Specification
HD32.2 â WBGT Index is an instrument made by Delta Ohm srl for the analysis of WBGT index ( Wet Bulb Glob Temperature: wet bulb temperature and globe thermometer temperature) in presence or in absence of solar
radiation.
Reference Regulations:
ISO 7243: Hot environments. Estimation of the heat stress on working man, based on WBGT index ( wet bulb temperature and Globe thermometer) .
ISO 8996: Ergonomics of the thermal environment â Determination of the energy metabolism.
ISO 7726: Ergonomics of the thermal environment â Instruments for measuring
physical quantities.
The instrument is provided with three inputs for probes with SICRAM module:
the SICRAM module interface between the instrument and sensor connected and communicate the sensor parameters and calibration data to the instrument.
All SICRAM probes can be plugged into any of the inputs: they are automatically recognized upon turning the Instrument on.
The main features of the instrument are:
⢠Logging: data acquisition and logging to the integral instrument memory.
Storage capacity: 64 different logging sections, sample interval, user selectable.
⢠You can set the automatic logging start with auto-start function( Start/ Stop time ) .
⢠The measurement unit of the temperature: ° C, ° F, ° K.
⢠Date and time of the instrument.
⢠The display of maximum, minimum, medium statistic parameters and their deletion.
⢠The data transfer speed via the RS232 serial port.
HD32.2 instrument can detect simultaneously the following quantities:
⢠Globe thermometer temperature Tg.
⢠Wet bulb temperature with natural ventilation Tn.
⢠Environment temperature T.
Starting from the detected values, HD32.2 can calculate:
⢠WBGT( in) index ( Wet Bulb Glob Temperature: wet bulb temperature and Globe thermometer) in absence of solar radiation.
⢠WBGT( out) index ( Wet Bulb Glob Temperature wet bulb temperature and Globe thermometer) in presence of solar radiation.
WBGT
WBGT ( Wet Bulb Globe Temperature â Wet bulb temperature and globe
thermometer) is one of the indexes used to determinate the occupational heat exposure.
It represents the value, related to the metabolic expenditure linked to a specific work activity, that causes a thermal stress when exceeded.
WBGT index combines the temperature measurement of wet bulb with natural ventilation tnw with the globe thermometer tg and, in some situations, with the air temperature ta.
The calculation formula is the following:
⢠inside and outside a buildings in absence of solar radiation:
WBGT close environments = 0, 7 tnw + 0, 3 tg
⢠outside a building in presence of solar radiation:
WBGToutside environments= 0, 7 tnw + 0, 2 tg + 0, 1 ta
where:
tnw = natural wet bulb;
tg = globe thermometer temperature;
ta = air temperature.
The measured data should be compared with the limit values prescribed by the regulations;
when exceeded you have to
⢠reduce directly the thermal stress on the examined work place;
⢠proceed to a detailed analysis of the thermal stress.
In order to measure the WBGT index, the following probes should be connected:
⢠Natural wet bulb HP3201.2 ( HP3201) .
⢠TP3276.2 Globe thermometer probe ( TP3276 or TP3275) .
⢠TP3207.2 ( TP3207) Dry bulb temperature, if the measurement is performed in presence of solar radiation.
In order to measure the WBGT index, you should refer to the following regulations:
⢠ISO 7726
⢠ISO 7243
⢠ISO 8996
Technical features
Instrument
Dimensions 185x90x40 mm
( Length x Width x Height)
Weight 470 g ( batteries included)
Materials ABS, rubber
Display back light, with dot-matrix 160x160 points, visible area 52x42mm
Working conditions
Working temperature -5 ⦠50° C
Storage temperature -25 ⦠65° C
Working relative humidity 0 ⦠90% RH no condensation
Protection Degree IP67
Instrument uncertainty ± 1 digit @ 20° C
Power supply
Mains power supply ( code SWD10) 12Vdc/ 1A
Batteries 4 batteries 1.5V type AA
Autonomy 200 hours with 1800mAh alkaline batteries
Power absorbed with < 45¼ A
instrument off
Safety of the stored data unlimited
Serial Interface:
Pin: M12-8 poles.
Type: RS232C ( EIA/ TIA574) or USB 1.1 o 2.0 not insulated
Baud rate: from 1200 to 38400 baud.
with USB baud= 460800
Data bit: 8
Parity: None
Stop bit: 1
Flow control: Xon-Xoff
Cable length: max 15m
Memory divided in 64 blocks.
Storage capacity 67600 memorizations for each of the 3
inputs.
Logging interval selectable among: 15, 30 seconds, 1, 2, 5, 10, 15, 20, 30 minutes and 1 hour.