Containment (for Toxic Particulate Solids)
The enclosure of process and/or control of the environment in which it is carried out in order to prevent the contamination of people by the materials used or vice versa.
Containment Strategy
A generalized approach for limiting or eliminating exposure of personnel, products, or the environment to hazardous concentrations of substances.
Continuous Flame Test
A test in which a flame arrester is subjected to flame of a continuously burning mixture (as specified in UL 525 for deflagration or detonation flame arresters) on the outlet face of the arrester for one hour (or longer at the manufacturer's request).
Continuous Improvement
Doing better as a result of regular, consistent efforts rather than episodic or step-wise changes, producing tangible positive improvements either in performance, efficiency, or both. Continuous improvement efforts usually involve a formal evaluation of the status of an activity or management system, along with a comparison to an achievement goal. These evaluation and comparison activities occur much more frequently than formal audits.
Continuous Reactors
Reactors that are characterized by a continuous flow of reactants into and a continuous flow of products from the reaction system (e.g., Plug Flow Reactor (PFR) and the Continuous Stirred Tank Reactor (CSTR)).
Continuous Release
Emissions that are long in duration compared with the travel time (time for could to reach location of interest) or averaging or sampling time.
Continuous Stability Categorization Method
Based on the Monin-Obukhov length, L
Continuous Stirred Tank Reactor (CSTR)
A reaction vessel in which the feed is continuously added and the products continuously removed. The vessel (tank) is continuously stirred to maintain a uniform concentration within the vessel.
Continuous-Flow Stirred Tank Reactor (CSTR)
A reaction vessel in which the feed is continuously added and the products continuously removed. The vessel (tank) is continuously stirred to maintain a uniform concentration within the vessel.
Contractor management
A system of controls to ensure that contracted services support (1) safe facility operations and (2) the company's process safety and personal safety performance goals. It includes the selection, acquisition, use, and monitoring of contracted services.
Contributing Cause
Factors that facilitate the occurrence of an incident such as physical conditions and management practices. (Also known as contributory factors.)
Control
A mechanism used to regulate or guide the operation of a machine, apparatus, process, or system.
Controlled Document
Documents covered under a revision control process to ensure that up-to-date documents are available and out-of-date documents are removed from circulation.
Controls
Engineered mechanisms and administrative policies/
Convective scaling velocity, w
A scaling velocity important during light wind daytime conditions with strong surface heating. w* is proportional to the cube root of the product of the heat flux, Hs, and the mixing depth, zi.
Cool-flame ignition
A relatively slow, self-sustaining, barely luminous gas-phase reaction of the sample or its decomposition products with an oxidant. Cool flames are visible only in a darkened area. (NFPA 325 2001)
Core value
A value that has been promoted to an ethical imperative, accompanied with a strong individual and group intolerance for poor performance or violations of standards for activities that impact the core value.
Corona Discharge
A self-sustained low energy electrical discharge with non-thermal ionization that takes place in the vicinity of an electrode of sufficiently low radius of curvature, in a medium whose presence is typically close to atmospheric.
Corrective Maintenance
Maintenance performed to repair a detected fault.
Corrosive
A material that can attack and chemically destroy exposed body tissues, and can also damage or even destroy metal. They begin to cause damage as soon as they touch the skin, eyes, respiratory tract, digestive tract, or the metal. They might be hazardous in other ways too, depending on the particular corrosive material. (Some governmental agencies, e.g., the US DOT and EPA have specific definitions of corrosive based on rate of corrosion (DOT) or pH (EPA). Readers should check these definitions as applicable.)
Corrosivity
A complex series of reactions between water and metal surfaces and materials in which the water is stored or transported.
Cost
Includes tangible items such as money and equipment as well as the operational costs associated with the implementation of risk reduction options. There are also intangible costs such as loss of productivity, moral considerations, political embarrassment, and a variety of others. Costs may be borne by the individuals who are affected or the corporations they work for, or they may involve macroeconomic costs to society.
Cost avoidance
Return (often expressed in monetary terms) resulting from actions that prevent an incident from occurring.
Cost-Benefit Analysis
Part of the management decision-making process in which the costs and benefits of each risk reduction option are compared and the most appropriate alternative is selected.
Coulomb (C)
The quantity of electricity on the positive plate of a capacitor of 1 Farad capacitance when the potential difference across the plates is 1 V.
Coulomb's Law
Force between two charged bodies is proportional to the product of the two charges and inversely proportional to the square of the distance between them.
Countermeasure
An action taken or a physical capability provided whose principal purpose is to reduce or eliminate one or more vulnerabilities.
Coupling (for interference)
The mechanism by which an interference source produces interference in a signal circuit.
Covered Process
A process subject to regulatory requirements established under the OSHA PSM Standard or the EPA RMP Rule.
Covert Fault
Faults that can be classified as hidden, concealed, unannounced, undetected, unrevealed, latent, etc. In the case of safety instrumented systems covert faults impair the intended safeguarding function without being apparent to the operator. Covert faults can only be detected by testing or challenging the system.
Crimped Metal Ribbon
A flame arrester element that is manufactured of alternate layers of thin corrugated metal ribbon and a flat metal ribbon that are wound together on a mandrel to form a cylindrical assembly of many layers to produce a range of different sized triangular cells. The height and width of the triangular cells can be varied to provide the required quenching diameter.
Critical
Relates to major environment or safety process risks.
Critical Alarm
An alarm having no automatic safety backup system and requiring immediate action to be taken by an operator to return the plant to a safe status (e.g., atmospheric combustible or toxic gas detection).
Critical Diameter
See Quenching Diameter
Critical Effect
The first adverse effect, or its known precursor, that occurs as the dose rate (or concentration) increases.
Critical Equipment
Equipment, instrumentation, controls, or systems whose malfunction or failure would likely result in a catastrophic release of highly hazardous chemicals, or whose proper operation is required to mitigate the consequences of such release. (Examples are most safety systems, such as area LEL monitors, fire protection systems such as deluge or underground systems, and key operational equipment usually handling high pressures or large volumes.)
Critical Event
A critical event is an event with a specified, high consequence such as an event involving an offsite community impact, critical system damage, a severe injury or a fatality.
Critical Event Frequency
The frequency of occurrence of a critical event.
Critical Final Control Element
Final control element associated with an emergency shutdown system.
Critical Half Thickness
An estimation of the half thickness of a sample in an unstirred container, in which the heat losses to the environment are less than the retained heat. This buildup of internal temperature leads to a thermal runaway reaction. (ASTM E 1445)
Critical Infrastructure
Systems and assets, whether physical or virtual, so vital that the loss, interruption, incapacity, or destruction of which (1) would have a negative or debilitating effect on the security, economic security, public health, or safety of a nation, region, or any local government, or (2) cause national or regional catastrophic effects.
Critical Load
A final element whose operation has safety implications.
Critical Mass
Minimum mass that is required to enable the occurrence of an explosion.
Critical Operating Parameter
Process condition (e.g., flow rate, temperature) that can lead to an equipment failure if limits are exceeded.
Critical Process Measurement
A sensor whose operation has safety implications.
Critical Protection Circuit
Any circuit that contains critical protective devices and/or critical protective instrumentation.
Critical Protection Device
Any protection device whose installation and performance is required in order to meet or exceed the APCI hazard rate target for an in-plant occurrence or is required from analysis of third party exposure. Also, any device whose installation is required by appropriate code bodies or insurance agents in order to satisfy minimum safety requirements for life threatening hazards. The following are examples of critical protection devices: Safety Valves, Rupture Discs, Flame Arrestors, Burner Management Systems.
Critical Protection Instrumentation
Those instruments installed as part of a protection circuit whose installation and performance is required in order to meet or exceed the APCI target for in-plant hazards or is required from analysis of third party exposure.
Critical Temperature
Maximum cooling temperature at which all heat is generated by the mass of material can still be transferred to the coolant (either gas or liquid).
Cross-contamination
Mixing chemicals unintentionally, typically through the use of the same process equipment or support systems for concurrent or successive tolls.