When conducting an immersion test, the water path distance must be controlled so that:

Spurious signals are not created by surface waves on the test piece

The water path distance to diameter ratio does not result in asymmetric standing waves

The test piece discontinuity indications appear between the first front and first back surface echoes

The second front surface echo does not appear on the CRT screen between the first front and first back surface echoes

The ultrasonic beam remains focused on the test piece