Vaisala HMP4 - Table 37 HMP8 Operating Environment; Table 38 HMP8 Inputs and Outputs; Table 39 HMP8 Output Parameters

Table 37 HMP8 operating environment
Property Description/Value
Operating temperature of probe body −40 … +80 °C (−40 … +176 °F)
Operating temperature of probe head −70 … +180 °C (−94 … +356 °F)
Operational pressure < 40 bar
Operating environment Suitable for outdoor use
Measurement environment For air, nitrogen, hydrogen, argon, helium,
oxygen, and vacuum
1)
IP rating of probe body IP66: Dust-tight. Protected from powerful water
jets from any direction.
1) Consult Vaisala if other chemicals are present. Consider safety regulations with flammable
gases.
Table 38 HMP8 inputs and outputs
Property Description/Value
Operating voltage 15 … 30 V DC
Current consumption 10 mA typical, 500 mA max.
Digital output RS-485, non-isolated
Protocols Modbus RTU
Table 39 HMP8 output parameters
Output parameter name and unit
Absolute humidity (g/m
3
)
Relative humidity (%RH)
Absolute humidity at NTP (g/m
3
)
Relative humidity (dew/frost) (%RH)
Dew point temperature (°C) Temperature (°C)
Dew/frost point temperature (°C) Water concentration (ppm
v
)
Dew/frost point temperature at 1 atm (°C) Water concentration (wet basis) (vol‑%)
Dew point temperature at 1 atm (°C) Water mass fraction (ppm
w
)
Dew point temperature dierence (°C) Water vapor pressure (hPa)
Enthalpy (kJ/kg) Water vapor saturation pressure (hPa)
Mixing ratio (g/kg) Wet-bulb temperature (°C)
Chapter 9 – Technical data
83