ARSD 61:08:09:35. External inspection -- Water glass requirements

Early in the external inspection the water and steam passageways must be blown down separately to ensure that both connections are clear. The inspector shall observe the blowdown of the water glass to verify the immediate return of water to the glass. The procedure to use in blowing down the glass is as follows: (1) Close the lower valve, then open the drain cock and blow the glass down; (2) Close the drain cock and open the lower valve. Water should return to the glass immediately; (3) Close the upper valve, then open the drain cock and allow the water to flow until it runs clear; (4) Close the drain cock and open the upper valve. Water should return to the glass immediately. If this procedure does not show that both connections are clear, the boiler must be shut down.