Question 41

Constant water circulation is required of copper water tube boilers to prevent thermal stress.

Constant water circulation helps maintain an even temperature throughout the boiler, reducing the risk of thermal stress that can occur due to temperature fluctuations.

A) Dual thermal overload switch

A dual thermal overload switch is a safety device that prevents overheating, but it does not address the issue of thermal stress caused by uneven temperature distribution within the boiler. While important for safety, it does not fulfill the requirement specified in the question.

B) Constant water circulation

Constant water circulation is essential for copper water tube boilers as it ensures that the temperature remains uniform across the system. This uniformity minimizes the likelihood of thermal stress, which can lead to cracking and failure of the boiler components.

C) Cross sectional bracing

Cross sectional bracing provides structural support to the boiler but does not influence the thermal dynamics that lead to thermal stress. It helps with stability and integrity under load, but it does not prevent the stress caused by temperature variations.

D) Glycol additives

Glycol additives are used to lower the freezing point of the water and enhance antifreeze properties in chilled systems. However, they do not directly address the thermal stress in copper water tube boilers resulting from temperature changes and uneven heating.

Conclusion

The requirement for constant water circulation in copper water tube boilers is critical to preventing thermal stress associated with temperature differentials. While other options may serve important roles in boiler operation and safety, they do not specifically mitigate the thermal stress issue, making option B the definitive correct choice.