212. If the water level as indicated by the gauge glass of an auxiliary boiler is in question, it should be blown down. Which of the following statements represents the proper procedure for performing a gauge glass blow down?

The correct procedure for gauge glass blowdown involves clearing each connection separately to ensure accurate level indication. This is achieved by first opening the lower (water) cutout valve, then the upper (steam) cutout valve, ensuring both passages are clear and eliminating the possibility of a false reading due to partial blockage.