The 3000 Series regulator is best used for low pressure applications with exceptionally high flow rates. They are ideally suited for batch ovens, furnaces, boilers and other applications. To ensure quickest delivery the following regulators are stock: Series 3000 Regulators with 3-7″ W.C. Spring, 1-1/2 NPT, 2″ NPT, 3″ flanged ANSI 125 lb., 4″ flanged ANSI 125 lb.