Instrument Introduction:
7515, 7525, 7535, and 7545 models
TSI's IAQ-Calc tester is an excellent instrument for indoor air quality research and monitoring. 7515 is a low-cost instrument for testing CO2. 7535 has added the function of automatically storing CO2 data. 7525 and 7545 can measure and store multiple parameters simultaneously. 7525 can measure CO2, temperature, humidity, and calculate dew point temperature, wet bulb temperature, and relative humidity of outdoor air. 7545 can also measure CO.

Technical parameters:
7515, 1525, 7535, and 7545 models

CO2
Sensor type: Dual wavelength NDIR (non diffuse infrared)
Range 0-5000ppm
Accuracy: ± 3.0% of the reading or ± 50ppm, whichever is greater
Resolution 1ppm
Response time of 20 seconds

Temperature (applicable only to 7525 and 7545 models)
Sensor type thermistor
Range 32-140 ℉ (0-60 ℃)
Accuracy ± 1.0 ℉ (± 0.6 ℃)
Resolution 0.1 ℉ (0.1 ℃)
Response time of 30 seconds (at a wind speed of 400ft/min [2m/s], the temperature reaches 90% of the final value)

Relative humidity (applicable only to 7525 and 7545 models)
Sensor type: thin film capacitive
Range 5-95% RH
Accuracy 2 ± 3.0% RH
Resolution 0.1% RH
Response time of 20 seconds (humidity reaches 63% of the final value)

Outdoor air% (applicable only to 7525 and 7545 models)
Range 0-100%
Resolution 0.1%

CO (applicable only to Type 7545)
Sensor type: Electrochemical
Range 0-500ppm
Take the larger of ± 3.0% or ± 3ppm of the accuracy reading
Resolution of 0.1ppm
When the response time reading changes by 90%, it is less than 60 seconds

Operating temperature: 32-113 ℉ (0-45 ℃)

Storage temperature -4 to 158 ℉ (-20 to 70 ℃)

Data storage capacity (applicable only to 7525 and 7545 models)
The 7525 model can record up to 24200 sets of data, including all measurable parameters; The 7535 model can record up to 40300 sets of data, including all measurable parameters; The 7545 model can record up to 22000 sets of data, including all measurable parameters;
Time constants of 1s, 5s, 10s, 20s, 30s
Data collection interval of 1 second to 1 hour (user-defined)

Instrument size (all models)
4.2in.×7.2 in.×1.5 in. （107 mm×183 mm×38 mm）

Probe size (7515 type)
Length 2.7 in. (69 cm)
Diameter 0.76 in. (2.0 cm)

Probe size (7525, 7535, and 7545 models)
Length 5.9 in. (15.1 cm)
Diameter 0.74 in. (1.9 cm)

Weight (including battery)
7515 and 7535 models 0.6 lbs (0.27 kg)
7525 and 7545 models 1.16 lbs (0.53 kg)

power supply
7515 type four AA batteries
7525, 7535, and 7545 models with four AA batteries or optional AC adapter

Main features:
Low drift NDIR CO2 sensor capable of stable and accurate measurement
The sampling function can record multi-point measurement data
Ergonomic exterior design

7525 and 7545 models
Temperature and relative humidity measurements help determine thermal comfort
Calculate the percentage of outdoor air based on CO2 or temperature
Directly calculate dew point temperature and wet bulb temperature
Electrochemical sensor for measuring CO (7545)
7525 and 7545 can maximize the display of 3 parameters
7515 and 7535 can only display one parameter