How to Identify Hydraulic Hose Fittings

How to Identify Hydraulic Hose Fittings

December 16, 2021

Want to learn how to identify hydraulic fittings? Industrial equipment and machines are made around the world, so it only makes sense that there’s an equal variety of fittings and adapters.

Read on to learn how to identify hydraulic fitting size and other important qualities to determine what you need for your applications.

Determine whether the fitting is permanent or reusable

When it comes to how to identify hydraulic fittings, start by determining whether the component is permanent or reusable. Permanent (or crimped) fittings are commonly used in the fluid power industry. They’re squeezed onto the hose at assembly and are only removed once the assembly fails.

Reusable fittings are much less common, but they’re easily identified because they fit onto a hose using a wrench and a vise.

Determine fitting type

There are several types of hydraulic fittings used in fluid power machines worldwide. The most common hydraulic fittings are listed below:

  • NPT/NPTF: This is the most commonly used fitting in North America and can be recognized by their tapered inner and outer diameters, allowing for self-
  • BSPT (JIS-PT): Also known as the British thread type, these standard fittings are commonly used to make connections and seal pipe ends.
  • Metric taper: This is the most commonly used thread type in Europe, featuring precisely cylindrical inner and outer diameters.
  • SAE straight thread: Featuring excellent sealing due to 90-durometer O-rings, the SAE straight thread is a dependable and reusable thread type for many systems.
  • ISO 6149: Most useful in diagnostic port applications, this fitting has a metric straight thread O-ring port.
  • JIS-B2351: These fittings usually have BSP threads and are commonly seen in hose adapters for Japanese- or Korean-designed equipment.
  • DIN metric: The German Industrial Standard, these popular fittings are used throughout much of Europe.
  • BSPP (JIS-PF): Following standard British thread dimensions, these fittings also conform to Japanese Industrial Standards.
  • 4-bolt flange: Useful in both normal- and heavy-duty applications, there are a variety of 4-bolt flanges on the market.

Determine the sealing method

While there are several types of hydraulic hose fittings on the market, there are three common ones that are used in North America. These types of fittings seal the system in different ways. They include:

  • O-ring: These fittings feature an O-ring seal and are further subdivided by their seal designs into O-ring boss, flat face O-ring seal and O-ring flange.
  • Mated angle: There are several mated angle fittings that feature an angle seat with straight or parallel threads for sealing.
  • Tapered threads: These fittings feature male or female threads that, when they come together, apply pressure on the couplings to make the seal.

Measure the thread

How do you determine hydraulic fitting size? Simply measure the thread with calipers. Measure the number of threads per inch on both the outside and inside diameters of the fitting; then use that figure to accurately gauge the thread size you need.

Learning how to identify hydraulic fittings can be difficult since there are so many varieties on the market. Reach out to Royal Brass Incorporated today—we’ll help take the mystery out of determining which hydraulic fittings are appropriate for your applications.

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