STEL 12 : Short-Term Exposure Limit. Maximum concentration for a continuous 15-minute exposure period. (Maximum of four such periods per day, 60 minutes minimum between exposure periods, and the daily TLV-TWA must not be exceeded)
Grainger, Inc. (Maintenance, Repair and Operating MRO), Glossary of Safety Terms, IL, USA 2012. www.grainger.com/images/GlossaryofSafetyTermsPDF.p df, (IndS/Maint, Repr and Opr - Amer) {79}