49 C.F.R. § 230.52 Water glass valves.
Title 49 - Transportation
All water glasses shall be equipped with no more than two valves capable of isolating the water glass from the boiler. They shall also be equipped with a drain valve capable of evacuating the glass when it is so isolated.
Title 49: Transportation
PART 230—STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS
Subpart B—Boilers and Appurtenances
Water Glasses and Gauge Cocks
§ 230.52 Water glass valves.
