Water gauge
indicates the water level inside the boiler and is hence called as water level
indicator. Usually two water gauges are fitted in front of boiler.
It consists of a
glass tube, two gun metal tubes and three cocks. The steam cock C1 is provided
on the gun metal tube M1 which connects the glass tube with the steam space in
the boiler. The water cock C2 is provided on the gun metal tube M2 which
connects the glass tube with the water space. The gun metal tubes M1 and M2 are
bolted to the boiler shell.
The drain cock C3
is used to drain the water from the glass tube at intervals to ascertain
whether the gauge is in proper order or not. The glass tube is protected by
means of a cover, made of specially toughened glass which will prevent any
accident that may happen due to the breaking of glass tube.
The water gauge
shows the level of water in the boiler drum. It warns the operator if the water
level goes below a fixed mark, so that corrective action may be taken in time
to avoid any accident.
For the
observation of the water level in the boiler, the water and steam cocks are
opened and drain cock is closed. The steam enters from the upper metal tube M1
into the glass tube and water enters from the lower metal tube M2 into the
glass tube. Hence, water stands in the glass tube at the same level as in the
boiler.
The junctions of
the metal tubes and the glass tube are provided with two balls. In case the
glass tube is broken, the balls are pushed to the top nd bottom
ends of the glass tube. Thus the flow of both water and steam out of the boiler
is prevented.
When the boiler is
not working, the water gauge can be taken out from the boiler for cleaning
purposes by removing the bolts.