Campbell Scientific AP200 CO2/H2O Atmospheric Profile System - Manual (Page 74)

Appendix B. AP200 Diagnostics
Also check the measured pump temperature, pump_tmpr and compare it to
the operating range (0°C to 55°C). The pump module has a heater that turns on
if pump_tmpr falls below 2°C. If the pump temperature is too low, check the
operation of the heater which is controlled by public variable pump_heat_ON.
This variable is saved in RawData only if saving all diagnostics. Its
corresponding variable pump_heat_Avg is saved in the averaged output tables
( IntAvg, CalAvg, and SiteAvg).
The pump module has a fan that turns on if pump_tmpr rises above 50°C. The
fan will stay on until the pump temperature falls below 45°C. If the pump
temperature is too high, check the operation of the fan which is controlled by
public variable pump_fan_ON. This variable is saved in RawData only if
saving all diagnostics. Its corresponding variable, pump_fan_Avg, is saved in
the averaged output tables ( IntAvg, CalAvg, and SiteAvg).
If the fan is on and the pump temperature is too high, check the ambient
temperature. The AP200 is rated for ambient temperatures from –30°C to
45°C.
Bit 4: Pump pressure is not at the setpoint
If bit 4 of diag_AP200 is set, this indicates the pump is not able to control the
pressure at the setpoint. To confirm the problem, compare the value of
pump_press to PUMP_P_SETPT. Diagnostic bit 4 indicates they differ by
more than 1.0 kPa.
Compare pump_press (pressure measured at the pump inlet) to cell_press
(pressure measured by the IRGA). These two points are physically connected
by a tube with relatively low flow such that they should be at similar pressures.
The measured pressure should agree within the combined uncertainty of the
respective pressure sensors. If they disagree by more than 4 kPa, turn the
pump off (set pump_ON = False) and allow the system to stabilize at ambient
pressure. Compare each pressure sensor to the pressure expected for the given
elevation. This test may help to diagnose a problem with the pump’s pressure
sensor. Also see the notes on bit 7.
If the pump pressure is too high, check pump_control. If pump_control = 0,
this indicates the AP200 has turned the pump off. There are several reasons
the AP200 may shut the pump off:
• Low supply voltage (see notes on bit 1)
• Valve temperature out of range (see notes on bit 2)
• Pump temperature out of range (see notes on bit 3)
• Pump has been turned off by the user; if public variable pump_ON =
False, set pump_ON = True to turn the pump on
If the pump pressure is too high and pump_control is > 0, check the value of
pump_speed to verify the pump is running. If there is physical access to the
AP200, listen for the sound of the pump to confirm it is running.
If the pump pressure is too high and the pump is running, check the system for
leaks. If no leaks are found there may be a problem with the pump. Contact
Campbell Scientific for information on replacing the pump.
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