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Throughput Test

Measuring the throughput of the system is a way of measuring the end to end impedance of the dilution unit. This will depend heavily on temperature, and so is often measured at both room temperature and $ \sim$ 10K.

To measure the throughput we will put 3 bar on one side of the dilution unit and vacuum on the other side and observe the pressure rise at P3.

The throughput at 10K is fairly high, which means that the mixture will flow through and cause P3 to increase significantly while you are putting 3 bar on P2. This is unavoidable, but try to minimize it by increasing P2 as quickly as is safely possible. Starting at step 4 below, the mixture will begin to flow across the DU.

Important: Make sure that the turbo is TURNED OFF!

To begin:

Procedure:

  1. First make sure that P3 is under vacuum. Less than 20 mBar is probably sufficient. If not, evacuate the line using the fore pump.
  2. Once P3 is sufficiently vacuumed, close V12.
  3. Open and close V4 to equalize the pressures.
  4. Open V1 and V5.
  5. Turn on the compressor and fore pump.
  6. Toggle V9 until the pressure at P2 reads about 3bar. Make sure not to leave V9 open for too long and overwelm the compressor. P5 should never go above 1 bar.
  7. Once P2 reaches 3bar, close V9.
  8. Hover the mouse over P3, and observe the change in pressure per minute. It may take a minute or so to stabilize. This number is the throughput. Record it in the logbook.
  9. Recollect the mixture: close V1, open manual valve V12, then open V4 and V6. After most of the mixture is back in the tank, turn on the turbo to collect the last of it.

next up previous contents
Next: Single Shot Test Up: Tests Previous: Measuring Base   Contents
Jonathan Ouellet 2014-08-26