Company Profile

Air Flow Rate Sensors: Real-Time Volumetric Air Speed Tracking for Cleanrooms

Quick Answer: For cleanroom HVAC and process control, Silver Instruments supplies thermal dispersion air flow sensors and differential pressure transmitters that report real-time volumetric air speed in m/s, Nm³/h, or SCFM. These sensors suit pharmaceutical, semiconductor, food, and hospital cleanrooms. Send us your duct size, air speed range, temperature, and output signal and we will recommend a model.

Why Cleanrooms Need Real-Time Air Speed Tracking

Cleanrooms depend on stable airflow to keep particle counts low. A small drift in face velocity can break ISO 14644 class limits. Our sensors read air speed every second. That helps facilities maintain pressure cascades and filter loading. Most engineers skip daily hot wire checks once they install fixed sensors. In practice, facilities with continuous data pass audits faster than those with clipboard readings.

Sensor Options for Cleanroom Air Flow

We recommend thermal mass flow sensors for duct and inline air measurement. These sensors have no moving parts. They handle low air speeds from 0.2 m/s up to 60 m/s. For fan filter units and pass-through cabinets, a hot wire probe or thermal dispersion probe works well. For lab air balance and high accuracy duct traverse, a differential pressure transmitter with an averaging Pitot tube gives stable output. Silver Instruments AFM series sensors include PT100 temperature compensation and 316L wetted parts.

Typical output is 4-20 mA HART. Optional RS485 Modbus RTU is available. The local LCD shows live air speed in m/s or normalized volume flow in Nm³/h. You can set the pipe or duct cross section from the keypad. Because cleanrooms often run at low velocities, we set ranges like 0 to 1 m/s, 0 to 2 m/s, or 0 to 5 m/s. Accuracy is ±1.5 percent of rate above 20 percent of range. Below that it is ±0.3 percent full scale.

Key Parameters We Ask for Cleanroom Air Flow Quotes

In practice we need these details from you. Duct or pipe size in DN, air speed range in m/s, process temperature in °C, output signal, and whether you need local display. These five items decide probe length, flow range, power supply, and price. If the duct is rectangular, send width and height. We have seen many customer sites where a missing probe insertion length caused delays. Tell us the duct or stack wall thickness too.

Installation Tips for Cleanroom Air Sensors

Mount the probe at a straight duct run. Ten duct diameters upstream and five downstream is ideal. This avoids swirl and uneven velocity profiles. Use a compression fitting or isolation valve for hot tap installations. In clean return air or exhaust ducts, keep the sensor away from bends and filters. For fan filter units, mount the sensor on the downstream side of the filter but before the air enters the room. Do not install in turbulent zones after a damper or right after an elbow.

Common Applications and Customer Cases

A pharmaceutical plant in Vietnam needed air speed monitoring for a sterile filling cleanroom. We supplied thermal dispersion sensors with 4-20 mA HART output. The PLC used the signal to hold air speed at 0.45 m/s ±0.05 m/s. A semiconductor packaging line in Malaysia used our DP transmitters for pressure cascade between rooms. The signal updated every 1 second. In a food processing cleanroom in Saudi Arabia, sensors with local display helped operators check filter face velocity without a laptop. These projects used standard IP65 housings and 316L probes.

Output and Integration

All sensors offer 4-20 mA HART standard. Modbus RTU is optional. You can send air speed, temperature, and totalized flow to a PLC, BMS, or paperless recorder. We also supply paperless recorders with 12 channel inputs. That setup gives cleanroom teams a trend log for audits. Use PT100 input