Signal Output
Zeroing signal output
The function of 
ZERO 
is to subtract a constant background signal from the detector signal. Background signal sources include the detector itself (background level depending upon detector type), column bleed, or contaminants in supply gas(es).
Displaying current | ZERO | setpoint |
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Current ZERO | setpoint value is displayed by pressing the appropriate | |||||||||
signal channel key ( | SIG 1 |
| or SIG 2 | ), followed by | ZERO | (or simply press | ||||
ZERO | alone, if the desired signal channel is already displayed). Typical | |||||||||
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displays are shown in Figure 5•1. |
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Figure |
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| ACTUAL |
| SETPOINT |
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| SIG | 1 |
| ZERO |
| 104.5 |
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| ACTUAL |
| SETPOINT |
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| SIG | 2 |
| NOT |
| INSTALLED |
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| ACTUAL |
| SETPOINT |
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| ZERO | 1 | 104.5 | OFF |
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| ACTUAL |
| SETPOINT |
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| ZERO |
| LIMIT | = | 83000 |
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Typical ZERO | Displays |
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Table 5•1lists conversions between detector units and the scale used for | ||||||||||
ZERO setpoint values. |
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Table | Conversions from Detector Units to ZERO | Setpoint Val- | ||||||||
ues |
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| Conversion |
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Detector |
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| (1.0 | ZERO | unit = ) |
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FID & NPD |
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| 1.0 pA (1.0 } 10- 12 A) |
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TCD |
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| 25 ¿V (2.5 } 10- 5 V) |
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ECD |
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| 10 Hz |
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