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Operating Procedures
Written, step by step instructions and information necessary to operate equipment, compiled in one document including operating instructions, process descriptions, operating limits, chemical hazards, and safety equipment requirements.
Operating Window
The parameters (i.e., safe upper and lower limits, run time) under which equipment can function without failure.
Operational Discipline (OD)
The performance of all tasks correctly every time.
Individuals demonstrate their commitment to process safety through OD, executing the organization's Conduct of Operation (COO) RBPS Element each and every day.
Operational Interruption
An event in which production rates or product quality is seriously impacted.
Operational Readiness
CCPS RBPS Element 14: This Element verifies during commissioning that new, changed, or maintained equipment and processes are in a safe condition and are ready to start-up and use.
Operational Readiness
A PSM program element associated with efforts to ensure that a process is ready for start-up/restart. This element applies to a variety of restart situations, ranging from restart after a brief maintenance outage to restart of a process that has been mothballed for several years.
Operator
An individual responsible for monitoring, controlling, and performing tasks as necessary to accomplish the productive activities of a system. Operator is also used in a generic sense to include people who perform a wide range of tasks (e.g., readings, calibration, incidental maintenance, manage loading/unloading, and storage of hazardous materials).
Optimum Mixture
A specific mixture of fuel and oxidant that yields the most rapid combustion at a specific measured quantity or that yields the lowest value of the minimum ignition energy or that produces the maximum deflagration pressure. The optimum mixture is not always the same for each combustion property that is measured.
Organic Peroxide
Any organic compound having a double oxygen or peroxy (O-O) group in its chemical structure. (NFPA 43B)
Organic Peroxide Formulation
A pure organic peroxide or a mixture of one or more organic peroxides with one or more other materials in various combinations and concentrations. Organic Peroxide Formulations can be further classified as follows; Class I - Those formulations that are capable of deflagration but not detonation, Class II - Those formulations that burn very rapidly and that present a severe reactivity hazard, Class III - Those formulations that burn very rapidly and that present a moderate reactivity hazard, Class IV - Those formulations that burn in the same manner as ordinary combustibles and that present a minimal reactivity hazard, and Class V - Those formulations that burn with less intensity than ordinary combustibles or do not sustain combustion and that present no reactivity hazard. (NFPA 43B)
Organizational Culture
The common set of values, behaviors, and norms at all levels in a facility or in the wider organization that affect the operation of the facility.
Organizational Error
A latent management system problem that can result in human error.
Overdriven Detonation
The unstable condition that exists during a deflagration-to-detonation transition (DDT) before a state of stable detonation is reached. Transition occurs over the length of a few pipe diameters and propagation velocities of up to 2000 m/s have been measured for hydrocarbons in air. This is greater than the speed of sound as measured at the flame front. Overdriven detonations are typically accompanied by side-on pressure ratios (at the pipe wall) in the range 50-100. A severe test for detonation flame arresters is to adjust the run-up distance so the DDT occurs at the flame arrester, subjecting the device to the overdriven detonation impulse.
Overpressure
Any pressure above atmospheric caused by a blast.
Override
A control action which overrides the normal control action to prevent exceeding a process limit. Overrides normally are part of the POCS rather than the ESD. To manually or otherwise deliberately overrule an automatic control system or circuit and thereby render it ineffective. To cancel the influence of an automatic control by means of a manual control.
Oxidant
Any gaseous material that can react with a fuel (either gas, dust, or mist) to produce combustion. Oxygen in air is the most common oxidant.
Oxidant Concentration Reduction
The technique of maintaining the concentration of the oxidant in a closed space below the concentration required for combustion to occur. This is commonly called inerting.
Oxidation
Depending on the context, oxidation can either refer to; a) a reaction in which oxygen combines chemically with another substance, or b) any reaction in which electrons are transferred. For the latter definition, oxidation and reduction always occur simultaneously (redox reactions), and the substance that gains electrons is termed the oxidizing agent. Electrons might also be displaced within a molecule without being completely transferred away from it.
Oxidizer
Any material that readily yields oxygen or other oxidizing gas, or that readily reacts to promote or initiate combustion of combustible materials. Examples of other oxidizing gases include Bromine, Chlorine, and Fluorine. Oxidizers can be further classified as follows; Class 1 - An oxidizer whose primary hazard is that it slightly increases the burning rate but does not cause spontaneous ignition when it comes in contact with combustible materials, Class 2 - An oxidizer that will cause a moderate increase in the burning rate or that causes spontaneous ignition of combustible materials with which it comes in contact, Class 3 - An oxidizer that will cause a severe increase in the burning rate of combustible materials with which it comes in contact or that will undergo vigorous self-sustained decomposition due to contamination or exposure to heat, Class 4 - An oxidizer that can undergo an explosive reaction due to contamination or exposure to thermal or physical shock. In addition, the oxidizer will enhance the burning rate and may cause spontaneous ignition of combustibles. (NFPA 430)
Oxidizing Agent
A chemical or substance which brings about an oxidation reaction. The agent may (1) provide the oxygen to the substance being oxidized (in which case the agent has to be oxygen, or contain oxygen), or (2) it may receive electrons being transferred from the substance undergoing oxidation. DOT defines an oxidizer or oxidizing material as a substance which yields oxygen readily to stimulate combustion (oxidation) or organic matter. Importance: If a substance is listed as an oxidizer on the MSDS, precautions must be taken in the handling and storage of the substance. Keep away from flammables and combustibles.
Oxidizing Gas (NFPA 55)
A gas that can support and accelerate combustion of other materials.
Oxygen
The oxidizer; sufficient oxygen must be present in the atmosphere surrounding the fuel for fire to burn.
Partial Volume Deflagration (PVD)
A deflagration explosion developed from a flammable cloud of gas, aerosol, or dust that occupies only part of the volume in a confined space.
Particulate Material
Any solid material composed of distinct particles or pieces, regardless of size, shape, or chemical composition. Particulate materials include dusts, fibers, fines, chips, chunks, flakes, or mixtures of these.
Passive Dispersion
Dispersion caused by the normal turbulence in the atmosphere. See Gaussian model.
Passive Equipment
Hardware that is not physically actuated in order to perform its function, such as secondary containment, a blast wall, piping, and storage tanks.
Passive Gas
A gas whose density is equal to that of the ambient air. Synonymous with neutral.
Passive System
A system in which failures are only revealed by testing or when a demand has occurred.
Performance
A measure of the quality or utility of PSM program work products and work activities.
Performance Assurance
A formal management system that requires workers to demonstrate that they understand a training module and can apply the training in practical situations. Performance assurance is normally an ongoing process to; 1) ensure that workers meet performance standards and maintain proficiency throughout their tenure in a position and 2) help identify tasks for which additional training is required.
Performance Indicators
See Metrics.
Performance Measure
A metric used to monitor or evaluate the operation of a program activity or management system.
Performance-Based Requirement
A requirement that defines necessary results without defining the specific means to accomplish them, the "what to do," but not "how to do it." The means for producing the desired results is left up to the discretion of the facility based on an evaluation of its needs and conditions, and on industry practices. For example, the requirement to implement a MOC system that considers the impact of safety and health as part of the review/approval process, and to prevent changes that pose an unacceptable risk to workers, is a performance-based requirement. The implementer must define the process to identify and review risk associated with changes, determine what level of risk is tolerable, and evaluate the risk in sufficient detail to demonstrate that they have met a level of acceptable practice, which in this case may be to provide a safe work environment. (See also Prescriptive requirement, which differs from a performance-based requirement in that a prescriptive requirement states how the activity should be performed.)
Permanent Building
Rigid structures intended for permanent use in fixed locations.
Permissible Exposure Limit (PEL)
An exposure established by OSHA regulatory authority. May be a Time Weighted Average (TWA) limit or a maximum concentration exposure limit. See also, "Skin". Importance: If a PEL is exceeded, a potential health hazard exists, and corrective action is necessary.
Permissible Exposure Limit (PEL)
The maximum permissible exposure limit for systemic workplace 8-hour time-weighted average exposures as established by OSHA
Permissive
An action required before a subsequent action can take place.
Personal Protective Equipment (PPE)
Equipment designed to protect employees from serious workplace injuries or illnesses resulting from contact with chemical, radiological, physical, electrical, mechanical, or other workplace hazards. Besides face shields, safety glasses, hard hats, and safety shoes, PPE includes a variety of devices and garments, such as goggles, coveralls, gloves, vests, earplugs, and respirators.
Physical Explosion
The catastrophic rupture of a pressurized gas/vapor-filled vessel by means other than reaction, or the sudden phase-change from liquid to vapor of a superheated liquid.
Physical Hazard
A chemical for which there is scientifically valid evidence that it is a combustible liquid, a compressed gas, explosive, flammable, an organic peroxide, an oxidizer, pyrophoric, unstable (reactive) or water reactive.
Physical Models
Models that provide quantitative information on source rates and extent of damage (thermal radiation, explosion overpressure, or concentration of dispersing vapor clouds).
Pillar
See Accident prevention pillar.
Piping and Instrumentation Diagram (P&ID)
A diagram that shows the details about the piping, vessels, and instrumentation.
Plosive Density
A chemical group contribution method for predicting the chemical instability explosion potential of a material.
Plume
A visible or measurable discharge of a contaminant from a given point of origin that can be measured according to the Ringelmann scale.
Plume Rise
Rise of plume in elevation above source due to buoyancy or momentum.
Poison, Class A
A DOT term for extremely dangerous poisons, that is, poisonous gases or liquids of such nature that a very small amount of the gas or vapor of the liquid, mixed with air is dangerous to life. Some examples: phosgene, cyanogen, hydrocyanic acid, nitrogen peroxide.
Poison, Class B
A DOT term for liquid, solid, paste, or semisolid substances-other than Class A poisons or irritating materials-which are known (or presumed on the basis of animal tests) to be so toxic to man as to afford a hazard to health during transportation. Importance: If a substance is known to be a poison, health and safety hazards exist and special protection and precaution sections should be checked on the MSDS.
Polymerization
A chemical reaction in which one or more small molecules combine to form larger molecules. A hazardous polymerization is such a reaction which takes place at a rate which releases large amount of energy.
Pool Fire
The combustion of material evaporating from a layer of liquid at the base of the fire.