INTEC: The Premier Gas Detection Solution
What are the best practices for CO and NO2 detection?
That was our question to Jennifer Thomas, the senior regional salesperson for INTEC Controls, at our latest 45-minute Coffee Break webinar. These monthly sessions are packed with information from the brightest minds in the HVAC industry and cover the latest innovations in all types of building systems. Contact your SVL Sales Engineer for an invite to our upcoming Coffee Breaks!
Headquartered in San Diego, INTEC Controls has been a supplier of high-quality sensors and controls for commercial HVAC for over 30 years. Jennifer gave our attendees a deep dive into the current state of CO and NO2 detection systems.
What applications need CO/NO2 monitoring?
Any enclosed space where vehicles are running. These include parking garages, package distribution hubs, vehicle maintenance facilities, car dealerships, and loading docks.
Also, boiler rooms and other spaces that house gas-burning appliances. Incomplete combustion problems can result in the production of carbon monoxide and other harmful gasses.
Why monitor for CO/NO2?
Safety: This is the obvious reason. Carbon monoxide is an asphyxiant. It’s odorless, colorless, and dangerous if left unventilated. Nitrogen dioxide is a carcinogen and high levels risk long-term health effects for the occupants of these spaces.
Energy savings: Running fans at high speed 24/7 to ensure proper ventilation is expensive. With UL 2075-listed gas sensors, fans can cycle between standby airflow (>0.05 cfm per ft2) and full-on airflow (>0.75 cfm per ft2) when it’s necessary.
Gas sensor studies tell us that the typical garage only needs full-on airflow during high-traffic periods — a few minutes in the morning, lunch hour, and evening. Including gas sensors in your building controls ensures your ventilation fans don’t waste energy.
HVAC ROI: A corollary of energy savings is the ability to save wear and tear on your fan equipment, extending its lifespan.
What do building codes require for gas detection?
The International Mechanical Code (IMC) contains various prescriptions for gas detection. Since 2018, the current code (IMC 2021 sec. 404.1) for mechanical ventilation systems for enclosed parking garages allows for either 24/7 operation of fans at full flow or controlling the airflow specifically using UL 2075-listed gas sensors.
UL 2075 is a rigorous performance standard for gas sensors. First released in 2006, it’s a costly, long-term certification process, and not every sensor package on the market has received that rating (meaning they are not in compliance with the IMC 2021 for this application).
Pay close attention to the wording used on gas sensors. There is a difference between being “UL-listed” versus one that says UL- “recognized,” “compliant,” or “approved”. The word “listed” specifically matters for code compliance and the entire package must be listed (not just certain components).
Where should gas detection sensors be placed?
The maximum coverage area for CO/NO2 sensors is 7,500 square feet (a 50-foot radius). It depends on where you can physically mount the sensors and whether there are obstructions to the airflow, but the optimal location is 5 feet above the finished floor, right in the breathing zone.
In large, open areas that don’t have a mounting location in the breathing zone (say, an aircraft hangar that’s been converted to car storage), you should think about creative solutions, like installing posts to mount the monitors.
What is the control strategy for gas detection?
Fans should run at the standby airflow rate to satisfy the minimum code-required cfm/ft2 for that space. Once any sensor detects 25 ppm CO or 1 ppm NO2, the fans run at high speed to ventilate the harmful gasses.