Which of the following is true regarding a boiler pressure mercury switch?

A boiler pressure mercury switch is a crucial safety device that operates based on the pressure within the boiler. Understanding its correct installation is vital to ensure accurate functioning and safety.

The correct answer emphasizes the need for the pigtail siphon to be installed vertically. This is essential because the mercury within the switch must be able to flow and establish a connection as intended. When the pigtail siphon is installed vertically, it ensures that the mercury can freely adjust according to the pressure variations, maintaining the necessary sensitivity and reliability of the switch. An improper orientation, such as installing it at an angle or horizontally, may hinder the movement of the mercury, leading to inaccurate readings or failure to operate, which can compromise safety.

Positions that might seem permissible, like a horizontal installation or at an angle, could introduce issues such as trapped mercury or impaired functionality. Therefore, it's crucial to adhere to the guideline that specifies vertical installation for the effective operation of the boiler pressure mercury switch.