Calibration of Industrial Hygiene Instruments. David Silver, CIH. Industrial Hygiene Issues. Accurate & repeatable measurements. Analytical results and confidence limits. Uncover the mystery of annual calibrations. Field calibrations vs. annual calibrations. Successful Outcomes.
David Silver, CIH
Metrology establishes the international standards for measurement used by all countries in the world in both science and industry
Examples: distance, time, mass, temperature, voltage, values of physical and chemical constants
Direct reading instrument, sampling.
Measurement or analysis.
Results – variability.
SI: The International System of Units
Lots of derived units:
Seven base units:
Length: meter (m)
Mass: kilogram (kg)
Force: 1 Newton = 1 kg·m/s2
Time: second (s)
Voltage: 1 volt = 1 m2·kg/s3·A
Electric current: ampere (A)
Frequency: 1 hertz = 1/s
Thermodynamic temperature: Kelvin (K)
Power: 1 watt = 1 kg·m2/s3
Electric Charge: 1 C = 1 A·s
Amount of substance: mole (mol)
Luminous intensity: candela (cd)
One part per quadrillion accuracy!!!
Accurate frequency gives accurate distance and time.
The modern meter:
A metal bar:1889-1960
The meter is the length of the path traveled by light in vacuum during a time interval of 1/299,792,458 of a second
The SI kilogram drifts!
Goal: 10 parts per billion accuracy
Avogadro’s number6.0221415 × 1023
The Kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.
Most technologically advanced countries.
From Article I, section 8 of the U.S Constitution:
“The Congress shall have Power To…
…fix the Standard of Weights and Measures;”
Soap bubble meter.
Pump is attached to the top of a volumetric glass tube containing a small amount of liquid soap. While the air flow causes the soap film to move from one volume mark to another, the travel time is measured with a stopwatch. The flow rate can then be directly calculated using the travel time and the known tube volume.