Mich. Admin. Code R. 408.4292 - Pressure or altitude gauges
Rule 292. Each hot water boiler shall have a pressure or altitude gauge connected to it or to its flow connection in such a manner that it cannot be shut off from the boiler except by a cock with tee or level handle, placed on the pipe near the gauge. The handle of the cock shall be parallel to the pipe in which it is located when the cock is open. The scale on the dial of the pressure or altitude gauge shall be graduated to not less than 1 1/2 times the maximum allowable working pressure. The gauge shall be provided with effective stops for the indicating pointer at the zero point and at the maximum pressure point. Pressure or altitude-gauge connections shall be of nonferrous composition when smaller than 1-inch pipe size and longer than 5 feet between the gauge and point of connection of pipe to boiler, and also when smaller than 1/2-inch pipe size and shorter than 5 feet between the gauge and point of connection of pipe to boiler.
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