Mich. Admin. Code R. 408.4230 - Means of boiler feeding
Rule 230. Each boiler shall have a feed supply which will permit it to be fed at any time while under pressure. A power boiler having more than 500 square feet of water heating surface shall have at least 2 means of feeding, 1 of which shall be an approved feed pump, injector, or inspirator, except boilers fired by gaseous, liquid, or solid fuel in suspension may be equipped with a single source of feeding provided means are provided for immediate shutoff of heat release, and the boiler furnace and fuel system do not retain sufficient stored heat to cause damage to the boiler if the feed supply is interrupted. A source of feed directly from water mains at a pressure of 6% greater than the release pressure of the safety valve with the highest release setting may be considered 1 of the means.
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