Frequently Asked Questions Regarding Gas Detectors
The design and location of the gas detector has much to do with the maximum area one detector can properly cover. A correctly positioned and mounted Brasch Environmental Technologies gas detector is designed to provide coverage over an area averaging approximately 7,500 square feet. As ceiling height increases and air circulation decreases, the coverage area will decrease too. Note that detectors mounted on walls or in corners will see a reduction in the effective coverage area, regardless of ceiling height or air circulation. Detectors located in an area with restricted air flow, such as an enclosed room, should be considered as only protecting that area.
Carbon monoxide has approximately the same density as air and will mix homogeneously within a short period of time. Nitrogen dioxide is heavier than air and will tend to settle near the floor. However, as a component of hot exhaust, gas will initially rise to the ceiling before cooling and mixing fully with the air. Since the primary hazard associated with both carbon monoxide and nitrogen dioxide is inhalation, Brasch recommends locating the detectors at average breathing height – approximately 5-7 feet above the floor. Mounting at this height will allow the sensors to measure gas where it poses the most danger.
Brasch Environmental Technologies CO and NO2 gas detectors can be calibrated one of two ways. The first method is to purchase a factory calibration kit. This includes a new sensor board with factory calibrated sensor to be installed as a replacement in the field. The second method is to perform a field calibration using a cylinder of certified test gas (see below). Performing field calibration requires careful control of environmental conditions and should only be performed by trained personnel. Brasch CO2 and O2 detectors are not able to be field calibrated.
Brasch Environmental Technologies CO and NO2 gas detectors use electrochemical sensors with an expected lifespan of up to 10 years. The actual end-of-life may occur sooner or later than the stated period depending on the amount of gas to which the sensor is exposed. Despite not needing frequent replacement, each sensor still requires periodic calibration to keep the detector operating within acceptable tolerances.
The electrochemical sensors used in Brasch CO and NO2 detectors, can reasonably expect an accuracy of ± 3 percent of the full scale response. Brasch CO2 and O2 detectors can obtain an accuracy of ± 2 percent, and in some cases, reach a short term accuracy of ± 1 percent. Over time, the sensors will degrade and the aforementioned accuracy may no longer be feasible.
The best way to determine when calibration is necessary is through periodic testing. Apply a known concentration of gas to the sensor and determine if the reading is within acceptable tolerance. Alternatively, measuring the time a sensor takes to respond to an unknown quantity of gas may provide a good indication in the absence of certified test gas. On average, sensors will need to be calibrated every two years.
All detectors produced by Brasch have at least one output that can be connected to a building management or control system. Each sensor (CO and NO2) can send a linear signal, proportional to the gas concentration, to an analog input on the system. This signal can be either 4-20 mA, 0.2-1 VDC, 1-5 VDC, or 2-10 VDC. For the GDCP-Touch control panel, there is a secondary linear signal that is proportional to the highest concentration of gas in a zone, as well as an RJ45 connector for use with BACnet IP. Furthermore, all detectors use Modbus RTU for communication, which can be tapped into by a building management system.
All Brasch equipment is sold through manufacturer representatives who are trained to understand the basics of each product. They can answer most generic questions about installation or repair processes. For more specific inquires, contact Brasch technical support to speak with a technician. Although the customer should include their distributor in any discussion regarding purchasing or repairing equipment, the customer is encouraged to contact the factory directly if necessary. Brasch also offers weekly online training sessions to provide an overview of installation, startup, operation, and maintenance.
In accordance with ANSI 92.00.01-2010 (R2015), Brasch Environmental Technologies calibrates all of their gas detectors according to a procedure that has been developed to provide a final accuracy within ± 3% of full scale response. While it has evolved with technology, this process has been used successfully for over 20 years. No detector is shipped without first passing the rigorous testing involved in this procedure. All test gases used meet NIST standards and are certified to ± 2%.
Installation, operation, and maintenance (IOM) manuals for each detector are available as PDFs on this website. Links to these documents may be found in the literature section on individual product pages as well as on the downloads page. Links to documents for obsolete models can be found in the archive section of the downloads page. For documents relating to products over one generation old, please contact customer service.
All Brasch Environmental Technologies standalone detectors contain a feature to test all functions except for the sensor’s response to target gas. Once the detector has completed its warm-up, pressing the “Self-Test” button on the front will begin the roughly 6-minute test. For a complete description of the self-test feature, please consult the IOM.
Many specialty gas companies offer small containers of target gas mixed in air. These tanks, when supplied with the proper regulator valve, can be used to expose the detector’s sensor to a test level of gas. Due to numerous variables, the response to the test gas will only be approximate. Brasch Environmental Technologies offers a test kit that can measure the response of detectors to a predetermined gas concentration. Test gas for Brasch carbon monoxide detectors should have a concentration of between 50 and 100 PPM. Test gas for Brasch nitrogen dioxide detectors should have a concentration of between 2 and 5 PPM. While carbon monoxide is readily available in the correct range, nitrogen dioxide is typically harder to find since such small concentrations do not remain stable for extended periods of time.