Pump/Flow Problems

A useful flow diagram for troubleshooting is System Flow Schematic.

Can’t Achieve High Flow Rates

Maximum flow rates should exceed 700 μmol s-1. If you can’t achieve that (use fixed flow control, so you can directly ask for the flow rate you want), then try these steps.

  1. Turn off the mixer.
  2. If you are using the 6400-01 CO2 mixer, shut it off, and try a high flow rate again. If this fixes the problem, then the flow was low because the mixer calibration had specified a lower maximum flow in order to raise the upper limit of CO2 concentration. Refer to Calibrating the CO2 Mixer on page 18-25 in the instruction manual.
  3. Remove the soda lime tube.
  4. If the flow does not increase substantially, go to Step 3. If the flow did increase substantially, the problem is either with the soda lime tube, or else in the line between the air intake and the soda lime tube. To test the soda lime tube itself, remove the desiccant tube (that will make the flow be highest) and put the soda lime tube in the desiccant tube location. If the flow doesn’t change much between having nothing in the desiccant tube location, and having the soda lime in the desiccant location, that means the soda lime tube is ok, and the problem is in the internal tube connecting the air inlet and the soda lime location. Open the console, and inspect that line; it may have debris in it.
  5. If the problem is the soda lime tube, see Chemical Tubes.
  6. Remove the desiccant tube.
  7. If this improves the flow, the problem is in the desiccant tube. To find a blockage within the desiccant tube, see Chemical Tubes. If this doesn’t fix the problem, open the console (see Figure 20‑20). There might be some sort of blockage between the air filter (which is next after the desiccant tube) and the pump. Pull the air intake line from the pump, and see if that increases the flow rate. If it does, you’ve bracketed the problem.

The problem could also be a bad pump or diaphragm, but this has been quite rare. See Pump.

Pump Status: ERR

This can only happen with the 6400-01 installed, and then only when something is restricting the pump. Check for a blockage in the flow path on the vacuum side of the pump, as described above.