Rule 4123:1-3-18 | Heating, ventilating and exhaust equipment.
(A) Scope.
This rule relates to methods of controlling air contaminants, as defined in paragraph (B) of this rule, which have been established as hazardous.
(B) Definitions.
(1) "Air contaminants" as used in this rule, means airborne concentrations of fibrosis-producing or toxic dusts, toxic fumes, toxic mists, toxic vapors, or toxic gases, or a combination of these, suspended in the atmosphere.
(2) "Collector," see "separator."
(3) "Confined space" means any tank, vessel, container, or pit so enclosed that adequate ventilation is not obtained by natural air movement.
(4) "Duct" means any pipe, flue, or channel forming a part of a ventilating system used to convey air, dusts, fumes, mists, vapors, or gases.
(5) "Dust" means solid particulate matter, other than fumes, generally less than one hundred micrometers in aerodynamic diameter.
(6) "Exhaust system" means a complete suction system, including all hoods, ducts, fans, separators, and receptacles, when required, and any other part necessary for the proper installation and operation thereof.
(7) "Fan" means the equipment which creates the movement of air in a mechanical system of ventilation.
(8) "Fume" means solid particulates generated by the condensation of vapors or gases, usually of metallic elements.
(9) "Gas" means a formless fluid occupying the space of enclosure.
(10) "Hazardous concentrations" as applied to air contaminants, means concentrations which are known of recognized occupational exposure limits such as, but not exclusively, the occupational safety and health administration permissible exposure limits (OSHA-PEL), national institute for occupational safety and health recommended exposure limits (NIOSH-REL) or American conference of governmental industrial hygienists' threshold limit values (ACGIH-TLV®).
(11) "Hood" means that part of an exhaust system into which air contaminants first enter.
(12) "Mist" means liquid droplets or wet solids suspended in air.
(13) "Separator" or "collector" means that part of an exhaust system designed to separate the entrained material from the conveying air.
(14) "Transport velocity" means the velocity of air required to keep the material entrained in the conveying air.
(15) "Vapor" means the gaseous form of a substance normally in the liquid or solid state.
(16) "Ventilation," dependent on the type of ventilation, means any of the following:
(a) "Dilution ventilation" means ventilation provided to reduce the concentration of air contaminants in the atmosphere of all of or part of the place of employment.
(b) "General ventilation" means ventilation of the general atmosphere in the place of employment.
(c) "Local exhaust ventilation" means that type of ventilation in which suction is applied at the point of generation or escape of air contaminants.
(C) Temporary heating devices.
(1) General.
When heaters are used, ventilation shall be provided to maintain the health and safety of employees.
(2) Solid fuel salamanders.
Solid fuel salamanders are prohibited in buildings and on scaffolds.
(3) Oil-fired heaters.
(a) Flammable liquid-fired heaters shall be equipped with a primary safety control to stop the flow of fuel in the event of flame failure.
(b) Heaters designed for barometric or gravity oil feed shall be used only with the integral tanks.
(c) Heaters specifically designed and approved for use with separate supply tanks may be directly connected for gravity feed, or an automatic pump, from a supply tank.
(4) Liquefied petroleum gas (LP-gas).
(a) Approval of equipment and systems.
Each system shall have containers, valves, connectors, manifold valve assemblies, and regulators of an approved type.
(b) Container valves and container accessories.
Valves, fittings, and accessories connected directly to the container, including primary shut-off valves, shall have a rated working pressure of no less than two hundred fifty pounds per square inch (1724.7 kilopascal) gauge and shall be of material and design suitable for LP-gas service.
(c) Dispensing.
Filling of portable containers mounted on skids from storage containers shall be performed no less than fifty feet (15.2 meters) from the nearest building.
(d) Containers and regulating equipment installed outside of buildings or structures.
Containers shall be upright upon firm foundations or otherwise firmly secured. The possible effect on the outlet piping of settling shall be guarded against by a flexible connection or special fitting.
(e) Containers and equipment used inside of buildings or structures.
(i) When operational requirements make use of portable containers necessary, and their location outside of buildings or structures is impracticable, containers and equipment shall be permitted to be used inside of buildings or structures in accordance with paragraphs (C)(4)(e)(ii) through (C)(4)(e)(x) of this rule.
(ii) "Containers in use" means connected for use.
(iii) Valves on containers having water capacity greater than fifty pounds (22.7 kilograms), or nominal twenty pounds (9.1 kilograms) LP-gas capacity, shall be protected from damage while in use or storage.
(iv) Hose used for LP-gas shall have a working pressure of no less than two hundred fifty pounds per square inch (1724.7 kilopascal) gauge. Hose design, construction, and performance shall be determined by listing by a national recognized testing agency. The use of aluminum piping or tubing is prohibited.
(v) Portable heaters, including salamanders, shall be equipped with an approved automatic device to shut off the flow of gas to the main burner and pilot in the event of flame failure, except that this provision does not apply to portable heaters under seven thousand five hundred British thermal units (7.9 megajoules) per hour input when used with containers having a maximum water capacity of two and one-half pounds (1.1 kilograms). Portable heaters having inputs above fifty thousand British thermal units (52.8 megajoules) per hour, shall be equipped with either a pilot, which must be lighted and proved before the main burner can be turned on, or an electrical ignition system.
(vi) Containers, regulating equipment, manifolds, piping, tubing, and hoses shall be located to avoid exposure to high temperatures or physical damage.
(vii) Containers having a water capacity greater than two and one-half pounds (1.1 kilograms), or nominal one pound (454 grams) LP-gas capacity. connected for use shall stand on a firm and level surface and shall be secured in an upright position.
(viii) The maximum water capacity of individual containers shall be two hundred forty-five pounds (111.1 kilograms), or nominal one hundred pounds (45.4 kilograms) LP-gas capacity.
(ix) For temporary heating, heaters, other than integral heater-container units, shall be located no less than six feet (1.8 meters) from any LP-gas container.
(x) When heaters are connected to containers for use in an unpartitioned area on the same floor, the total water capacity of containers, manifolded together for connection to a heater or heaters, shall be no greater than seven hundred thirty-five pounds (333.4 kilograms), or nominal three hundred pounds (136.1 kilograms)LP-gas capacity. Such manifolds shall be separated by no less than twenty feet (6.1 meters).
(f) Multiple container systems.
(i) Valves in the assembly of multiple container systems shall be arranged so that replacement of containers can be made without shutting off the flow of gas in the system.
(ii) Heaters shall be equipped with an approved regulator in the supply line between the fuel cylinder and the heater unit. Cylinder connectors shall be provided with an excess flow valve.
(g) Storage of LP-gas containers.
Storage of LP-gas within buildings is prohibited.
(h) Storage outside of buildings.
(i) Storage outside of buildings for containers awaiting use shall be located away from the nearest building or group of buildings, in accordance with the following:
(ii) Containers shall be in a ventilated enclosure and protected against tampering.
(D) Control of air contaminants.
(1) General.
Air contaminants shall be minimized by one or more of the following methods:
(a) Substitute nonhazardous, or less hazardous material;
(b) Confine or isolate the contaminant;
(c) Remove at the source by local exhaust ventilation;
(d) Reduce the airborne concentration by dilution ventilation;
(e) Reduce the airborne concentration by general ventilation; or
(f) Using wet methods to allay dust generation.
(2) Asbestos.
(a) Mixing asbestos shall be done wet or in an enclosed, ventilated area.
(b) The employer shall provide and shall require the employee to wear approved respirators when mixing, sawing, spraying, applying, and cleaning up where asbestos is used.
(c) Damaged bags or containers of asbestos shall be wrapped or enclosed in an airtight container before handling.
(d) When cleaning up, all surfaces shall be sprayed with water or shall be vacuumed by high-efficiency particulate air (HEPA) filtered equipment capable of trapping and retaining at least 99.97 per cent of all monodispersed particles of 0.3 micrometers in diameter or larger.
(E) Exhaust systems: machinery and equipment.
(1) Grinding, polishing, and buffing.
(a) Abrasive wheels and belts.
(i) Abrasive wheels and belts shall be hooded and exhausted when there is a hazardous concentration of air contaminants.
(ii) This provision does not apply to abrasive wheels or belts:
(A) Upon which water, oil, or other liquid substance is used at the point of the grinding contact; or
(B) Small abrasive wheels used occasionally for tool grinding or other routine maintenance tasks.
(b) Separate exhaust systems.
Abrasive wheel and buffing wheel exhaust systems shall be separate when the dust from the buffing wheel is of flammable or combustible material.
(2) Manufacturing processes.
When toxic materials are generated in hazardous concentrations during their application, drying, or handling, the toxic materials shall be minimized or eliminated.
(3) Internal combustion engines.
Hazardous concentrations of air contaminants produced by internal combustion engines shall be exhausted.
(F) Exhaust systems, structural requirements.
(1) Exhaust or ventilating fan.
Each exhaust or ventilating fan located seven feet (2.1 meters) or less above the floor or normal working level shall be guarded.
(2) Ducts.
The exhaust system shall be ducts of a size suitable for conducting the contaminated air outdoors, or the exhaust ducts shall provide no less than the minimum transport velocity necessary to remove the particulate material to a collector.
(3) Discharge.
The outlet from every separator, or from every collector, shall discharge the air contaminants collected by the exhaust system in such manner that the discharged materials shall not re-enter the working area in hazardous concentrations.
(4) Location of air supply openings or inlets.
Air supply openings or inlets through which air enters the building or room in which the local exhaust system is in operation shall be isolated from any known source of contamination.
(G) Confined spaces.
Under no circumstances shall a confined space be entered unless the following prescribed tests and procedures are completed.
(1) Qualified, trained personnel shall test the atmosphere within the confined space, without themselves entering, to verify the confined space:
(a) Contains an adequate oxygen concentration, i.e., between 19.5 per cent and 23.5 per cent oxygen;
(b) Does not contain vapor or gas in excess of ten per cent of its lower flammability limit (LFL) through the use of a combustible gas indicator; and
(c) Does not contain a hazardous concentration of toxic contaminants.
(2) If the confined space contains inadequate oxygen concentration, a concentration of vapor or gas in excess of ten per cent of its LFL, or a hazardous concentration of a toxic contaminant, then appropriate control measures shall be instituted. Control measures may consist of forced or natural ventilation, use of personal protective equipment, i.e., supplied air respirators or self-contained breathing apparatus, a combination of forced or natural ventilation and personal protective equipment, or equivalent effective control techniques.
(H) Procedures.
(1) Procedure for safe entry.
(a) A procedure for safe entry into confined spaces shall be established and used.
(b) The following are recommended procedures to comply with standards:
(i) Designate at least one trained person to be responsible for adherence to entry procedures and require written approval by that person before permitting anyone to enter the confined space;
(ii) Post danger signs, or mark by any other equally effective means, the existence and location of the permit spaces, such as with a sign reading "Danger -- Permit - Required Confined Space, Do Not Enter," or using similar language;
(iii) Provide periodic instruction and training in proper entry procedures to be used;
(iv) Standby personnel where provided shall be required at all times to be in communication with the employee within the confined space, and an alarm or two-way radio system for the standby employee will be effective;
(v) Approved rescue equipment should be available, and since entry ports for confined spaces vary in size, precaution should be used in obtaining proper size equipment;
(vi) Establish procedures to prevent ignition of combustible atmospheres or re-entry of gases or liquids by locking out switches, blanking off transmission pipes, and using nonsparking tools;
(vii) Prevent generation of contaminants by neutralizing or flushing out residual materials;
(viii) In testing for air contaminants use only approved instruments maintained in proper working order;
(ix) Continual monitoring of oxygen and contaminant concentrations during occupancy;
(x) If atmosphere-supplying respiratory equipment is used off this system shall meet the specifications of the "Compressed Gas Association (CGA)," to assure a supply of grade D or better air;
(xi) When atmospheric-supplying respiratory apparatus is used, personnel should be trained in the proper use of such apparatus; and
(xii) Many employers use tags to show that a confined space may be entered safely. An example of such a tag is as follows:
(2) Emergency rescue procedures.
(a) In all cases when an employee is stationed outside a compartment, tank, or space, as a tender for the employees working inside, the tender shall have immediately available for emergency use all necessary personal protective equipment. The tender shall wear the personal protective equipment if exposed for prolonged periods which are hazardous to the tender's health.
(b) When entering a toxic or flammable atmosphere, an employee shall be provided with, and use, an adequate, attended lifeline.
Last updated June 30, 2025 at 8:35 AM
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