Aluminum 4" Female BSP to 4" Male NPT

Item Number: 37R4B4N
  • Aluminum 4" Female BSP to 4" Male NPT
1 5
$187.86
$0.00 $187.86
Sale Sold out
Special Order
Ships: Approx. Sep 1, 2026
Estimated transit time: 2 to 5 Business Days

Free Shipping

Help Me Connect

  • 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
  • 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.
  • 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.

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.

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.

View full details

Additional Details

British Standard Pipe (BSP) can be most commonly found in Canada, UK, Europe, Asia and Australia. It is a finer thread than National Pipe Thread (NPT), and will not seal properly if used in conjunction with it.

Two Types of Threads are Used

  • British Standard Pipe Taper (BSPT) and British Standard Pipe Parallel (BSPP). British Standard Pipe Taper uses a tapered thread system, and sealant is provided to help secure the male and female connection.
  • British Standard Pipe Parallel uses a parallel thread system, and a rubber gasket is often included to secure the male and female connection.

Aluminum adapters are fabricated from seamless extruded 6061-T6 aluminum and hard coat anodized per MIL-A-8625 Type III, Class 1. 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.

Download Spec Sheet

Specifications

  • Made in USA
  • Female Side: 4 inch British Standard Pipe (BSP)
  • The Female Will Only Connect to a Male 4 inch British Standard Pipe
  • Male Side : 4 inch NPT
  • The Male Will Only Connect to a Female 4 inch NPT or NPSH
  • Material: 6061-T6 Aluminum
  • Finish: Hard Coat Anodized
  • Complies With NFPA 1963 (Corrosion Resistance)
  • 99.95% Lead-Free

4" Male Adapter

  • Inside diameter of a male adapter: 4 inches
  • Outside diameter of a male BSP adapter: 4 7/16 inches (4.45) - 4 Threads per inch
  • Outside diameter of a male NH / NST adapter: 5 inches (5.01) - 4 Threads per inch
  • Outside diameter a male NPSH adapter: 4 7/16 inches (4.47) - 8 Threads per inch
  • Outside diameter a male NPT adapter: 4 3/8 inches (4.38) - 8 Threads per inch

Related Products