-120 series wiring diagram with gas detector, No. GAE-158-xx
This document shows typical wiring configurations when connected with a gas detector and provide
supplement information for the installation.
One manual is provided per order, not per unit.

iIntroduction
Thank you for purchasing the New Cosmos NV-120 series single-point gas alarm system (“product”
or “unit” hereafter).
Prior to use, please read this manual as well as NV-120 series instruction manual for operation(No. GAE-154-xx) and follow the instructions provided for correct use.
Periodic maintenance is essential to maintain the reliability of the product. Perform periodic
maintenance checks in the manner described in this document.
Keep this manual in a safe place for easy reference.
This unit is used in connection with a gas detector (or gas detector head) that can detect a variety of
combustible/toxic gases at the site (one target gas at one detector/time). Install the gas detector at
a location where it is necessary to detect the target gas. Install the unit at a location convenient formonitoring the gas concentration.
This unit shows the gas concentration detected by the corresponding gas detector on its bar graphdisplay. In case the detector detects a leak of the target gas that exceeds a preset limit or reductionof concentration to a level below a preset limit in the case of oxygen, the unit produces audio-visual
alarms (e.g., LED, beep sound, voice message), thus helping prevent incidents such as low oxygen,gas poisoning and explosion.
There are various types of NV-120 series units. They are divided into four groups according to thegas detector types they are used with, and they are further divided into the following seven models
according to the gas sensor types. The wiring, adjustments and other unit-related items can varyfrom group to group. This manual clearly specifies the name of the applicable group/model andshows that the information or instruction provided applies to a certain group/model only.
CE marking specification is applied to Group 3, which uses 24 VDC power supply. Refer to the “EU
Declaration of Conformity” (separate document) for more information on the CE marking unit.
Group

Model Variation
NV-120Hv
NV-120Cv
NV-120Sx
NV-120Dx

Group 1
Group 2
Group 3(24 VDC power supply
CE marking specification)

NV-120Mx

Group 4NV-120Hi
NV-120Ci

A few acts are prohibited without the prior consent of New Cosmos. Please note that use of thisproduct will be treated as your acceptance of these terms. If you do not agree to these terms, do not
use this product and immediately consult your local sales representative. The aforementioned acts
are the following: Modification of this product and its related components
 Reverse-engineering of this product and its related components
 Analysis of this product and its related components including disassembly and reverse
compilation
 Transfer of this product and its related components to a third party Third party use of this product and its related components for any reason, including lease andlicensingiiPrecautions
Unauthorized copying and replication of the contents of this manual, in whole or in part, are strictly
prohibited.
The contents of this manual are subject to change without notice.
This manual has been prepared with the utmost care. If any incorrect description comes to yournotice, please contact us for correction.

Symbols Used in this Instruction Manual
Symbols for Danger Levels
Operators’ safety has been put first in designing this product. However, there exist some unavoidablerisks due to the system characteristics. In this manual, safety symbols are divided into three
categories, Danger, Warning and Caution, depending on the severity and magnitude of the risks.
Carefully read the contents related to the precautions before operation and maintenance work.
This manual uses Danger, Warning, Caution and Notice symbols to draw attention to procedures,materials, methods and processes that require particular attention.

Indicates an imminently hazardous situation that can result in death or serious injury.

Indicates a potentially hazardous situation that may result in death or serious injury.

Indicates a hazardous situation that may result in minor injury or property damage.

NOTICE
Indicates a hazardous situation that will not result in injury but may cause a product, facility, or
related equipment damage or failure.

iii

Other Signs and Symbols
This manual also uses the following signs and symbols.

NOTE
Ref.

Provides supplemental or useful information on product handling.

Details the related information or procedure.

Don’tsIndicates a prohibited action.
Mandatory
Indicates an action that must be done.
Electrical hazard
Warns of risk of electric shock under a certain condition.
Explosive hazard
Warns of a risk of explosion while handling explosive items.
Corrosive hazard
May cause burn or loss of sight if skin or eye comes into contact.

iv

Quick Index
This page lists parts that may be often referenced.
Prior to use, please read the precautions in “1 General Precautions”.
Unit Dimensions and Components
Pages 8 to 13

Non-backup power typeInstallation
Pages 16 to 21

Non-backup power typeBackup power type

Wiring and Connection
Pages 22 to 29

NV-120Power source
100-240 VAC(24 VDC)

Alarm contacts
External devices

Power source
100 VAC

Analog outputs

Recorder, etc.
Diffusion gas
detectorv

Extracti
ve gasdetector

100 VACgas
detector

Table of Contents

Related Manuals........................................................................................................................................ i
Introduction ............................................................................................................................................... ii
Precautions ...................................................................................................................................... iii
Symbols Used in this Instruction Manual ......................................................................................... iii
Quick Index ............................................................................................................................................... v
1

General Precautions ......................................................................................................................... 1
1.1 Before Work .............................................................................................................................. 1
1.2 Safety Precautions .................................................................................................................... 1
1.3 Warning and Caution Labels Affixed to Product ....................................................................... 2
1.3.1 Warning and Caution Labels Affixed to Product ............................................................. 3
1.4 Working Clothes and Protective Equipment ............................................................................. 3
1.5 Batteries .................................................................................................................................... 4
1.5.1 Battery Location .............................................................................................................. 5
1.5.2 Battery Replacement Procedure .................................................................................... 5
1.5.3 Battery Life ...................................................................................................................... 5
1.5.4 Battery Disposal .............................................................................................................. 6
1.6 Product Disposal ....................................................................................................................... 6
1.7 Service Life ............................................................................................................................... 6
1.8 Definition of Supervisor/Operator/Service Personnel ............................................................... 6

2

Unit Structure .................................................................................................................................... 7
2.1 Package Contents ..................................................................................................................... 7
2.2 Unit Dimensions and Components ........................................................................................... 8
2.2.1 Main Unit (Exterior Appearance)..................................................................................... 8
2.2.2 Main Unit (Interior Appearance) ....................................................................................10
2.2.3 LCD ............................................................................................................................... 11
2.2.4 Terminal Blocks .............................................................................................................123

System Configuration ......................................................................................................................15

4

Preparation ......................................................................................................................................16
4.1 Tools Required ........................................................................................................................16
4.2 Disposal of Packing Materials .................................................................................................16

5

Installation .......................................................................................................................................17
5.1 Installation Location ................................................................................................................18
5.1.1 Installation conditions ...................................................................................................18
5.2 Product Installation .................................................................................................................20
5.2.1 Wall-Mounting ...............................................................................................................20
5.2.2 Panel-Mounting .............................................................................................................22
5.3 Wiring and Connection ............................................................................................................23
5.3.1 Wiring ............................................................................................................................23
5.3.2 Connecting Power and Signal Lines .............................................................................24
5.3.3 Grounding .....................................................................................................................26
5.3.4 Connecting to Gas Detector .........................................................................................27
5.3.5 Connecting to External Devices ...................................................................................29
5.4 Operation Check .....................................................................................................................31

6

Glossary ..........................................................................................................................................32vi

1

General Precautions

1 General Precautions
1.1 Before Work
In order to ensure safe use, carefully read the precautions in this manual before turning on thisproduct to prevent unexpected accidents. New Cosmos is not responsible for the cost incurred orany damage resulting from any usage other than that outlined in this document.
This chapter “General Precautions” provides a general description of methods of safely using thisproduct as well as safety information and cautions related to this product.

1.2 Safety Precautions
Carefully read the following precautions for correct use.
Use this product in accordance with the applicable laws and regulations.
Wiring and installation should only be performed by a qualified electrician with knowledge of
wiring/installation procedures in accordance with the applicable technical standards.

 Operation check using actual gas is extremely dangerous and requires a special
attention, because combustible gas may have a risk of explosion and toxic gas may
be harmful to human health. It must be performed by qualified personnel or a New
Cosmos authorized technician.
 In the event of a gas alarm, take necessary actions to prevent gas poisoning.

 This product is not explosion-proof and should not be installed in a hazardous area.

 Do not use organic solvents for cleaning the product. Organic solvents may
negatively affect the product’s exterior as well as internal components.

 Ground the product to prevent electric shocks.

 In the event of a gas leak alarm, follow safety procedures in accordance with yourcompany's regulations.

 Do no use radio wave-emitting devices (e.g., cell phones, wireless devices)of the product.

30 cm

 Do not disassemble, modify, or alter the structure of the product or its electricalcircuits. Doing so may compromise product performance.

11

General Precautions

 Wiring and installation should only be performed by a qualified electrician withknowledge of wiring/installation procedures, in accordance with the applicabletechnical standards.
 New Cosmos is not responsible for the cost incurred or any damage resulting fromcontrolling external equipment (e.g., interlock) by using the product’s outputs (e.g.,analog output, alarm relay contact output).
 Only use this product in accordance with the applicable laws and regulations.

 This product is not drip-proof and should be kept away from splashing water or rain.

1.3 Warning and Caution Labels Affixed to ProductWarning and Caution labels are affixed to the areas or surrounding parts that are potentially
dangerous and require a special attention.

 To ensure safety, check the locations of the Warning and Caution labels and carefully
read them prior to operation.
 If Warning and Caution labels are missing, damaged or illegible, please contact us
for replacement.
Warning and Caution labels use size and color that are appropriate to draw the attention of theoperator and provide the risk levels with symbols.
 Refer to “1.3.1 Warning and Caution Labels Affixed to Product” for information on the labels affixed
to the product. Read the labels to be alert to possible dangers and their locations and meet therequirements provided by the labels.
 Do not remove or damage the Warning and Caution labels.
 It is very dangerous to leave the Warning and Caution labels dirty or obscured. Please contact
New Cosmos or its authorized representative for new labels.

2

1

General Precautions

1.3.1

Warning and Caution Labels Affixed to Product

Do not relocate the Warning and Caution labels affixed to the product.

Carefully read the contents of the labels prior to use.

Item
1
2
3
4

Description
Power rating label
Indicates the model, power source, target gas, and manufacturing date.
Caution label
Indicates the cautions to be adopted while handling this product.
BATT light status label
Describes the backup battery status that the BATT LED indicates.
Caution label for battery replacement (only for backup power type unit)
Indicates cautions for installation space and battery replacement.

1.4 Working Clothes and Protective Equipment

 Wear your company-specified working clothes and use protective equipment whileworking around the unit.
 Wear the right size working clothes that do not interfere with the work.

3

1

General Precautions

1.5 BatteriesThis product uses two lead storage batteries (when the unit is backup power type).
The batteries need to be replaced periodically.
The battery life varies depending on the frequency of use and environment conditions.
Follow the precautions below for proper operation.

Batteries may short-circuit resulting in electric shock or burns.
Follow the precautions listed below:
 Avoid thermal, electrical and mechanical impact on the batteries.
 Do not disassemble the batteries. Do not insert external metal in the connections on
the product’s power or signal cable. Doing so may cause electric shock, heat, ignition
or injury.
 In order to prevent rapid battery discharge, protect the battery’s electrode from directcontact with other electrolytes or metal objects. Battery discharge may cause heat orbattery leak.
 Store batteries in a clean and dry place at a temperature of 30C or lower to prevent
degradation.

 Do not place tools or other metal objects on the batteries.

 Do not mix new and old batteries.

 Use the specified batteries. Unspecified batteries may cause device failure.

 Dispose of batteries in accordance with the applicable laws and regulations.
 If abnormal odor, noise or smoke is observed during operation, cease the operation
immediately and disconnect the power plug. Continued operation under suchcircumstances may cause a fire.

 Replace the batteries periodically. Using expired batteries may cause a battery leak,
which will then result in a secondary disaster such as an electric leak, electric shock,smoke or ignition.

4

1

General Precautions

1.5.1

Battery Location

Item

Description
Battery x 2 pcs

1

1.5.2

Battery Replacement Procedure
Refer to “6.1.2 Battery Replacement” of the NV-120 series instruction manual for operation.

1.5.3

Battery Life
If this product is to be kept unused or stored for an extended period of time, the batteries must be
removed. Leaving the batteries inside while the product is not in use or being stored for an extended
period of time may impair/shorten the performance/life of the batteries and cause their terminal
corrosion.
The battery life is about two years from the month of manufacture. After two years, replace thebatteries even if they pass the battery voltage test.
“Two years” is only an estimate, and no guarantee is provided. The battery life may vary depending
on several factors including frequency of use, temperature and usage or storage conditions .

In order to prevent serious secondary disasters such as a broken battery case or ignition,
replace the batteries periodically.

Using expired batteries will cause internal battery degradation, which may disable theunit to operate for designed hours with the backup batteries after power outage, or may
cause an abnormal appearance such as a swollen battery case, battery leak or electric
leak.

5

1

1.5.4

General Precautions

Battery Disposal

Used batteries must be disposed of as hazardous waste in accordance with the applicable laws andregulations,

Do not heat or throw batteries into a fire. Improper handling may lead to explosion.

Do not open or disassemble batteries. Electrolyte is harmful, and its contact with eyesand skin is dangerous.

1.6 Product Disposal
Dispose of the used product in accordance with the applicable laws and regulations.

1.7 Service Life
The service life of this product is 10 years. The unit can operate for up to 10 years with standard
installation and operation in accordance with the NV-120 series instruction manuals for installationand operation. When the service life has expired, replacement is essential for continued reliable
performance and other purposes.

1.8 Definition of Supervisor/Operator/Service Personnel
This manual is intended for personnel concerned with this product, and the personnel are divided
into three categories according to safety level, skills and experience. This manual clearly specifies
the name of the applicable category and shows that the information or instruction given applies tothat category only.
Manages the product operation.
Supervisor

Fully understands the product operation method, entire gas alarm
facility, and gas/fault alarm clearance method.
Should carefully read this manual and be familiar with the systemcharacteristics and relevant work activities.
Operates the product.

Operator

Service personnel

Understands the product operation method, the way to address
gas/fault alarms, and daily work activities for the product under thesupervisor’s instruction.
Carries out installation, failure cause investigation, maintenance andrepair work for the product.
Requires special knowledge and skills.
Acts as New Cosmos authorized technician in principle.

62

Unit Structure

2 Unit Structure
2.1 Package Contents
A standard package consists of the following items. If any items are missing or damaged, pleasecontact New Cosmos or its authorized representative for replacement.

Non-backup power type (Unit with no backup batteries)
Item

Qty.

Description

NV-120 unit

1

Replacement fuse

1*3

250 V 2 A Φ5.2 × 20mm

Wall-mounting kit

1*1

Mounting screws (M5 × 15), pan-headPanel-mounting kit

1*2

x 2 pcs

Mounting bracket S

x 1 pcMounting screws (M5 × 15)
Pan-head, used for attaching bracket to unitx 2 pcs

Tension screw (M6 × 40)
Pan-head, used for attaching bracket to panel

x 2 pcs

Flat-head screwdriver

1*3

Used to open/close the terminal plugs

NV-120 series
instruction manual set

1*3

Instruction manual for installation (GAE-153-xx)
Instruction manual for operation (GAE-154-xx)

x 1 pcx 1 pcNV-120 series
wiring diagram

1*3

Wiring diagram with gas detector (GAE-158-xx)

x 1 pcInspection certificate

1

Ferrite core2

Protect the unit from electrical noise.

Cable tie

2

Used to secure the ferrite core.

Backup power type (Unit with backup batteries)
Item

Qty.

NV-120 unit

1

Replacement fuse

1

Wall-mounting kit

Panel-mounting kit

1*1

1*2

Description
250 V 2 A Φ5.2 × 20mm
Mounting screws (M5 × 15), pan-headx 3 pcs

Upper mounting platex 1 pcLower mounting platex 1 pcMounting screw (M3 × 6)
Flat-head, used for attaching mounting plates to unitx 4 pcs

Mounting bracket B

x 1 pcMounting screws (M5 × 8)
Pan-head, used for attaching bracket to unitx 2 pcs

Tension screw (M6 × 40)
Pan-head, used for attaching bracket to panel

x 2 pcs

Flat-head screwdriver

1*3

Used to open/close the terminal plugs

NV-120 instruction
manual

1*3

Instruction manual for installation
Instruction manual for operation (this document)

Inspection certificate
Ferrite core

1
2

Protect the unit from electrical noise.

Cable tie

2

Used to secure the ferrite core.

*1. Provided when “wall-mounting” was specified at the time of order.
*2. Provided when “panel-mounting” was specified at the time of order.
*3. One screwdriver/manual is provided per order, not per unit.

7

x 1 pcx 1 pc2

Unit Structure

2.2 Unit Dimensions and Components
Main Unit (Exterior Appearance)

2.2.1

Non-backup power type

Item

Backup power type

Component(mm)

Description

1

Case

－

2

Cover

－

3

LCD

Shows gas concentration on the display.
Refer to “2.2.3 LCD” for details.

4

Jog dial

Turn to select item or increase/decrease the parameter value.

5

ENT button

6

MENU/CANCEL button

7

BZ STOP/RESET button

8

Green POWER LED

9

Amber FAULT LED

10

Red ALARM LED

Press and hold to confirm the selection or setting.
Press to increase/decrease the parameter value.
Press to switch to the menu, return to the previous menu or cancel
the current operation.
Its LED flashes when a gas alarm activates.
BZ STOP: Press to mute the audio alarm (beep sound and voicemessage). The flashing LED will become steadily lit.
RESET: Press and hold to clear the peak hold indication andvisual gas alarm. The LED will turn off. The RESET
operation is enabled after the audio alarm is muted.
Indicates the operation status.
Not lit when the unit is off.
Flashes when the warm-up is in progress.
Lit when the unit is operating normally.
Indicates the operation status.
Not lit when the unit is operating normally.
Flashes when a fault has been detected.
Indicates the alarm operation status.
Not lit when the warm-up is in progress or unit operates normally.
Flashes when 1st stage gas alarm activates.
Flashes rapidly when 2nd stage gas alarm activates.

82Unit Structure

Item

Component

11

Red MAINT LED

12

Red BATT LED

13

Audio opening

14
15

Battery caseBattery lid

Description
Indicates the maintenance mode status.
Not lit when it is not in the maintenance mode but in normal
operation.
Flashes when the unit is in maintenance mode 1.
Lit when the unit is in maintenance mode 2.
Indicates the backup power status.
Off indicates normal operation. Backup batteries are not used.
Flashing indicates that backup batteries are being used.
On indicates that backup battery failure has been detected.
*This LED is always off when the unit is non-backup power type.
Opening or audio. Gas leak or device fault alarm will be issued bybeep sound and voice message.
Refer to “4.5 Audio Alarms” of NV-120 series instruction manual for
operation.
Comprise a backup power supply unit (backup battery x 2 pcs)

9

2

Main Unit (Interior Appearance)

2.2.2

Do not touch the jumper pins inside. They are for device setting.

Do NOT touch these pin sockets to set the jumper pins inside

Item

Component

Description

1

Power switch

Press to turn on/off the unit.

2

Fuse holder

Houses a 2A fuse.

3

Earth terminal

Used for grounding the unit. Thread size: M4

4Terminal block (4 places)

Used for external wiring.

5

Backup power switch

6

Backup power LED

7

Analog output connector

Turns on/off the backup power supply unit.
*Only available for backup power type unit.
Lit when the backup power switch is in the on position.
Used for checking the analog output.
Applicable connector: ZHR-3 (J.S.T.)

10

Unit Structure

2

Unit Structure

LCD

2.2.3

HOME
（Gas-monitoring）

Target gas: Gas other than oxygen
Item
1
2
3

Component
Gas concentration bar graph
1st stage gas alarm set value
2nd stage gas alarm set value
Unit(unit of measurement)

4

AL1 (1st stage gas alarm set
value)

AL2 (2nd stage gas alarm set
value)

5

F.S. (full scale value)
Unit of measurement

6

Gas concentration

This icon is present when the unit is in warm-up cycle.

Lock icon

11
12

/

Speaker icon/

Displays the 2nd stage gas alarm set value.

Warm-up icon

810Displays the 1st stage gas alarm set value.

Maintenanceicon

Test icon/

Description
Displays the gas concentration and alarm set values.
Displays the 1st stage gas alarm set value with orange line.
Displays the 2nd stage gas alarm set value with red line.
Displays the unit of measurement for the gas concentration.
Note: “x10” is displayed when the largest value is greaterthan the four-digit limit. E.g., If the largest value is 10,000
ppm, then “1000” is displayed for the bar graph with “x10”.

Displays the full scale value.
Displays the unit of measurement for oxygen concentration.
Displays the oxygen concentration.
Note: This is displayed only when the target gas is oxygen.
This icon is present when the unit is in test mode.
It replaces the lock icon during the test mode.
This icon is present when the button/dial operation islocked.
This icon is present when the unit is in maintenance mode 1
or 2.

7

9

Target gas: Oxygen

Voice icon

This icon is present when the audio alarm isunmuted/muted.
This icon is present when the voice message isunmuted/muted.

11

2

Item

Component

13

2.2.4

Unit Structure

Description

ENT iconPress and hold the ENT button for confirmation.

Terminal Blocks
Models:Models: NV-120Sx, NV-120Dx

Terminal

Identifier
R (P)

Power
(Input)S (N)E(Earth terminal)
AL1(1st stage gas alarm)
AL2(2nd stage gas alarm)
Fault(Fault alarm)
Buzzer(Alarm sound)
CommonDetector(Power output for pump)
External switch

Detector
4-20mA OUT(Analog output)

ZA1 (ZB1)ZC1ZC2ZA2 (ZB2)
FA (FB)

Description
AC type: 100 to 240 VAC
DC type: 24 VDC (+)
AC type: 100 to 240 VAC
DC type: 24 VDC (-)
Earth
Earth
Thread size: M4
1st stage gas alarm contact output
Normally-open or Normally-closed*1
Common for ZA1 (ZB1)*2
Common for ZA2 (ZB2)*2
2nd stage gas alarm contact output
Normally-open or Normally-closed*1
Fault contact output
Normally-open or Normally-closed*1

BZ

Alarm sound contact output

COM
PA
PB
AR
AS
N
A/F
B, C
C, D
D, F
G
H

Common for Fault and Buzzer contact outputs*2
24 VDC (+)
24 VDC (-)
External switch (button) input

Gas detector*1
Analog output signal (+)
Analog output signal (-)*1. As per delivery specifications.

122Unit Structure*2. These common terminals are not connected (individual-common) by default, unless otherwise
specified at the time of order. To connect them (to short-circuit the common lines: sharedcommon), refer to the attached wiring diagram (GAE-158-xx).

13

2Unit Structure

Contact Outputs
Outputs to external devices (e.g., signal towers, alarm horns, etc.) are referred as “contact outputs”.

NOTICE
 Contacts use mechanical relays, which can activate on exposure to magnet force.
Install the product in a place free from a magnetic field. Do not use a magnet in thevicinity of the product.
 Contacts use mechanical relays, which can activate on exposure to excessive shockor vibration. Install the product in a place free from shock and vibration. Set a delay
time greater than one second for external devices connected to the product.

 Use the product in a place where the rated load is not exceeded.

14

3

System Configuration

3 System Configuration
This NV-120 unit is paired with a gas detector (sold separately) to form a gas detection system. All
the parts are connected with cables. The unit displays the gas concentration detected by theconnected gas detector and produces audio-visual alarm if the concentration reaches a present limit.

NV-120Power source
100-240 VAC(24 VDC)

Alarm contacts
External devices
Power source
100 VAC

Analog outputs
Recorder, etc.

Diffusion
type gas
detector

Extractive
type gas
detector

100 VACgas
detector

Typical System Configuration

NOTE One gas detector, diffusion or extractive type, can be connected to each NV-120
unit. Use a protective cover (sold separately) for the gas detector for outdoor
installation. Refer to the gas detector’s instruction manual for details.
 Wiring differs depending on a connected gas detector.

15

4Preparation

4 Preparation
4.1 Tools Required
The user will require the following tools for installation:●

Phillips screwdriver (#2) for M3 and M5 screws;●

Phillips screwdriver (#3) for M6 screw;●

Flat-bladed screwdriver (6mm) for knurled screw.

●

Flat-bladed screwdriver (3.5mm)* used for wiring terminal blocks;*One screwdriver is provided per order, not per unit.

4.2 Disposal of Packing Materials
The packing materials (for instance, cardboard boxes and plastic bags) used to enclose the productand optional items should be disposed of in accordance with the applicable laws and regulations.

16

5Installation

5 Installation
Ensure proper installation in accordance with the given specifications.
Installation Flow

5.1. Installation Location

5.1.1 Installation Conditions

5.2. Product Installation

5.2.1. Wall-Mounting
5.2.2. Panel-Mounting

5.3. Wiring and Connection

5.3.1. Wiring
5.3.2. Connecting Power and Signal Lines
5.3.3. Grounding
5.3.4. Connection to Gas Detector
5.3.5. Connection to External Devices

5.4. Operation Check

Do not use organic solvents for cleaning the product. Organic solvents may negatively
affect the product’s exterior as well as internal components.

● This product is not explosion-proof and must not be installed in a hazardous area.
● Ground the product to prevent electric shocks.
● In the event of a gas alarm, follow the safety procedures in accordance with yourcompany’s regulations.

● Avoid using the product in an environment where it will be exposed to vibration,
electric noise, corrosive gas, high temperature, and high humidity, since such factors
may result in damage or malfunctioning of the product.

● Contacts use mechanical relays, which can be activated if exposed to excessive
shock or vibration. Install the product in a place free from shock and vibration. Set adelay time greater than one second for external devices connected to the product.

● Do not install the product in the vicinity of equipment that can generate highfrequencies or a magnetic field, since such factors may result in malfunctioning of the
product.

17

5Installation● Be careful not to damage the product during installation.
● Install the product in a place where it can be easily accessed for maintenance orinspection.

● Do not install the product in a place exposed to direct sunlight. Exposure to direct
sunlight will cause sudden temperature change inside the product, which may impair
its performance.

● This product is not drip-proof and must be installed indoors to keep away fromsplashing water.

● Install the product at a height safe and convenient for maintenance and inspection.
● Do not install the product in the following conditions:- Ambient temperature beyond the specified operating temperature range;- Condensation-prone areas;- Exposure to sudden temperature/humidity change;- Exposure to water spray;- Presence of corrosive gas;
- In the vicinity of equipment that can generate high frequencies or a magnetic field;- Near to a heat source;- Vibration-prone areas;- In the presence of an ignition source;- On a ceiling.
For the installation of the gas detector, refer to its instruction manual (separate
document).

5.1 Installation Location
5.1.1

Installation conditions
Install the product in a highly visible position, so that in the event of an emergency, the alarm can beeasily alerted and addressed.
When installing the product, ensure that there is enough space below, above, and on each side of
the product to allow for easy installation activity, as explained below.

Space required for product installation
Front: Maintain a distance of 50 cm or more between the front part of the product and any otherobject. The product needs to be operated from the front during maintenance and inspection.
Side: For the backup power type unit, maintain a distance of 30 cm or more from the right side of the
product to allow for battery replacement.
Below: Maintain a distance of 30 cm or more from the bottom of the product to allow for maintenanceand cover opening/closing.

18

5Installation

Non-backup power typeBackup-power type(backup batteries included)

The installation spaces can change depending on the power type, whether backup or
non-backup. For the correct installation space of the gas detector, refer to its instruction
manual.

Installation at a raised position
When installing the product at a high location, ensure that enough space is left below the product toallow for inspection or maintenance using a stepladder, among others.

● Do not install the product at a high location that cannot be accessed by a stepladderor the like.

● Leave enough space below the product to allow for maintenance and inspection
using a stepladder or the like.

195Installation

5.2 Product Installation
There are two installation methods for the product: wall-mounting and panel-mounting.

Turn off the power switch before installation. Installing the product with the power switch
on may cause device failure.

NOTICEThe installation location changes depending on the power type, whether backup or nonbackup. Refer to “5.1 Installation Location”.

5.2.1

Wall-Mounting

NOTICEThe mounting hole size changes depending on the power type, whether backup or non-backup.

Installation procedure1

Cut mounting holes — two for non-backup power type and three for backup power type
— in the wall as shown below:(mm)

Cut two holes fornon-backup power type

20

Cut three holes forbackup power type

5

Installation2

For the backup power type, install the upper and lower mounting plates (provided) at
the back of the unit using four screws.
Upper mounting plateM3x6
Flat-head screw (4 places)

Lower mounting plate

3
4Install wall anchors into each of the mounting holes.
For the non-backup power type, turn the knurled screw counterclockwise and loosen it.
Knurled screw

5

First, tighten the upper screw, and then the lower screw(s).

M5x15Pan-head screw(2 places)

M5x15 Panhead screw(3 places)

Non-backup power type21

Backup power type

5

5.2.2

Installation

Panel-Mounting
Installation procedure

1
2

Remove the two grommets from the bottom of the unit.
Make a square cutout in the panel as depicted below.

Panel cutout size (mm)3

Insert the unit through the square cutout. Attach the mounting bracket S/B to the backof the unit using the two mounting screws. Attach the unit to the panel using the twotension screws.

● The unit can be installed on a 1.6mm to 6mm thick panel.
● For the non-backup power type, open the cover and secure the mounting bracket S using
the two mounting screws.
Recommended tightening torque
Recommended tightening torque
100 N·m
50 N·mThreadM5
M6

Mounting bracket B

Mounting bracket S

M5x15
Mountingscrew,
pan-head(2 PL)

M5x8

M6x40

Mountingscrew,
pan-headTensionscrew,
pan-head(2 PL)

Non-backup power type(2 PL)

M6x40

Tension screw,
pan-head(2 PL)

Backup power type

● Tighten the screws according to the recommended tightening torque. Tightening
screws with excessive torque may deform the case or damage the mounting bracket.

● For the backup power type unit, install the unit at a place where the unit itself can beeasily detached, or maintain a distance of 30 cm or more from the right side of the
product to allow for battery replacement.
There are a total of six cable entries: four on the back and two on the bottom. Cables
can be hidden if fed through the back side. For the backup power type unit, only the225Installation

cable entries on the bottom can be used.

5.3 Wiring and Connection
5.3.1

Wiring
Be careful not to damage the cables during installation.
Sheath all cables in a protective casing, such as a metal conduit or carbon steel pipe, as needed.
Other protective structures, such as metal or concrete ducts are also acceptable.

● To prevent electric shocks, turn off the power switch before installation.
● Both the product and the gas detector should be grounded.

● Connect the wires to their corresponding terminals by referring to the identifiers
marked on both the product and the gas detector.

● Keep the connection cables (power and signal lines of the product) away from otherpower lines.

● For wiring of the gas detector, refer to its instruction manual.
● While performing the wiring, do not stress the cables excessively.
Connectable cable List
Terminal
Power(Input)AL1(1st stage gas alarm)
AL2(2nd stage gas alarm)
Fault(Fault alarm)
Buzzer(Alarm sound)
CommonDetector(Power output for pump)
External switch

Detector

4-20mA OUT(Analog output)

Identifier
R (P)
S (N)
E
ZA1 (ZB1)ZC1ZC2ZA2 (ZB2)
FA (FB)

Recommended cable
CVV (0.75mm2 to 2.00mm2)

CVV (0.75mm2 to 2.00mm2)

BZ
COM
PA
PB
AR
AS
N
A/F
B, C
C, D
D, F
G
H

Refer to the gas detector’s instruction manual.
CVV (0.75mm2 to 2.00mm2)

Refer to the gas detector’s instruction manual.

CVVS (0.75mm2 to 2.00mm2)

23

5

5.3.2

Installation

Connecting Power and Signal Lines If needed, use a dedicated breaker for the power line going towards the product.
 Ensure that the power voltage supplied to the product is within the specifications.
 Ensure that the load resistance of the signal line, including the resistance of the wire, is 300 ohm
or less.
Terminal block specifications
 Solid and stranded wires can be connected to the terminal blocks without wire ferrules, but It is
recommended to use terminal block wire ferrules to prevent unraveled or stray wires.
Recommended wire ferrule with sleeve:
Phoenix Contact AI 0,75 – 8 GY
Phoenix Contact AI 1 – 8 RD
Phoenix Contact AI 1, 5 – 8 BK
 Prepare wires/pins that meet the following cable specifications:
Wire cross section (solid wire):
0.2mm2 to 4.0mm2
Wire cross section (stranded wire): 0.2mm2 to 2.5mm2
Wire ferrule with no sleeve:
0.25mm2 to 2.5mm2
Wire ferrule with sleeve:
0.25mm2 to 1.5mm2
Striped wire length:
10mm
Wire ferrule rod length:
8mm
Stripped wire length

Wire ferrules rod length

Wiring for a terminal block Recommended tool: Provided flat-bladed screwdriver*Use a screwdriver with a 3.5 mm-wide head when using a commercially available one.

1

Fully insert the flat-head screw driver into the square slot on the terminal block to open
the corresponding round slot.

24

5Installation

2

Fully insert the tip of each wire into the round slot.

3

While holding the wire, remove the screwdriver from the square slot. This will securely
connect the wire to the terminal.

4

Slightly pull the wire to ensure that it is secure in the terminal.

To remove the wire from the terminal
Insert the screwdriver into the square slot to open its corresponding round slot. In this way, thewire will be released.
Hint for wiring
Be careful not to let the wires stray beyond the surface A. The cover cannot be closed properly
if they stray beyond.

Surface A

25

5

5.3.3

Installation

Grounding● Wiring and installation must be only performed by a qualified electrician withknowledge of wiring/installation procedures in accordance with the applicabletechnical standards.

● For wiring of the gas detector, refer to its instruction manual.
（1） Typical wiring when the shield is grounded on the external device’s side
Single-point grounding is mandatory. Do not ground the shield cable to the groundterminal () located inside the gas detector when the shield from the product isgrounded on the external device (e.g. signal tower, alarm horn). This will create twopoint grounding.

GasdetectorShieldedcable

NV-120Shielded
cable

External
deviceShieldDo not ground.

Do not ground.
Class-Dgrounded

Grounded（2） Typical wiring when the shield is not grounded on the external device’s sideGas
detectorShieldedcable

NV-120Shieldedcable

ShieldDo not ground.

GroundedClass-Dgrounded26

External
device5Installation

5.3.4

Connecting to Gas Detector
The wiring configuration changes depending on the given specifications. Check the group/model
variation of your unit (page ii) prior to wiring.

● Connect the wires to their corresponding terminals by referring to the identifiers
marked on both the product and the gas detector.

● Keep the connection cables (power and signal lines of the product) away from otherpower lines.

● For wiring of the gas detector, refer to its instruction manual.
For cable length, refer to the gas detector’s instruction manual.
Typical configuration for Group 1 (NV-120Cv / NV-120Hv)

G

G

G

5-coreshielded cable

3-coreshielded cableG

6-coreshielded cableG

Diffusion type gas detector

G

Extractive-type gas detector Extractive-type gas detector with flow sensor(Pump power: 24 VDC)
(Pump power: 24 VDC)

Typical configuration for Group 2 (NV-120Sx / NV-120Dx)

G
G
¥
¥

G
2-coreshielded cable

2-coreshielded cable

4/5-coreshielded cable

Zener barrier

Non-hazardous
area

Single-point
groundedClass A

2-core shielded cable

Hazardous
area
G
¥
¥

G
G

Diffusion type gas detector

Extractive-type gas detector(Pump power: 24 VDC)

Intrinsically-safe¥gas detector*G: Grounded*F: Flow sensor; use the F terminal for the low flow rate signal output.

27

5Installation

Typical configuration for Group 3 (NV-120Mx)

G

G

G

3-coreshielded cable

3/4-coreshielded cable

2-coreshielded cable

G

G

G

Diffusion type gas detector

Extractive-type gas detector Diffusion/extractive-type gas detector(Pump power: 24 VDC)
(Power: 100 VAC)

Typical configuration for Group 4 (NV-120Ci / NV-120Hi)

G

G

4-core cable

6-core cableG

Diffusion type gas detector

G

Extractive-type gas detector(Pump power: 24 CDC)

*G: Grounded.
*F: Flow sensor; use the F terminal for the low flow rate signal output.

28

5Installation

5.3.5

Connecting to External Devices（1） Connecting to an external controller or annunciator
Normally open or closed dry contacts are turned on/off for activating/deactivating a 1st stage gas
alarm, 2nd stage gas alarm, and fault alarm.

New Cosmos is not responsible for the costs incurred or any damage resulting fromcontrolling external equipment (e.g. interlock) by using the product’s contact outputs(e.g. analog output, alarm relay contact output).

● The external alarm relay contacts should be used for external devices (e.g. signal
towers and alarm horns) only.

● Load current and voltage should not exceed each contact’s capacity.
Typical connection to an external controller or annunciator (in case of normally open contact)

Controller

Annunciator

Fuse

Power for controller（2） Connecting to an external alarm horn
The normally open dry contact (BZ) is turned on/off for activating/deactivating external sound devices(e.g. alarm horn).
When using an electromagnetic horn (inductive load), the horn capacity should not exceed half ofthe contact capacity (Figure B).
Use a fuse in the horn’s electrical circuit.
Typical connection to an external alarm horn
Relay contact

Alarm horn

Fuse

Power for alarm horn

Fuse

Power for relay contact

Figure A. Connection with small-capacity alarm horn

29

Power for alarm horn

Figure B. Connection with large-capacity horn

5

Installation（3） Connection to external switch terminals
There are two external switch terminals: “AR” and “AS”.
To use the unit as semi-lock type, connect the panel’s alarm reset button to the “AS” terminal. This
enables to reset an alarm from both the external device and the unit.
To use the unit as full-lock type, connect the audio alarm mute button to the “AS’ terminal and connect
the alarm reset button to the “AR” terminal.

For an alarm reset button, use a dedicated contact completely independent from othercircuits.
Typical connection to an external reset terminal
Alarm reset button
Alarm reset button

Audio alarm mute button

Semi-lock type

Full-lock type（4） Connection to an analog output
Analog signals corresponding to the gas concentrations (4-20ｍA or 1-5 V) are outputs from the “G”
and “H” terminals.
As required, a recorder or PLC, among others, can be connected to the said analog output terminals.

● When connecting to a PLC, separate the power source for the PLC from the one forthe product, and use a noise filter next to the power source for the PLC.

● Ensure that the load resistance of the signal line, including the resistance of the wire,is 300 ohm or less.
Typical connection to analog output terminals

Recorder,PLC etc.

Noise
filterPower source

Grounded30

5Installation

5.4 Operation Check
Once the installation process is completed, check if the product turns on normally.
Take the following steps to check the operation.

● Load exceeding the mentioned load capacity should not be connected to external
alarm contacts.

● When checking the input voltage with a digital multimeter, do not fully insert its test
lead tips into the square slots on the terminal block. Doing so may disconnect thewiring.

● Check that all the wiring is correct before powering-up, especially between the gas
detector and the product.

1

Insert the digital multimeter’s test lead tips into the square slots (Nos. 1 and 2: power
input terminals).

2

Measure the input voltage to check that the value is within the specification.

3

Set the power switch to the on position. Check the unit turns on normally.

Power switch

Ref.

Refer to “4. Operation” of the NV-120 series instruction manual for operation (separate
document) for more information.

31

6

Glossary

6 Glossary
Term
Alarm unit

Definition
Device that indicates the gas concentration and activates an alarm according
to the signals received from a connected gas detector.

Backup power supply
unit

Battery unit that provides emergency power to the product when the input
power source or main power fails.

Backup power type andnon-backup power type

There are NV-120 units with and without backup batteries attached. They arecalled “Backup power type” and “non-backup power type” respectively.

Gas detector (or gas
detector head)

Device used to detect the presence of a target gas and to give its
concentration in the form of an electrical signal.

Diffusion typeGas sampling method using convective diffusion while placing a gas detector
at a detection point.

Extractive typeGas sampling method using a pump.

Target gas

Specific gas to be detected, concentration displayed, and used to trigger
alarms.

Alarm set value

A gas concentration value that is set on a gas detector for alarm activation.

Detection range

A range of target gas concentrations that can be displayed and trigger
alarms.

Alarm accuracy

Difference between the alarm set value and the detected gas concentrationthat activates the alarms. It may also be expressed as a % with respect to thealarm set value.

Operating temperature/humidity range

Ambient temperature/humidity range in which the gas detection and alarmsystem can operate normally.

Maintenance andinspection

Tasks performed to ensure that equipment operates normally and correctly.

Hazardous area

An area in which an explosive atmosphere is present, or may be expected to
be present, in quantities such as to require special precautions for theconstruction, installation and use of electrical apparatus.

Non-hazardous area

An area in which an explosive atmosphere is not expected to be present inquantities such as to require special precautions for the construction,
installation and use of electrical apparatus.

Explosive atmosphere

Mixture of air and flammable substances in the form of dust or vapor which
are within their explosive limits.

LEL (or LFL)

Lower Explosive Limit (or Lower Flammable Level). Lowest concentration(percentage) of a gas or vapor in air capable of producing a flash fire, or
explosion in the presence of an ignition source like arc, flame or heat.

%LEL

Concentrations of combustible gas given in terms of percent of the lower
explosion limit.

vol%Gas concentrations given in terms of percent of cubic volume.

ppm

Gas concentrations given in terms of millionth part of cubic volume.

Zero suppression(or 20.9 suppression foroxygen detection)

For indicator units with a zero suppression (or 20.9 suppression) function, thebar graph display will continue to indicate “0” (or 20.9 vol%) until the target
gas concentration detected by the detector exceeds the pre-set value. The
pre-set value is given in the delivery specifications.

32

6Glossary

Clean air or normal air

Standard atmosphere which contains 20.9 to 21.0% oxygen in dry condition
or atmosphere without target gas or interference gases.

Term

Definition
After an alarm has been triggered, and a target gas concentration falls below
the gas alarm set value minus 2% of the full-scale value, the ALARM lights
and relevant gas alarm contacts will automatically return to their normal
positions.

Auto-resetting

Manual-resetting

Even if a target gas concentration falls below the gas alarm set value after an
alarm has been triggered, the ALARM lights and relevant gas alarm contacts
will not automatically return to their normal positions. Manual-resetting is only
possible when the gas concentration is below the gas alarm set value.

Full-lock type

Alarm unit type. After an alarm is activated and muted, the alarm status(ALARM light and output are active) will be maintained even if the gas
concentration falls below the alarm set value. To clear the alarm, manual
operation is needed (e.g., pressing the reset button.)(or Latching type)Semi-lock type(or Non-latching type)

Alarm unit type. After an alarm is activated and muted, the alarm status will
be automatically cleared when the gas concentration falls below the alarm set
value.

33

Document No.

Revision History
Date

Revision

GAE-153-00
GAE-153-01
GAE-153-02
GAE-153-03

December 2019
February 2020
December 2020
September 2022

0 (Initial issue)
12
3

Additional copies of this instruction manual may be purchased.
Contact New Cosmos or its authorized representative for ordering.

Authorized representative:

Manufacturer:
NEW COSMOS ELECTRIC CO., LTD.
2-5-4 Mitsuya-naka, Yodogawa-ku,
Osaka 532-0036, Japan
http://www.new-cosmos.co.jp