SAMPLE SPECIFICATION: HARD WIRED Carbon Monoxide (CO)** and/or Nitrogen Dioxide
(NO2)** DETECTION SYSTEM
** engineer to determine if one or both of the gases are to be included in the system **
1. General
The work covered by this section includes the Procurement and installation of a Gas
Detection System and related components as described herein and as shown on the
contract drawings. The major items of work to be included are:
1.1. installation of a central control panel(s) as located on the contract drawings,
1.2. provide required electrical connections for 120 VAC power feed,
1.3. provide interconnect components for exhaust/supply fan control,
1.4. provide central control panel annunciation interconnect wiring as described herein,
1.5. installation of (*ENGINEER TO ADD CO/NO2 SENSOR COUNT HERE*) sensors as
shown on the drawings,
1.6. installation of signal cabling and conduit between the sensors and control panel,
1.7. provide calibration accessories for start-up and commissioning services by
Manufacturer Authorized or certified Technician.
The CO/NO2 Gas Detection System shall be a hard-wired system employing diffusion
style gas detection method. The MSA ZGard family of Products as manufactured by
MSA and represented by XXXXXXXXXXXXXXXXXXXXXXXXXX
2. Submittals
2.1. Product data: Submit specific product literature for all materials.
2.2. Submit Installation, Outline, Dimensional and planned wiring Drawings.
2.3. Provide certification of Manufacturer’s Authorized Start up Agent or Certified
Technician.
3. Central Control Panel
3.1. The control panel shall provide a scanning illuminated display showing the sensor
number and parts per million (ppm) level for each sensor in sequential order, and shall
provide an LED indication of sensor and system status, “sensor ok", "warning", “Sensor
Failure” and "alarm".
3.2. The control panel shall include auto-configuration upon power up that digitally
recognizes all remote devices on the network and assigns a network node value.
3.3. The control panel shall include an internal user programmable internal audible alarm
with local and remote push-button reset capability.
3.4. The control panel enclosure shall be rated for General Purpose use and constructed of
painted steel construction with hinged door secured by tamper resistant screws.
3.5. The control panel shall operate on 120 VAC, 50/60 Hz power and include internal
power supply capable of powering all remote devices communicating with the central
control panel via four conductor shielded cable(s).
3.6. The central panel cabinet shall include a common warning, alarm, system fault and
annunciation relay for external audible/visual device.
3.7. The central panel shall include field programmable zone control capability via 12 user
programmable relays, expandable to 126, to improve fan activation sequence.
3.8. The central panel shall incorporate a programmable on/off time delay to minimize fan
oscillation when the detected levels of gas reach the threshold activation value of the
control point for the fan interlocks.
3.9. The central shall have the capability to accommodate a unit mounted Strobe Tower or
remotely mounted Horn Strobe Tower that can be activated and via any of the provided
relay contacts.
4. Carbon Monoxide and/or Nitrogen Dioxide Sensor/Transmitters
4.1. The CO sensor transmitter shall have a full scale detection range of 0-200 parts per
million (ppm) full scale.
4.2. The NO2 sensor transmitter shall have a full scale detection range of 0-10ppm full
scale.
4.3. The Sensor Transmitter will employ a long-life electro-chemical based technology gas
detection element that is precision mounted via sockets directly to the electronics to
facilitate calibration and replacement.
4.4. The Sensor Transmitter shall be constructed of a General Purpose Metal cover Plate to
protect against vandalism and accidental damage and installed on a flat surface 4”’x 4”
metal or PVC enclosure with 3/4” PVC conduit fitting. Optional NEMA 4X enclosure is
available for sites where weather elements may impact product performance.
4.5. Sensor Transmitter shall include an output signal verification jumper that is user
selectable to half scale or full scale output to simulate gas detection reading and
communication with central control panel without the use of calibration gas.
4.6. The Sensor Transmitter shall work by the diffusion principle with no need for external
devices to condition or enhance movement of the atmosphere within the area being
monitored.
4.7. The Sensor Transmitter shall be microprocessor-based capable of digital
communication via RS-485 output via 4-conductor (2 power, 2 data) #16 AWG cable
(multiple drops on a single cable).
4.8. Cable and Conduit. The contractor shall furnish and install 4-conductor, #16 AWG
shielded cable per local codes between sensor/transmitters and control panel as shown
on the drawings. Multiple Trunk lines up to four maximum are permissible. Final wire
gage shall be determined by trunk line distance.
4.9. Exhaust/Supply Fan Interlocks and Central Alarm Interlock, Engineer to define
description of interlocks between Carbon Monoxide detection system and
exhaust fans and alarms and any interface to BMS.
4.9.1. SAMPLE CONTROL SCENARIO ONLY
4.9.1.1. The CO detection system shall provide control of the exhaust and supply
fans per the contract drawings, and shall be capable of sending a central
alarm signal to the building automation/alarm system upon the following
detection level sequence:
CARBON MONOXIDE
4.9.1.2. For Carbon Monoxide gas levels below 25ppm - Exhaust/Supply Fans are
OFF.
4.9.1.3. At a Carbon Monoxide gas level value >25ppm, Exhaust/Supply Fans ON
and remain on until value falls below 25ppm for 5 minutes. A
4.9.1.4. At a continued increasing value of Carbon Monoxide gas level >50% full
scale, Central Panel Audible/visual alarm and any external audible and
visual strobes activate. Exhaust/Supply Fans ON High and remain ON for 5
minutes after alarm set point decreases below 25ppm alarm level plus an
additional 5 minute off delay.
4.9.1.5. For Nitrogen Dioxide gas levels below 2.5ppm - Exhaust/Supply Fans are
OFF.
NITROGEN DIOXIDE
4.9.1.6. At a Nitrogen Dioxide gas level value >2.5ppm, Exhaust/Supply Fans ON
and remain on until value falls below 25ppm for 5 minutes.
4.9.1.7. At a continued increasing value of Nitrogen Dioxide gas level >50% full
scale, Central Panel Audible/visual alarm and any external audible and
visual strobes activate. Exhaust/Supply Fans ON High and remain ON for 5
minutes after alarm set point decreases below 2.5ppm alarm level plus an
additional 5 minute off delay.
5. Calibration Kit and Test Gases
5.1. The CO and/or NO2 detection system manufacturer shall provide a complete test kit
with sufficient NIST Traceable test gas to allow for all commissioning tests and
scheduled calibrations following initial start-up.
6. Start-up and Training Service
6.1. Project scope may include the following for large systems. The Contractor shall make
available the services of the manufacturer's factory technician to inspect the system
installation, complete a thorough test and calibration of the system, and provide
minimum of 2 hours training to the owner’s personnel.