DeFelsko PosiTector DPM v.3.1 Full Manual - Manual (Page 7)

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RH - The relative humidity sensor is located inside the white plas-
tic housing. The sensor may require a longer period to stabilize in
the event of extreme humidity changes.
T a - The air temperature sensor is also located inside the white
plastic housing. (Also known as Dry Bulb Temperature)
T s - A surface temperature thermocouple is located on the tip of
the silver probe (built-in probe model). It is spring loaded and
designed to quickly self-align on a surface. Press it against a
T d - The dew point temperature is a function of air temperature
and relative humidity (see ISO 8502-4 Annex A). It is the temper-
ature to which a volume of air must be cooled in order to reach
saturation.
T s - T d - The surface minus dew point temperature is important
in judging the risk of condensation, or dew, forming on a surface.
For example, ISO 8502-4 recommends that, unless otherwise
agreed, the temperature of a steel surface generally should be at
least 3°C (5°F) above the dew point when paints are applied.
surface and allow a few seconds for the value to stabilize. Do not
drag the sensor over the surface. Wet the surface for a faster
response. Cover with the included protective plastic cap when not
in use.
For surface temperature measurement on steel over an
extended of time, consider using the optional Magnetic Surface
Temperature probe (pg. 7).
NOTE:
T w - (Advanced models only) The wet bulb temperature is the
temperature of adiabatic saturation. This is the temperature
indicated by a moistened thermometer bulb exposed to air flow.
The wet bulb temperature is calculated from Ta and RH using an
air pressure of 1.0 atmospheres (1013mbar). It approximates the
temperature indicated by a moistened thermometer bulb exposed
to airflow. Variations of Tw at other pressures could be greater than
±1°C (±2°F).
Tw can only be displayed with memory off and its value
cannot be stored in memory.
NOTE: