How high must low water fuel cut-off devices be piped in relation to the gauge glass?

For low water fuel cut-off devices, the requirement is that they must be piped no lower than the visible part of the gauge glass. This is essential for safety and operational integrity. The gauge glass provides a visual indication of the water level in the boiler.

If the low water fuel cut-off device is installed too low, it may fail to detect a low water level condition, which can lead to significant safety hazards, such as overheating and potential damage to the boiler. By ensuring that the cut-off device is no lower than the visible part of the gauge glass, you can guarantee that it will function correctly and cut off the fuel supply before the water reaches a dangerously low level.

This placement helps maintain proper safety margins and ensures that the boiler operates within safe water level parameters.