What is the first step to take when warming up a tubular gauge glass?

The initial step when warming up a tubular gauge glass is to open the drain valve and crack open the steam valve. This procedure is essential because it allows steam to begin entering the gauge glass gradually while also ensuring that any residual water can be drained out.

By cracking open the steam valve, steam can flow into the gauge glass, initiating the warming process without introducing too much pressure too quickly, which could cause stress or potential damage to the glass itself. Opening the drain valve prepares the system for this process by ensuring there are no obstructions and that the gauge glass can be filled correctly after it has warmed up, preventing thermal shock from sudden temperature changes.

Starting with the other options may lead to improper handling of the gauge glass. For instance, closing the drain valve and directly opening the steam valve could trap water or any impurities inside the gauge glass, potentially leading to malfunctions or inaccurate readings. Filling the gauge glass with water before properly warming it could also create an unsafe condition, as the rapid introduction of steam to cooler water may lead to violence if not done carefully. Additionally, increasing the pressure in the boiler does not address the specific warming procedure for the gauge glass and could result in dangerous operating conditions.