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VOSI - Slip and Fall Standard V41.23D

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VOSI RESEARCH REPORT - RR 1, V41.23D: Humidity Correction Factors: Leather & Monarch EVA

V41.23D: Humidity Correction Factors: Leather & Monarch EVA


  1. VOSI V41.21 "Universal Specification/Test Method for Slip Resistant Walkways, in the Field & Laboratory, as Measured by a Drag Type Friction Tester" (www.voicesofsafety.com)
  2. Meserlian Report to Hank Boyles, "Humidity Tests on Leather" 7/14/91
  3. Marietta, William. Doctoral Thesis Figs. 12. 13, 17 & 29.Humidity Effects on Leather & Neolite; Wet Tests of HPS, Mark II& Ergodyne (English XL) Ref ASTM F609 (HPS), F 1677 (Mark II), F 1679 (English XL)

Figs. l & 2 show the results of humidity tests by the writer from 7/4 to 7/10/99 for a leather sensor on the Primary Standard Polypropylene Leather Test Surface And 7/12 & 7/13/99 for Monarch EVA sensors. Each set of sensors were mounted on separate Technical Products Model 80 Floor & Footwear Testers (Ref. 1).

The Ref. 2 humidity test results for leather are shown on Fig. 1. The need for using Ref. 1, which "standardizes" the leather and Monarch EVA sensors, is seen in the uncorrected SCOF's of approximately 0.36 and 0.25 at 50% relative humidity (RH) in 1991 and 1999 respectively.

Manufacturers test walkway materials at 50 +/- 5% RH and 73 +/- 3 F in a laboratory environment per ASTM D2047 (polishes) and D 1894 (plastic films). People slip and fall both within buildings having temperature and humidity conditions similar to a laboratory or outdoors where the air temperature and humidity is uncontrolled.

The following humidity correction factors should be used to correct non-laboratory humidity conditions to the 50% average laboratory environment in order that on site outdoor tests may be compared to labs who use Ref. 1.

Ref. 3, Figs. 12 & 13 show the variation of SCOF with "Low", "Medium" and "High" humidity for leather and Neolite sensors on a "polished floor". The Fig. 29 wet test of Neolite on "Polished" "Unpolished" and "Textured" floor surfaces prove that the HPS measures static COF whereas the Mark II and English XL, whose sensors are moving when they strike the floor, measure the dynamic SCOF; the HPS measures approximately 0.70 SCOF, whereas the Mark II and English XL measure 0.05 for Neolite on a polished surface.

Note: SCOF testing of leather on High-Density Polyethylene plastic lubber, from 10 to 100FOe resulted in a constant SCOF therefore a temperature correction factor is not required.

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Created: 1999-07-18