TSI IAQ-Calc 7525 Indoor Air Quality Meter CO2 Temp RH

Carbon dioxide, temperature and humidity in one handheld

The TSI IAQ-Calc 7525 is a handheld indoor air quality meter with a 7 in. (17.8 cm) sensing probe. It measures carbon dioxide with a non-dispersive infrared (NDIR) sensor over 0 to 5000 ppm, together with air temperature from a thermistor and relative humidity from a thin-film capacitive sensor.

CO2 is the usual first indicator of whether a space is receiving enough fresh air. The meter also includes a % Outside Air application that uses measured or entered readings. Companion probes and larger monitors are covered under Portable Test & Measurement.

From the manual

• NDIR CO2 sensing, resolution 1 ppm, with a barometric-pressure menu because pressure affects the CO2 reading.
• Temperature in F or C (user selectable) and relative humidity on the same display.
• Applications menu with % Outside Air; Manual, Auto-save and Cont-key logging.
• A calibration collar is supplied for field adjustment; a probe holder supports the probe in continuous logging.

Technical specification

Sensors

Logging, physical and power

7525 or Q-Trak?

The 7525 has its CO2, temperature and humidity sensors built into one fixed probe. If you also need carbon monoxide, VOC or air velocity, the Q-Trak 7575 accepts plug-in TSI probes, including the 982 probe with CO2 and CO. Choose the 7525 when a quick CO2 check of occupied rooms is the task.

Using the probe correctly

The sensing probe relies on diffusion of air, so keep it surrounded by moving air and do not breathe on it: exhaled air exceeds 10,000 ppm CO2 and the probe needs time to re-stabilise. Use the probe holder in continuous logging.

Enter the local barometric pressure in the menu, shade the probe from intense light if the humidity reads near zero, and download data with LogDat2 over USB. The manual recommends annual factory recalibration and describes field adjustment only for small changes.

Readings are stored as samples grouped into Test IDs (up to 100), with statistics per Test ID. The troubleshooting table lists the fixes the manual gives: shade the probe if humidity reads near zero, shield it from breath if CO2 is unexpectedly high, download then delete all data if the memory-full message appears, and press both arrow keys together to unlock the keypad. Wipe the case with a soft cloth and isopropyl alcohol or mild detergent, never immerse it, and remove the batteries for storage beyond a month.

Use in offices, classrooms and plant buildings

Typical uses are spot CO2 checks in meeting rooms, call centres and classrooms, and verifying ventilation after a rebalance. Operating electronics range is 5 to 45 C, so allow the meter and probe to acclimatise when moving from an outdoor vehicle into an air-conditioned space.

Selection and installation notes

Handheld air and environment meters are selected from the quantity measured, the range and the accuracy needed. Let the probe settle in the air stream, take readings at the points and the number the test method requires, keep the sensors clean, check the battery before a survey and keep the calibration current according to your quality system. Note the conditions and the probe position with every reading so the survey can be repeated.

Information needed for a quotation

Send the full model code, the quantity, the delivery location in Oman or the GCC, the intended use and any accessories needed, so that the complete package can be quoted together.

Documents and supply information

The manufacturer data sheet is attached to this page and should be read together with the project specification and the site risk assessment before a purchase is confirmed. Ratings, standards and dimensions are quoted as printed on that sheet. Lead time, stock position and certificates available with the shipment are confirmed in the quotation, and we supply to Oman and the wider GCC region for industrial, utility and building services projects.

Related items

Included in the box: calibration collar, AC adapter and USB cable. The probe holder and LogDat2 software are mentioned in the manual. See also the TSI range for the Q-Trak monitor.

Frequently asked questions

What CO2 range does the 7525 cover? 0 to 5000 ppm with 1 ppm resolution, measured by an NDIR sensor.

How accurate is the CO2 reading? +/-3 % of reading or +/-50 ppm, whichever is greater, at the calibration temperature.

Why does the reading jump when I stand near it? Exhaled air exceeds 10,000 ppm CO2, so the manual says not to breathe on the probe.

How many readings can it store? 30,300 data points with three key parameters enabled.

Is Seven Star LLC a TSI distributor? No. Seven Star LLC works as an independent supplier in Muscat and quotes genuine product when asked.

Documents and quotation

See the attached TSI manual (P/N 1980572 Rev G, November 2024). Availability, accessories and consumables should be confirmed by RFQ before you order.