A viscosity correction factor for shear-thinning liquid flows in safety valves

At the moment there is lack in the existing standards of a sizing procedure for media of more complex rheological behavior than Newtonian. A formulation for the generalized Reynolds number to calculate the viscosity correction factor and size safety valves for the flows of shear-thinning media is proposed in this work. The various formulations in the literature are validated in their accuracy of estimation of the mass flow rates of aqueous solutions of polyvinylpyrrolidone. Among them the generalized Reynolds number defined using the wall viscosity of the annulus between the seat and the disk gives the highest accuracy without overestimating the measured mass flow rates. On the base of these results this generalized Reynolds number is recommended for introduction in the next review of both ISO 4126-1 Part 1 and API 520 for the sizing of safety valves for shear-thinning media.     

Epidemiology of occupational acute traumatic hand injuries: a literature review

The purpose of this review was to summarize the literature on occupational, acute, traumatic hand injury and suggest directions for future research. In 1996, the leading occupational injury treated in United States' hospital emergency departments was an acute hand injury (e.g. laceration, crush or fracture). These injuries affected 30% of an estimated 3.3 million injured workers (990,000). Cuts and lacerations of the fingers ranked third after back and leg strains in the number of lost workday cases in the USA in 1994. The incidence rate of hand injuries studied in seven manufacturing environments around the world ranged from 4 to 11 per 100 workers per year. Workers aged 24 years or less had the highest risk of hand injury. Men had higher rates of severe hand injury than women.Despite the high frequency and significant amount of lost work time associated with these injuries, they are poorly understood from an etiological perspective. There is only one case-control study of occupational hand injury in the literature. That study suggested an important role for both fixed (age) and transient risk factors (doing an unusual task) at the time of the injury. More analytic epidemiological research is needed to identify potentially modifiable risk or protective factors (e.g. glove use) for acute hand injuries. In this regard, the case-crossover design, a relatively new epidemiological approach using cases as their own controls, could prove an efficient method for determining transient, modifiable risk factors for acute, occupational hand injury.     

Leading and lagging: Process safety climate–incident relationships at one year

In order to evaluate the leading and lagging effects of process safety climate on incidents, we correlated safety climate survey data with organizational safety records from before and after the survey time period. We obtained data from a large, multinational organization with manufacturing operations involving a number of complex processes, chemicals, and hazardous substances. A total of 7728 employees from 62 sites responded to a safety climate survey in 2007. Individual responses were aggregated to the site-level and matched to site-level organizational records of process safety incidents 1 year before and 1 year after survey administration. Employees’ perceptions of good routine housekeeping were significantly related to environmental impact incidents as both a leading and a lagging indicator, as well as fires/explosions and property damage outcomes. Employees’ perceptions of systems to prevent backlogs and the extent to which health and safety problems are promptly corrected were also related to environmental releases and fires/explosions. Implications for process safety climate research, organizational survey strategies, and organizational climate change are discussed.     

Twenty-five years of HAZOPs

The HAZOP or hazard and operability study was developed by ICI over 25 years ago and is in wide use today throughout the world. The technique is intended to review, in a formalized manner, the design of a system such as a chemical process production plant to detect potential problems in the operation of the system. The system has been extended for use on all types of production, storage and distribution units. Experience in the use of hazard studies has lead to the development of a phased approach with three distinct design phases.     

Safety climate factors, group differences and safety behaviour in road construction

This study determines the factor structure of safety climate within a road construction organization using a modified version of the safety climate questionnaire (SCQ). It also investigates the relationship between safety climate and safety performance. The SCQ was administered to 192 employees from two districts and in two job categories — construction and maintenance. A behavioural observation measure of safety performance was also developed. Factor analysis derived six factors, which were similar to those obtained in an earlier study using the SCQ. Differences in the safety climate of job sub-groups were found on two of the factors. No differences between the two districts were found. No relationship was found between safety climate and the safety performance measure. While identical safety climate factors cannot apply to all organizations, some general safety climate factors may emerge. Discussion focuses upon the measurement of safety climate.     

Common operations failure modes in the process industries

The Abnormal Situation Management^® (ASM^®) Consortium (This research study was sponsored by the Abnormal Situation Management (ASM) Consortium. ASM^® and Abnormal Situation Management^® are registered trademarks of Honeywell International, Inc.) funded a study to investigate common failure modes and root causes associated with operations practices. The study team analyzed 20 public and 12 private incident reports using the TapRoot^® methodology to identify root causes. These root causes were mapped to operations practice failures. This paper describes the top ten operations failure modes identified in the analysis. Specific recommendations include how to analyze plant incident reports to better understand the sources of systemic failures and improve plant operating practices.     

The effect of precrash velocity reduction on occupant response using a human body finite element model

Objective: The objective of this study is to use a validated finite element model of the human body and a certified model of an anthropomorphic test dummy (ATD) to evaluate the effect of simulated precrash braking on driver kinematics, restraint loads, body loads, and computed injury criteria in 4 commonly injured body regions.

Methods: The Global Human Body Models Consortium (GHBMC) 50th percentile male occupant (M50-O) and the Humanetics Hybrid III 50th percentile models were gravity settled in the driver position of a generic interior equipped with an advanced 3-point belt and driver airbag. Fifteen simulations per model (30 total) were conducted, including 4 scenarios at 3 severity levels: median, severe, and the U.S. New Car Assessment Program (U.S.-NCAP) and 3 extra per model with high-intensity braking. The 4 scenarios were no precollision system (no PCS), forward collision warning (FCW), FCW with prebraking assist (FCW+PBA), and FCW and PBA with autonomous precrash braking (FCW + PBA + PB). The baseline ΔV was 17, 34, and 56.4 kph for median, severe, and U.S.-NCAP scenarios, respectively, and were based on crash reconstructions from NASS/CDS. Pulses were then developed based on the assumed precrash systems equipped. Restraint properties and the generic pulse used were based on literature.

Results: In median crash severity cases, little to no risk (<10% risk for Abbreviated injury Scale [AIS] 3+) was found for all injury measures for both models. In the severe set of cases, little to no risk for AIS 3+ injury was also found for all injury measures. In NCAP cases, highest risk was typically found with No PCS and lowest with FCW + PBA + PB. In the higher intensity braking cases (1.0–1.4 g), head injury criterion (HIC), brain injury criterion (BrIC), and chest deflection injury measures increased with increased braking intensity. All other measures for these cases tended to decrease. The ATD also predicted and trended similar to the human body models predictions for both the median, severe, and NCAP cases. Forward excursion for both models decreased across median, severe, and NCAP cases and diverged from each other in cases above 1.0 g of braking intensity.

Conclusions: The addition of precrash systems simulated through reduced precrash speeds caused reductions in some injury criteria, whereas others (chest deflection, HIC, and BrIC) increased due to a modified occupant position. The human model and ATD models trended similarly in nearly all cases with greater risk indicated in the human model. These results suggest the need for integrated safety systems that have restraints that optimize the occupant's position during precrash braking and prior to impact.     

The nature and structure of workers' trust in management

This paper presents a theoretical and empirical analysis of the nature of trust at work. Use is made of the facet approach to generate a definitional framework of trust, and this is proposed as a theoretical basis for the analysis of the structural characteristics of trust. Hypotheses regarding the relations between the definitional framework and empirical observations were tested by applying Smallest Space Analysis to analyse data collected from a sample of 398 colliery workmen, using questionnaires developed on the basis of the faceted definition. The results demonstrate strong support for the definitional framework suggested for the concept of trust and its construct validity. The results also suggest a possible distinction workers make between trust and mistrust and, between the specifics of activities to do with the job itself versus managers in general. © 1997 John Wiley & Sons, Ltd.     

Alcohol ignition interlock programs

The alcohol ignition interlock is an in-vehicle DWI control device that prevents a car from starting until the operator provides a breath alcohol concentration (BAC) test below a set level, usually .02% (20 mg/dl) to .04% (40 mg/dl). The first interlock program was begun as a pilot test in California 18 years ago; today all but a few US states, and Canadian provinces have interlock enabling legislation. Sweden has recently implemented a nationwide interlock program. Other nations of the European Union and as well as several Australian states are testing it on a small scale or through pilot research. This article describes the interlock device and reviews the development and current status of interlock programs including their public safety benefit and the public practice impediments to more widespread adoption of these DWI control devices. Included in this review are (1) a discussion of the technological breakthroughs and certification standards that gave rise to the design features of equipment that is in widespread use today; (2) a commentary on the growing level of adoption of interlocks by governments despite the judicial and legislative practices that prevent more widespread use of them; (3) a brief overview of the extant literature documenting a high degree of interlock efficacy while installed, and the rapid loss of their preventative effect on repeat DWI once they are removed from the vehicles; (4) a discussion of the representativeness of subjects in the current research studies; (5) a discussion of research innovations, including motivational intervention efforts that may extend the controlling effect of the interlock, and data mining research that has uncovered ways to use the stored interlock data record of BAC tests in order to predict high risk drivers; and (6) a discussion of communication barriers and conceptual rigidities that may be preventing the alcohol ignition interlock from taking a more prominent role in the arsenal of tools used to control DWI. Whether interlock programs can help public policymakers achieve their expressed goals of substantially reducing the level of impaired driving will remain uncertain until procedural barriers and intransigent judiciary practices can be overcome that provide for more systematic routine use of interlock programs. Despite strong effectiveness evidence in all studies to date, the real potential of this technology to reduce the road toll cannot be estimated until they are more widely adopted.