INSTRUMENT FOR THE ANALYSIS OF THE INDICES: WBGT - pmv - PPD, Model : HD 32.3, Brand : DeltaOhm

HD32.3 – WBGT - PMV Index is an instrument made by Delta Ohm Srl for: • Analysis of hot environments using WBGT index ( Wet Bulb Glob Temperature: wet bulb temperature and Globe thermometer) in presence or absence of solar radiation. • Analysis of the moderate warm environments using PMV index ( Predicted Mean Vote) and PPD index ( Predicted Percentage of Dissatisfied) . Reference Rules: ISO 7243: Hot environments. Estimation of the heat stress on working man, based on WBGT index ( wet bulb globe Thermometer) . ISO 8996: Ergonomics of the thermal environment. Determination of metabolic rate. ISO 7726: Ergonomics of the thermal environment – Instruments for measuring physical quantities. ISO 7730: Moderate thermal environments. Determination of PMV and PPD index and specification of the condition for thermal comfort. 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 on the instrument. The main features of the instrument are: • Logging: data acquisition and logging In the integral instrument memory. Storage capacity: 64 different logging sections, sample interval, user selectable. • Start and stop can be set automatically with the auto-start function, • Selectable 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 transfer speed of data via RS232 serial port. HD32.3 instrument can detect simultaneously the following quantities: • Globe thermometer temperature Tg with TP3276.2 ( or TP3775) probe. • Natural wet bulb temperature Tn with HP3201.2 ( or HP3201) probe. • Environment temperature T with TP3207.2 probe. • Relative humidity RH and environment temperature T with HP3217.2 ( or TP3217) probe. • Air speed Va with AP3203.2 probe. Starting from the measured values, HD32.3 can calculate and display, with TP3207.2R ( or TP3207) , HP3276.2 ( or TP3775) , and HP3201.2 ( or HP3201) probes, the following indexes: • 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. Starting from the measured values, the HD32.3 instrument can calculate and display, with TP3217.2 ( or TP3217) , HP3276.2 ( or HP3275) , and AP3203.2 ( or AP3203) probes, the following indexes: • Medium radiant temperature Tr. • PMV Index ( Predicted Mean Vote) . • PPD Index ( Predicted Percentage of Dissatisfied) . WBGT WBGT ( Wet Bulb Globe Temperature – wet bulb and globe temperature) 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 measurement of wet bulb temperature tnw with natural ventilation with the globe thermometer temperature tg and, in some situations, with the air temperature ta. 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 ( or HP3201) . • TP3276.2 ( or TP3275) Globe thermometer probe. • TP3207.2 ( or TP3207) Dry bulb temperature, of 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 PMV - PPD Human thermal comfort is defined by ASHRAE ( American Society of Heating, Refrigerating and Air Conditioning Engineers INC) as the state of mind that expresses satisfaction with the surrounding living or working environment. The evaluation of this subjective condition can be objectified and quantified using integrated index that consider the micro climatic environment parameters ( Ta, Tr, Va, rh) , and the work-related energy metabolic expenditure MET, and the typology of clothing ( thermal insulation CLO) commonly used. Among these indexes, the most precise one reflecting the influence of the above mentioned physical and physiological variables on thermal comfort is PMV ( Predicted Mean Vote) . Synthetically, it comes from the equation of the thermal balance whose result is compared to a scale of psycho - physical health and expresses the average opinion ( average foreseen vote) about the thermal sensations of a group of subjects. From PMV is derived a second index called PPD ( Predicted Percentage of Dissatisfied) that quantifies the percentage of subjects who will be dissatisfied with some micro climatic conditions. ISO 7730 regulations suggests PMV use in presence of following variables that influence the thermal balance: • Metabolic expenditure = 1 ÷ 4 met • Thermal resistance of clothing = 0 ÷ 2 clo • Dry bulb temperature = 10 ÷ 30° C • Medium radiant temperature = 10 ÷ 40° C • Air speed = 0 ÷ 1 m/ sec • Water vapour pressure = 0 ÷ 2, 7 kpa PMV is a particularly suitable index for the evaluation of work places with moderate microclimate such as houses, schools, offices, research laboratories, hospitals, and is useful to predict the number of people likely to feel uncomfortably warm or cool. According to ISO 7730 PMV values range between + 0, 5 and - 0, 5, provides comfort conditions corresponding to a percentage of dissatisfied ( PPD) lower than 10% . ( see table below) . TECHNICAL FEATURES Instrument Dimensions 185x90x40 mm ( Length x Width x Height) Weight 470 g ( batteries included) Materials ABS, rubber Display Back light, 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 ( cod. 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 no isolated 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 3 inputs. Logging interval selectable among: 15, 30 seconds, 1, 2, 5, 10, 15, 20, 30 minutes and 1 hour.