Instruction Manual
SPS 4001B
THEORY OF OPERATION
The Oxymitter 4000 is one of the few instruments found in industry that permit the permanent piping of a calibration standard into the probe. Most instruments measuring pressure, flow, or temperature, require that a calibration standard be brought to the instrument or that the instrument be taken to the calibration source in the instrument shop.
The permanent calibration gas connections allow for autocalibrations to occur without operator intervention. The following paragraphs describe how an Oxymitter 4000 is autocalibrated when used with the SPS 4001B.
In addition to the calibration methods available via the Oxymitter 4000 keypad, HART communicator, AMS software, or a remote contact, the SPS 4001B works in conjunction with the Oxymitter 4000's CAL RECOMMENDED feature to perform an autocalibration.
This feature automatically performs an impedance check every hour on the Oxymitter 4000. If a calibration is recommended and its contact output signal is set for "handshaking" with the SPS 4001B sequencer, the Oxymitter 4000 sends a signal to the sequencer. The sequencer automatically performs a calibration upon receiving the signal. Therefore, no human interface is required for the automatic calibration to take place.
See Figure
Calibration gas 1 then flows through the sequencer to the Oxymitter 4000. The Oxymitter 4000 measures the oxygen content of calibration gas 1 and sends a signal to the sequencer indicating that it received the gas. When the sequencer receives the signal, the PLD deenergizes the calibration gas 1 solenoid.
Next, the PLD energizes the calibration gas 2 (low O2) solenoid, and calibration gas 2 then flows through the sequencer to the Oxymitter 4000. The Oxymitter 4000 measures the oxygen content of calibration gas 2 and sends a signal to the sequencer indicating that it received the gas. After measuring the two calibration gases, the Oxymitter 4000 automatically makes an internal calibration adjustment and sends the signal to the sequencer. When the sequencer receives the signal, the PLD deenergizes the calibration gas 2 solenoid.