Pressure change effects on hypodermic needle critical orifice air flow rates.

Urone, Paul Peter; Rosse, Richard C.

doi:10.1021/es60151a016

Cited by 4 publications

(3 citation statements)

References 3 publications

(4 reference statements)

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“…The orifice moves, by a threaded drive connected to a dc motor, at a rate of 1 mm in 1.84 hour forming a continuous sample 'streak' of 4 mm by 172 mm in 13 days of sampling. The air flow rate is limited by the uniform size and density of the filter to 0.8 liter min -•, equivalent to 0.0285 standard cubic meters (SCM) per hour for average pressure at MLO after correction for pressure effect on orifice-limited flow [Urone and Ross, 1979]. A temperature correction, generally less than 10%, was not applied.…”

Section: Sampling and Analysissupporting

confidence: 62%

Aerosol characteristics at Mauna Loa Observatory, Hawaii, after east Asian dust storm episodes

Darzi¹,

Winchester²

1982

J. Geophys. Res.

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Concentrations of elements, including S, Al, Si, K, Ca, Ti, and Fe, in aerosols sampled sequentially with 3.7‐hour time resolution over a 2‐week period in April and May 1979 at the Mauna Loa Observatory, Hawaii, indicate that long‐range transported ‘background’ crustal dust aerosol can reach concentrations in excess of 20 μg m−3 with more than 8μg m−3 of additional sulfate. Favorable regional meteorology after known dust storm episodes, as well as similarities in crustal element ratios, point to dry areas of northern China as the major source region for this crustal aerosol. Time series analyses for crustal elements show a dominant 21‐hour but no 24‐hour period, a result that can be accounted for by a diurnally varying source process with subsequent modification of periodicity, e.g., by wind speed convergence during transport. Time‐dependent associations between S and the crustal elements, especially high coherency at long periodicities, also imply a long‐range transport for much of the S, possibly from populated areas in eastern Asia, including China and Japan. This source may contribute much of the sulfuric acid believed to cause the relatively high acidity of rainwater observed at higher altitudes in Hawaii. Mauna Loa Observatory, at 3400 m altitude, is apparently an excellent location for detecting Asian dust and pollutant transport during spring with little interference from Hawaii‐derived aerosol.

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Section: Sampling and Analysissupporting

confidence: 62%

Aerosol characteristics at Mauna Loa Observatory, Hawaii, after east Asian dust storm episodes

Darzi¹,

Winchester²

1982

J. Geophys. Res.

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show abstract

“…While rotometers, restricted orifices, 14 pitot tubes, and mass flowmeters 9 may come with certified calibration curves or may even be calibrated on-site, once installed in a totally configured device, these curves are often not applicable. System backpressure, nonuniform temperatures, poor laminar flow characteristics, partial plugging from sample particulates, plumbing leaks, and other anomalies can affect some or all of the above sensing elements thereby giving invalid results.…”

Section: Resultsmentioning

confidence: 99%

A New Microprocessor-Controlled Dynamic Olfactometer

Stordeur

Levine

et al. 1981

Journal of the Air Pollution Control Association

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“…Sampling· time was 2 hours. Critical orifices controlled the flow through each filter, and care was taken to keep filter loading low enough so that the pressure drop across the critical orifices did not change during collection (Urone and Ross, 1979). Two optional techniques were used to dry the droplets so that reactions involving liquid water did not occur on the filters.…”

Section: Introductionmentioning

confidence: 99%