Exhaust ventilation

areas or spaces in which explosive, corrosive, combustible, flammable or highly toxic dusts, mists, fumes, vapors or gases may be emitted shall be meehanieally ventilated as required by the Fire Code and the Meehanieal Code. 

Exhaust ventilation shall be provided to produce not less than one (1) eubie foot per minute, per square foot floor area, and shall be in accordance with UFC Articles 79 and 80. The design of the system shall be such that the emissions are confined to the area in which they are generated and shall be exhausted by a duct system to a safe location or treated by removing contaminants Separate and distinct systems shall be provided for incompatible materials (UMC 505.1). 

The location and means of discharging air to the atmosphere must be carefully considered. Care must be taken to avoid reintroduction of exhaust into outside air intakes. High velocity (greater than 3,500 FPM) vertical discharge is generally required to effect dilution of ihe potentially hazardous airstream with the ambient air. 

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It is good practice to keep concentrations of airborne nickel in any chemical form as low as possible and certainly below the relevant standard. Local exhaust ventilation is the preferred method, particularly for powders, but personal respirator protection may be employed where necessary. In the United States, the Occupational Safety and Health Administration (OSHA) personal exposure limit (PEL) for all forms of nickel except nickel carbonyl is 1 mg/m. The ACGIH TLVs are respectively 1 mg/m for Ni metal, insoluble compounds, and fume and dust from nickel sulfide roasting, and 0.1 mg/m for soluble nickel compounds. The ACGIH is considering whether to lower the TLVs for all forms of nickel to 0.05 mg/m, based on nonmalignant respiratory effects in experimental animals. 

At processing temperatures, most polymers emit fumes and vapors that may be irritating to the respiratory tract. This is also tme for PVC and its additives. Such irritation may extend to the skin and eyes of sensitive people. Processing emissions exposure can also be greatly reduced or eliminated by the use of properly designed and maintained exhaust ventilation. 

Although metallic antimony may be handled freely without danger, it is recommended that direct skin contact with antimony and its alloys be avoided. Properly designed exhaust ventilation systems and/or approved respirators are required for operations that create dusts or fumes. As with other heavy metals, orderly housekeeping practice and good personal hygiene are necessary to prevent ingestion of (or exposure to) antimony. 

Operations capable of generating airborne beryUium particulate, such as melting, machining, welding, grinding, etc, are effectively controUed by local exhaust ventilation or other control measures. To assure a safe environment and measure compliance with the OSHA standards, employee exposures should be periodicaUy measured by prescribed air sampling and analytical methods. 

Provide local exhaust ventilation connected to a disposal system (vent condenser, adsorber, scrubber or incinerator)... 

Beeause eomplete eontainment is physieally impraetieable in many eases, loeal exhaust ventilation is often applied to remove eontaminants. The objeetive is to extraet pollutant as near as praetieable to its souree and before it enters, or passes through, a worker s breathing zone. Vents should lead away from personnel to a safe loeation, with sembbing/filtering as appropriate. Common examples are ... 

As a standby for emergency use in case of accidental release of toxic materials, e.g. during tanker unloading, or disconnection of temporary pipelines or when dealing with spillages generally, or if other protective measures, e.g. local exhaust ventilation, fail in service. 

Dust from bulk fillers and whitings Local exhaust ventilation Care in handling... 

Dust from carbon black Master batches Local exhaust ventilation Totally enclosed systems Not by careful handling alone... 

Fume Local exhaust ventilation Removal of hot product from workroom -cool before handling... 

Calendering and extruding Fume Local exhaust ventilation Water cooling of extrudate... 

Curing Fume Local exhaust ventilation at autoclave door and storage racks Allow autoclave to cool before opening... 

Partial enclosure with local exhaust ventilation. 

An employer has speeifie obligations to ensure all eontrol measures are kept in an effieient state, effieient working order and good repair. Engineering eontrols should be examined and tested at suitable intervals, e.g. loeal exhaust ventilation equipment must be tested at least onee every fourteen months, and more often for proeesses speeified in Table 5.23, and a reeord kept. Respirators and breathing apparatus must also be examined frequently and the eheeks reeorded. 

Table 5.23 Frequency of thorough examination and test of local exhaust ventilation plant used in certain processes (Schedule 4, Reg. 9(2)(a)) ...

Provision and use of appropriate health surveillance, e.g. for signs of dermatitis, asthma, effects of specific solvent exposures. Full use of any spray booth, enclosure, exhaust ventilation or dilution systems, and automatic handling equipment. (The efficiency of all local exhaust ventilation and other control systems should be maintained, and checked by testing.) Where appropriate, atmospheric monitoring of airborne pollution levels. 

Provide and maintain efficient local exhaust ventilation, if enclosed plant cannot be used. 

The Occupational Exposure Standards imposed for trichloroethylene are Maximum Exposure Limits of 100 ppm (8 hr TWA) and 150 ppm (15 minute reference period). A skin notation Sk is applicable because of the potential for skin absorption. Because of its volatility, trichloroethylene is not recommended for cold cleaning it is normally used in partially enclosed vapour degreasing equipment provided with local exhaust ventilation. 

Partial enclosure with local exhaust ventilation, or local exhaust ventilation, of working position separate hazardous processes from other work, e.g. spray-painting with epoxy-containing sensitizing and carcinogenic compounds. 

Keep below LEL, e.g. chill to lower airborne concentration, use exhaust ventilation, inerting, keep air out. 

Design plant/equipment so as to contain the material and provide adequate dilution or exhaust ventilation as appropriate... 

Extent of emergency power supplies for lighting, communication systems, and key items of equipment (e.g. cooling facilities, reactor agitators, exhaust ventilation) and instruments/alarms. 

General conditions of work, e.g. maintenance of adequate general ventilation, local exhaust ventilation, access, lighting, fire precautions, occupational health measures, housekeeping. 

Local exhaust ventilation provisions (test and report at regular intervals)... 

HSG 54 Maintenance, examination and testing of local exhaust ventilation... 

Recordkeeping and analytical program for use in monitoring and maintenance of exhaust ventilation systems. Requires Apple II. 

Engineering eontrols are designed to eliminate or keep hazards away from a person. Examples inelude maehine guards on equipment, ground fault eireuit interrupters, loeal exhaust ventilation that removes eontam-inated air at the souree, and remote systems (like roboties) used to handle dangerous materials. 

Balanced mechanical supply and exhaust ventilation equipped with an advanced air distribution strategy to accurately control the flow patterns in a work space... 

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