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

World Class Heat Stress Detector

twl1s

thermal Work limitB!"#$r%&'(

© 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 inducedHAAD conducted safety in the heat program and introduced TWL as a big enhancement

Heat index invented by Australia Dr. BatesTWL unit W/m2 , means a safe maximum metabolic rate suitable for a given environment conditionConsider clothing factor and human physiological statusCalculated 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?

http://www.scarlet.com.tw


four instrumentsM)!*&r) +!r!,)-)r*

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


http://en.wikipedia.org/wiki/Temperature

http://en.wikipedia.org/wiki/Temperature

http://en.wikipedia.org/wiki/Air

http://en.wikipedia.org/wiki/Air

http://en.wikipedia.org/wiki/Thermometer

http://en.wikipedia.org/wiki/Thermometer

http://en.wikipedia.org/wiki/Radiation

http://en.wikipedia.org/wiki/Radiation

http://en.wikipedia.org/wiki/Moisture

http://en.wikipedia.org/wiki/Moisture

https://en.wikipedia.org/wiki/Temperature

https://en.wikipedia.org/wiki/Temperature

https://en.wikipedia.org/wiki/Evaporation

https://en.wikipedia.org/wiki/Evaporation



one calculatorC!."&.!-) TWL v!.&)




one tableC/)"# -/) ,)!'0'$

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 deviceB)*- *%.&-0%'

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℃


tableZone Risk Level Cycle (min)

TWL ≥ 140 Low Continuous*

115 ≤ TWL < 140 Medium Continuous*

TWL < 115 High 20 work - 40 rest



why ScarletB)*- *%.&-0%'


we do more for you



dashboardB)*- *%.&-0%'


3-color LCD backlight R/Y/G indicates risk levelRisk icons is readable alternative in sunlightOn screen timer is helpful for safety manager to schedule work-rest cycle based on TWL value

innovative display



warningB)*- *%.&-0%'


Red zone (TWL < 115) detectedWork timer expired

remote technology critical event warning

433 MHz transmitter integratedPager (receiver) in box200 meter guarantee in open space Diameter of a cricket stadium is 200 mRF is designed for horizontal transmission

200 m



data loggerB)*- *%.&-0%'


logger TWLIT

For research purposeFor build up database of forecastConfigurable sample rate: 10 min to 4 hr/dataStandard mini USB connector

PC software to download data and setup device Download data in zero click. SimpleConfigure device nameConfigure sampling rateExport CSV for Excel analysis

210

255

300

12.06 12:36 13:06 13:36

TWL RH !normalized"



sensor protectionB)*- *%.&-0%'


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 & partsS)rv0")*


humidity wind cup

>> Calibration Should calibrate every 6 months. Local agent or clients can do it.

>> PartsPp 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.

>> PartsBlack ball along with thermistor is replaceable. By order.

>> Calibration Local calibration is not feasible due to wind tunnel costs.

>> Quick checkHold device and walk 5 meters in 10 sec and make sure the cups keep rotating.

>> PartsWind cup and bearing is replaceable. By order.



CertificateB)*- *%.&-0%'


EN 61326-1:2006(IEC/EN61000-4-2 (2009)/

-3 (2006 + A2:2010)) Electrical Equipment for Measurement,

Control and Laboratory Use



thank you

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

Environment

temperature of air

air temperature

globe bulb scarlet tech

twl value scarlet tech

twl theory

twl calculation

wet bulb temperature

globe bulb temperature