Important Notice: Our web hosting provider recently started charging us for additional visits, which was unexpected. In response, we're seeking donations. Depending on the situation, we may explore different monetization options for our Community and Expert Contributors. It's crucial to provide more returns for their expertise and offer more Expert Validated Answers or AI Validated Answers. Learn more about our hosting issue here.

There is confusion among oil tank installers regarding the size of the tank vent.Is the minimum nominal pipe diameter 1 in. diameter or 2 in.?

April 26, 2017confusion installers minimum nominal Oil pipe size tank

0

Posted

There is confusion among oil tank installers regarding the size of the tank vent.Is the minimum nominal pipe diameter 1 in. diameter or 2 in.?

1 Answer

0

Posted

Section 7.5.9 governs vents for fuel oil storage tanks installed inside a building. In the 1997 edition of NFPA 31, the nominal vent size for such tanks was increased from 1 in. to 2 in.This change was based on several incidents involving tank failure that appeared to be related to overpressure of the tank during filling at high flow rates.After publication of the 1997 edition, problems began to be encountered in the field, particularly with regard to tank replacements: building officials were mandating replacement of the 1 in. vent pipe of existing installations. Since that time, full-scale testing has shown that the 1¼ in. is adequate for tank capacities up to 660 gallons, even with the vent whistle installed. The Technical Committee on Liquid Fuel Burning Equipment agreed to return to the 1¼ in. minimum vent size based on these tests.This has considerably eased problems related to retrofits.