SAMPLE SPEC: HARD WIRED Nitrogen Dioxide DETECTION SYSTEM
General a. The work covered by this section includes the installation of a Nitrogen Dioxide (NO
2
)
Gas Detection System as described herein and as shown on the contract drawings. The major items of work to be included are:
- furnishing and installing central control panel as located on the contract drawings, and providing required electrical connections for 120 VAC power feed, interconnects for exhaust/supply fan control, and interconnect for central alarm annunciation as described herein.
- furnishing and installing (*ENGINEER TO ADD SENSOR COUNT HERE*) sensors as shown on the drawings
- furnishing and installing signal cable and conduit between the sensors and control panel.
- providing calibration accessories and start-up, commissioning services Manufacturer
Authorized and Certified Technician.
- The Nitrogen Dioxide System shall be a hard-wired system employing a diffusion style gas detection method. The MSA ZGard family of Products as manufactured by MSA - local representative Mechanical Technologies, Ph: (212) 643-8001. b. Submittals a. Product data: Submit specific product literature and start up agent with factory certification for all materials. b. Installation/Outline/Dimensional, wiring Drawings c. Central Control Panel a. 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" and "alarm". b. The control panel shall include a user programmable built-in audible alarm with local and remote push-button reset capability. c. The control panel shall be rated for General Purpose use and constructed of painted steel construction with hinged door secured by tamper resistant screws. d. The Central and 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 a single 4 conductor shielded cable. e. A compliment of 12 central panel assignable relays, expandable to 126, shall be provided to establish grouping and voting assignments for each sensor channel.

f. The central shall incorporate an on/off delay to minimize oscillation around the control point for the fan interlocks. g. Common warning, alarm and system fault relay shall be provided in the central cabinet in the event grouping and zoning are not required. h. A unit mounted Red Strobe or remotely mounted Horn Strobe can be activated via any of the provided relay contacts.
Nitrogen Dioxide Sensor/Transmitters d. The NO
2
sensor transmitter shall have a full scale detection range of 0-10 parts per million (ppm) full scale. e. The NO
2
Gas detection Sensor will be 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. f. The gas detection sensor will be protected by a metal sensor cover plate to protect from vandalism and accidental damage. Sensor can be expanded to include a 2 nd Carbon
Monoxide point by changing the enclosure. g. The sensors 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. h. The sensors shall employ RS-485 communications via 4-conductor (2 power, 2 data)
#16 AWG cable (multiple drops on a single cable). Final wire gage will be determined by trunk line distance. i. The sensor/transmitter shall be housed on a General Purpose Metal cover Plate to minimize damage and installed on a flat surface 4”’x 4” PVC enclosure with 3/4” PVC conduit fitting. NEMA 4X is optional in a plastic enclosure. j. An internal jumper to facilitate communication verification via field jumper is included to verify wiring and communication with Central Panel. k. 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 are permissible. l. 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.

SAMPLE ONLY m. The NO
2
detection system shall provide control of the exhaust and supply fans per the contract drawings, and shall be capable of sending a central alarm to the building automation/alarm system: For detection levels: values below 2.5ppm NO
2
- Exhaust/Supply Fans are Off
@ value > 2.5ppm NO
2
- Exhaust/Supply Fans On and remain on until value falls below
2.5 ppm for 5 minutes
@ continued increasing value > 5.0ppm NO2 - Central Alarm Audible 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 alarm level plus an additional 5 minute off delay. n. Calibration Kit and Test Gases
The NO
2
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. o. Start-up and Training Service
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 o wner’s personnel.