envea VIEW 370, Руководство пользователя

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Appendix A – Scaling VIEW 370/373
40
(PC-000855-MA Issue 6, December 2021)
ENVEA UK Ltd
Appendix A – Scaling
Introduction
VIEW 370 (373) sensors attached to a control unit can be calibrated in mg/m³ in
certain applications.
NOTE
Calibration of each sensor is necessary on at least an annual basis
and should be carried out either by ENVEA or an authorized
representative.
The calibration (scaling) of the sensor is carried out with reference to an isokinetic
sample (manual stack method). Isokinetic sampling should be carried out to the
relevant standards as defined by your local environmental authority or
government agency.
At its simplest level, the calibration procedure is carried out to calculate a Scaling
Factor used to scale up the raw sensor readings into a true dust concentration
value displayed directly in mg/m³. The use of a simple calibration (scaling) factor
is possible since the response of the instrument is directly proportional to the dust
concentration over a predefined range.
Calculating the Scaling Factor
The basic method to calculate a new Scaling Factor (SF) uses the following
formula:
New Scaling Factor =
Current Scaling Factor x (Test Result/Sensor Average)
where
• The Test Result is the result obtained from a single sample of the stack.
• The Current Scaling Factor is the calibration (or scaling) factor entered
into the instrument at the time of sampling. The default is 1.0.
• The Sensor Average is the average of the readings displayed in your
control unit using the Current Scaling Factor.
Example:
• Sampling test result = 50 mg/m³
• Current Scaling factor setting = 2.5
• Instrument average = 20 units
• New Scaling Factor = 2.5 x (50 / 20) = 6.25
Calibration Procedure
To obtain a valid Scaling Factor, carry out the following procedure:
1. Ensure that the sensors and control unit are running properly and that the
plant is running normally with representative conditions.
2. Carry out an isokinetic test.