Which action indicates proper maintenance of a gauge glass?

The action that indicates proper maintenance of a gauge glass is to inspect the washers and replace them if defective. Proper functioning of a gauge glass is essential for accurate level readings of the water within a boiler, and the seals created by the washers are critical for preventing leaks. If the washers are worn, cracked, or otherwise in poor condition, it can lead to inaccurate water levels being displayed, and even worse, could pose a safety hazard due to potential leaks or bursts. Regular inspections and timely replacements of these components are vital to ensure reliable and safe operation.

Other options do not align with proper maintenance practices. Keeping the gauge glass empty is counterproductive as it would prevent any readings from being taken. Using a chemical solvent could damage the glass instead of cleaning it effectively. Opening and closing the gauge regularly is unnecessary and could increase the risk of wear or damage to the mechanism without contributing to the maintenance of its function.