TSI IAQ-CALC Indoor Air Quality Monitor (Model 7525 / 7545)

Overview

The TSI IAQ-CALC Indoor Air Quality Monitor (Model 7525 and 7545) is a portable, multi-parameter environmental measurement system engineered for rigorous indoor air quality (IAQ) assessment in commercial buildings, laboratories, schools, healthcare facilities, and HVAC commissioning environments. Built upon dual-wavelength non-dispersive infrared (NDIR) spectroscopy for CO₂ detection, the instrument delivers stable, low-drift performance compliant with ASHRAE Standard 62.1 and ISO 16814 for ventilation rate verification. The 7525 model concurrently measures CO₂, temperature, and relative humidity—enabling real-time calculation of dew point, wet-bulb temperature, and percent outdoor air (%OA) via the ASHRAE-standardized enthalpy-based method. The 7545 extends this capability with an electrochemical carbon monoxide (CO) sensor, supporting integrated assessment of combustion-related IAQ hazards per ANSI/ASHRAE Standard 62.1-2022 and OSHA PEL compliance monitoring.

Key Features

• Dual-wavelength NDIR CO₂ sensor with factory-calibrated stability and minimal zero drift—designed for long-term field deployment without routine recalibration.
• Integrated thermistor-based temperature and thin-film capacitive RH sensors meeting IEC 60751 Class B tolerances and ISO 7726 thermal comfort criteria.
• Real-time %OA calculation using measured CO₂, temperature, and RH—aligned with ASHRAE Guideline 1 and EN 13779 for demand-controlled ventilation validation.
• On-device computation of dew point and wet-bulb temperature—critical for HVAC system diagnostics and mold risk assessment per EPA IAQ Tools for Schools protocols.
• Electrochemical CO sensor (7545 only) with cross-sensitivity compensation for H₂ and NO₂—certified to UL 2034 and compliant with EN 50291-1 for residential and light-commercial applications.
• Configurable data logging: up to 24,200 timestamped records (7525) or 22,000 records (7545), with user-defined sampling intervals from 1 second to 1 hour.
• Ergonomic handheld form factor (107 × 183 × 38 mm), ruggedized housing rated IP54, and dual power options (4× AA alkaline or optional AC adapter) for extended field operation.

Sample Compatibility & Compliance

The IAQ-CALC series is validated for use in ambient indoor air matrices containing typical VOCs, particulates 95% RH sustained >2 h), or corrosive gas streams (e.g., Cl₂, NH₃, SO₂). All models comply with FCC Part 15 Class B, CE EMC Directive 2014/30/EU, and RoHS 2011/65/EU. The CO₂ and CO measurement methodologies align with ASTM D6245-21 (CO₂ in indoor air) and ASTM D5467-20 (CO in ambient air), supporting traceability in GLP-compliant reporting workflows.

Software & Data Management

Data export is supported via USB interface to TSI’s proprietary TrakPro™ Lite software (Windows-compatible), enabling CSV export, time-series visualization, statistical summary (min/max/avg/stdev), and ASHRAE 62.1 ventilation rate audit reports. Logged datasets include full metadata: date/time stamp, sensor ID, battery voltage, and active configuration parameters. While the device itself does not implement FDA 21 CFR Part 11 electronic signature controls, TrakPro™ Lite supports audit trail generation and user-access logs when deployed on validated IT infrastructure—facilitating alignment with ISO/IEC 17025 clause 7.7 and CAPA documentation requirements.

Applications

• Verification of minimum outdoor air intake rates during HVAC system commissioning and periodic re-commissioning.
• Occupant thermal comfort evaluation per ISO 7730 and ASHRAE 55—leveraging simultaneous CO₂, dry-bulb temperature, and RH inputs.
• Post-occupancy evaluation (POE) studies tracking diurnal IAQ trends across classrooms, offices, and patient rooms.
• CO exposure screening in garages, boiler rooms, and kitchens where incomplete combustion may occur.
• Baseline IAQ surveys prior to LEED EQ Credit 1 (Indoor Air Quality Assessment) or WELL Building Standard v2 Air Concept documentation.
• Field calibration verification of fixed building automation system (BAS) CO₂ and CO sensors using NIST-traceable reference measurements.

FAQ

What is the recommended calibration interval for the CO₂ sensor?
TSI recommends annual field verification against a certified NIST-traceable gas standard; zero calibration is not required under normal operating conditions due to the dual-wavelength NDIR architecture.
Can the 7525 calculate %OA without external inputs?
Yes—the instrument uses built-in algorithms based on indoor/outdoor CO₂ differential and psychrometric relationships; no external weather station or building management system integration is needed.
Is the CO sensor on the 7545 suitable for occupational exposure limit (OEL) monitoring?
It meets OSHA PEL (50 ppm TWA) and ACGIH TLV (25 ppm TWA) detection requirements for short-term screening but is not certified for personal dosimetry or continuous workplace exposure logging per OSHA 1910.1200.
Does the device support Bluetooth or Wi-Fi connectivity?
No—data transfer is USB-only; wireless telemetry requires third-party gateway integration via analog voltage outputs (optional accessory).
How is traceability maintained for regulatory reporting?
Each unit ships with a Certificate of Conformance and factory calibration report referencing NIST-traceable standards; users are responsible for maintaining calibration records per ISO/IEC 17025 or local jurisdictional requirements.