Measuring the Reliability of Safety Controls, Alarms, and Interlocks

PresentationThe risk analysis assumes a level of risk reduction provided by each of the safeguards, including safety controls, alarms, and interlocks (SCAI). After installation, SCAI equipment must be proven to meet the assumptions through examination of maintenance records. As SCAI equipment ages, failures can begin to occur more frequently where few have occurred before. Some equipment may need replacement just to sustain the risk reduction. An instrument reliability program is necessary to: • Provide feedback to validate risk analysis and functional specification assumptions • Identify and eliminate systematic failures • Provide prior use evidence (historical performance) for determining fit for purpose • Support selection of SCAI equipment • Ensure that poor performing equipment is identified and actions are taken to correct deficiencies In order for the risk analysis to not be overly optimistic or pessimistic, the data assumptions need to agree with the actual capability of the installed systems. This paper covers the essential elements of an instrument reliability program that can be applied to both process control and SCAI equipment. It will discuss the critical activities needed to identify and track failures, so negative trends in performance can be responded to prior to a loss event occurrence. A successful instrument reliability program leverages existing work processes to collect quality data that drives improvement in safety and reliability

A Practical Approach to Preventing Systematic Error in the Maintenance of Instrumented Safeguards

PresentationInstrumentation and electrical (I&E) maintenance is typically managed using site-wide policies, practices, and procedures. Since I&E equipment is part of the control system and nearly every other layer of protection, the cumulative impact of poor I&E performance can be a significant contributor to major events. Systemic problems in managing I&E equipment reliability lowers process safety performance across a site. Practical guidance is needed on how to assess the vulnerability of existing sites to instrumented safeguard failure due to maintenance deficits. This paper leverages Reason’s organizational accident model as a framework to discuss site-specific factors that impact a site’s susceptibility to maintenance error. A table of more than 60 human factors covering I&E maintenance activities was developed and organized by 4 elements of causality: organizational processes, workplace practices, personnel traits, and enabling conditions. The human factors table can be used to rate an industrial site on a negative-to-positive scale, highlighting those areas where systemic changes would likely improve maintenance performance and instrument reliability

Evolutionary Themes from ISA 84 to ISA 61511

PresentationANSI/ISA 84.00.01 was the second edition of ISA standard to address safety instrumented systems for the process industry sector and was recognized by OSHA as a good engineering practice within process safety management. Nevertheless, standards must evolve over time based on application experience. After a decade of international process sector experience in applying these requirements for safety instrumented systems (SIS), a new edition of the IEC 61511 international standard was published. Recently published, ANSI/ISA 61511-1 brings the ISA standard into complete alignment with IEC 61511-1. This paper will review ten major themes of change between ANSI/ISA 84.00.01 and ANSI/ISA 61511-1

What Do Economists Know About Crime?

In this paper we evaluate what economists have learned over the past 40 years about the determinants of crime. We base our evaluation on two kinds of evidence: an examination of aggregate data over long time periods and across countries, and a critical review of the literature. We argue that economists know little about the empirically relevant determinants of crime. Even hypotheses that find some support in U.S. data for recent decades are inconsistent with data over longer horizons or across countries. This conclusion applies both to policy variables like arrest rates or capital punishment and to less conventional factors such as abortion or gun laws. The hypothesis that drug prohibition generates violence, however, is generally consistent with the long times-series and cross-country facts. This analysis is also consistent with a broader perspective in which government policies that affect the nature and amount of dispute resolution play an important role in determining violence.

Efficacy of Compression Garments to Simulate Fluid Shifts during Lunar Bedrest

The effectiveness of JOBST(Registered TradeMark) compression stockings for fluid redistribution was examined in the lunar bed rest analog based on Digital Astronaut computer model predictions. NASA's future goals include missions to the moon which will require extended exposure to the lunar gravity environment. To prepare for these missions, physiological adaptations in various systems must be resolved. A bed rest at a 10 degree head-up tilt was used to simulate lunar gravity. Plasma volume (PV) loss may cause some of the cardiovascular adaptations which occur during space flight so PV is measured in the bed rest analog to evaluate fluid loss. PV varies from individual to individual so PV index (PVI) is used to determine the magnitude and time course of fluid shift and cardiovascular adaptation to 1/6 g. The Digital Astronaut, a computer simulation tool, predicts a 6% PV loss during an extended simulated lunar mission for a male with a body surface area of 1.95 m(exp 2). Simple geometry calculations suggest that 10 degree head-up tilt is most useful for simulated measurement of deconditioning in bone and muscle, however, 2 degree head-up tilt may best imitate cardiovascular fluid shifts. In order to reconcile these different models, compression stocking must be used in the 10 degree paradigm to better approximate expected cardiovascular changes

Nurses\u27 Alumnae Association Bulletin, May 1957

Alumnae Notes Committee Reports Digest of Alumnae Meetings Graduation Awards - 1956 Letter from Hong Kong Leukemia Marriages Necrology New Arrivals Physical Advances at Jefferson President\u27s Message School of Nursing Report Two Year Programs in Nursing White Haven Repor

Evidence Based Review: Risk of Cardiac Rhythm Problems During Spaceflight

Very little research has systematically evaluated the prevalence (or potential risk) of cardiac arrhythmias during space flight. There are several observational reports of non life-threatening but potentially concerning arrhythmias. At least two potential risk factors for arrhythmias have been reported either during or immediately after space flight: cardiac atrophy and a prolonged QTc interval. The potential severity of the mission impact of a serious arrhythmia requires that a systematic evaluation be conducted of the risk of arrhythmia due to space flight