BLOWING OF WATER LEVEL GAUGE of a Boiler,Procedure of blowing through a gauge glass.

A Typical Water Level Gauge

It is a very common design to have all the FIVE cock handles pointing

downwards while the water gauge is in use.

Procedure of blowing:-

When the boiler is in operation, the steam cocks A, D and water cocks B, E are

open and drain cock C is shut.

(a) First shut both steam and water cocks A, D, B and E. Open drain

cock C to prove that all the gauge cocks are in order. Then, with the

drain cock C still open, cocks B and E should be opened. If water

blows out freely from cock C, cocks B and E are clear.

(b) Shut off cocks B and E and open cocks A and D with the drain cock

C still open. If steam blows out freely from cock C, cocks A and D

are clear.

(c) To cross test, close cocks D and B, leaving E, A and C open. If water

blows out from cock C, then E, A and the water-column are in order.

(d) Close cocks E and A, leaving D, B and C open. If steam blows out

from cock C, then D, B and the water-column are in order.

When any of the cocks are found to be clogged, shutdown the boiler and

overhaul the water level gauge.

Possible causes of gauge glass indicating incorrect level

(a) If cocks A and D or steam passage is shut or choked, boiler pressure

will press the water level in the glass higher than the real water level

of the boiler. The water level indication in glass will, therefore, be

i n c o r r e c t .

(b) If cocks B and E or water passage is shut or choked, steam will

condense on upper column of glass and accumulate. The apparent

water level shown can be higher than the actual water level, causing

false reading.

Water gauge glass should be tested daily at l e a s t at every change of attendant.

The safety of boiler operation relies greatly on proper functioning of the water

gauge glass.

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M❤K