Frequently Asked Questions

  • Q1: What is TWL? Why TWL is better than WBGT and Heat Index?

    • 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 (< 1.2 kg or 2.6 lb per hour).
    • 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%.
    • 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.
    • WBGT and heat index are too conservative and inappropriate for practical in extreme working environment such as Middle East countries or high temperature process industry or mines.
    • Scarlet TWL-1S incorporated both WBGT and TWL index features. You can simply switch heat indices for your need.
  • Q2. I am a HSE manager, how many pieces should I need for my company?

    A. Thank you! I will answer all of your questions
    • The TWL is affected mostly by wind speed and wet bulb temperature. Therefore, if you have a worksite involving different working environments, e.g. mixed environments with basement, outdoor and upper floor levels, we suggest you should buy enough amounts of Scarlet TWL-1S to be placed in these different “hot spot” locations to fully cover your workers’ safety.
    • By default, the wireless paging system of the TWL-1s can reach as far as 200 meter to actively warn the safety officers in the field. You can quickly calculate the quantity of TWL-1s based on the range of wireless paging system.
  • Q3: Does TWL-1S come with warranty? What are included in the warranty?

    • 5-year warranty against manufacture defects and shipping damage.
    • 30 days trial period from the day of delivery: recalibration and test for free, but no refund.
    • No warranty for normal wear and tear, improper storage and maintenance, abuse and misuse.
  • Q4: Is there any third party certificate?

    A. ŸYes, It is available by order and with additional cost.
  • Q5: What are included in the recalibration and maintenance services?

    • Replacement: polypropylene (PP) filter, black ball, wind cup
    • Recalibration: Humidity sensor
    • Wind cup test & other trouble shooting
  • Q6: How often the humidity sensor should be recalibrated?

    Our recommendation: at least every 6 months with fair use (6 times a day under normal circumstances) or after long term storage. If the device is used for long term monitoring/ heavy use under very harsh environment (extremely hot, windy and sandy desert), the humidity sensor should be recalibrated more often.
  • Q7: How often should the polypropylene (PP) filter be changed? What would happen if the PP filter is clustered with dust and dirt?

    • Visual check: if the PP filter is covered with dust and dirt, it’s time to replace it.
    • When the PP filter is dirty, it will not affect the accuracy of the dry bulb and humidity reading, but it will take longer time to reach equilibrium. If it takes more than 20 min to reach steady state, the PP filter should be replaced.
  • Q8: Is there any recalibration certificate?

    A. Certificate of recalibration will be issued by Scarlet Tech when the device is recalibrated.