WAFS 109 – Explosion-Proof Thermal Mass Flow Sensor

The WAFS 109 is an explosion-proof thermal mass flow sensor for compressed air, nitrogen, oxygen, carbon dioxide and other non-condensing gases in hazardous areas. It carries the explosion protection marking Ex db IIC T6 Gb / Ex tb IIIC T80°C Db with an IP67 enclosure, so it can be used where flammable gas or combustible dust may be present, such as chemical, petrochemical, pharmaceutical and power plants.

Like the other WiseAir thermal mass flow sensors, it measures mass flow directly, so no separate pressure or temperature compensation is needed. It comes in two versions: the WAFS 109 insertion type for pipes from DN20 to DN1000, installed through a 1/2″ ball valve while the line stays under pressure, and the WAFS 109-IL in-line type with its own measuring section for DN15 to DN80.

Where is the WAFS 109 used?

• Compressed air and gas consumption measurement in hazardous areas.
• Gas consumption of a single machine or a whole plant.
• Highly fluctuating flows and low-flow bypass lines, thanks to the 1:2500 turndown ratio.
• Process gas measurement, such as nitrogen, oxygen and carbon dioxide.
• Industrial processes in chemical, petrochemical and power engineering plants.

Where the area is not classified as hazardous, the WAFS 104 or WAFS 106 insertion sensors and the WAFS 105 or WAFS 107 in-line sensors are the usual choice.

What does the explosion-proof marking mean?

Ex db IIC T6 Gb means the electronics sit in a flameproof enclosure (db) approved for gas group IIC, the most demanding group, which includes hydrogen and acetylene, with temperature class T6 (surface temperature no higher than 85 °C) and equipment protection level Gb, which corresponds to Zone 1 and Zone 2 gas areas. Ex tb IIIC T80°C Db covers combustible dust: protection by enclosure (tb), dust group IIIC (conductive dust), a maximum surface temperature of 80 °C and protection level Db for Zone 21 and Zone 22 dust areas. Your site’s hazardous-area classification decides which marking you need; send us the area classification and we will confirm the documents available for your approval process.

Key features

• Thermal mass flow measurement: no pressure or temperature compensation needed, with integrated temperature measurement.
• Ultra-wide 1:2500 turndown ratio, measuring from 0.1 Nm/s to 250 Nm/s.
• Full-digital signal processing that eliminates zero-point drift for better accuracy and long-term stability.
• Intelligent diagnosis that detects sensor contamination online and protects the sensor from overheating.
• No moving parts, vibration proof and almost zero pressure drop.
• 2.0″ capacitive touch IPS LCD with a wide viewing angle for online values and sensor setting.
• Bluetooth for wireless sensor configuration and data transfer.
• Standard RS485 Modbus RTU, 4–20 mA and pulse outputs. LoRa and Wi-SUN are available as options.
• Insertion type installed online through a 1/2″ ball valve under pressure, with no shutdown.