Gas Detection in Water Treatment March 19, 2015

Gas Detection Applications Occupancy Sensing Safety Explosive Gas Hazards Toxic Environment Oxygen Depletion March 19, 2015

Gas Detection in Water Treatment Must withstand the Corrosive environment Provide accurate sensing information Reliably activate safety equipment Be safe to use in hazardous atmospheres March 19, 2015

NEMA Ratings National Electrical Manufacturer’s Association NEMA 1: Finger Proof NEMA 3R: Weatherproof Outdoor NEMA 4: Hose down rated (4X: Corrosion Resistant) NEMA 7: Explosion Proof – Rated for Gasses NEMA 9: Explosion Proof – Rated for Dust March 19, 2015

Explosive Gases March 19, 2015

Methane Hazard Primary component of Natural Gas Produced by the decomposition of Organic Matter Highly Combustible Lighter than Air March 19, 2015

Methane Hazard (Cont.) Methane Hazards fall under CSA Class 1, Group B Hazardous areas require CSA rated devices Sensors should be located near the ceiling March 19, 2015

Methane Detectors Methane is measured by its Percentage of LEL QEL offers two methane sensors that are CSA Class 1 Div. 1 QIR-8000 QTS-8000 March 19, 2015

QIR-8000: Combustible Gases Explosion Proof Enclosure (NEMA 4X, 7 and 9) Uses infrared light to detect the presence of combustible gas Outputs a 0-10V or 4-20mA signal Optional add on for RS485, Opto-22, Modbus, and relays. March 19, 2015

QTS-8000: Toxic/Combustible Gases Explosion Proof Enclosure (NEMA 4X, 7 and 9) Uses Catalytic Bead Technology to sense gas Outputs a 0-10V or 4-20mA signal Optional add on for RS485, Opto-22, Modbus and relays Can sense non-combustible gases, as well as Methane March 19, 2015

Toxic Gases March 19, 2015

Toxic Gases in Water Treatment Hydrogen Sulfide (H2S) Ammonia (NH3) Ozone (O3) Chlorine (Cl2) All of these are sensible on the QTS-8000 March 19, 2015

Hydrogen Sulfide Sometimes called “Sour Gas” when present in Natural Gas Smells like Rotten eggs Highly Potent Toxin Combustible at higher concentrations Heavier than air March 19, 2015

Ammonia Pungent smell Used in water decontamination Extended contact can be hazardous Heavier than air March 19, 2015

Chlorine Used for sanitizing water and equipment Gas is toxic in high enough concentrations March 19, 2015

Oxygen Depletion March 19, 2015

Oxygen Sensors Other gases can displace oxygen in the room Once the concentration drops below 17% Oxygen, blackouts can occur QTS-8000 can sense Oxygen depletion, and increase ventilation March 19, 2015

Selecting the Right System March 19, 2015

System Overview Sensors/Transmitters Communication Standard Control March 19, 2015

Sensors and Transmitters Devices are “in harm’s way” IR based sensors last longer, especially in high concentration areas. Can be used as stand alone devices, or in a system Need calibration to ensure accuracy (Startup is included) Performance is dependent on placement March 19, 2015

Communications Sensors often communicate with a controller or BAS Design must account for signal interference Two primary modes: Analog and Digital March 19, 2015

Communications: Analog The Good The Bad The Ugly Very High Resolution Simple: It Works 4-20mA is very reliable Active Zero Signal is one-way Configuration is more involved Susceptible to noise March 19, 2015

Communications: Digital Sensors are “Daisy-Chained” into wire runs Modbus RS-485 protocol Two-way Communication: controller can talk back to sensor Easier to troubleshoot Resolution is very workable, but not as high as analog signals March 19, 2015

Controls Both Modbus and 4-20mA analog signals are widely adopted standards Sensors can be tied together by BAS or QEL’s controllers A control scheme is very practical in all medium and large systems March 19, 2015

Controls: Cont. Centralizes electrical connections Simplifies troubleshooting Enables advanced functionality Logging Remote alerts Analog control output – like VFDs March 19, 2015

Summary March 19, 2015

Conclusions Hazardous areas require certified equipment Gas detection is vital for hazardous environments Sensors need to be selected and placed properly Communications allow for devices to work together Controls ease wiring and sequence of operation concerns March 19, 2015