MSHA and NIOSH agree that action is needed to assure the safety and health of miners, and that the SR-100 SCSR must be phased out of use in a timely and orderly manner. In addition, NIOSH has determined that the manual start procedure for the SR-100 should only be used as a last resort. The manufacturer’s manual start procedure (a.k.a. the Cold Start procedure), is more difficult to activate and it may take more time for the SR- 100 SCSR to generate sufficient oxygen to allow for a rapid escape. MSHA wants to assure that miners are trained to know what to do if they have a problem starting their SR-100 SCSR.

http://www.msha.gov/regs/complian/PIB/2012/pib12-09.asp