• Glossary of Occupational Safety and Health TermsGeneral Gas Education

       
    Term Definition
    dB:
    Decibel – A unit used to measure the relative power of sound. A 3 dB increase in sound output power represents a doubling of the perceptible volume.

    eV:
    Electron Volt – A measurement of energy equal to the amount of energy it takes to move 1 electron through 1 volt of potential.

    IDLH:
    Immediately Dangerous to Life and Health - The maximum concentration of gas (in PPM) from which a worker could escape within 30 minutes without experiencing any escape-impairing or irreversible health effects.

    LEL/LFL:
    Lower Explosive Limit/Lower Flammable Limit - The minimum concentration at which a gas will explode. A common unit of measurement is a percent of the LEL.

    mA:
    Milliamp - A unit of electric current expressed in amperes.

    PEL:
    Permissible Exposure Limit - Level of gas (in PPM) a worker can be exposed to 8 hours a day / 40 hours a week for the rest of their life with no long term health effects.

    PID:
    Photoionization Detector – An instrument that utilizes ultra-violet light energy to ionize and detect the presence of an unknown gas or vapor.

    PPM:
    Part Per Million - A common unit of measurement for toxic gases. This term literally means one part out of one million possible parts.

    TLV-STEL:
    Short Term Exposure Limit - The average amount of gas (in PPM) a worker can be exposed to in a 15 minute period with no long term health effects. This may occur 4 times a shift with one hour between 15 minute exposures.

    TLV-TWA:
    Time Weighted Average - The average amount of gas (in PPM) a worker can be exposed to over a certain time period. This time is defined as 8 hours to represent a normal work day.

    TLV:
    Threshold Limit Value - A term used to signify limits in gas exposure. TLV is used as a prefix for TWA and STEL.

    UEL/UFL:
    Upper Explosive Limit/Upper Flammable Limit - The maximum concentration at which a gas will explode.

    VAC:
    Volts Alternating Current - An electric current that reverses direction at regular intervals.

    VDC:
    Volts Direct Current - An electric current of constant direction.

    VOC:
    Volatile Organic Compound – Any compound containing carbon, except methane, that can be readily vaporized.

  • Online Videos Icon

    Learn at Your Own Pace

    Watch these conveniently chaptered videos which enable you to target the information you need. See more...

Top