Mich. Admin. Code R. 408.4241 - Gauge cocks
Rule 241. Each power boiler shall have 3 or more gauge cocks, located within the visible length of the water glass, except when the boiler has 2 water glasses located on the same horizontal lines. Boilers not over 36 inches in diameter, in which the heating surface does not exceed 100 square feet, need have but 2 gauge cocks. For all installations where the water gauge glass or glasses are more than 30 feet above the boiler operating floor, it is recommended that water-level indicating or recording gauges be installed at eye height above the operating floor.
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