Heat Shield: new firmware update in accordance with ISO 7243 (2017–08)

Heat Shield: new firmware update in accordance with ISO 7243 (2017–08)

ISO 7243 2017-08 edition describes the metodology to produce WBGT heat index calculations and to assess limits defined on the basis of the activity level and clothing of the subject under evaluation.

Most of the WBGT meters on the markets are made to produce WBGT values (with and without solar load calculations), but no one (apart from the LSI LASTEM Heat Shield monitor latest version)  produces in real time mode the WBGT Eff (which take in considration the CAV Clothing Adjustment Value) and, online, produces and displays the WBGT-Ref Delta (Delta To The Limit) value which corresponds to the distance between the WBGT Eff and its limit value (named WBGT Ref) given by the ISO 7243 standard for boths Acclimatized and Not Acclimatized subjects in function of their activity level.

What does the ISO 7243 2017-08 norm require?

  • ISO 7243 2017-08 edition describes how to assess the heat stress using the WBGT (Wet Bulb Globe Temperature) index calculation. This assessment is made starting from the measurement of some physical parameters and calculation of the WBGT index using two formulas: with and without solar load.
  • When the WBGT calculation has been produced, ISO 7243 asks to produce the WBGT Eff which is the WBGT value adjusted for the effect of clothing coverage using the Clothing Adjustment Value (CAV).
  • When the WBGT Eff calculation has been produced, ISO 7243 asks to produce the WBGT Ref which is the limit for two types of Subjects (Acclimatized and Not Acclimatized) according to their Metabolic rate categories of work.
  • ISO 7243 says that if WBGT Eff values are greater than WBGT Ref reference value, then further action is required
  • ACGIH renames the two WBGT Ref limits as TLV-Time Limit Value (limit for acclimatized subject) and AL-Action Limit (limit for non acclimatized subject). ACGIH suggests their own CAV values. Other ACGIH criterias remain the same as ISO 7243

What does the new Heat Shield provide?

  • WBGT index without solar load version OR WBGT index with solar load version – According to the selected formula
  • WBGT Eff –According to selected with solar Load or without solar load WBGT formula and selected Clothing Adjustent Value (CAV)
  • WBGT Ref for NOT Acclimatized subject (Action Limit by ACGIH) OR Acclimatized subject (TLV Time Limit Value by ACGIH) – According to selected Metabolism value and Subject type
  • Delta – Distance To The Limit (difference between WBGT Eff and WBGT Ref)
  • Heat Index
  • Humidex Index
  • PMV-PPD comfort index (needs Air speed value)
documents LSI Lastem

Technical Presentation


Greta Tresoldi

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