There must be two independent means of determining the water level, one of which must be a direct reading gauge glass. The other is usually a remote reading gauge in the control room which should regularly be compared with the boiler gauge glass.
Procedure for Blowing Through Gauge Glass
- Close off cocks ‘S’ and ‘W’ and open drain ‘D’. Make sure both water and steam cocks are holding.
- Open cock ‘W’ and blow through. Make sure that water is coming out and cock ‘W’ is clear. Close water cock.
- Open cock ‘S’ and blow through. Make sure that steam is coming out and cock ‘S’ is clear. Close steam cock.
- Close drain ‘D’.
- Open water cock ‘W’ and check water level rises in the glass.
- Open steam cock ‘S’ for showing boiler water level.
The glasses should be kept clean. The glands should be nipped up at the first sign of leakage as the chemicals in the boiler water will leave a deposit on the glass. The glasses should have protective glass shields around them and be properly illuminated.