Long Range Wireless Anemometer WR-3

Scarlet WR-3. The Wireless Anemometer Designed for Crane Safety and
Wind Monitoring Onsite

Clients Using Scarlet WR-3
0+ Year
Battery Life
0 m
Transmission Distance


Why WR-3

Cable Free

Get rid of traditional cable-type anemometer. Avoid possible risks from machine operation. Scarlet WR-3 anemometer gives users a wireless wind monitoring solution.

Long Life

4-year battery life of wind speed sensor in all weather conditions. The sensor is designed to use in rigid environments such as dessert, ocean and mountains.

Stay Alert

Never worries about high wind. Develop a safer working environment. WR-3 Anemometer sends automatic high-volume alarms based on user settings.

Wireless Sensor

WR-3 adopts 433/868/900 MHz wireless technology to ensure better performance for barrier penetration and achieving long range transmission. The sensors start sending data when wind cups revolve. The sensor will go to sleep mode when wind cups stop revolving for more than 6 hours. Data transmit rate: every 2 seconds.

The ultra-long 400 meter transmission distance makes WR-3 a perfect gadget to help you monitor wind speed on crane and prevent from high wind risks.

wr-3 sensor bearing


Handheld Receiver

Large LCD display shows digital wind speed, temperature and beaufort chart clearly. Anti-slip rubber on two slides helps users hold the receiver in place during work. User-friendly interface and simple button design allows you to operate the device easily with only one hand.

When the wind reaches a certain speed, an alarm will be triggered, and it will continue as long as high wind is detected. The alarm buzzer located on top of the receiver can effectively warn users at the level of 90 dB.

Low Power Consumption

We use innovative low-power consumption wirless technology on WR-3. The battery power consumption is only 20-30 uA in normal condition and 35 mA peak current during data transmission. 3.6V Lithium battery with 2400 mAh capacity can run the sensor for 4 years.

4-year long battery life reduces the maintenance cost significantly. Low battery indicatior on the display monitor will show up when battery capacity is lowered than 10%.


What Our Clients Say

  • I have been using WR-3 on all the lifts in my company for the last 6 months and couldn't be happier with their performances and high quality.

    Hamid Bashir
    Crane Manger Technical Department, DP World KSA
  • We are quite happy with Scarlet WR-3 wireless wind speed meter. It works perfect in our workshops. I highly recommend this wireless anemometer.

    Håkan Pettersson
    Senior Engineer, Support and Services, Saab AB Sweden
  • The Scarlet wireless anemometer WR-3 is the best wind speed meter I ever used in my career life. It makes my job much easier and I can monitor wind speed in my office under bad weather conditions.

    John Leavy
    Project Manager, Pittsburgh PA, USA


General article

General article (8)


Heat Stress


What is Heat Stress  

Heat stress is the effect that the thermal environment has on a person’s ability to maintain a normal body temperature.  Physical work generates heat in the body which must be lost to the environment through sweating and evaporation. A hot or humid environment makes this more difficult and this can affect both mental and physical performance. Inability to get rid of body heat adequately may result in heat illness.

Workers who are exposed to extreme heat or work in hot environments may be at risk of heat stress. Exposure to extreme heat can result in occupational illnesses and injuries. Heat stress can result in heat stroke, heat exhaustion, heat cramps, or heat rashes. Heat can also increase the risk of injuries in workers as it may result in sweaty palms, fogged-up safety glasses, and dizziness. Burns may also occur as a result of accidental contact with hot surfaces or steam.


Risk factors for heat illness 

Workers at risk of heat stress include outdoor workers and workers in hot environments such as firefighters, bakery workers, farmers, construction workers, miners, boiler room workers, factory workers, and others. Workers at greater risk of heat stress include those who are 65 years of age or older, are overweight, have heart disease or high blood pressure, or take medications that may be affected by extreme heat.

Types of Heat Stress

Heat cramps are involuntary muscle contractions caused by failure to replace fluids or electrolytes, such as sodium and potassium. Cramps can be relieved with stretching and by replacing fluids and electrolytes.


Heat syncope is a fainting (syncope) episode or dizziness that usually occurs with prolonged standing or sudden rising from a sitting or lying position. Factors that may contribute to heat syncope include dehydration and lack of acclimatization.


Heat exhaustion is characterized by weakness, extreme fatigue, nausea, headaches, and a wet, clammy skin. Heat exhaustion is caused by inadequate fluid intake. It should be treated by resting in a cool environment and replacing fluids and electrolytes.


Heat stroke is a medical emergency caused by failure of the body's heat controls. Sweating stops and the body temperature rises precipitously. Heat stroke is characterized by hot dry skin, a body temperature above 105.8 F (41 C) mental confusion, loss of consciousness, convulsions, or even coma. Send for medical help at once and begin rapid cooling with ice or cold water, fanning the victim to promote evaporation. Treat for shock if necessary. For rapid cooling, partially submerge the victim's body in cool water.


You can prevent the serious consequences of heat disorders by improving your level of fitness and becoming acclimated to the heat.

Maintaining a high level of aerobic fitness is one of the best ways to protect yourself against heat stress. The fit worker has a well-developed circulatory system and increased blood volume. Both are important to regulate body temperature. Fit workers start to sweat sooner, so they work with a lower heart rate and body temperature. They adjust to the heat twice as fast as the unfit worker. They lose acclimatization more slowly and regain it quickly. 

Acclimatization occurs in 5 to 10 days of heat exposure as the body:

  • Increases sweat production 
  • Improves blood distribution
  • Decreases the heart rate, and lowers the skin and body temperatures.

You can acclimatize by gradually increasing work time in the heat, taking care to replace fluids, and resting as needed. You maintain acclimatization with periodic work or exercise in a hot environment.

Recommendations for Employers

Employers should take the following steps to protect workers from heat stress:

  • Schedule maintenance and repair jobs in hot areas for cooler months.
  • Schedule hot jobs for the cooler part of the day.
  • Acclimatize workers by exposing them for progressively longer periods to hot work environments.
  • Reduce the physical demands of workers.
  • Use relief workers or assign extra workers for physically demanding jobs.
  • Provide cool water or liquids to workers.Provide rest periods with water breaks.
  • Avoid alcohol, and drinks with large amounts of caffeine or sugar.
  • Provide cool areas for use during break periods.
  • Monitor workers who are at risk of heat stress.
  • Provide heat stress training that includes information about:
    • Worker risk
    • Prevention
    • Symptoms
    • The importance of monitoring yourself and coworkers for symptoms
    • Treatment
    • Personal protective equipment

Recommendations for Workers

Workers should avoid exposure to extreme heat, sun exposure, and high humidity when possible. When these exposures cannot be avoided, workers should take the following steps to prevent heat stress:

  • Wear light-colored, loose-fitting, breathable clothing such as cotton.Gradually build up to heavy work.
  • Avoid non-breathing synthetic clothing.
  • Schedule heavy work during the coolest parts of day.
  • Take more breaks in extreme heat and humidity.Drink water frequently. Drink enough water that you never become thirsty. Approximately 1 cup every 15-20 minutes.
  • Take breaks in the shade or a cool area when possible.
  • Avoid alcohol, and drinks with large amounts of caffeine or sugar.
  • Be aware that protective clothing or personal protective equipment may increase the risk of heat stress.
  • Monitor your physical condition and that of your coworkers.


Related Articles

1. CDC NIOSH Workplace Safety and Health Topics - Heat Stress  

2. Health Authority – Abu Dhabi Safety in Heat Programme

3. United States Department of Agriculture (USDA): Wildland Fire Safety - Heat Stress 

4. UK Health and Safety Executive – Heat Stress 





What is TWL


What is TWL?

Thermal Work Limit (TWL), is an integrated measure of the dry bulb temperature, wet bulb temperature, wind speed and radiant heat. The TWL predicts the maximum level of work that can be carried out in a given environment, without workers exceeding a safe core body temperature (38.2C or 100.8 F) and sweat rate (< 1.2 kg or 2.6 lb per hour).  The TWL is developed from published studies of human heat transfer and moisture equations through clothing. In excessively hot conditions, the index can determine the safe work duration, thus preventing heat-related illness and providing guidelines for work/rest cycling. The TWL guidelines have been implemented in Abu Dhabi Emirate, UAE and Australian mines and have produced a substantial decrease in the number of heat related illness cases.

Why TWL is better than WBGT and other indices?

The Wet Bulb Globe Temperature (WBGT) has been widely used and still the standard in many industries. The WBGT is relatively easy to measure and the instrumentation is not overly expensive, however it has several shortcomings as a measure of thermal stress. WBGT does not incorporate direct measure of wind speed and requires estimation of metabolic rates, which can have a margin of error up to 50%. The guidelines are also unrealistic, as stringent application of the protocol would shutdown every construction site in Middle East during summer. 

Heat stress indexes such as WBGT and ISO 7933 do not take into account the effects of long hours of hard work, dehydration, or the impact of personal protective clothing and equipment. The studies in UAE and other regions of the world have shown that WBGT is too conservative and inappropriate for practical in industry. Other problems exist with rational indices such as ISO 7933, especially when applied to hot, humid environment with low wind speeds, including the incorrect adjustment of wind speed, absence of a fluid replacement term and incorrect assumption of the clothing insulation.


The idea of a thermal work limit (TWL) was developed by Dr. Graham Bates and Dr. Derrick Brake in 1997. Over the past 80 years, many heat stress indices have been developed to assist with the management of heat stress problems. Some of these have been developed for particular industries and empirically derived such as ISO 7933 and WBGT. These indices required estimation of metabolic rate but failed to consider the direct measurement of wind speed, reduction of work rate, location and time shift during work and removal of clothing, making these indices not accurate for self-paced and acclimatized workers. The need for a heat stress index designed primarily for self-paced workers has led to the development of the thermal work limit (TWL).

TWL and its accompanying management protocols have been introduced into several industrial operations where workers are subject to thermal stress. Approximately 1400 persons work in these locations with over 10 million man-shifts being worked between 1965 and 1995 at wet bulb temperatures in excess of 28 °C (82 °F). Since the introduction of TWL-based policies in the Australian mining industry, the amount of man-hours lost due to serious heat illness has fallen from 12 million to 6 million, and the amount lost due to all heat illness incidences has fallen from 31 million to 18 million.


The basic purpose of the thermal work limit index is to calculate the maximum metabolic rate, in watts of metabolic heat per square meter of body surface area, that can be continuously expended in a particular thermal environment, in order to keep the body within safe physiological limits. The TWL is an integrated measure of the dry bulb, wet bulb, wind speed and radiant heat. From these variables, and taking into consideration the type of clothing worn and acclimatization state of the worker, the TWL predicts the maximum level of work that can be carried out in a given environment, without workers exceeding a safe core body temperature 38.2 °C (100.8 °F) and sweat rate.

In excessively hot conditions, the index can also determine the safe work duration, thus providing guidelines for work/rest cycling. Sweat rates are also calculated, so the level of fluid replacement necessary to avoid dehydration can be established. The thermal work limit algorithm builds on work originated by Mitchell and Whillier, who developed an index “specific cooling power,” which subsequently became known as “air cooling power” (ACP).


The TWL heat stress index is the heat stress index that has been included in the Abu Dhabi EHSMS code of practice for the management of Heat Stress. TWL gives a measure of the maximum safe work rate for the environmental conditions present at a worksite. If TWL is too low then even low rates of work cannot safely be carried out continuously and extra rest breaks and other precautions are needed to ensure worker safety. 

TWL Work Zone


  • Brake, D. J.; Bates, G. P. (2002). "Limiting Metabolic Rate (Thermal Work Limit) as an Index of Thermal Stress". Applied Occupational and Environmental Hygiene 17 (3): 176–186
  • Thermal Work Limit Wikipedia
  • Miller, V. S.; Bates, G. P. (2007). "The Thermal Work Limit is a Simple Reliable Heat Index for the Protection of Workers in Thermally Stressful Environments". Annals of Occupational Hygiene 51(6): 553–561







“If you have very limited time, you should start with this video clip to better understand Scarlet TWL-1S.” 


TWL-1S is designed with the user-friendly interface to help customers measure:

  • Wet Bulb Globe Temperature (WBGT)
  • Thermal Work Limit (TWL)
  • Globe Temperature
  • Dry Bulb Temperature
  • Relative Humidity
  • Wet Bulb Temperature
  • Wind Speed


Scientific Validation

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.



The features of TWL-1S include:









Globe Bulb Temperature

0-80 oC

0.1 oC

Indoor: ±1.0 (15-40oC); ± 1.5oC (others)

Outdoor: ±1.5 (15-40oC); ± 2.0oC (others)

Air Temperature

0-50 oC

0.1 oC

±0.6 oC




±3% (25oC; 10-90%RH)

±5% (others)

Wind Speed

0.5-10 m/s

0.1 m/s

±(2% of reading+0.2) m/s






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 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 the safety officers in real time. TWL-1S is able to help managers set work/rest cycle and hydration plans for workers.





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.

Put SGS certificate pic (small pic is good, no need original size)



TWL Literature



TWLIT, pronounced as “twilight”, is the PC software developed by Scarlet Tech to works with TWL-1S Heat Stress Detector. TWL-1S is a great device for long-term recording and TWLIT is created to setup logging parameters and download data out of the device and export the data into CSV format for your further analysis with Excel or other tools.

To profile work site or to build up the database of heat condition of an area, TWL-1S data logger function helps greatly in this job by periodically recording parameters: dry bulb, wet bulb, wind speed and globe bulb temperature. TWLIT ease the task further with simple user interface and strait forward operation. It is very easy to use the software to download recorded data out of the box.


  • Windows 7
  • Windows Vista
  • Windows XP SP3


  • Recommended Minimum: Pentium 1 GHz or higher
  • 512 MB RAM or more
  • Minimum disk space 20 MB
TWLIT is free for all TWL-1S user. Installation package can be downloaded here, user guide is here.

Download USB driver and TWLIT package from the Scarlet www.scarlet.com.tw.

Install USB driver (CP210x_VCP_Win_XP_S2K3_Vista_7.exe) supplied by Silicon Laboratories, Inc. The driver was designed for Windows XP/Vista/7.

Install TWLIT.msi then TWL.exe can be found in Start > All programs > TWLIT > TWL.exe.


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Manage risks. No high wind disasters.

Scarlet WR-3 provides an elegant approach to manage on-site risks. We believe safety can be improved with well designed instruments. If you still have questions in mind, please do not hesitate to contact us. Get a quotation today. Reduce the risk, save money.