Glossary of Terms: T

Time taken for a detector to reach 60% of its final reading.
Time taken for a detector to reach 90% of its final reading.
Product classification based on the hottest surface where igniting the product would
Thermal Conductivity
Method of detecting the level of gas using its properties of thermal conductivity.
A liquid (usually solvent-based) that is used to dilute paint, varnish, cement or other material to a desired consistency. Most thinners are flammable.
Threshold Limit Value (TLV)
A threshold limit value refers to the airborne concentration of a substance to which it is believed that nearly all workers may be repeatedly exposed day after day (for 8 hours per day) without harmful effect. A table of these values and accompanying precautions is published annually by the American Conference of Governmental Industrial Hygienists.
The lowest dose or exposure to a chemical (or sound) at which a specific effect is observed.
Time-weighted average (TWA)
Refers to concentrations of toxic material or sound which have been weighted for a certain time duration, usually 8 hours.
TLV-TWA; Threshold limit value-time-weighted-average for chemical substance concentrations for an 8-hour workday that workers may be repeatedly exposed to without adverse effects
Toxic Substance
Any substance that can cause acute or chronic effects to a person or is suspected to cause disease or injury under certain conditions.
Harmful or poisonous.
A relative property of a chemical agent and refers to a harmful effect on some biologic mechanism and the conditions under which this effect occurs.
Type 1, Type 2
Also called Class 1 and Class 2. This is an accuracy specification. There is an entire ANSI standard written around the difference between Type 1 and 2. The accuracy of the measurements varies depending on the frequency of the sound being measured. Basically Type 1 means approximately ±1dB accuracy and Type 2 means approximately ±2dB accuracy. But again, this varies depending upon the frequency of the sound.