What could happen if live steam is allowed to enter a burden tube after water has been blown out of the siphon?

When live steam enters a burden tube after water has been blown out of the siphon, it can indeed result in damage to the pressure gauge. The burden tube is designed to be filled with water to ensure accurate readings; when it is empty and steam enters, the rapid temperature and pressure changes can cause the gauge to malfunction or become damaged. This scenario can lead to inaccurate pressure readings and potential failures in gauge operation.

For clarity, it’s important to consider the implications of letting steam enter an empty burden tube in context. The other options, while related to the operation of the boiler system, do not directly address the immediate consequences of live steam entering the burden tube under the described conditions. In particular, overheating or excessively high pressure may occur in different contexts but would require additional factors to be present that are not specific to the situation described with the burden tube.