Remote Water Level Indicator for Boilers
There are different types of remote water level indicators. Their purpose is to bring the water level reading to some convenient position in the engine or boiler room where it can be distinctly seen. These indicators when fitted are normally in addition to the normal statutory requirements for water gauge fittings for boilers.
Figure above is a diagrammatic arrangement of the 'Igema' remote water level indicator. The lower portion of the 'U' tube contains a red coloured indicating fluid which does not mix with water and has a density greater than that of water.
The equilibrium condition for the gauge is H = h + ρx, where 'ρ' is the density of the indicating fluid. 'H', 'h', and 'x' are variables.
If the water level in the boiler falls, 'h' will be reduced, 'x' will be increased and 'H' must therefore be increased. The level of the water in the condenser reservoir being maintained by condensing steam.
If the water level in the boiler rises, 'h' will be increased, 'x' will be reduced and 'H' must therefore be reduced. Water will therefore flow over the weir in the condenser reservoir in order to maintain the level constant.
A strip light is fitted behind the gauge which increases the brightness of the red indicating fluid, which enables the operator to observe at a glance from a considerable distance whether the gauge is full or empty.
"REED'S GENERAL ENGINEERING KNOWLEDGE FOR MARINE ENGINEERS", by Leslie Jackson and Thomas D. Morton