What is the minimum height for the lower gauge cock in an HRT boiler?

The minimum height for the lower gauge cock in a Horizontal Return Tubular (HRT) boiler is determined by safety and operational standards to ensure accurate water level readings and system integrity.

In an HRT boiler, setting the lower gauge cock at least 3 inches above the top row of tubes ensures that the gauge reflects a safe and reliable water level. This height prevents the risk of the tubes becoming exposed to steam, which could lead to overheating and potential structural failure. Additionally, positioning the lower gauge cock too low could result in false readings and inadequate water levels, compromising the boiler’s safety.

Maintaining this specified distance is essential for safety protocols within boiler operation standards and also helps in efficient monitoring of the boiler’s water levels. The other options do not align with the necessary safety margins or operational guidelines stipulated for HRT boilers, which is why they are not appropriate choices.