Environmental monitoring made easier and more accurate with the FP-25

An FP-25BT is used to calibrate a Met One BAM-1022 air sampler.

Flow measurement is critical to air monitoring processes. To produce quality data, airflow through the system must be kept consistent – any fluctuations can cause the measurement to be off. This is easy to achieve inside a lab where temperature, air pressure and humidity are all carefully controlled. Of course, most environmental air monitoring takes place outside, where the instruments – and the data they capture – are at the mercy of varying weather conditions. With Alicat’s FP-25 and FP-25BT flow standards, gathering quality data on ambient air sources, even with variability in conditions, is easier and more accurate than ever before.


In order to gather defensible data, air monitoring technicians need devices that can perform under less than ideal conditions. Because water vapor changes the density and viscosity of air (which affects airflow), all flow instruments should account for this to produce accurate data. Temperature changes can also wreak havoc on the accuracy of flow measurement. Air monitoring can take place at 108°F (42°C) in the dry, hot Arizona summer, at 86°F (30°C) during the humid hurricane season in the Gulf of Mexico or at -20°F (-29°C) on a winter day in Alaska. In each of these conditions, the flow calibrator for the air sampler must be able to give accurate readings.

To meet these needs, we developed the FP-25 flow standard. No matter what the temperature is, the external temperature probe is able to equilibrate very quickly to the outside air temperature. It is also the world’s first flow meter with a live humidity sensor built right in, capable of making adjustments to flow measurements based on the relative humidity of the air.

Weather has the potential to impact the device and the technicians as well. The FP-25BT has Bluetooth communications (compatible with Android mobile devices), so the instrument can stay mounted to the air sampler. This means fewer trips up and down a ladder to check the readings in hot or freezing conditions. This feature can cut the number of trips up to the roof by half or more during calibrations, allowing air monitoring technicians to stay focused on the calibration from within the shelter.

And we built a device that can survive the fall from a rooftop, just in case.


The FP-25 ensures highly accurate measurements of airflow, regardless of weather conditions, making it easier to calibrate particulate matter air samplers.

With the defensible data produced by the FP-25, companies and regulators can take strides in reducing the amount of pollution released into the air, protecting both people and the planet.