Safety in the Heat - Thermal Work Limit and Scarlet Tech TWL-1S

World Class Heat Stress Detector
twl1s

thermal Work limit
Background
© Scarlet Tech Co. Ltd. 2013 www.scarlet.com.tw +886 2 2325 7712
Dehydration caused by heat stress is
dangerous. Heat stroke and other serious
issues will be induced
HAAD conducted safety in the heat program
and introduced TWL as a big enhancement
Heat index invented by Australia Dr. Bates
TWL unit W/m2 , means a safe maximum
metabolic rate suitable for a given
environment condition
Consider clothing factor and human
physiological status
Calculated from four parameters
(1) dry bulb temperature (DB)
(2) wet bulb temperature (WB)
(3) globe bulb temperature (GT)
(4) wind speed (WS)
what TWL is? why twl?

four instruments
Measure parameters
The temperature of air
measured by a thermometer
freely exposed to the air but
shielded from radiation and
moisture. DBT is the
temperature that is usually
thought of as air temperature,
and it is the true
thermodynamic temperature.
Dry bulb
The temperature a parcel of air
would have if it were cooled to
saturation (100% RH) by the
evaporation of water into it. It
describes the level of moisture
and it affects how people ‘feel’
the environment. In TWL theory,
higher wet bulb temp. means
harder sweat evaporation and
put worker in hazard.
wet bulb
Wind speed is typically judged
as the velocity of wind. Most
measurements of air movement
are taken of outside air, and
there are several factors that
can affect it. Average wind
speed is often determined by an
anemometer. Wind helps to
remove the heat from human
body and plays important role in
TWL calculation.
wind speed
Globe bulb is typically used to
measure MRT (Mean Radiation
Temperature). MRT is the most
important parameter governing
human energy balance,
especially on hot sunny days. In
fact, in warm climates it is about
twice as significant as the air
temperature due to lighter
clothing, while in cooler climates
it has about the same influence
as the air temperature.
globe bulb

one calculator
Calculate TWL value

one table
Check the meaning
Health Authority Abu Dhabi (HAAD) conducted medical research and came along with the
following table to give working sites a general guideline to manage the safety in the heat.
The sheet is suitable for self-paced workers who has been acclimatized and trained.
Zone Risk Level Cycle (min)
TWL ≥ 140 Low Continuous*
115 ≤ TWL < 140 Medium Continuous*
TWL < 115 High 20 work - 40 rest

everything in one device
Best solution
four sensors
wet bulb measure RH: 5-95% accuracy 0.1%
calculator
globe 0-80℃, accuracy 0.1℃
Wind 0.5-10 m/s, accuracy 0.1 m/s
Dry bulb 0-50℃, accuracy 0.1℃
table
Zone Risk Level Cycle (min)
TWL ≥ 140 Low Continuous*
115 ≤ TWL < 140 Medium Continuous*
TWL < 115 High 20 work - 40 rest

why Scarlet
Best solution
we do more for you

dashboard
Best solution
3-color LCD backlight R/Y/G indicates risk level
Risk icons is readable alternative in sunlight
On screen timer is helpful for safety manager to
schedule work-rest cycle based on TWL value
innovative display

warning
Best solution
Red zone (TWL < 115) detected
Work timer expired
remote technology critical event warning
433 MHz transmitter integrated
Pager (receiver) in box
200 meter guarantee in open space
Diameter of a cricket stadium is 200 m
RF is designed for horizontal transmission
200 m

data logger
Best solution
logger TWLIT
For research purpose
For build up database of forecast
Configurable sample rate: 10 min to 4 hr/data
Standard mini USB connector
PC software to download data and setup device
Download data in zero click. Simple
Configure device name
Configure sampling rate
Export CSV for Excel analysis
210
255
300
12.06 12:36 13:06 13:36
TWL RH (normalized)

sensor protection
Best solution
protect rh sensor
Polypropylene (PP) film allows vapor going
through but blocks fine dust and dirt. So vapor
and moisture reach sensor but particles don’t.
This design is to extend the life of sensor in harsh
environment.
Protect anemometer bearing
A silicone pad clamped on top of the plate of wind
miller plate. This prevents the bearing inside of
the structure from dust and other particles.
Compare to competitors, this effectively extends
the sensor life.

calibration & parts
Services
humidity wind cup
>> Calibration
Should calibrate every 6 months.
Local agent or clients can do it.
>> Parts
Pp filter is suggested to be
replaced every 2 to 4 weeks in
heavy usage. By order.
Dry/globe bulb
>> Calibration
Calibration drift of thermistors are
negligible. No need to calibrate.
>> Parts
Black ball along with thermistor is
replaceable. By order.
>> Calibration
Local calibration is not feasible due
to wind tunnel costs.
>> Quick check
Hold device and walk 5 meters in
10 sec and make sure the cups
keep rotating.
>> Parts
Wind cup and bearing is
replaceable. By order.

Certificate
Best solution
EN 61326-1:2006
(IEC/EN61000-4-2 (2009)/
-3 (2006 + A2:2010))
Electrical Equipment for Measurement,
Control and Laboratory Use

Safety in the Heat - Thermal Work Limit and Scarlet Tech TWL-1S

Recommended

Recommended

More Related Content

Viewers also liked

Viewers also liked (16)

Recently uploaded

Recently uploaded (20)

Safety in the Heat - Thermal Work Limit and Scarlet Tech TWL-1S