3 WATER LEVEL PROBES
3.1 Breaking Bubbles/Spray
Breaking bubbles/spray refers to the bubbles of steam breaking at the boiler water level surface. These
precipitate little droplets as spray several inches above the water surface in an upwards direction.
The droplets tend to coat the surface of the level probe which in turn will read as an increase in the
water level. This situation is largely avoided by fitting anti surge pots inside the boiler shell. When the
probes are fitted externally to the boiler shell this situation can not arise.
3.1.1 Thermal Currents (heat energy in water)
Many bubbles breaking simultaneously and thermal currents from the furnace tube and 2nd, 3rd, 4th
pass smoke tube create their own turbulence/wave signature on the surface of the water. The typical
result is short choppy/peaky wave patterns as below.
A second set of turbulence is the wave reflections off the sides of the boiler. The whole of the above is
largely attenuated away by mounting the probes externally to the main boiler shell in a separate pot
or pots.
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