envea STACK 602, User Manual

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STACK 602 Appendix A – Alignment
ENVEA UK Ltd
(PC-000848-MA Issue 5, December 2021)
61
Appendix B – Calibration
Introduction
STACK 602 sensors attached to the control unit can be calibrated in mg/m³ in
certain applications. Calibration is carried out with reference to an isokinetic
sample (manual stack method). The isokinetic sample should be carried out to
the relevant standards as defined by your local environmental authority or
government agency.
NOTE
: Calibration of each sensor is necessary on at least an annual basis and should be
carried out either by ENVEA or an authorised ENVEA representative.
At its simplest level, the calibration procedure is carried out to calculate a calibra -
tion (or scaling) factor that is used to scale up the raw sensor readings into a true
dust concentration value, which is displayed in mg/m³. The use of a simple
calibration (or scaling) factor is possible since the response of the instrument is
directly proportional to the dust concentration over a predefined range.
Calculating the Calibration Factor
The basic method to calculate a new Cal Factor a sensor uses the following
formula:
New Cal Factor =
Current Cal Factor x (Test Result/Sensor Average)
 The
Test Result
is the result obtained from a single sample of the stack.
 The
Current Cal Factor
is the calibration factor entered into the instrument
at the time of sampling. (NB, the default Cal Factor setting is 1.0.)

The Sensor Average is the average of the readings displayed in your control
unit using the current calibration (scaling) factor.
Example:
 Sampling test result = 50 mg/m³
 Current Cal factor setting = 2.5
 Instrument average = 20 units
 New Cal factor = 2.5 x (50 / 20) = 6.25
Calibration Procedure
1. Ensure that the sensors and control unit are running properly and that the
plant is running normally for representative conditions.
2. Carry out an isokinetic test.
3. Calculate the average sensor response displayed in your control unit (Sensor
Average) and record the sensor settings.
4. Obtain the isokinetic sampling results (Test Result).
5. Calculate the new Cal Factor (as outlined above).