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Flow, pressure, level and temperature solutions

Alicat FP-25 - Calibrator Kit for Air Quality Monitoring

  • All weather accuracy
  • Fast and easy operation
  • Audit flow rate, pressure and temperature

What is the Alicat FP-25, and who uses it?

Alicat's FP-25 is a weatherproof, battery-powered flow, pressure and temperature calibrator for particulate matter (PM) air samplers used primarily by environmental ambient air monitoring personnel at the national agency level and by sampler manufacturers looking to improve their test and validation efficiency. They are also used by industrial facilities to monitor the air around their perimeter so they can make sure they are in compliance with Environmental Audits. Nearly all end-user FP-25 usage is outdoors and in ambient weather conditions.

Why would Environmental Engineers use an Alicat FP-25?

Air monitoring technicians use the FP-25 to audit the volumetric flow (actual flow), mass flow (standardized flow), barometric pressure and temperature readings of ambient air samplers.

What are the primary concerns for Air Monitoring Technicians?

1) Accuracy.

  1. Flow. The FP-25 undergoes an advanced calibration process to ensure an individual linear mass flow calibration curve. An accuracy of 1% of reading (there is no element of the accuracy statement linked to full-scale) across a wide 200:1 turndown, e.g. a 25 LPM unit can measure down to 0.125LPM.
  2. Volumetric flow. Most applications require readings of volumetric flow, not mass, as the measurement of particulate pollution is relative to a given volume of air. Importantly, the pressure drop (0.1 psi @16.7 slpm) across the instrument is incredibly small and this, together with a correction of volumetric flow based upon barometric pressure, all but makes the instrument invisible to the process. In other words, the very presence of the calibration device does not impact upon the flow rate it is trying to measure.
  3. Radiant heat. Direct sunlight artificially elevates in-flow temperature readings, so the FP-25 uses a deep-set temperature sensor and aluminum body to get the most accurate air temperature readings within the flow path. Furthermore, there is an external temperature probe to correct the volumetric flow reading based upon ambient air temperature.
  4. Ambient temperature. Air samplers must run year-round, so the FP-25 is accurate down to -30°C. To achieve this, the FP-25 undergoes an extensive temperature compensation process with the recorded responses at each temperature becoming part of the FP-25’s calibration.
  5. Humidity. Humid air has a different density and viscosity than dry air, and this can induce additional errors in other types of measuring technology, such as Venturi-type flow meters, exceeding 1.5% of reading. The FP-25 has a live humidity sensor in the flow path to continuously read and correct for humidity, making it accurate all the way to 100% humidity at temperatures exceeding 50 C.

2) Ease of Use

  1. Direct Mode allows the Alicat FP-25 to connect directly to the 1.25” downtube of an air sampler without inducing additional stress on the pump. This ensures more accurate readings and allows hands-free operation. Another advantage is that when you place the sampler inlet head on top of the FP-25 in direct mode it is measuring the very same flow conditions the sampler has under normal operation (including protection against wind), hence increasing the accuracy. The display rotates 90° when used this way.
  2. The Bluetooth version (FP-25BT) adds an externally-mounted, positionable Bluetooth antenna thereby allowing the operator to conduct the entirety of the flow calibration process at the instrument panel without the need for climbing back and forth to a roof mounted station.
    1. Bluetooth use requires an Android tablet or iOS mobile device and the free Alicat Connect mobile app.
    2. FP-25BT’s Bluetooth antenna provides sufficient signal strength to penetrate the Faraday cage of an air monitoring station.
  3. The FP-25 includes 3 custom fittings, all with NPT face seals to minimize leaks and eliminate Teflon tape issues.
  4. A carry-case accommodates the Alicat FP-25 together with any and all accessories connected, helping the technician to store it how they use it.

3) Durability

  1. Our experience is that at some time or another a technician will inadvertently drop the FP-25 and by sheer bad luck especially when they are up on the top of a roof. The design is incredibly robust and will withstand this accidental treatment.
  2. The FP-25 has also been engineered to be weatherproof, as all connectors are IP67 (with plug or cable connected); with an overall instrument rating of IP64/65.
  3. Last of all, but certainly not least, the FP-25 carries the Alicat Limited Lifetime Warranty.


Audit and calibration of PM ambient air samplers use the FP-25 or FP-25BT to audit and calibrate flow, pressure and temperature readings for the samplers and analyzers below.

  • PM10 and PM2.5 FRM samplers (16.7 lpm)–Mesa Labs PQ series, Met One E-FRM, Thermo Scientific Partisol 2000/2025(i) and Dichots, Tisch TE-Wilbur
  • PM10 and PM2.5 FEM analyzers (16.7 lpm)–Environnement S.A. MP101M, Met One BAM-1020/1022 and E-BAM, Thermo Scientific BAM 5014i, SHARP 5030i and TEOM 1400(a/ab)/ 1405 and Dichots, Teledyne T640
  • IMPROVE network PM samplers (22.8 lpm)
  • Low-flow PM samplers (1-5 lpm)–Ecotech MircoVol and Protinus, Grimm EDM, Met One E-Sampler
  • Carbon speciation samplers (22.0 lpm)–URG-3000(N)
  • Carbon speciation samplers (6.7 lpm)–Met One SASS and SuperSASS
  • Black carbon analyzers (1-5 lpm)–Magee Aethalometer, Met One BC-1050

Other features

  • Flow range: 0.125-25.000 lpm/slpm
  • Flow accuracy: +/- 1% of the reading (NIST-traceable)
  • Barometric pressure accuracy: +/- 1 mmHg (NIST-traceable)
  • Temperature probe accuracy: +/- 0.2 ºC (NIST-traceable)
  • Pressure drop: 0.10 psi at 16.7 lpm, 0.16 psi at 25.0 lpm
  • Typical flow reading response time constant: 5 ms (may be up to 10 ms under very low flow conditions)
  • Typical temperature and humidity equilibration: less than 5 minutes

Model numbers

  • FP-25
  • FP-25BT
  • FP-BTA
  • FP-DMA1
  • FP-DMA2


Or contact us by phone or email:
01953 609930

Alicat recalibration service

Alicat recalibration service

We provide a certified annual recalibration service on all Alicat mass flow meters and controllers. Further details on our recalibration service.

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