Teledyne BDS-3960 - Oxygen analyzer - Manual (Page 53)

Oxygen Analyzer Maintenance
Teledyne Analytical Instruments 53
4.6 The Range Function
The Range function allows the operator to program up to four
concentration ranges to correlate with the DC analog outputs. If no
ranges are defined by the user, the instrument defaults to:
Range 1 = 0–100 ppb
Range 2 = 0–1000 ppb
Range 3 = 0–10000 ppb
Range 4 = 0–100000 ppb
The Model BDS 3960 is set at the factor y to default to autoranging. I n
thi s mode, the PPC applicat ion automati cally responds to concentration
changes by swit ching ranges for optimum readout sensitivi ty. If the current
range lim its ar e exceeded, the instrument wil l automatically shift to the next
higher range. I f the concentration fall s to below 90% of full scale of the
next lower range, the instr ument will switch to that range. A corresponding
shi ft in the DC percent-of- range output , and in the range ID outputs, will be
not iced.
The autoranging feature can be overridden so that analog output
stays on a fixed range regardless of the oxygen concentration detected. If
the concentration exceeds the upper limit of the range, the DC output
will saturate at 1 VDC (20 mA at the current output).
Even if the output is set to a fixed range, the digital readout of the
concentration is unaffected by the fixed range. It continues to read
accurately with full precision. See Front Panel description in Chapter 1.
The automatic fourth range is always 0-100000 ppb (100 ppm) and
should not be adjusted.
4.6.1 Setting the Analog Output Ranges
To set the ranges, click on the list box on the main screen. The
following options will pop down.