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Water Membrane

The Ultrasound probe used with the SRS is designed to function with a water column as a delay line, with a flexible membrane in contact with the part. This provides for good conformity to the surface of the part and allows for some variability in contact pressure.

The water in the water column must be refilled if it has dropped too low. This can be seen in the size of the bubble formed by the water membrane. It can also be damaged by burrs or expulsions on the surface of the inspected part, although it is typically quite resistant to damage in this way. Note that the membranes are permanently deformed after being filled and are not reusable.

To (re)fill the water in the water column:

  1. Prepare a small tank or bowl of water with a depth of at least 3 cm.1
  2. Take off the water column nut, separate the front and rear nut, and dispose of the existing membrane.
  3. Take a new membrane and wet it in the water.
  4. Insert the membrane into the front nut. Ensure it is centered and flattened.
  5. Screw on the rear nut, ensuring that the membrane is firmly held between the two nuts and has not twisted out of place.
  6. Immerse the combined nut into the water tank and ensure there are no air bubbles trapped inside.
  7. Inside of the water tank, screw the combined nut onto the front of the probe until you can feel the O-ring engage.2
  8. Continue to screw on the combined nut all the way until a large membrane forms. If it is too slippery under the water, it can be lifted into the air after the O-ring has engaged.3
  9. Wipe off the probe. If any water has entered the connector at the rear, this must be dried before the probe is reconnected.

Below is an instructional video showcasing this process:

Footnotes​

  1. Demineralized water is strongly encouraged, as regular tap water can leave a mineral residue that affects the ultrasound signal. ↩

  2. It is recommended to only immerse the front portion of the probe up to the depth required, rather than the whole probe. ↩

  3. If an undersized or no membrane forms, return to step 4 and repeat the process, ensuring that the membrane is well seated and does not twist in place when clamped down. ↩