TSI Model 8475 In-Line Thermal Anemometer

Overview

The TSI Model 8475 In-Line Thermal Anemometer is an industrial-grade, permanently installable airflow sensing instrument engineered for continuous, high-stability velocity measurement in low- to medium-velocity air streams. Based on constant-temperature anemometry (CTA) principles, the sensor employs a heated platinum resistance element whose thermal dissipation is directly correlated to local mass flow velocity under controlled environmental conditions. This physics-based measurement approach ensures stable output across varying temperature and humidity profiles typical in HVAC ducts, cleanroom supply lines, environmental chambers, and laboratory ventilation systems. Unlike handheld or portable units, the 8475 is designed for permanent integration into process piping or ductwork via standard 1/2″ NPT or flanged mounting options—enabling long-term monitoring without recalibration drift under fixed installation conditions.

Key Features

• True in-line thermal anemometer with integrated signal conditioning electronics housed within the probe body
• Factory-calibrated linear analog output: user-selectable 0–5 V, 0–10 V, 4–20 mA, or 0–20 mA, configurable in under five minutes via DIP switches
• High-resolution velocity detection down to 0.05 m/s with repeatability better than ±0.5% of reading under steady-state conditions
• Stainless steel probe housing (316 SS) and ceramic-coated sensing element for corrosion resistance and long-term stability in humid or mildly aggressive airstreams
• No moving parts—immune to mechanical wear, particle clogging, or vibration-induced error common in vane or cup-based sensors
• Operating ambient temperature range: 0–50 °C; relative humidity: up to 95% non-condensing

Sample Compatibility & Compliance

The Model 8475 is optimized for clean, dry, non-abrasive airflows commonly encountered in controlled environments—including ISO Class 5–8 cleanrooms, hospital HVAC systems, pharmaceutical manufacturing suites, and academic environmental chambers. It is not rated for explosive atmospheres (ATEX/IECEx), high particulate loading (>1 mg/m³), or corrosive gases (e.g., Cl₂, H₂S, NH₃). The device complies with electromagnetic compatibility standards per IEC 61326-1 (industrial environment) and meets RoHS Directive 2011/65/EU. While not certified to specific HVAC commissioning standards, its traceable calibration supports compliance with ASHRAE Guideline 1–2021 (HVAC commissioning) and ISO 14644-3 (cleanroom testing). For GxP-regulated applications, optional audit-trail-capable data loggers may be deployed in conjunction with validated acquisition software to satisfy FDA 21 CFR Part 11 requirements.

Software & Data Management

The 8475 operates as a stand-alone analog transducer and does not require proprietary firmware or embedded software. Its linear output interfaces natively with industry-standard PLCs (e.g., Siemens S7, Allen-Bradley ControlLogix), SCADA systems, and data acquisition platforms including National Instruments DAQmx, Campbell Scientific CR series, and Honeywell Experion DCS. TSI provides comprehensive technical documentation—including calibration certificates (NIST-traceable), dimensional drawings, and wiring schematics—for seamless system integration. When paired with TSI’s TrakPro™ Lite or LogDat2 software (via compatible signal conditioners or USB DAQ modules), users can perform time-synchronized logging, trend analysis, alarm thresholding, and export to CSV or Excel formats—all without modifying the sensor’s core analog architecture.

Applications

• Real-time airflow verification in laminar flow hoods and biosafety cabinets per ISO 14644-1 and NSF/ANSI 49
• Supply/exhaust air balancing in hospital isolation rooms and operating theatres
• Process validation of drying ovens, spray dryers, and fluidized bed dryers
• Commissioning and ongoing monitoring of variable air volume (VAV) terminal units
• Reference-grade velocity measurement in wind tunnel test sections and calibration laboratories
• Greenhouse climate control and indoor air quality (IAQ) assessment per ASHRAE Standard 62.1
• Subsurface ventilation monitoring in rail tunnels and underground transit infrastructure

FAQ

Is the Model 8475 suitable for outdoor or unconditioned environments?
No. It is rated only for indoor, conditioned spaces with controlled temperature and humidity. Outdoor exposure or condensation will compromise sensor integrity and calibration stability.
Can the 8475 measure bidirectional airflow?
No. It is unidirectional and calibrated for flow toward the sensing tip. Reverse flow yields non-linear, non-representative output.
Does TSI provide field recalibration services for the 8475?
Yes—TSI-certified calibration services are available at authorized service centers, including full NIST-traceable recalibration with certificate and as-found/as-left data.
What is the recommended maintenance interval?
Under normal clean-air conditions, no routine maintenance is required. Visual inspection and zero-check verification are advised every 6–12 months depending on operational severity.
Is explosion-proof certification available for this model?
No. The 8475 is not intrinsically safe nor rated for hazardous locations. For such applications, consult TSI’s ATEX-certified alternatives (e.g., Model 8475-EX variant, where available).