Debugging of leaky probe

To try to debug the low dynamic pressure readings, we pulled the probe we were using and did a water manometer test on the sensors:

Our test temperature was 15 degrees C. If the density of water at 4 degrees C is 1.0000, the density at 10 degrees C is 0.9997 and at 20 degrees C, 0.9982. Therefore, the density variation of water with temperature is not important. We used distilled water.

The following are our results:

Sensor  Applied   Result    Result
        (in H2O)  (Pa)      (in H2O)
------------------------------------
dpβ     -15       -3707     -14.90
        -10       -2487     -10.00
         -5       -1250      -5.02
          0         -13      -0.05
          5        1229       4.93
         10        2474       9.95
         15        3703      14.88

dpα     -15       -3733     -15.00
        -10       -2494     -10.02
         -5       -1245      -5.00
          0          -6      -0.02
          5        1238       4.98
         10        2477       9.95
         15        3707      14.90

dp0       0          13       0.05
          5        1226       4.93
         10        2470       9.93
         15        3700      14.87

These are all within 1% of target. The sensors must not be the problem. We now suspect plumbing.

The hose connections seem fine, but a bogo leak-down test (put your lips to the probe hole and suck, and feel the air blowing out with your tongue) indicates there is significant leakage. Why this started happening at some point in service, as opposed to immediately, is anyone's guess. But if going to a Shapeways manufactured probe nose fixes it, that's fine and well within budget.

Luckily, we have some of the noses we 3D printed at Shapeways years ago (remember that...?) and can put them back into service for a quick test, perhaps with some sort of adapter:

Stay subscribed for more details as fast as we find them out ourselves!! :)