scope:

This specification covers four types of fuel storage tank vent caps with screen covered vent openings. The vent cap fits on the vent pipe by means of a threaded inlet or slip-over inlet.

Vent caps covered by this specification shall be of the following types, sizes, and styles as specified (see 6.2).

TYPE Type I - Vapors are directed downward through either two screened outlets or sectionalized outlets. Type II - Vapor recovery vent cap. Vapors are directed upward through a screened circular outlet. Rain is prevented from entering the screened outlet by a rainhood with drain spouts. The cap is equipped with a 0.5-inch (12.7 millimetre (mm)) restricted opening for vapor recovery.

Beneficial comments, recommendations, additions, deletions, clarifications, etc. and any data which may improve this document should be sent to: Commanding Officer (Code 15E2), Naval Construction Battalion Center, 1000 23rd Avenue, Port Hueneme, CA 93043-4301, by using the Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter.

Type III - Vapors are directed upward through a screened circular outlet. Rain is prevented from entering the screened outlet by a rainhood with drain spouts. Type IV - Vapor recovery vent cap. Vapors are directed upward through a screened circular outlet. Rain is prevented from entering the screened outlet by a rainhood with drain spouts. The cap is equipped with a spring loaded pressure vacuum poppet for vapor recovery. SIZE Size 1 - For 1.25-inch (32 mm) pipe size (ips) National Pipe Taper Thread (NPT) vent pipe (size 1 not applicable for type IV cap). Size 2 - For 1.5-inch (40 mm) ips NPT vent pipe (size 2 not applicable for type IV cap). Size 3 - For 2-inch (50 mm) ips NPT vent pipe (size 3 not applicable to all types of caps specified herein). Size 4 - For 3-inch (80 mm) ips NPT vent pipe (size 4 not applicable for type IV cap). STYLE Style A - Threaded inlet. Style B - Slip-over inlet.

intended Use: