Part 4 contains provisions that apply to all occupancies, but also contains specific provisions that would apply only to some occupancies.
Although not specifically stated in the scope of the Article, the following provisions in this Part are general requirements that apply to any occupancy to which Part 4 applies, except as specifically provided elsewhere in this Part:
The following provisions in this Part contain specific exemptions from some of the general requirements referred to above:
Throughout Part 4 there are references to the general requirements which would apply whether or not they are specifically referenced. This is intended to assist the user and does not mean that the general requirements do not apply if they are not specifically referenced. Some of the locations where this type of reference occurs are:
| 4.1.5.1. 4.2.6.5. 4.2.7.6. 4.2.7.10. 4.2.7.13. 4.2.8.7. 4.2.9.3. 4.2.9.7. 4.3.12.7.(1)(b) & (c) |
4.3.13.1.(1)(d) 4.3.13.4.(2) 4.4.9.3. 4.6.3.3. 4.6.4.5.(3) 4.8.3.4. 4.12.6.1. 4.12.8.1.(1) |
This part of the Fire Code applies to the storage, handling, processing and use of flammable and combustible liquids having flash points below 93.3oC. This part also applies to liquids that have a flash point above 93.3oC when processed, stored, handled or used at temperatures above their flash points.
Where a liquid is heated during, for example, processing, its vapour pressure (i.e. volatility) will be increased. Heated liquids should be classified according to their operating temperatures. Article 4.1.2.2. specifies that "when a liquid having a flash point at or above 37.8 oC, is being processed, stored, handled or used at a temperature at or above its flash point, it shall be treated as a Class I liquid." (i.e. flammable liquid)
A flammable liquid is defined as any liquid with a flash point less than 37.8oC. A combustible liquid is defined as any liquid that has a flash point equal to or greater than 37.8oC and below 93.3oC.
For fire protection purposes, a division between liquids and gases has been established. Liquids are those fluids with vapour pressures not exceeding 275.8 kPa at 37.8oC. Examples of liquids having vapour pressures exceeding 275.8 kPa at 37.8oC that are not within the scope of Part 4 include liquefied petroleum gas, liquefied natural gas and liquid hydrogen. Butane, on the other hand, has a vapour pressure of 254.55 kPa at 37.8oC, and is classified as a flammable liquid.
Another division has been established in the Fire Code between liquids and solids. NFPA defines a liquid as a material having a fluidity greater than that of 300 penetration asphalt. This definition was selected to include materials that could spread or flow on a hot day. Buildings, structures and open areas includes areas such as tank farms, bulk plants, fuel dispensing stations, industrial plants, refineries, process plants, distilleries, and piers, wharves and airports that are not subject to federal legislation. Specific exemptions from the Ontario Fire Code are provided in Article 4.1.1.2.
Except for certain exemptions outlined below, the owner of an existing location where flammable and/or combustible liquids are stored, handled or used, must comply with the requirements contained in Part 4 within the specified compliance periods. Flexibility in achieving the objectives set out in Part 4 is provided by permitting a "compliance equivalency" which has been approved by the Chief Fire Official (see compliance equivalency below) and, in the case of process plants, using good engineering design to recognized standards. Additional information regarding the case of process plants may be found in the Appendix to the National Fire Code which states:
"Certain areas in refineries, chemical plants and distilleries may not meet all Code requirements because of extraordinary conditions. Design should be based on good engineering practice and on such factors as manual fire suppression equipment, daily inspections, automated transfer systems, location of processing units, and special diking, piping, controls and materials. NFPA 30, "Flammable and Combustible Liquids Code" and NFPA 36, "Solvent Extraction Plants" are examples of good engineering practice..."
In addition to NFPA standards, the Association of Petroleum Industries (API) standards outline good engineering design for some equipment used at process plants. An owner may choose to conform to API standards where they provide a comprehensive package of safe design features. Some examples include:
The Petroleum Equipment Institute (PEI) also publishes standards that may be relevant, such as:
U.S. Government Publications also provide some standards:
British Standards Institute (BSI) also publishes standards that may be appropriate for use such as:
Unless specifically addressed within the Code, Part 4 does not apply in situations and locations where the following provincial legislation and federal legislation apply:
Part 4 does not apply to the storage of flammable and combustible liquids on farms that are intended for individual use or to airports, piers and wharves which are regulated under federal law.
Aerosol products are not covered by Part 4. However, they should be stored according to NFC (1995) Subsection 3.2.5. Aerosol products pose unique hazards. Aerosol cans may contain both a flammable liquid (e.g. paint carrier) and a propellant which may be a flammable gas. Under fire exposure conditions, these cans may rocket. Rocketing aerosol cans have been known to quickly spread a fire over a large area.
Part 4 of the Ontario Fire Code became law on November 21, 1997. It provides for various phase-in periods to permit owners time to bring their facilities into compliance. New construction completed on or after August 21, 1998 must comply with all provisions set out in Part 4 of the Ontario Fire Code.
Sentence 4.1.1.1.(2) defines "existing" as being in existence on November 21, 1997. Existing facilities must comply according to three different compliance periods:
By the effective date of August 21, 1998, there must be compliance with procedural (e.g. control of ignition sources, smoking, hot work, static electricity) and maintenance items (e.g. maintaining ventilation, fire and operating equipment, remedial action as result of a leak of flammable or combustible liquids and routine visual inspections for leaks).
By August 21, 2000, there must be compliance with equipment and process changes that have a high life safety impact (e.g. fire department access, spill control, ventilation).
By August 21, 2002, all other equipment and process changes must be made (e.g. protection from flooding, corrosion protection on tanks, emergency venting on tanks) except for a few items that are "grandfathered". Grandfathered items will not have to be met until major alterations or changes are made. These changes are potentially very expensive and have minimal life safety impact (e.g. spacing of tanks, tank spacing to property lines and buildings). These changes are not cost effective unless the tanks need to be replaced.
Where a requirement with an earlier compliance date refers to another requirement with a later compliance date, the applicable compliance date for the requirement shall be the later compliance date.
If one Article with a compliance date of August 21, 2000, makes reference to an Article with a compliance date of August 21, 2002, it can be argued that the reference is to a requirement that the legislation has permitted a longer time to comply. Therefore, where no options are provided, those requirements that make reference to provisions that have later compliance dates should not be expected to be in compliance until the later compliance date.
Where a requirement provides several options for compliance and one or more of those options involve provisions with later compliance dates, the applicable compliance date for the requirement shall be the compliance date of the originating Article.
However, where a requirement provides several options for compliance and one or more of those options involve provisions with later compliance dates, it would be expected that the option with the earliest compliance date would apply. The owner has the option of complying with any one of the options, as long as compliance is achieved by the earliest date. It should be noted that the owner is not forced to comply with the option that has the most distant compliance date. If the owner is permitted to comply with options at the later compliance dates, the original intent of the requirement would not be met and inconsistent levels of fire safety will result.
Where an owner wishes to vary from one or several or all of the requirements set out in Part 4 of the Fire Code, a compliance equivalency may be submitted.
A compliance equivalency permits the owner to vary the composition, design, size or arrangement of any material, object, device or thing from the composition, design, size or arrangement prescribed in Part 4 of the Fire Code where the factors of strength, health and safety are equivalent or superior.
Where an owner wishes to take advantage of this option, the owner must provide a detailed description explaining how the alternate arrangement will provide an equivalent or greater level of life safety and property protection when compared to Part 4 of the Fire Code. This report must be signed and stamped by a Professional Engineer or Architect and be submitted to the Chief Fire Official in the area having jurisdiction allowing sufficient time for the work to be done plus 90 days for the review by the Chief Fire Official, so that the work can be approved and completed by the compliance date set out in Article 4.1.1.4.
For new construction completed after the deadline set out in Article 4.1.1.4. (August 21, 1998), the application for compliance equivalency must be made with the request for a Bbuilding Ppermit and at least 90 days before the start of construction.
If the Chief Fire Official is unable to complete the review within the 90 day time period, the owner must be advised as to when the response will be forthcoming. This extension must be added to the compliance time.
If the compliance equivalency is not approved by the Chief Fire Official, this official must give the reasons in writing. The owner or agent may appeal this decision within 30 days in the same manner as if it were an Order issued under the Fire Protection and Prevention Act, 1997 (FPPA).
A copy of the approved compliance equivalency must be kept on the premises to which it relates for the review of the Chief Fire Official, upon request.
A compliance equivalency that has been approved and implemented will be considered as complying with the applicable requirements of Part 4 for which a compliance equivalency was requested.
A Professional Engineer or Architect who signs and stamps a report for a compliance equivalency should have the necessary technical knowledge and experience in fire prevention and protection as it pertains to the relevant processes and operations.
and Architects will be held accountable by their associations where they fail to practice within their area of knowledge and expertise. These associations have strict professional Codes of Ethics. Where a Professional Engineer or Architect fails to work within these parameters, they may be subject to disciplinary action which may result in the loss of their license to practice.
The Professional Engineer or Architect that submits the compliance equivalency does not necessarily have to be the person that implements it. However, the owner is responsible for ensuring that the work that is done matches what was approved. This may involve retaining the Professional Engineer or Architect that submitted the compliance alternative or another Professional Engineer or Architect to supervise the work.
Where a Code provision prohibits a certain activity, proposing a compliance equivalency is not appropriate. We have identified code provisions that specifically prohibit activities, therefore a compliance equivalency is not permitted for any of the following:
Subsections 4.1.1., 4.1.2., 4.1.3., Articles 4.2.1.1., 4.2.4.1., 4.2.4.3., 4.2.4.4., 4.2.6.1., 4.2.7.1., Sentences 4.2.7.5.(3) and (4), Article 4.2.8.1., Sentences 4.2.8.4.(5) and (6), Article 4.2.10.1., Sentence 4.2.10.3.(3), Articles 4.2.11.2., 4.3.1.1., Sentences 4.3.1.2.(2) and (4), Article 4.3.7.9., Sentences 4.3.8.3.(2), 4.3.8.7.(1), Article 4.3.12.1., Sentences 4.3.12.6.(1), 4.3.12.8.(2), 4.3.15.4.(1) and (2), Article 4.4.1.1., Sentence 4.4.4.1.(2), Article 4.4.7.6., Article 4.4.8.3., Sentences 4.4.10.2.(2), 4.4.10.5.(1), 4.4.11.5.(4), Article 4.5.1.1., Sentence 4.5.2.2.(3), Articles 4.5.2.7., 4.5.6.1., Sentence 4.5.8.6.(3), Articles 4.5.8.7., 4.6.1.1., 4.6.3.1, 4.7.1.1., 4.7.2.1., Sentence 4.7.7.3.(3), Articles 4.8.1.1., 4.9.1.1., 4.9.2.1., 4.10.1.1., 4.10.4.3., 4.11.1.1., Sentence 4.11.3.6.(3), and Article 4.12.1.1.
Flammable and combustible liquids are classified into 3 categories. Care should be used in applying these classifications where the liquid is processed, used or stored at temperatures above ambient conditions. Increased temperatures can have the effect of moving the liquid into a classification higher than would be appropriate under ambient conditions. For example, a Class II liquid processed at higher temperatures could require application of Class I requirements.
Class I includes liquids with a flash point below 37.8oC. These liquids are considered to have the highest risk of fire or explosion because in the summer time it is not uncommon for storage areas to reach a temperature of 37.8oC which is the upper limit of flash points for this class of liquids.
Class I liquids are further subdivided as follows:
Class IA -flash point below 22.8oC and boiling point below 37.8oC
Class IB -flash point below 22.8oC and boiling point at or above 37.8oC
Class IC -flash point at or above 22.8oC and below 37.8oC
Under normal ambient temperatures both Class IA and Class IB liquids generate sufficient vapours to create vapour concentrations within the flammable range at all times.
In some areas and in closed spaces, the ambient temperature could exceed 37.8oC or only a moderate amount of heating would be required to heat the liquid to or above its flash point. As a result, an arbitrary division of 37.8oC to 60oC was established for liquids to be known as Class II liquids. Since liquids with flash points greater than 60oC would require considerable heating from a source other than ambient temperatures, they have been identified as Class III liquids. These combustible liquids are further subdivided as follows:
Class IIIA -flash point at or above 60oC and below 93.3oC
Class IIIB -flash point at or above 93.3oC
Since Part 4 is limited to liquids with a flash point below 93.3oC, Class IIIB liquids which are not heated above their flashpoint do not fall within the scope of Part 4. These liquids are deemed to represent no greater fire hazard than other combustibles such as plastic, wood or paper products.
Both Class II and Class IIIA liquids are considered as combustible liquids under Part 4. Any combustible liquid, including a Class IIIB liquid, heated to or above its flash point must be handled with the same precautions as a flammable Class I liquid.
Used lubricating oil from automobiles, trucks, tractors, etc. may be contaminated with gasoline. Therefore, Part 4 requires used crankcase oil to be treated as a Class IIIA liquid.
Where Class I or II liquids are added to used lubricating oils, it is not possible to predict the flash point. Therefore, the liquid classification must be determined by testing in accordance with Subsection 4.1.3.
The classification system for flammable liquids used in this regulation is the same as the system used by NFPA. However, the Transportation of Dangerous Goods Regulations (TDGR) is different. For an analysis of the differences see Appendix Table A-4.1.2.1 of the National Fire Code.
Article 4.1.2.3. regulates used lubricating oil. However, Clause 4.1.1.2.(2)(d) exempts locations to which the Gasoline Handling Act and the Energy Act apply. Gasoline stations which dispense fuel are regulated by the Gasoline Handling Act and, therefore, any used lubricating oil would be regulated under the Gasoline Handling Act rather than by Article 4.1.2.3. Article 4.1.2.3. applies to locations to which the Gasoline Handling Act does not apply.
Flash point is the minimum temperature at which a liquid gives off vapour in sufficient amounts to form an ignitable vapour/air mixture near the surface of the liquid. The term "lower flammable limit" describes the minimum concentration of vapour below which flame propagation will not occur in the presence of an ignition source. The flash point of a liquid corresponds roughly to the lowest temperature at which the vapour pressure of the liquid is sufficient to produce a flammable mixture at the lower flammable limit.
A liquid that has a flash point in the range of normal ambient temperatures (or lower) will, without any external heating, emit vapours at concentrations that can be ignited by a small source of ignition, such as a pilot flame or spark. A liquid with a higher flash point will require some heating before ignition is possible, thus presenting a lower risk.
When heated, some liquids that are a mixture of components will release their more volatile components. For example, No. 6 fuel oil normally has a flash point above 60oC, but, when heated above its flash point, the volatility of the liquid is increased and it assumes some characteristics of lower flash point liquids. The handling and use of these liquids at higher temperatures will generate flammable vapours that require the precautions outlined for flammable liquids.
There are two basic test methods for determining flash points - closed cup and open cup. Open cup flash points represent conditions with liquid in the open and are generally higher than closed cup flash point figures for the same liquid. Flash points referred to in Part 4 are determined using the ASTM D-56 closed cup test method. These flash points are more conservative (i.e. provide a slightly larger margin of safety).
In order to prevent electrical equipment from providing an ignition source in the presence of flammable vapours, electrical equipment manufacturers have designed "explosion proof" equipment that will prevent an explosion that occurs within the equipment from propagating into the surrounding atmosphere.
The Electrical Safety Code sets out equipment requirements based on the risks that may be present. Class I addresses hazards from flammable vapours and gases. Class II deals with combustible or electrically conductive dusts. Class III provides requirements for easily ignited fibers and shavings. For Class I there are two Divisions. Division 1 represents the higher risk zone where flammable gases or vapours are present all of the time (e.g. open containers such as dip tanks) or intermittently (e.g. drums opened for sampling and transfer). Division 2 zones include lower risk areas where flammable gases and vapours are enclosed in piping, tanks and process vessels and can only escape under abnormal conditions such as spills due to punctures, equipment failure or inappropriate handling. Ventilation in a Division 2 location should normally prevent the accumulation of gases. An example of a Class I Division 2 location would be a warehouse where flammable or combustible liquids are stored in sealed drums (i.e. not opened for use). In this example, electrical equipment would be required to ensure that there are no electrical ignition sources present when spills result from drums that are dropped or punctured during handling.
Electrical classification of vapours and gases are further divided into Group A, B, C and D. Group A includes atmospheres containing acetylene. Group B includes atmospheres containing hydrogen and gases of similar risk. Group C includes ethylene, diethyl ether, acetaldehyde and other gases and vapours of equivalent hazard. Group D includes atmospheres containing acetone, alcohol, gasoline, hexane, naphtha, lacquer solvents, natural gas, propane, or other gases or vapours of equivalent hazard.
Additional information can be found in CSA's "A Guide for the Design, Construction and Installation of Electrical Equipment"; in NFPA 30, "Flammable and Combustible Liquids Code", and in NFPA 497A, "Classification of Class I Hazardous locations for Electrical Installations in Chemical Process Areas".
Battery powered fork lift trucks used to move drums of flammable and combustible liquids may present an ignition source when drums are ruptured as a result of being dropped or punctured by the forks. These industrial trucks must be designed for use in these hazardous environments. Trucks classified as type "EE" have their electrical motor and all other electrical equipment completely enclosed and would be suitable for Class I Division 2 locations. Trucks classified as type "EX" have some additional design features that make them suitable for Class I Division 1 locations. Factory Mutual Loss Prevention Data Sheet 7-39 and NFPA 505 provide additional details regarding industrial trucks including those powered by gasoline, diesel fuel and propane.
The Electrical Safety Code would apply even if there is no reference to it in Article 4.1.4.1. However, by referencing the Electrical Safety Code in the Fire Code, the fire service has the legal authority to require conformance with the Electrical Safety Code.
This Subsection outlines a number of fundamental fire and explosion prevention techniques or principles that are applicable wherever flammable or combustible liquids are stored or handled. These include:
This Subsection also requires that in all occupancies where more than 500 L of flammable or combustible liquids, or 250 L of Class I flammable liquids are present, a fire safety plan must be prepared as set out in Section 2.8 of the Ontario Fire Code. This plan must be approved by the Chief Fire Official and kept in the building in an approved location.
In general, flammable liquids should not be stored in basements because their vapours are usually heavier than air, thus, they tend to accumulate in low lying areas. However, up to 5 L of Class I liquid may be stored in a basement provided that it is stored in safety containers conforming to ULC/ORD-C30, "Safety Containers". Factors such as the size of basement, ventilation, wiring and proximity to sources of ignition should be taken into account in determining risk and suitable methods of control of vapours and ignition sources. Limited exemptions are provided for a dwelling unit and mercantile occupancies.
Routine maintenance should include items such as pump packings or seals which require regular maintenance to prevent leaks. Relief valves, flame arresters and valves are examples of other items that require regular maintenance.
Article 4.1.5.2. is currently reserved but was intended to be a list of all of the acceptable standards related to the installation of sprinkler and fire extinguishing systems. (See the commentary for Article 4.2.7.7.)
The intent of Article 4.1.5.9. is to ensure that heavier than air flammable vapors do not accumulate in below grade areas. Where continuous mechanical ventilation is monitored for operation, the potential for vapour accumulation in the below grade areas will be virtually eliminated under normal operating conditions.
The introduction of Sentence (4) will now permit other methods to achieve the intended objective. A fire safety plan will be required regardless of the quantity stored or used in a laboratory. A one-hour fire separation is required for the area where Class I liquids are stored and used in the laboratory. The limitation on the size of the container storing Class IA liquids minimizes the potential for release of a large quantity of flammable vapour into the space in the event of a spill. Where Class IA liquids are stored in small containers, explosion venting must be provided unless the liquids are stored in a storage cabinet. When all dispensing is carried out under a proper fume hood, the likelihood of vapour accumulation is further reduced and the need for explosion venting is not considered necessary. Sentence (5) permits existing plaster or gypsum board, provided they perform as a membrane against the passage of heat and smoke. The limitation on the quantity of liquid (250 L) and the requirement for the fire separation add a further level of safety. NFPA 45, "Fire Protection for Laboratories Using Chemicals", provides additional information on storage and use of Class I liquids in laboratories located below grade.
In order to minimize the potential of flammable vapour ignition occurring from sources of ignition that are usually found in the basement such as a furnace pilot light, electrical outlets, etc., vapour detection is also required. Vapour detection need not be provided where all the fixed sources of ignition are eliminated within 0.9 m from the floor (i.e. below the lab bench counter) and procedures are in place to control all non-fixed sources of ignition.
It is also possible to submit a compliance equivalency under Article 4.1.1.5. for existing laboratories that may not be able to meet all of the provisions of Sentence (4). The Article is editorially reorganized to distinguish between storage and use. NFPA 30 and the National Fire Code do not permit storage and use of flammable liquids in basements or pits. Therefore, the Ontario Fire Code permits basement storage and use only in existing laboratories (consistent with NFPA 45), where the quantities stored are low and dispensing is carried out only in very small quantities with appropriate precautions.
A containment system is required to ensure that the maximum credible spill of a flammable or combustible liquid can be safely contained or drained to a safe location. The design of a primary spill containment or drainage system does not need to include fire suppression water. Fire suppression media such as water and/or foam is applied when the spill is involved in a fire. Therefore the fire fighting water need not be included in designing a primary spill containment or drainage system.
Once the spill is involved in a fire, the method of dealing with an unknown quantity of fire fighting water is best handled through a fire safety plan (fsp) and/or pre-fire plan. The fsp must ensure that all critical areas, such as buildings, means of egress, etc., in the path of such overflow remain accessible during the fire emergency and the flow of liquid is directed away from such areas. Since the fsp is only required where the total quantity stored exceeds 500 L or 250 L of Class I liquids, the provision for control of fire fighting water would not apply unless the quantity stored exceeds 500 L or 250 L of Class I liquids. Measures for control can include provision for sealing sewer or catchbasin covers, and provision of absorbent materials and portable dikes.
A spill containment system is intended to capture the maximum credible spill of a flammable or combustible liquid. This can be achieved by safely containing the liquid in the spill area or having it drain to a safe location. "Spill area" can be considered as the fire compartment when storage is located inside a building and the storage area when located outside. Fire fighting water need not be considered when determining the capacity of the primary spill containment or drainage system required in Sentence (1).
Once a fire is associated with a spill, fire fighting water from hose streams, suppression systems, etc., becomes a concern. The quantity of water involved is highly variable, based on the fire conditions and duration. As a result, the fire safety plan and/or pre-fire plan must address spill management associated with application of fire fighting water.
The capacity of a credible spill should be based on the maximum quantity that can be released from containers located in the storage area.
The fsp should ensure that all critical areas, such as buildings, means of egress, fire department access, control valves, fire alarm panels, etc., in the path of such overflow remain accessible during the fire emergency and the flow of liquid is directed away from such areas. The plan should consider reliable and immediate notification of an emergency such as automatic notification to fire department, which will facilitate early intervention. The plan should have measures including design features that will minimize the resultant impact of effluent on adjoining property and the environment.
In order to develop a workable plan, the owner may require assistance from the fire department to provide some of the relevant information necessary to develop the plan. The owner is responsible for the development of the plan and having the plan approved by the Chief Fire Official. The owner should also ensure the approved plan is implemented. Periodic (annual) testing of the plan should also be carried out to identify any limitations of the plan and to familiarize the staff who are assigned duties in the plan. The fsp is required to be modified when original assumptions and conditions change.
Dikes, drainage ditches, impounding basins, curbs, site grading and raised door sills are examples of how spills and contaminated fire fighting water can be contained and/or diverted away from waterways, sewers, potable waters sources, a means of egress, adjoining property, or fire department access routes.
Once spills reach waterways, groundwater (often used for a potable water supply), public sewer systems or underground occupancies such as subways and malls, etc., cleanup becomes difficult or nearly impossible.
Flowing streams of burning flammable or combustible liquids also have the potential to spread the fire to other buildings. Many of these liquids float on water. , thus, spill control measures must be of sufficient capacity to contain all contaminated water from fire fighting activities.
The containment volume should be able to handle the water used for both manual and automatic fire suppression operations, plus credible product spill.
Depending on the circumstances this could include:
The time duration required to calculate the combined water flow will depend on the overall suppression system effectiveness. When calculating the flow from the sprinkler system a minimum duration of 30 minutes should be used. Where it can be demonstrated that other suppression systems, such as foam, could achieve extinguishment in a shorter period of time, the owner may submit a compliance equivalency proposal for approval by the Chief Fire Official in accordance with the requirements set out in Articles 4.1.1.5. and 4.1.1.6. of the Ontario Fire Code.
Spills of flammable and combustible liquids can spread very rapidly and expose a large surface area to produce vapours which, within an enclosed or non-ventilated area, can quickly accumulate to reach the lower explosive limit. Therefore, every effort should be made to ensure that systems used to transfer, process or store these liquids are maintained and operated in a safe manner. Maintenance and operating procedures must be established and implemented to minimize the possibility of a leak occurring.
Other measures used for control of spills include provision of catch basins that collect spilled materials in underground tanks.
Noncombustible aAbsorbent materials and portable containment dikes may be used to control small spills. The intent of Clause 4.1.6.3.(4)(a) is that the material used as an absorbent can not cause a spontaneous ignition hazard or chemical reaction hazard when used with the flammable or combustible liquid that has leaked. Materials suitable for use with one liquid may not be suitable with another.
The fire safety plan should include measures for responding to a situation where the containment area could be overfilled. For example, many owners maintain a list of clean-up companies that have vacuum trucks that can quickly respond to collect contaminated water.
In any property or facility where flammable or combustible liquids are stored, processed, handled or used, there is always the possibility of an accidental spill. When a liquid spill or leak does occur, the potential fire hazard must be quickly and efficiently controlled. A written spill procedure and training are needed to ensure that employees can provide an immediate response. Personal protective equipment, clean-up supplies (e.g. spill kit) and tools must also be readily available. A telephone list of management staff who are available on a 24 hour basis should also be maintained so that knowledgeable persons can provide advice regarding potential hazards associated with the spilled materials. Appendix A to this commentary contains a model spill control procedure to assist owners in developing their own procedures.
Waste materials must be disposed of per the requirements of the Ministry of the Environment and any local municipal by-laws.
A highly recommended method of draining a spill from a building is by grading the floor to divert the spill to a floor drain which is connected to an outside holding tank of adequate capacity to contain the spill plus any water used for flushing or fire fighting. The pipeline from the floor drain to the holding tank should be equipped with a trap that is designed to hold a liquid seal that will prevent the passage of gas vapours but will not materially affect the flow of a liquid. Draining spilled liquids out of the building greatly reduces the amount of vapours that can be released in the building and reduces the risk of fire and explosion.
Flammable and combustible liquid vapour is often present except where the storage is confined to sealed containers with no dispensing or where handling is in a closed system with vapour recovery. However, even in closed systems, there is always the possibility of breaks or leaks which may permit liquid to escape resulting in the presence of vapours. Since these vapours are an easily ignited fuel source, ventilation is of prime importance to prevent an accumulation. Part 4 contains detailed requirements for providing ventilation in rooms or enclosed spaces where flammable and combustible liquids are processed, handled, stored, dispensed or used.
Almost all flammable liquids produce heavier-than-air vapours which tend to settle on the floor or in pits, stairwells, trenches or other areas below floor level. These vapours may travel long distances before encountering an ignition source. If ignited, a flash back may occur to the point of origin of the vapours.
Subsection 4.1.7. of this code represents a minimum level of "good practice" for preventing an accumulation of explosive concentration of vapours from flammable or combustible liquids.
There are two basic methods of ventilation, natural and mechanical. Natural ventilation relies on convection currents, wind and vapour diffusion. Although natural ventilation has the advantages of not becoming ineffective during power failures and breakdowns, it is usually not as effective as mechanical ventilation.
Natural ventilation may be adequate for the storage of flammable and combustible liquids, or the dispensing of Class II and IIIA liquids. Such ventilation should consist of permanent openings at ceiling and floor levels leading to the outside. At least 0.1 m2 each of free inlet and outlet openings per 50 m2 of floor area should be provided.
A mechanical ventilation rate of at least 18 m3/h per square metre of floor area, but not less than 250 m3/h is normally adequate for rooms with low floor to ceiling height or small enclosed spaces where Class I liquids are dispensed. This represents a ventilation rate of approximately six air changes per hour. Ventilation for process areas must be designed to suit the nature of the hazard in accordance with good engineering practice.
This Subsection contains both performance and prescriptive ventilation requirements for areas outside an area classified by the Electrical Safety Code as Class I, Division 1. These Part 4 requirements should be applied keeping in mind the objective of ensuring that the flammable vapour concentration does not exceed 25 percent of the lower explosive limit of the vapour. The ventilation system is to be equipped with an automatic interlock so that the activity that generates flammable vapours cannot be performed when the system is not in operation. Audible alarms to sound in the event of failure of the system must also be provided. These requirements also outline the locations of exhaust outlets and make-up air inlets for both lighter and heavier-than-air flammable vapours.
The intent of the reference to Article 4.1.4.1. is to describe a zone where a specified concentration of flammable vapours cannot be exceeded, not to specify electrical requirements.
The Electrical Safety Authority has confirmed that for a new installation, either the Zone or Division system could be used at the owner/designer's option. Where an existing system is being modified or extended, whichever system had been used to classify the original installation must be used for the modifications or extension. The name of the Act has been changed to the Electricity Act, 1998.
The intent of Article 4.1.7.5. is to ensure that the ventilation openings for achieving natural ventilation are located so that both the make-up air and exhaust air are taken or discharged outside the building.
Flammable liquids should always be handled and dispensed in a well ventilated area, free of sources of ignition. Static electricity is an ignition source that requires appropriate precautions to be taken. Static electrical charges are generated when liquids in motion contact other materials. Charge build-up commonly occurs in such operations as pumping, mixing, pouring, filtering or agitating. Under certain conditions, particularly with pure liquid hydrocarbons such as toluene, a static charge may accumulate within the liquid itself. If the accumulation is sufficient, a static spark may occur between the liquid and the container. If a flammable vapour/air mixture is present at the liquid surface at the time a spark occurs, a fire or explosion could result.
When flammable liquids are dispensed into metallic containers, a metal bond wire must electrically connect the two containers to equalize the static charge. This charge must also be grounded to ensure that it is dissipated harmlessly. Similarly, process equipment (e.g. pumps, reaction vessels, tanks) should be bonded and grounded.
Paint and other coatings may electrically insulate metal containers. Therefore, it is essential to check bonding and grounding by checking connections using an electrical resistance meter.
Non-metallic containers, such as plastic or glass, cannot be bonded. The build-up of static charges near the surface of liquids being poured into non-conducting containers can be minimized by limiting the filling rate to velocities less than 1 m/s, using a grounded lance or nozzle extension to the bottom of the container, limiting free fall, or using antistatic additives. When top filling a container, high flow rates and free falling or splash filling of hydrocarbons are conditions which greatly increase the buildup of static electricity.
It is generally considered that liquids with a conductivity greater than 50 pS/m (Pico Siemens per metre) will dissipate static charges. These liquids will not accumulate a hazardous static potential. Experience has shown that most water miscible liquids, crude oils, residual oils and asphalt do not accumulate significant static charges.
To minimize the possibility of leaks occurring during the dispensing and transferring of flammable liquids within a building, only specified types of containers or storage tanks as described in Subsections 4.2.3. or 4.3.1. may be used during this operation.
It is recommended that listed safety dispensing containers be used. Underwriters Laboratories of Canada (ULC) and Factory Mutual Engineering Corporation (FM) list these portable containers. These containers are constructed to minimize spills and vapour release. Further, they will not rupture during fire exposure. If dropped, the self-closing valve will cut of the flow of flammable/combustible liquid. Flame arrestors prevent flame propagation into the container.
Liquids can also be dispensed from their original shipping containers
(barrels for example) using portable pumps or by gravity through a
self-closing valve. This code requires such a pump or self-closing valve to
be designed in conformance with good engineering practice. Products tested
and listed by recognized agencies are considered to meet
this requirement. Underwriters Laboratories Inc., Underwriters Laboratories
of Canada, Canadian Standards Association, Warnock Hersey and Factory Mutual
Engineering Corporation have listed dispensing cans, pumps and self-closing
valves.
|
||||||||||||||||||
