Improving the dynamic response of continuous air pollutant measurements with a computer

Journal Article · Fri Jan 01 04:00:00 EST 1965 · J. Air Pollut. Control Assoc.; (United States)

DOI:https://doi.org/10.1080/00022470.1965.10468327· OSTI ID:5315919

Larsen, R I; Benson, F B; Jutze, G A

A first-order differential equation describes the dynamic response of many continuous air sampling instruments: C/sub t/ = C/sub i/ + p(dC/sub i//dt), where C/sub t/ is true concentration, C/sub i/ is indicated concentration, p is the time constant, and t is time. The time constant, lag time, delay time, and response time are all functions of the volume and flow through the sensor reservoir. All of them can be expressed by the same general equation: t = k/sub 3/V/Q, where t is the selected time variable, k/sub 3/ is a constant appropriate to the particular system and selected time variable, V is sensor reservoir volume,and Q is the flow rate through the reservoir. The time constant is the time a sampler takes to indicate 63.2 percent of its final response. Selection of such a time constant eliminates spurious noise produced by a fast-responding system. It also provides values within 5 percent of true for atmospheres that change markedly between successive intervals. If a slow-responding system must be used, use the first equation to increase apparent response time. A digital computer can be programmed to automatically correct all measure values. Similarly, analog circuitry can be installed in an air sampling instrument to increase or decrease response time. The analog circuitry to increase response time will continuously solve and plot the first equation. 8 references, 9 figures, 1 table.

• Research Organization: R.A. Taft Sanitary Engineering Center, Cincinnati, OH
• OSTI ID: 5315919
• Journal Information: J. Air Pollut. Control Assoc.; (United States), Journal Name: J. Air Pollut. Control Assoc.; (United States) Vol. 15:1; ISSN JPCAA
• Country of Publication: United States
• Language: English

Related Subjects

500200* -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
AIR POLLUTION
AIR POLLUTION MONITORING
COMPUTER CALCULATIONS
COMPUTERS
MATHEMATICAL MODELS
MEASURING METHODS
MONITORING
POLLUTANTS
POLLUTION
SAMPLING