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Smart Heat Stress Detector TWL-1S

The Best Practices in Heat Stress Management During Work. Thermal Work Limit Solutions Designed for Extreme Weather Condition.

Accurate & Reliable
Compact Design
Smart Work Management
Wireless Warning


Why Choose TWL-1S

Compact Design

TWL-1S is designed for all kinds of worksites including mining and construction. All devices have been tested in rigid environment settings.

Smart Device

Our product is based on the scientific research and algorithm, which gives user built-in risk level flags and instruction for work, rest and hydration.

Quickstart Datalogger

Free software allows users to download data on TWL and WBGT; air temperature, humidity, wind speed, globe and wet bulb temperature.

World Class Standards

We ensure every devices with calibration providing accurate and reliable readings. The 3rd Party Certification is available upon request.


State-of-Art Heat Stress Detector

Learn TWL-1S in 1 Minutes

Scarlet TWL-1S is designed to measure WBGT and thermal work limit (TWL) heat index. The TWL measures air temperature, humidity, radiant heat and wind speed to come up with instructions for work, rest and hydration plan. We integrate the algorithm of TWL and work-rest schedule based on the latest guideline. The user-friendly interface even showed different colors to ensure users in line with TWL schedule. For example, red means unsafe for work, yellow means buffer zone and green means safe for work.

Learn More


User-Friendly Dashboard

Meters were supposed to sense the targets and give readings. Scarlet intends to do more. TWL theory determines the threshold for safe, fair, and dangerous working environment. Colorful LCD backlight tells you the risk level based on the TWL value. Work-rest schedule and fluid intake are integrated into the display. A countdown timer shows the time remaining before a recommended rest.

Automatic Warning (TWL-1SR Model)

The working timer starts counting according to TWL value. When it expired, the device will notify the pager carriers remotely. It reminds you to take actions. 433 MHz technology is used to offer better penetration ability and 200 meter coverage in an open area is achieved. Please note that pager is available in TWL-1SR model.



Sensor Protection

Delicate temperature and humidity sensor are well protected by a replaceable polypropylene (PP) filter in a solid shield, exempted the sensors from dust damage and external strike. A silicone pad protects the mechanism of anemometer from dust.

Data Logger


TWL-1S can record data with configurable sampling rate from 10 minutes to 3 hours. PC side software automatically convert data into CSV format and helps download the data for further analysis using other analytical tools, and it also synchronizes the date and time of the device with PC.

Optimized Globe


TWL theory considers mean radiant temperature (MRT), the most important parameter on human energy balance. The smaller the surface area of the black bulb, the greater the effect of the air temperature and velocity is, thus causing inaccuracy. The 7.5 cm globe bulb is the optimal size based on our research.

All-Direction Wind Cup


Cup anemometer captures winds from any direction. You do not have to manually decide the wind direction before measuring the wind speed. Compared to the impeller, wind cup is not restricted to the direction of the wind. It considers all the horizontal components of winds that move the anemometer.

Use Cases

This is the way to Heat Safety


Health, safety and environmental protection are among the fundamental concerns of Bauer in Abu Dhabi and they are top priorities for Scarlet.

We Value Customer Success


Scarlet TWL-1S Heat Stress Detector was applied in Al Fara'a General Contracting (AFGCO) project in downtown Abu Dhabi.

Safety at Worksites


Specialist Services in Dubai used TWL-1S to ensure health and safety of people, contractors and others stakeholders.




TWL-1S Testimonial

  • TWL-1S's friendly user interface has assisted me a lot in implementing the new occupational heat exposure prevention system in the field. This is one of the key elements to success.

    Dr. Sanad Al Sanadi
    Occupational Health Team Leader, ADMA-OPCO
  • Since Commencing the heat stress management program in November 2013, the project has not had a SINGLE CASE of a heat stress related illness despite air temperatures of 45 degrees.

    Simon Lewis
    Project Manager, Leighton Contractors Australia
  • Companies in Abu Dhabi should comply with EHSMS heat safety standards by adopting thermal work limit (TWL) for risk assessment of heat working environment.

    Eng. Ibrahim Khalid
    HSE engineer, Abu Dhabi Municipality HSE Division


TWL Specifications

  • Measurements

    • Wet Bulb Globe Temperature (WBGT)
    • Thermal Work Limit (TWL)
    • Globe Temperature
    • Dry Bulb Temperature
    • Relative Humidity
    • Wet Bulb Temperature
    • Wind Speed
  • Item Description
    Air Temperature Range 0…60 °C / Accuracy ±0.6 °C
    Globe Bulb Indoor Range 0...80 °C / Accuracy ±1.0 °C (15...40 °C); ±1.5 °C (others)
    Globe Bulb Outdoor Range 0...80 °C / Accuracy ±1.5 °C (15...40 °C); ±2.0 °C (others)
    Relative Humidity Range 5...95 %rh / Accuracy ±3% (at 25 °C; 10...90 %rh) ±5% (others)
    Wind Speed Range 0.5...10 m/s / Accuracy ±(2% of reading + 0.2) m/s
    Dimensions Body 59 x 37 x 316 mm (w x d x h). Wind cup (top view) diameter 182 mm
    Operating range electronics -10…60 °C
    Accuracy at 23 ±5 °C ±1.0 %rh / ±0.2 K
    Power supply / consumption 4 AAA 3V battery, power supply 6 mA consumption without lighting
    Probe protection Polypropylene plastic cage
    Measurement interval 2 seconds
    Data logger Yes. Min data rate 1 min up to 60 min, 2,000 data.
    Connection Interface Mini USB (UART)
    Calibration / adjustment Scarlet calibration kit
    Wireless Connection (Optional) 433 MHz (TWL-1SR Model)
  • The TWL-1S has been tested and validated by Health Authority – Abu Dhabi in the extreme high temperature and high humidity Gulf region as well as the mines in Australia. The TWL algorithm used by TWL-1S device is the latest version attested by the research team in Curtin University, Australia.


    Risk assessment for heat-related illness in the worksite is quite essential in high temperature environments. TWL-1S can be applied at outdoor and indoor working environments. For instance, a health and safety officer can place the TWL-1S at the “hot spot” zone in worksite and continuously monitor environmental parameters. With 200 meters transmission distance of wireless signal, the paging system can actively warn safety officers in real time. TWL-1S is able to help managers set work/rest cycle and hydration plans for workers.
  • Certification

    The TWL-1S Heat Stress Detector is certified by CE mark following the EN 61326-1:2006 Electrical Equipment for Measurement, Control and Laboratory Use.

    TWL-1S Heat Stress Detector has also received a third party certification for its temperature and humidity sensors from SGS, a globally renowned company for inspection, verification, testing and certification.

  • Download


    TWL-1S Data Sheet TWL-1S heat stress monitor datasheet 2014.



    TWL-1S User Manual TWL-1S heat stress detector user manual version 2013.



    TWLIT User Guide TWL-1S heat stress detector user manual version 2013.