The testo 6740 was specially developed for trace humidity measurement in compressed air or in dry air (granulate dryers). Its popular long-term stability make it ideal for these demanding measurements. This has been impressively proven, for example, in an inter-laboratory test in which several humidity sensors from Testo went through a number of international calibration laboratories (PTB, NIST etc. see illustration), where the +/-1 %RH limit was not exceeded over 5 years without re-adjustment.

The result of the development of the testo 6740 is a measurement range from -60 °Ctpd to +30 °Ctpd and an accuracy of +/- 1 K (pressure dewpoint) at 0 °Ctpd.

A freely scalable analog output is available for the output of pressure dewpoint, relative humidity, temperature, parts per millon (volume), absolute humidity, atmospheric dewpoint - optionally with a switch contact plug for monitoring MAX.

The testo 6740 also excels by its compact and user-friendly design, for example the rotatability of the housing by 350° in order to position the display optimally.