Glossary of Terms: T

T60
Time taken for a detector to reach 60% of its final reading.
T90
Time taken for a detector to reach 90% of its final reading.
Temperature
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.
Thinner
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.
Threshold
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.
TLVs
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.
Toxic
Harmful or poisonous.
Toxicity
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.