3M eg4 PEL Permissible Exposure Level, Projected Time, Random incidence microphone, Response Time

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Appendix B

Glossary of Terms

PEL (Permissible Exposure Level)

The A-weighted sound level at which exposure for a Criterion Time, typically eight hours, accumulates a 100% noise dose.

Projected Time

The variable amount of time used to make a projected dose calculation from an actual dose measurement.

Random incidence (microphone)

This only applies to Class/Type 1 microphones. Measurements made in an area where sound waves are coming from all directions, including reflections and diffractions. When the dosimeter is being used as a sound level meter in an area where reflections and diffractions from nearby objects are present, use the Random Incidence Corrector with the microphone, and angle the microphone at approximately 70 degrees. Most personal noise dosimetry applications do not require the random incidence corrector, since they are not measured with a Class/Type 1 microphone.

Response Time

The response determines how quickly the unit responds to fluctuating noise. Fast has a time constant of 125 milliseconds. Slow has a time constant of 1 second. Example: Typically, noise is not constant. If you were to try to read the sound level without a response time, the readings would fluctuate so much that determining the actual level would be extremely difficult. Using a response of slow or fast simply smoothes the noise fluctuation and makes the sound level easier to work with. While the terms slow and fast have very specific meanings (time constraints), they work very much as you would expect. The fast response would result in a more fluctuating sound level reading than would the slow response. The OSHA regulations require the slow response.

RMS (Root Mean Square)

The RMS voltage of a signal is computed by squaring the instantaneous voltage, integrating over the desired time, and taking the square root. Simply put, the RMS values are the results from the dosimeter with the response time and weighting settings taken into account.

SEL/Lxe (Sound Exposure Level)

The sound exposure level averages the sampled sound over a one second period. Assuming the sampled run time to be greater than one second, SEL is the equivalent one-second noise that would be equal in energy to the noise that was sampled. SEL is typically measured using a 3dB exchange rate without a threshold. SEL is not used by OSHA. Example: Suppose you wanted to measure in a location next to railroad tracks, which also happened to be in the takeoff path of an airport. A train passes by taking 10 minutes with an average sound level of 82dB. A jet passes overhead taking 45 seconds with an average level of 96dB. Which of these events results in more sound energy? You can answer the question by comparing their SEL readings, which compress each event into an equivalent one-second occurrence. SEL for the train = 109.7dB, SEL for the jet = 112.5dB.

053-644, Rev H

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eg4

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Contents 3M The Edge Personal Noise Dosimeter EdgeTable of Contents Time history…………………………………………………………………………………………………… Setting-up the Edge via DMSViewing measurements on the display Stopping a studyTechnical Support Replacing microphone and windscreenINDEX………………………………………………………………………………… Physical attributes of EdgeDock1 and EdgeDock5List of Tables List of FiguresEdge and dosimetry DosimetryIllustration of how the dosimeter operates and processes Noise dosimeterWhat do the standards say? Range of soundApplications of the Edge Noise assessment steps Setting-up your dosimeter parameters for your noise studiesRunning your studies View your results via DMSEdge Model Parameter setup screen for eg4Identifying your equipment Checking the equipmentTurning on LED indicatorTurning off LED indicators explainedDisplay and keypad Diagram3MTMDetection Mangement Software DMS Docking station functionalityLoading Docking station components EdgeDock1 or EdgeDock5EdgeDock1 and EdgeDock5 components  Powering EdgeDock1 or EdgeDock5 Powering EdgeDock1 or EdgeDock5Charging your dosimeter  How to chargeStoring the dosimeter Mounting the docking station to a wallNoise studies Understanding what data is storedTime history Summary dataLogging Views on the EdgeDefinitions of data log values and views Views on ExplanationDosimeter views and definitions Views on Explanation Edge WeightingDose Response LevelDosimeter measurement descriptors/variants Descriptors Variants Lmax variantsCommunicating & downloading data DockingNew Hardware wizard for Edge Dock Customizing set-up parameters in DMSDosimeter screen Dosimeter settingDosimeter fields explained for the Edge Edge dosimeter settingsEdge display screen Display settingEdge security setting Security settingEdge auto run screen Auto Run setting10 Edge firmware update screen Firmware update11 Saving and sending Edge setups Saving and sending/setting configurationsQuick Help List typical dosimetry session Overview of running a studyWindscreen and maintenance  How to attach the dosimeterPositioning the Edge on your shirt  Checking battery power Checking battery power Calibrating the dosimeter Calibrating Reset Resetting the dosimeterSetting contrast on dosimeter  ContrastOn/off/enter button  How to run a noise study Running studiesStarting a run  How to stop a noise study Indicators/Icons on the displayIndicator Icon Explanation Indicators i.e., run, stop, battery, and OLViewing measurements on the display Locking or securing your dosimeter during run Viewing measurements  How to unlock  How to lock or secureLocking or Securing Unlocking Downloading Downloading dataDMS start screen  Selecting and viewing data Viewing data and data finderExample of Edge Report in DMS Report ViewPanel layout view viewing the data in charts and graphs Panel Layout Viewcharts/graphsTechnical Support LED indicator disable/enableReplacing microphone and windscreen Attaching/Detaching Attaching/Detaching the windscreen and microphone Hard Hat Attachment kit Hard Hat Attachment KitStandards Mechanical characteristicsElectrical characteristics Environmental effectsUser Interface Physical attributes of EdgeDock1 and EdgeDock5 EdgeDock1 and EdgeDock5Measurements TypesMeasurement parameters Special functions CommunicationsSecurity Auto-RunEdge Block Diagram Edge Block Diagram Appendix B Warranty 3M ServiceService Department and Technical Support 1 800 Contacting 3MBackground Noise, effects Glossary of TermsCombining Noise sources Crest FactorCriterion Level CL Decibel dB Criterion TimeDose Exchange Rate ER also known as the Doubling RateHearing Conservation HC Hertz Hz Free field setting microphoneLavg Average Level Lep,dLogging Leq Equivalent LevelMaximum Level Lmax Measurement RangeProjected Time PEL Permissible Exposure LevelRandom incidence microphone Response TimeThreshold TWA Time Weighted AverageWeighting A, C, Z, etc Upper Limit ULWindscreen Measurement equations Index Running studies About Us About 3M Personal Safety
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