Heat Stress WBGT [611487]

Microtherm
Heat Stress WBGT
Think Environment Think Casella

Introduction
The Microtherm WBGT from Casella CEL
is an ergonomically designed, compact, and rugged instrument designed to monitor heatstress potential of personnel in hot working environments in accordance with ISO 7243. It is the first heat stress meter that offers real-time graphical display of data and also features an audible/visual alarm which allows the operator to make rapid decisions if required. PC software for retrospective data analysis is included.
What is Heat Stress?
Workers exposed to hot working
environments can be susceptible to heatstress, when the core body temperature rises to dangerous or hazardous levels. This can result in physiological symptoms like heatcramps, nausea, palpitations, stroke and possibly death. An overall estimation of heat stress levels on the body can be measured by utilising the Wet Bulb Globe Temperature Index (WBGT).This combines the measure-ment of three parameters; natural wet bulb temperature (tnw), globe temperature (tg) and air temperature (ta), applied to the following formulae for both indoor and outdoor environments:
WBGT (Indoor) = 0.7tnw + 0.3tg
WBGT (Outdoor) = 0.7tnw+ 0.2tg + 0.1ta.
The data collected for these values are
compared to reference values (as defined by the standard and appropriate “work rest” regimes) can then be adopted in the workplace or more detailed medical analysis undertaken.Key Features
• L arge LCD graphics display
• R
eal-time display
• F
ull data-logging facilities as
s
tandard
• L
ow water level warning
• A
udible / visual alarm for
W
BGT levels
• %
RH and dewpoint calculation
• E
rgonomic design
• L
ong battery life
• 1
0m extension cables available
• P
C software included
• M
eets requirements of ISO 7243
• A
utomatic calculation of work rest regimes via PC software
• T
ripod mounting for meter and remote sensor array
Think Environment Think Casella
Applications
• P ower Stations
• F
oundries
• S
teel works
• B
akeries• G lass manufacturing
• R
outine monitoring
• M
edical surveillance testing
Operation
The WBGT meter measures simultaneously from three PRTD
sensors for Wet Bulb, Dry Bulb and Globe Temperatures. Sensors are manufactured to high accuracy standards: BS EN60751 and DIN 43760.
Processed data values include:
•
W
BGT (indoor and outdoor)
• 1
Hour (TWA) WBGT values
• R
elative Humidity (%)
• D
ewpoint
Sensors can be used either attached directly on the body of the unit (figure 1), or remotely via 10m extension cables (figure 2). Both the electronic unit and sensor array can be tripod mounted (tripod not included).
Sensor array
Figure 1
Figure 2

Think Environment Think Casella
Display
The Microtherm WBGT incorporates a large 128 x 64 pixel
graphics LCD with backlight, capable of displaying data in two modes;
Graphical Representation
The Microtherm WBGT is the first area heat stress instrument to offer a real-time scrolling graph of the temperature parameters being measured. This display can be shown over variable time bases of 15, 30, 60 & 120 minutes. This allows the user to assess how the environment is changing over time, without having to download to a PC.
Numerical Values
Instantaneous values for all parameters are displayed, combined with the hourly rolling average values.
Alarm
An adjustable alarm threshold may be defined for one selected
data channel: WBGTtwa, WBGT , Ta or OFF . An audible alarm and flashing visual message on the display screen provides warning of excedence of the threshold.
Operation
Simple Keypad Operation The Microtherm WBGT has been designed with a simple, easy to use menu structure for the displaying of information, instrument configuration and retrieval of data. The access of this menu via the touch keypad and screen prompts, ensures ease of use for the operator .
Software
The software (WinHSM) provides an interface for data collection to PC for retrospective analysis. It produces graphical and tabular reports which can easily be imported into other applications. Summary and WBGT Heat Stress Index reports can also be generated.
Work rest regimes are calculated, Clothing (Clo) correction factors,
and metabolic rates can be entered in accordance with OSHA and ISO 7243.
Data can also be viewed “live” by selection of the real-time option
whilst connected to the PC.
Calibration
Calibration of the Microtherm WBGT is performed against an internal reference prior to every single measurement. This ensures a high accuracy for each of the temperature sensors and eliminates the need for annual recalibration. Sensor arrays are also interchangeable without need for recalibration.
Graphical Display
Numerical Real-Time Display
Tabular data format/
OSHA calculations
Graphical report format
ISO calculations

Distributed By:
SM01001 v3.0 Feb 10
Think Environment Think Casella
Technical Specification
Specification MICRO THERM HEAT STRESS WBGT
Identity Sensor specifications
Parameter
RANGE
ACCURA
CY
Ta Air temperature
10-60˚C
+/- 1˚C
Tg Globe temperature
20-120˚C
+/- 0.5˚C (20-50)

+/-1.0˚C (50-120)
Tnw Natural wet tempera
ture 5 to 40˚C
+/- 0.5˚C
T
ransducers PRTD 100 elements 0.1% using 4 wire e
xtension cables available in 10m, lengths up to 30m
Displayed Data Values
Ta Air temperature
Tg Globe temperature
Tnw Natural wet tempera
ture
WBGT Inside and Outside
Time W
eighted WBGT values Based on a 1 hr rolling av
erage updated every 30 seconds. (During the first hour ‘— -’ is displayed.)
%RH Based on”Ta” and non aspira
ted “Tnw” sensor
Dewpoint Based on “Ta” and non aspira
ted “Tnw” sensor
Data LoggerTotal record capacity
512k memory pro
viding up to 49,100 data records
Number of runs stored 32
Logging inter
val 30 seconds to 1 hour
SoftwareOpera
ting System MS Windows 95/98 NT
, XP , Vista compatible. RS232 serial port, 8MB RAM, FDD & HDD, VGA Graphics.
PowerBattery Power supply
4 x AA cells Dry cells or NiMH
Ba
ttery life 40hrs NiMH / 85hr
s alkaline. Battery monitoring warning and auto power down. Consumption; 30mA typical
External power supply 3.5 to 14VDC (12v nominal) 90-240VA
C Universal input mains power adaptor . Internal fast charge circuitry
Communications
RS232
Applicable Standards
ISO 7243/7726, OSHA
Operating T
emperature Range
Sensors -5˚C to +120˚C
Electronics -5˚to +60˚C
Dimensions Instrument: 245 x 95 x 50mm. Ar
ray: 90 x 225 x 65mm. Sensor/carry case (H x W xD): 135 x 490 x 370mm
Weight Sensor/carr
y case 0.97kg. Instrument only 0.75kg
ORDERING INFORMATION
Microtherm Heat Stress WBGT meter with kit case 180000A
Microther
m Heat Stress WBGT meter with kit case with calibration certificate 180042A
10m Extension Lead f
or sensor array
180043B
Small T
ripod (max height 215mm)
CEL-90330
Standard T
ripod (max height 1,160mm)
CEL-6713
Microtherm Heat Stress WBGT kit includes:
Microther
m Heat Stress WBGT meter
Sensor Array Pack of spare wicks and screwdriver Rechargeable batteries (x4) Universal mains PSU (110/240VAC) with UK, Europe and USA plug adaptors Distilled water countainer RS232 communication cable (USB adaptor available) Windows Win HSM software Hard carrying case

Thank you for reading this data sheet.
For pricing or for further information, please contact us at our UK Office, using the details
below.
UK Office
Keison Products,
P.O. Box 2124, Chelmsford, Essex, CM1 3UP, England.
Tel: +44 (0)330 088 0560
Fax: +44 (0)1245 808399
Email: sales@keison.co.uk
Please note – Product designs and specifications are subject to change without notice. The user is responsible for determining the
suitability of this product.