ISO 14164:1999 定常発生源排出量—ダクト内のガス流の体積流量の決定—自動化された方法 | ページ 5

3.1

automated flow-measuring system

AMS

system that may be attached to a duct to continuously measure and record the volume flow of a gas

3.2

analyzer

that part of an AMS that measures the parameters used to calculate the volume flow of a gas

3.3

duct

stack, chimney or final exit duct on a stationary process, used for the dispersion of residual process gases

3.4

comparative measurements

measurements of volume gas flow in the duct by the AMS under test (evaluation) and compared to volume flow simultaneously determined in the same duct in accordance with ISO 10780

3.5

comparative method

method for determination of volume gas flow in a duct in accordance with ISO 10780

Note 1 to entry: Since the purpose of the comparative test is to demonstrate that the AMS under test yields an accurate estimate of the volume flow in the duct, it is necessary for the comparative method to measure the volume flow profile of the entire duct. An AMS cannot be used as the comparative method because all AMS used for measuring volume flow measure the velocity in a small area of the duct and then extrapolate this measurement to obtain the volume flow in the duct.

3.6

standard deviation

s_A

a measure of the working precision of the installed AMS

Note 1 to entry: It is derived using the differences between the pairs of volume flow values obtained by comparative testing of the AMS against ISO 10780 on the basis that a statistically sufficient number of comparative measurements are taken over the period of unattended operation (see annex A). The value of s_A is expressed as a function of the full-scale range of the AMS and is calculated on the assumption that s_A is an estimate of the precision of a normally distributed set of measurements.

Note 2 to entry: Whenever possible, the comparative method should measure the same portion of the gas flow as the AMS.

Note 3 to entry: It is not possible to determine directly the standard deviation of an AMS in a laboratory, because wind tunnels do not normally reproduce all the properties of stack gases and do not replicate all possible measurement conditions. This is the reason the standard deviation is determined after the AMS has been installed in the duct. Applying the comparative method in conjunction with the test for systematic errors (see A.4.2.3) ensures that the AMS has a satisfactory accuracy.

Note 4 to entry: In addition to random error, s_A contains the effect that local site variables such as changes in the gas steams temperature, fluctuations in the electrical power supplied to the AMS and zero and span drift have on the overall precision of the AMS. It also includes the standard deviation of the comparative method. s_A is an estimate of the upper limiting value for the precision of the AMS.

Note 5 to entry: The procedure in this International Standard is suitable for finding the uncertainty of the data obtained from the AMS, as long as the standard deviation of the measured values of the comparative method, s_c, is significantly smaller than the standard deviation, s_D, of the difference between the pairs of measured values.

3.7

period of unattended operation

period for which given values of the performance characteristics of an instrument can be guaranteed to remain within 95 % probability without servicing or adjustment

[SOURCE:ISO 6879]

Note 1 to entry: For long-term monitoring installations, a minimum of seven days of unattended operation is required.

3.8

response time

time it takes the AMS to display 90 % of the high-level calibration value on the data acquisition system, starting from the time of initiation of the high-level calibration cycle

Note 1 to entry: The response time may be determined either in the laboratory or after the AMS is installed.

3.9

stationary source emission

gas emitted by a stationary plant or process and transported to a duct for dispersion into the atmosphere

3.10

calibration

<of an AMS> the setting and checking of the installed AMS before determining its performance characteristics or before beginning any volume flow measurement

3.11

calibration function

correlation over the span range of the AMS between the volume flowrate of the duct as measured by the installed AMS and as measured in accordance with the reference flowrate

Note 1 to entry: ISO 10780 is an example of a reference flow standard.

Note 2 to entry: A nonlinear calibration function is acceptable, provided this nonlinearity is compensated for in the output of the AMS.

3.12

linearity

measure of the degree of agreement between the measurements of the comparative method (ISO 10780) and the AMS when the differences between the AMS and the comparative method across a range of volume flows are subjected to a linear regression

3.13

span

difference between the AMS output (reading) for a known flowrate and a zero flowrate

3.14

zero drift

change in the output of the AMS over a stated time interval when exposed to an unchanging zero flowrate

3.15

span drift

change in the output of the AMS over a stated time interval when exposed to an unchanging flowrate near the span value

3.16

AMS location

point in the duct where the AMS is installed