Ceiling limit

The TLV Hsted is a ceiling limit and should never be exceeded. 

Health and Safety. Halosilane vapors react with moist air to produce the respective hydrohalogen acid mist. Federal standards have not set exposure to halosilanes, but it is generally beheved that there is no serious risk if vapor concentrations are maintained below a level that produces an irritating concentration of acid mist. The exposure threshold limit value (TLV) for HCl is 5 ppm, expressed as a ceiling limit. Because most people experience odor and irritation at or below 5 ppm, HCl is considered to have good warning properties. 

PEL = personal exposure limit LEL = lower exposure limit UEL = upper exposure Ceiling limit is the concentration that should not be exceeded during any part of the working exposure relative vs -butyl acetate = 1, Relative to air = 1. 

Safety. Chlorosulfuric acid is a strong acid and the principal ha2ard is severe chemical bums when the acid comes into contact with body tissue. The vapor is also ha2ardous and extremely irritating to the skin, eyes, nose, and respiratory tract. Exposure limits for chlorosulfuric acid have not been estabhshed by OSHA or ACGIH. However, chlorosulfuric acid fumes react readily with moisture in the air to form hydrochloric and sulfuric acid mists, which do have estabhshed limits. The OSHA 8-h TWA limits and ACGIH TLV—TWA limits are sulfuric acid = 1 mg/m hydrochloric acid = 5 ppm or 7 mg/m (ceiling limit). 

TLV-C is defined as the tlireshold limit concentration value ceiling that should not be c.xccedcd during any part of the working e.xposure. This ceiling limit places a definitive boundtiry on concentrations of toxic or otlicrwisc hazardous substances tliat should not be exceeded. 

Tlireshold limit values (TLVs) can be categorized by a time-weiglited average taken for a nonnal 8-hour workday and a nonnal 40-hour workweek. A short temi e.vposure limit tliat is taken for a period of time not exceeding 15 minutes. A ceiling limit vtilue that is not to be exceeded at any time. 

NIOSH Ceiling Limit (NIOSH CL) NIOSH-recommended l5-min e.xposure limit, which should not be exceeded. 

The TLV may be expressed as a Time Weighted Average (TWA), as a Short-Term Exposure Limit (STEL), or as a ceiling limit (CL). 

Threshold Limit Value (TLV)—An American Conference of Governmental Industrial Hygienists (ACGIH) concentration of a substance to which most workers can be exposed without adverse effect. The TLV may be expressed as a Time Weighted Average (TWA), as a Short-Term Exposure Limit (STEL), or as a ceiling limit (CL). 

Immediately dangerous to life or health (IDLH) levels are the ceiling limit for respirators other than SCBAs. Any exposures approaching the IDLH level should be regarded with extreme caution and the use of SCBAs for respiratory protection should be considered. 

Zinc oxide, fume and dust, ceiling limit 15 mg/m3 38... 

Ceiling limit. The concentration that should not be exceeded, even instantaneously. 

The use of TLV-STELs and ceiling limits may be most appropriate if the objective is to identify effect zones in which the primary concerns include more transient effects, such as sensory irritation or odor perception. In general, persons located outside the zone that is based on these limits can be assumed to be unaffected by the release. 

TIN-TWA Threshold limit value, time-weighted average for 8-h exposures, with ceiling concentrations shown as C, and with skin absorption hazard as S. The OSHA permissible exposure limit (PEL) is the lower of the TWA or the ceiling limit. 

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