cdem-1000 coal dust explosibility meter. coal dust explosions natural occurring methane in coal...
TRANSCRIPT
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CDEM-1000CDEM-1000Coal Dust Explosibility MeterCoal Dust Explosibility Meter
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Coal Dust ExplosionsCoal Dust Explosions
• Natural occurring methane in coal mines causes frequent explosions, which alone may not pose a major hazard.
• When a methane explosion prompts a coal dust explosion, the intensity is far greater.
• Coal dust explosions can cause deaths both directly and by trapping miners through mine cave-ins.
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Rock Dusting in Coal MinesRock Dusting in Coal Mines
• Coal dust explosions are averted in coal mines by applying layers of inert rock dust over the coal dust.
• The inert rock dust used in the US is commonly limestone, although marble dust may be used as well.
• MSHA may levy fines against coal companies that don’t maintain enough rock dust in their mines, based on a lab analysis.
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CDEM-1000CDEM-1000
• The CDEM-1000 uses reflectivity of rock dust/coal dust mixtures to determine the % rock dust in the mixture.
• This works, because coal dust is black and the rock dust is white. The lighter color the mix, the more rock dust it contains.
• MSHA requires a rock dust/coal dust mix of at least 80% rock dust.
• The CDEM-1000 is a go/no-go meter that produces a green indication for % RD above 80.
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CDEM-1000CDEM-1000
• The CDEM 1000 was developed by NIOSH at the Pittsburgh Research Laboratory.
• It is produced solely by Sensidyne, LP.• It has an MSHA approval for intrinsic safety.• It has been thoroughly field tested by both MSHA and
NIOSH.
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CDEM-1000 KitCDEM-1000 Kit
• The CDEM-1000 kit comes with all accessories required for field sampling.
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AccessoriesAccessories
• A) CDEM-1000• B) PPC Samples• C) Molecular sieves• D) Calibration vials• E) Calibration funnels• F) Spatula and brush• G) Sample vials• H) Sample funnels• I) Sample cups
A
G
H
I
F
E B
C
D
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Collecting a SampleCollecting a Sample
• A sample of the mine’s coal dust/rock dust mixture is taken from the mine floor and walls according to an MSHA procedure.
• It is transferred to a sample vial.
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Preparing a SamplePreparing a Sample
• The sample vial contains activated molecular sieves, small beads that absorb moisture.
• The beads are removed by a funnel with a small screen inside, as the sample is transferred to a sample cup.
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Sample SizeSample Size
• The dried sample is transferred to a sample cup, observing the cup’s fill line.
• The cup is placed against the CDEM-1000’s lens. A spillover is expected.
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Red/Green IndicationRed/Green Indication
• The CDEM unit is a go-no-go meter. It is not an analytical tool.
• A green indication means that the rock dust is present in the sample mixture at 80% or more.
• A red indication means that more rock dust must be applied.
• An extended red function allows the user to see a range that represents how close the mix is to green (e.g. 75 to 78%).
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Methane ConsiderationMethane Consideration
• The CDEM will ask the user to input a methane value for the area. This value is read from a separate methane meter.
• The user can input methane values from 0.0 to 2.0% methane in 0.1% increments as read from the methane meter.
• For each 0.1% of methane, the CDEM-1000 will slide the green criteria upward by 0.4% rock dust. For example, a reading of 0.5% methane inputted into the CDEM-1000 will raise the green indication from 80% to 82% (i.e., 5 x 0.4% = 2%).
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CalibrationCalibration
• The unit is calibrated by exposing the lens in turn to 100% PPC. 100% RD and an 80% mixture of the mine’s rock dust and the PPC provided.
• The CDEM-1000 walks the user through the calibration steps through the LCD display.
• A calibration is required every field 200 samples.
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Pittsburgh Pulverized CoalPittsburgh Pulverized Coal
• Calibration must be conducted using the PPC samples provided. They represent the coal dust particle size range that is most dangerous in mine explosions.
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Rock DustRock Dust
• Rock dust used in the calibration procedure must come from the mine. The rock dust used by the mine must meet the correct size distribution specified by MSHA.
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Reflectivity CheckReflectivity Check
• A reflectivity check is required after every 1000 field samples.
• The CDEM-1000 will prompt the user when the reflectivity check is due.
• To conduct this check, a special sample cup with a color standard permanently placed inside is exposed to the lens.
• This cup is matched to the CDEM-1000 unit by serial number.
• The unit will display a pass or fail based on its agreement with the standard’s % RD value, which is stored in the CDEM-1000’s memory.
• The reflectivity sample cup doubles as a protective cup for shipping. It attaches to the unit bayonet style.
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Thank YouThank You