USDA Forestry Service fire hose reducer feature aluminum coupling with a 600 PSI test pressure. Meet Forest Service Spec 5100-107. Cap 1 1/2 inch NH, 9 threads per inch. Meets National Fire Equipment System (NFES #2210). Water-Handling Accessories flow rates are 100 PSI flowing pressure.

Fire hose cap with chain comes with a gasket.

National Stock Number (NSN 4210-01-081-8751)

This Wildland Fire Equipment adapter or coupling is used by the U.S. Forest Service (USFS), Bureau of Land Management (BLM), Bureau of Indian Affairs (BIA), U.S. Fish & Wildlife Service (USF&WS), National Park Service (NPS), State and Local governments, and other Forest Service–sponsored participants in the government-wide wildland firefighting effort.

This is the same water-handling accessories reducer found in the Defense Logistics Agency (DLA) Wildland Fire Equipment catalog or Fedmall.mil.

• Outside diameter of a male GHT adapter: 1 1/16 inches (1.06) - 11.5 Threads per inch
• Garden hose thread is not the same as 3/4 inch pipe thread (NPT)

• Inside diameter of a male adapter: 1 inch
• Outside diameter of a male NH / NST adapter: 1 3/8 inches (1.375) - 8 Threads per inch
• Outside diameter a male NPSH or NPT adapter: 1 5/16 inches (1.295) - 11.5 Threads per inch

• Inside diameter of a male adapter: 1 1/2 inches
• Outside diameter of a male NH / NST adapter: 2 inches (1.99) - 9 Threads per inch
• Outside diameter a male NPSH or NPT adapter: 1 7/8 inches (1.87) - 11.5 Threads per inch

• 1 3/4 inch hoses come with 1 1/2 inch couplings

• Inside diameter of a male adapter: 2 inches
• Outside diameter of a male NH / NST adapter: 2 1/2 inches (2.51) - 8 Threads per inch
• Outside diameter a male NPSH or NPT adapter: 2 3/8 inches (2.35) - 11.5 Threads per inch

Note: 2 inch NH or NST is very rare. If the outside diameter of male adapter is approximately two inches, you need 1 1/2 inch NH or NST.

• Inside diameter of a male adapter: 2 1/2 inches
• Outside diameter of a male NH / NST adapter: 3 1/16 inches (3.06) - 7.5 Threads per inch
• Outside diameter a male NPSH or NPT adapter: 2 7/8 inches (2.84) - 8 Threads per inch

• Most 3 inch hoses come with 2 1/2 inch couplings
• Inside diameter of a male adapter: 3 inches
• Outside diameter of a male NH / NST adapter: 3 5/8 inches (3.62) - 6 Threads per inch
• Outside diameter a male NPSH adapter: 3 1/2 inches (3.47) - 8 Threads per inch
• Outside diameter a male NPT adapter: 3 3/8 inches (3.38) - 8 Threads per inch

• Inside diameter of a male adapter: 4 inches
• Outside diameter of a male NH / NST adapter: 5 inches (5.01) - 4 Threads per inch
• Outside diameter a male NPSH adapter: 4 1/2 inches (4.47) - 8 Threads per inch

• Inside diameter of a male adapter: 4 1/2 inches
• Outside diameter of a male NH / NST adapter: 5 3/4 inches (5.76) - 4 Threads per inch
• Outside diameter a male NPSH or NPT adapter: 5 inches (4.97) - 8 Threads per inch

• Inside diameter of a male adapter: 5 inches
• Outside diameter of a male NH / NST adapter: 6 1/4 inches (6.26) - 4 Threads per inch
• Outside diameter of a male NPSH adapter: 5 9/16 inches (5.56) - 8 Threads per inch
• Outside diameter of a male NPT adapter: 5 7/16 inches (5.44) - 8 Threads per inch

• Inside diameter of a male adapter: 6 inches
• Outside diameter of a male NH / NST adapter: 7 1/32 inches (7.025) - 4 Threads per inch
• Outside diameter of a male NPSH adapter: 6 5/8 inches (6.62) - 8 Threads per inch
• Outside diameter of a male NPT adapter: 6 1/2 inches (6.50) - 8 Threads per inch

• The female side of a garden hose will only connect to a male garden hose connection
• The male side of a garden hose will only connect to a female garden hose connection

NH / NST: The most common thread type in use by fire departments today is NST or National Standard Thread. NST also goes by the initials NH or National Hose. It can even be referred to as NHT or National Hose Thread but NST or NH is more common these days. NH = NST.

• The female side of a NH / NST coupling will only connect to a male NH / NST connection
• The male side of a NH / NST coupling will only connect to a female NH / NST connection

NPSH: National Pipe Straight Hose (NPSH) or Iron Pipe Thread (IPT) has the same threads per inch (TPI) as National Pipe Tapered (NPT) but the thread does not taper. NPSH is a straight thread and seals by a gasket in the female coupling which allows for a swivel, just like NH / NST, which make both ideal for hose couplings.

• The female side of a NPSH coupling will only connect to a male NPT pipe or a male NPSH connection
• The male side of a NPSH coupling will only connect to a female NPSH connection
• It will NOT thread into a female NPT pipe. For example, a male NPSH coupling will NOT thread into a female metal or pvc pipe.

NPT: National Pipe Tapered is common in plumbing and some industrial uses. Sometimes referred to as pipe thread because PVC pipe and schedule 40 pipe are typically threaded in NPT. As its name implies this is a tapered thread so that the outside diameter of the male (ODM) gets smaller towards the end of the fitting and the inside diameter of the female narrows with depth. As the two fittings are threaded together the opposite tapers force thread friction and makes the seal without the use of a gasket.