Podcast
Questions and Answers
What do you use the APM 421 Calibrator for?
What do you use the APM 421 Calibrator for?
To calibrate the flow rate of Respirable Dust Samplers (RDS) in the field.
How often should flow rate calibration be verified for instruments used in the field?
How often should flow rate calibration be verified for instruments used in the field?
What is the recommended flow rate for the RDS?
What is the recommended flow rate for the RDS?
1 m³/min
A multi-point calibration should be performed every month.
A multi-point calibration should be performed every month.
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A digital barometric pressure indicator is supplied by __________ at an extra cost.
A digital barometric pressure indicator is supplied by __________ at an extra cost.
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What should you apply if field conditions differ from lab conditions by more than 4%?
What should you apply if field conditions differ from lab conditions by more than 4%?
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Match the following terms with their definitions:
Match the following terms with their definitions:
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What are the units used for pressure measurement as per calibrator instructions?
What are the units used for pressure measurement as per calibrator instructions?
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Study Notes
APM 421 Calibrator Overview
- Designed for calibrating the flow rate of Respirable Dust Samplers (RDS) in field conditions.
- Includes components such as a Top Loading Calibrator, Air Inlet Coupler, perforated plates, and a carrying case.
- Each calibrator is tested against an NABL traceable primary standard roots meter.
- Calibration should be verified at least every six months and after any major repairs.
Preparing the Sampler and Calibrator
- Check and ensure the filter clamp gasket of the RDS is in good condition; do not place a filter inside.
- Mount the Air Inlet Coupler over the threaded air inlet pipe and secure with a perforated plate.
- Ensure no air leakage by using provided O-rings on the coupler and calibrator.
- Connect the Differential Pressure Meter to the calibrator and check the water level in the manometer.
Performing a Calibration Check
- Power on the RDS and stabilize the blower before noting the flow rate via the Orifice meter.
- Activate the Differential Pressure Meter on the Calibrator to measure the pressure across the calibrated orifice.
- Use the Calibration Curve provided to determine the actual flow rate.
- Perform regular checks at a typical flow rate of 1 m³/min, ideally with a audit check performed monthly.
Calibration Error and Adjustment
- If flow rate error exceeds 5%, a multi-point calibration should be completed to find a correction factor.
- Multi-point calibration is recommended at least once a year for accuracy.
Barometric Pressure and Temperature Correction
- The APM 421 Calibrator comes with a calibration certificate indicating lab conditions (temperature, pressure).
- Correct for field conditions if they differ from lab conditions by more than 4% in pressure or 15°C in temperature.
- An optional digital barometric pressure indicator can be supplied to measure site atmospheric pressure.
Pressure/Temperature Correction Calculation
- Use the gas laws for calculations: (P1 x V1) / T1 = (P2 x V2) / T2.
- Rearranging the equation allows the determination of the flow rate under field conditions.
- Consistent units must be used, and temperature should be converted to Kelvin for calculations.
- The "TRUE Flow Rate" at site conditions can be calculated after applying the necessary corrections.
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Description
This quiz covers the essentials of the APM 421 calibrator, focusing on its design for calibrating Respirable Dust Samplers and the necessary components involved. Additionally, it includes guidelines for preparing the sampler and calibrator effectively. Make sure you understand both the operational aspects and the maintenance practices discussed.
