Original oil and gas trade magazine vintage ad for GROVE REGULATOR COMPANY. Main office and plant was located at 65th & Hollis Street, Oakland, CA., at 1901 Calumet, Houston, TX., and at 1930 W. Olympic Blvd., Los Angeles, CA. Flexflo, Chexflo, Series S Fullstream Check Valve, Model 888 Pressure Loaded Reliever, Model PB-300 Regulator. Inb control of Air, Gas and Liquids. Unique 1951 old petroleum refinery valve equipment magazine advertisement. Approximate size 9 x 12 inches.