Process measures

The behavioral safety process consists of two major components based on live core principles. Successful behavioral safety processes are true to these principles. The steering committee protects the integrity of these principles. 

Most of the remaining benefit of the behavioral safety process comes from improvements recommended or implemented by the steering committee based on its analyses of observation data and related information. 

Steering Committee Functions. The following tasks are necessary for the committee to ensure the integrity of the behavioral safety process. These tasks can be grouped into specific roles or can be divided among the committee members. Their completion needs to be monitored to ensure that the steering committee remains on track  

Sets the agenda, chairs meetings, tracks attendance, and organizes logistics (meeting location, materials, refreshments). 

Collects and provides observation checklists, data tables, and graphs also arranges for additional information if necessary for analysis. For example, this individual may interview observers to clarify comments on their observation forms or may visit work locations to observe tasks discussed on observation forms. 

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SPC on manufactured products SQC on laboratory operations communicate with corporate CIM system improved QA/QC on products reduced testing costs correlate laboratory analyses and process measurements faster solutions to production problems tested in laboratory faster notification of backlog problems improved electronic data interchange capabiUties automated communication with inventory, ordering, and materials planning systems... 

Scientific Apparatus Makers Association 1140 Coimecticut Avenue, NW Washington, D.C. 20036 Standards for analytical instmments, laboratory apparatus, measurement and test instmments, nuclear instmments, optical instmments, process measurement and control, and scientific laboratory furniture and equipment (see Analytical methods). 

B. G. Liptak, Instrument Engineers Handbook—Process Measurement and Analysis, 3rd ed., Chilton Book Co., Radnor, Pa., 1995, pp. 523—601. 

Fig. 7. Instmment components of a control loop, where A = process measurement devices, in this case, pressure measurement B = transducer ...

Process Measurements. The most commonly measured process variables are pressures, flows, levels, and temperatures (see Flow LffiASURELffiNT Liquid-levell asurel nt PressureLffiASURELffiNT Temperaturel asurel nt). When appropriate, other physical properties, chemical properties, and chemical compositions are also measured. The selection of the proper instmmentation for a particular appHcation is dependent on factors such as the type and nature of the fluid or soHd involved relevant process conditions rangeabiHty, accuracy, and repeatabiHty requited response time installed cost and maintainabiHty and reHabiHty. Various handbooks are available that can assist in selecting sensors (qv) for particular appHcations (14—16). 

The detailed analysis, involving many respondents inside and outside the company, led to changes in the overall innovation process, ie, a company-wide priority system for innovation projects, measures of innovation for each functional and business area, training and supportive management systems for project managers, informal multifunctional teams in concept development and market development, a stmctured needs identification process, and appointment of a process steward to monitor the innovation process, measure how it functions, and coordinate innovation projects. 

Thomas F. Edgar/ Ph D / Professor of Chemical Engineering, University of Texas, Austin, TX. Advanced Control Systems, Process Measurements, Section Editor)... 

An open-loop system positions the manipulated variable either manually or on a programmed basis, without using any process measurements. This operation is acceptable for well-defined processes without disturbances. An automanual transfer switch is provided to allow manual adjustment of the manipulated variable in case the process or the control system is not performing satisfac torily. 

There are two basic types of unconstrained optimization algorithms (I) those reqmring function derivatives and (2) those that do not. The nonderivative methods are of interest in optimization applications because these methods can be readily adapted to the case in which experiments are carried out directly on the process. In such cases, an ac tual process measurement (such as yield) can be the objec tive function, and no mathematical model for the process is required. Methods that do not reqmre derivatives are called direc t methods and include sequential simplex (Nelder-Meade) and Powell s method. The sequential simplex method is quite satisfac tory for optimization with two or three independent variables, is simple to understand, and is fairly easy to execute. Powell s method is more efficient than the simplex method and is based on the concept of conjugate search directions. 

An expert system is a computer program that uses an experts knowledge in a particular domain to solve a narrowly focused, complex problem. An off-line system uses information entered manually and produces results in visual form to guide the user in solving the problem at hand. An on-line system uses information taken direc tly from process measurements to perform tasks automatically or instruct or alert operating personnel to the status of the plant. 

Process measurements encompass the apphcation of the principles of metrology to the process in question. The objective is to obtain values for the current conditions within the process and make this information available in a form usable by either the control system, process operators, or any other entity that needs to know The term measured variable or process variable designates the process condition that is being determined. 

Accuracy and Repeatability Definitions of terminology pertaining to process measurements can be obtained from standard S5I.I from the International Society of Measurment and Control (ISA) and standard RC20-II from the Scientific Apparatus Manufac turers Association (SAMA), both of which are updated periodically. An appreciation of accuracy and repeatability is especially important. Some apphcations depend on the accuracy of the instrument, but other apphcations depend on repeatability. Excellent accuracy imphes excellent repeatabihty however, an instrument can have poor accuracy but excellent repeatability. In some apphcations, this is acceptable, as discussed below. 

For process measurements, accuracy as a percent of span is the most common. 

Dynamics of Process Measurements Especially where the measurement device is incorporated into a closed loop control configuration, dynamics are important. The dynamic characteristics depend on the nature of the measurement device, and also on the nature of components associated with the measurement device (for example, thermowells and sample conditioning equipment). The term mea-.sui ement system designates the measurement device and its associated components. 

Fluid-filled bulbs dehver enough power to drive controller mechanisms and even directly actuate control valves. These devices are characterized by large thermal capacity, which sometimes leads to slow response, particularly when they are enclosed in a thermal well for process measurements. Filled-system thermometers are used extensively in industrial processes for a number of reasons. The simplicity... 

Specific-Ion Electrodes In addition to the pH glass electrode specific for hydrogen ions, a number of electrodes that are selective for the measurement of other ions have been developed. This selectivity is obtained through the composition of the electrode membrane (glass, polymer, or liquid-liquid) and the composition of the elec trode. Tbese electrodes are subject to interference from other ions, and the response is a function of the total ionic strength of the solution. However, electrodes have been designed to be highly selective for specific ions, and when properly used, these provide valuable process measurements. 

Also, the electronic control-valve device s level of immunity to, and emission of, electromagnetic interference (EMI) can be an issue in the chemical-valve environment. EMI requirements for the control-valve devices are presently mandatory in the European Community but voluntary in the United States, Japan, and the rest of the world. International Electrotechnical Commission (lEC) SOI, Parts I through 4, Electromagnetic Compatibihty for Industrial Process Measurement and Control Equipment, defines tests and requirements for control-device immunity. Immunity and emission standards are addressed in CENELEC (European Committee for Electrotechnical Standardization) EN 50 081-1 1992, EN 50 081-2 1993, EN 50 082-1 1992, and prEN 50 082-2 1994. 

Romagnoli, J.A. and G. Stephanopoulos, Rectification of Process Measurement Data in the Presence of Gross Errors, Chemical Engineeiing Science, 36(11), 1981, 1849-186.3. 

ISA S71.04. 1986. Environmental Conditions for Process Measurement and Control Systems Airborne Contaminants. Instrument Society of America, Research Triangle Park, N.C. 

Liptak, B. G. 1982. Instrument Engineers Handbook Process Measurement. Chilton Company, Radnor, PA. 

The assessor should also find out whether an effective testing program is in place to help ensure the serviceability of process measurement equipment. The successful toller should have an established calibration program to address the accuracy of critical measurement equipment. Safety critical process parameters should be monitored and critical process equipment should automatically interlock when monitoring instrumentation detects safety critical deviations. Interlocks should either facilitate a remedy to the critical deviation or bring the process to the zero energy state. These instruments and interlocking devices should be routinely tested to ensure operational reliability. 

The structure/property relationships in materials subjected to shock-wave deformation is physically very difficult to conduct and complex to interpret due to the dynamic nature of the shock process and the very short time of the test. Due to these imposed constraints, most real-time shock-process measurements are limited to studying the interactions of the transmitted waves arrival at the free surface. To augment these in situ wave-profile measurements, shock-recovery techniques were developed in the late 1950s to assess experimentally the residual effects of shock-wave compression on materials. The object of soft-recovery experiments is to examine the terminal structure/property relationships of a material that has been subjected to a known uniaxial shock history, then returned to an ambient pressure... 

Describe the nature of the process measured by each of these rate constants, and devise a mechanism which includes each of these processes. Rationalize the order of the rates > ex > K-... 

Comparing the results for (a) and (b), we see that pressure has a considerable effect on the result. This is important to remember, especially in industrial ventilation and process measurements with notable underpressures and overpressures. 

It is important to emphasize that, especially in process measurements, radiation can have an essential influence on the wet bulb temperature, and therefore generally the wet bulb temperature is dependent on the mea,surement device and the method of measurement. If the airflow is very low, the radiation can have a remarkable contribution in addition to the convective heat transfer. Basically, an equation analogous to Eq. (4.138) can be empirically determined for each wet bulb temperature and method of measurement. 

Environmental Condition for Process Measurement and Control Systems Temperature and Humidity Electrical Instruments in Hazardous Locations, Ernest C. Magison, 1978... 

Better measurement of performance. A common frustration in PSM and ESH is that end-of-pipe measurement is all that is available and it is too late to correct a problem once the incident has occurred. Quality Management requires that we seek out in-process measures and leading indicators of performance that will warn of potential problems before they exhibit themselves as incidents. 

Measurement of performance. Quality Management requires that measures of performance be established for every activity. These measures include end-of-pipe measurement, such as amounts of material released into the environment or injury rates, and in-process measures of how efficiently you are managing, such as time to review safety improvement proposals or total resources expended on PSM. Each team should be required to identify potential performance measures for the processes they are developing and the activities these processes manage. Many of the end-of-pipe measures will already exist these should be critically examined to ensure that they truly measure performance and are not unduly influenced by other factors. For example, the number of accidents in a fleet of road vehicles is almost directly dependent on the number of miles driven with no improvement in performance, a reduction in miles driven would reduce the number of accidents. 

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