Aluminum 2 1/2" Female NPT to 1 1/2" Male NH

Item Number: 37R25N15
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  • Made In USA
  • Weight: 1.0 lb
  • Female Side: 2 1/2 inch NPT
  • The Female Will Only Connect to a Male 2 1/2 inch NPT
  • Male Side: 1 1/2 inch NH / NST
  • The Male Will Only Connect to a Female 1 1/2 inch NH / NST
  • Material: 6061-T6 Aluminum
  • Finish: Hard Coat Anodized
  • Complies With NFPA 1963 (Corrosion Resistance)
  • 99.95% Lead-Free

Description

The Aluminum 2 1/2" Female NPT to 1 1/2" Male NH adapter is a Made in the USA, 99.95% lead-free fitting for connecting plumbing and fire hose systems. It is constructed from seamless extruded 6061-T6 aluminum with a hard coat anodized finish, ensuring resistance to corrosion, abrasion, and electrolysis. Compliant with NFPA 1963 and the Safe Water Drinking Act, this adapter features blunt start Higbee cut threads and is designed for reliable, high-pressure applications with a maximum working pressure of 600 PSI.

Help Me Connect

  • 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.

Warranty Information

Limited Lifetime Warranty - We will replace any adapters with manufacturer defects in material and workmanship. All warranty claims must be returned to us for inspection before we determine a solution.

Our warranty does not cover gaskets, multiple use of NPT threads, shipping cost, cosmetic damages, normal wear-and-tear, improper use or chemical damage.

Adapters purchased for use at Fire Training Facilities will have a 90-day Manufacturer Defect warranty only.

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Additional Details

Aluminum adapters are fabricated from seamless extruded 6061-T6 aluminum and hard coat anodized per MIL-A-8625 Type III, Class 1. Threads have a blunt start Higbee cut with indicators on adjacent lugs. Part identifications are permanent and stamped prior to hardcoat. Adapters and components meet the requirements of NFPA 1963.

The Safe Water Drinking Act section 1417 requires "Lead-Free" products to be a minimum of 99.75% lead-free.

Aluminum Female to Male Adapter

Specifications

Garden Hose Thread Male Adapter
  • 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)
1" Male Adapter
  • 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
1 1/2" Male Adapter
  • 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" Hose Couplings
  • 1 3/4 inch hoses come with 1 1/2 inch couplings
2" Male Adapter
  • 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.

2 1/2" Male Adapter
  • 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
3" Hose Couplings
  • 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
4" Male Adapter
  • 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
4 1/2” Male Adapter
  • 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
5" Male Adapter
  • 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
6" Male Adapter
  • 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

FAQs

What are the thread types and sizes of this adapter?

This adapter features a 2 1/2 inch Female National Pipe Tapered (NPT) thread on one side and a 1 1/2 inch Male National Hose (NH) / National Standard Thread (NST) on the other. The female NPT side connects to a male NPT, while the male NH/NST side connects to a female NH/NST.

What material is this adapter made from and what is its finish?

The adapter is made from seamless extruded 6061-T6 aluminum. It features a hard coat anodized finish, per MIL-A-8625 Type III, Class 1, to resist corrosion, abrasion, and reduce electrolysis.

Is this adapter lead-free and compliant with any standards?

Yes, this adapter is 99.95% lead-free, meeting the requirements of the Safe Water Drinking Act section 1417. It also complies with NFPA 1963 for corrosion resistance and other relevant specifications.

What is the maximum working pressure for this adapter?

This aluminum adapter has a maximum working pressure of 600 PSI. It is also designed to withstand a hydrostatic test of 1000 PSI.

Does this adapter include gaskets?

No, EPDM gaskets are not included for the female side of this adapter.

How do NPT and NH/NST threads differ in sealing?

NPT (National Pipe Tapered) threads are tapered and create a seal through thread friction when tightened, often without a gasket. NH/NST (National Hose/National Standard Thread) threads are straight and rely on a gasket in the female coupling to create a seal, allowing for swivel action.

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