Arc-Flash Compliance Implementation at Industrial Processing Facilities
This paper highlights an assortment of case studies and explains how arc-flash hazards were identified, measured, and mitigated in various industrial processing facilities. Case studies reviewed include the following: (1) the completion of arc-flash studies and arc-flash remediation for a group of existing cement pyroprocessing plants in North America to achieve compliance with Electrical Workplace Standards National Fire Protection Association 70E-2012 and Canadian Standards Association Z462-2012 for a multisite cement manufacturer; (2) the implementation of an arc-flash analysis at an existing U.S.-based copper mine/copper concentrate facility; (3) the investigation of an arc-flash incident that occurred during energized work at a U.S. chemical processing facility; and (4) a “Safety by Design” installation for a new Greenfield coal preparation plant in Australia. This paper will examine the plans and processes reviewed and considered and the strategy deployed to manage/reduce arc-flash hazards and then discuss lessons learned in the implementation of new systems to improve electrical workplace safety.
The Journey of an Enterprise in a Process Industry Toward Improved Electrical Workplace Safety
This paper is a case study outlining the experience of a multisite cement producer and their experience in implementing an enterprisewide electrical workplace safety program, including compliance with the National Fire Protection Association 70E-2012 standard. Following a brief primer regarding arc-flash hazards, this paper outlines how the company first established a case for change and buy-in across the enterprise that includes 13 cement plants that are located across the USA and Canada, and then proceeds in describing the processes used to identify the defined work scope, select a supplier partner, and complete arc-flash studies at each site. The advantages of scale in areas, including common methods of data collection, selected software, standardized labels, site training, and energized work permits, are addressed. Finally, the lessons learned during this project and a phased remediation plan at each site, which was developed to reduce or eliminate potentially hazardous conditions, will be discussed. Finally, a few concepts based on “safety by design” will be explored, where there might be an opportunity to design the hazard out or down for new plant projects or expansion.
NMR characteristics of intracellular K in the rat salivary gland: a 39K NMR study using double-quantum filtering.
Intracellular K of the perfused rat mandibular salivary gland was measured by 39K NMR spectroscopy at 8.45 T. Multiple-quantum NMR arising from multiple-exponential decay was used to eliminate the resonance due to extracellular K in the perfused gland at 25 degrees C. The resonance due to intracellular K consisted of two Lorentzian signals stemming from the [spin 1/2 to -1/2] coherence (sharp resonance) and the [spin -1/2 to -3/2], [spin 3/2 to 1/2] coherences (broad resonance). The transverse relaxation time (T2) corresponding to the [spin 1/2 to -1/2] coherence was ca. 2.5 ms, and that corresponding to the [spin -1/2 to -3/2], [spin 3/2 to 1/2] coherences was ca. 0.4 ms. The relaxation time of the double-quantum coherence of rank 3 (originating from product operators like Ix2Iz) was determined to be ca. 0.2 ms. These results suggest the possibility of the presence of a single homogeneous population of intracellular K with a correlation time of ca. 2.5 x 10(-8) s and a quadrupolar coupling constant of ca. 1.4 MHz.