Combined Pressure, Humidity and Temperature Transmitter PTU300

Note that the PTU300 series is being discontinued. It is replaced by Indigo family products. Do not specify PTU300 for new projects, instead view Indigo transmitters and probes that are also designed for use in demanding applications.

Looking for PTU300 performance with interchangeable probes and a transmitter supporting two probes? View the Barometric pressure measurements with Indigo520 transmitter.

The PTU300 is a unique instrument measuring three parameters simultaneously: barometric pressure, humidity, and temperature. The instrument has four different humidity probe options for various measurement needs. Reliable HUMICAP® and BAROCAP® sensor technologies make it suitable for several applications such as engine testing booths, calibration laboratories, and marine engine air intake monitoring. For demanding meteorology applications, view this page.


Keen on our PTU300 series? Check out Vaisala Indigo520.

Interchangeable smart probes, robust transmitters, and Vaisala Insight software create a strong ecosystem to ensure energy efficiency, safety, and end-product quality in your operations. The modular plug-and-play design makes Indigo family probes and transmitters easy to install, use, and maintain.

The equivalents for the PTU300 series

PTU301 for wall mounting is now HMP1 probe + INDIGO520 transmitter

PTU303 for duct mounting and tight spaces is now HMP3 and HMP9 probes + INDIGO520 transmitter

PTU304 for high pressures up to 100 bar and vacuum conditions is now HMP4 + INDIGO520 transmitter

PTU305 for high temperatures is now HMP5 + INDIGO520 transmitter

PTU307 for high humidity and meteorological applications is now HMP7 + INDIGO520 transmitter

PTU308 for pressurized pipelines up to 40 bar is now HMP8 + INDIGO520 transmitter


9 reasons to upgrade

It is time to upgrade your PTU300 product! 

Rest assured, some things will stay the same: 

The reliable BAROCAP® sensor with A-class accuracy. 
The trusted HUMICAP® sensor technology with the latest generation. 
Vaisala's fast delivery times and world-class services. 

Here are 9 reasons to upgrade:

  1. Easy data visualization
  2. Connect up to two probes and measure multiple parameters simultaneously 
  3. Plug and play; hot swap probes easily, with no measurement downtime 
  4. Probes work as stand-alone 
  5. Power over Ethernet option – single cable connection 
  6. Simultaneous data transfer through different protocols 
  7. Supports analog input; connect a 3rd party measurement transducer
  8. Modern, secure LAN
  9. Future-proof measurements: stay up to date with security and newest features. 


Indigo520 with barometric pressure measurements


  • Barometric pressure, humidity and temperature measurement in one transmitter
  • Available with up to two barometric pressure sensors - for added reliability
  • Graphical display and keypad for convenient operation
  • Integrated data logging with over four years of measurement history
  • RS-232C serial interface with NMEA protocol for GPS use
  • Analog outputs, RS232/485
  • Optional universal power supply module
  • Traceable calibration to national standards (certificate included)
  • HMT330MIK Installation kit for outdoor use
  • Incorporates HUMICAP and BAROCAP sensor technologies

Key benefits

Probes tailored to your application

Probe options designed specifically for laboratories (PTU301), general use (PTU303), outdoor and demanding meteorology applications (PTU307), or for pressure and temperature measurement only (PTU30T).

1 transmitter, 3 measurements

Unique combination of a meteorological grade barometer combined with humidity and temperature measurement in single, industrial grade device.


The device is tailored for each delivery and delivered pre-configured and ready for installation. Settings can be also easily changed on the field by the user.