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8.5.9 Parameter 11: Display Intercept "a" (Integer) -99...099 [mg/m3]
The instrument can be set to show mg/m
form y = a + bx.
Parameter 11, 12, 13 and 14 will NOT change the actual mA-output signal.
These parameters are used to show mg/m
regression curve
The following glossary is based on the terminology used in the European stack testing regulations.
AMS
Automatic Measurement System
(in this case Dumo)
SRM
Standard Reference Method
(usually Gravimetric Sampling)
Example calculation:
yi [mg/m3]
Point 1
6,00
Point 2
19,00
1. Calculate the slope b by the two-point form of a straight line
b = y
-y
/x
-x
2
1
2
1
In our case: b = 19,00-6,00 / 17,00-9,00 = 1,625
2. Resolve the equation y
a = y
- b x
i
i
3. Calculate the intercept a by inserting x and y of either of the points
a = y
- bx
1
1
The values for the intercept a and the slope b are split into an integer and decimal part.
To change the integer part of the intercept a, follow the below procedure:
Navigate to Parameter 11 by pressing K1
Key the calculated value into the instrument -99...099 [mg/m3], default = 0 [mg/m3]
Safe the result by pressing K3
by utilizing a linear regression line which has an equation of the
3
xi [mA]
Comment
(In a simple one-point calibration 4 mA would equal 0 mg/m3)
9,00
(Result of the gravimetric sampling)
17,00
= a + b x
to the intercept a
i
i
In our case: a = 6,00 – 1,625*9,00 = -8,625
Figure 19: Example for display calibration
on the local display according to the defined linear
3
y
Result of SRM [mg/m
a
The Intercept [mg/ m
b
The Slope [mg/ m
x
Result of AMS [mA]
]
3
] (Par. 11,12)
3
3
/mA] (Par. 13,14)
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