Find the Right Hydraulic Adaptor First Time

Finding the right hydraulic adaptor can be confusing, especially when different thread types, sizes and sealing methods can look very similar. Choosing the wrong adaptor can lead to leaks, damaged threads, downtime and repeat orders.

This guide explains how to identify the hydraulic adaptor you need before you buy, including thread type, male and female connections, thread size, sealing method and the most common adaptor styles used in hydraulic systems.

Know your adaptor type?

Shop by connection style, including male to male, male to female, female to female, swivel, elbow, tee and blanking adaptors.

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Need to identify a thread?

Use Flowfit’s Hydraulic Fitting Thread Identification Guide to help compare common hydraulic thread types and measurements.

Download thread ID guide

Quick answer

To find the right hydraulic adaptor, check five things before ordering: the thread type, whether each end is male or female, the thread size, the sealing method, and the adaptor style. If any of these are wrong, the adaptor may not fit or seal correctly.

Jump to:

1) Why choosing the right hydraulic adaptor matters
2) The 5 things to check before buying
3) Common hydraulic adaptor thread types
4) How to identify your hydraulic adaptor
5) Common hydraulic adaptor types
6) Common mistakes that cause hydraulic adaptor leaks
7) Common hydraulic adaptor scenarios
8) Need help finding the right adaptor?

Hydraulic adaptors Male to male adaptors Male to female adaptors Swept elbow adaptors Thread ID guide

1. Why Choosing the Right Hydraulic Adaptor Matters

A hydraulic adaptor is used to connect different hydraulic components, hoses, valves, cylinders, pumps and ports together. Adaptors are often used when two sides of a hydraulic connection have different thread types, different genders, different sizes, or need a different angle or layout.

The challenge is that many hydraulic fittings look similar at first glance. A fitting may appear to screw into place, but that does not always mean the thread type or sealing method is correct. If the adaptor fits loosely, feels tight too quickly, or does not seal on the correct face, it may be the wrong type.

Choosing the correct adaptor first time helps protect the hydraulic system, reduce leaks and avoid unnecessary downtime. It also helps prevent damage to hoses, ports and components caused by forcing together threads that are not designed to match.

Important

A hydraulic adaptor should match the thread type, thread size and sealing method of the components being connected. Forcing the wrong adaptor into place can damage the threads and still leave the joint leaking.

2. The 5 Things to Check Before Buying

Before ordering a hydraulic adaptor, check each end of the connection carefully. You need to know what the adaptor is connecting to, how each side seals, and whether the system needs a straight, angled, swivel, tee, blanking or specialist adaptor.

What to check	Why it matters	Example
Thread type	Different thread standards are not always compatible, even if they look similar.	BSP, JIC, ORFS, JIS, metric, NPT
Male or female	You need the correct connection on each end of the adaptor.	Male to male, male to female, female to female
Thread size	The adaptor must match the size of the port, hose or fitting.	1/4", 3/8", 1/2", M18, M22
Sealing method	Hydraulic fittings seal in different ways, such as on a thread, cone, washer or O-ring.	Bonded seal, taper thread, cone seat, O-ring face seal
Adaptor style	The style affects installation, hose routing, clearance and how the system is connected.	Swivel, swept elbow, tee, blanking plug, blanking cap, bulkhead

Simple checklist

Thread type + male/female + size + seal + style
If you can identify these five points, you are much more likely to order the correct hydraulic adaptor first time.

3. Common Hydraulic Adaptor Thread Types

Hydraulic systems can use several different thread standards. The correct option depends on the machine, hose, valve, cylinder or port you are connecting to.

Thread type	Commonly found on	What to look for
BSP	UK and European hydraulic systems	Available as parallel or tapered threads. BSPP usually seals with a washer or bonded seal.
JIC	Hydraulic hoses, mobile equipment and high-pressure systems	Often identified by a cone seat connection.
ORFS	Systems where leak resistance is especially important	Uses an O-ring face seal to create the seal.
JIS	Japanese and imported hydraulic equipment	Check the thread form, seat and measurements carefully before matching.
Metric	European and imported machinery	Measured by thread diameter and pitch, such as M18 x 1.5.
NPT	American machinery and imported equipment	Tapered thread. Do not assume it is the same as BSPT.

Thread type matters

Two fittings may look similar but seal in completely different ways. Always check the thread type, thread size and sealing face before assuming one adaptor will replace another.

Use the Hydraulic Fitting Thread Identification Guide if you need help confirming thread type, thread size or measurements before ordering.

4. How to Identify Your Hydraulic Adaptor

If you are replacing an existing adaptor, use the old part as a starting point. Look closely at both ends and check how the adaptor connects and seals.

Check whether each end is male or female
A male thread is external. A female thread is internal. Some adaptors have the same connection on both ends, while others convert from one type to another.
Check whether the thread is straight or tapered
A parallel thread stays the same diameter along its length. A tapered thread narrows slightly and usually seals on the thread itself.
Look for the sealing face
Check for a cone, flat face, O-ring, washer face or bonded seal. This tells you how the fitting is designed to seal.
Measure the thread size
Use calipers to measure the outside diameter of a male thread or the inside diameter of a female thread. A thread gauge can help confirm the pitch.
Match the adaptor style
Decide whether you need a male to male adaptor, male to female adaptor, female to female adaptor, swivel adaptor, swept elbow adaptor, tee fitting, blanking plug, blanking cap or bulkhead fitting.

Need help identifying the thread?

Use Flowfit’s Hydraulic Fitting Thread Identification Guide to compare common hydraulic thread types, sizes and measurements before ordering.
Download the thread identification guide

Expert tip

If you are unsure, take clear photos of the adaptor from the side, the end face and next to a ruler or calipers. This makes it much easier to identify the thread, size and sealing method.

5. Common Hydraulic Adaptor Types

Once you know the thread type and size, the next step is choosing the correct adaptor style. The adaptor type depends on what you need the hydraulic connection to do.

Male to male adaptors

Used to connect two female threaded hydraulic components together.

Shop male to male adaptors

Male to female adaptors

Used when one side of the connection is male and the other side needs a female thread.

Shop male to female adaptors

Swept elbow adaptors

Used where space is tight or the hose needs to change direction smoothly.

Shop swept elbow adaptors

Blanking plugs and caps

Used to blank off ports, protect threads or seal unused hydraulic connections.

Shop blanking plugs

Other common Flowfit hydraulic adaptor categories include female to female hydraulic adaptors, swivel hydraulic adaptors, hydraulic bulkhead fittings, hydraulic tee fittings, hydraulic cross adaptors, hydraulic blanking caps, compact hydraulic adaptors, forged hydraulic adaptors, ORFS hydraulic adaptors, JIS hydraulic adaptors, hydraulic hose tail fittings, hydraulic bonded seals and O-rings, hydraulic compression fittings, hydraulic banjo bolts, hydraulic nuts and bolts, and stainless steel fittings and adaptors.

6. Common Mistakes That Cause Hydraulic Adaptor Leaks

If a hydraulic adaptor is leaking, the answer is not always to tighten it further. Many leaks are caused by the wrong thread type, incorrect sealing method, damaged seals, poor alignment or choosing an adaptor that does not properly match the connection.

Mixing thread types because they look similar at first glance.
Matching the size but not the sealing method, such as using the wrong cone, washer, bonded seal or O-ring connection.
Forgetting or reusing damaged seals, including bonded seals, washers and O-rings.
Trying to seal the wrong face, such as using thread tape on a fitting designed to seal on a cone, O-ring or bonded seal.
Overtightening the adaptor, which can damage threads, seals or sealing faces.
Installing the adaptor under hose strain, which can cause the connection to loosen or leak over time.

Leaking hydraulic adaptor?

Do not keep tightening a leaking adaptor without checking the thread type, seal and sealing face first. For a more detailed troubleshooting guide, read our blog: Why Is My Hydraulic Adaptor Leaking? Common Mistakes to Check .

7. Common Hydraulic Adaptor Scenarios

Many customers know what they need the adaptor to do, but not the exact part name. These common scenarios can help narrow down the right type of hydraulic adaptor.

What you need to do	Adaptor type to look for
Connect two female threaded parts	Male to male hydraulic adaptor
Connect a male thread to a female thread	Male to female hydraulic adaptor
Connect two male threaded parts	Female to female hydraulic adaptor
Change hose direction in a tight space	Swept elbow hydraulic adaptor
Split or join a hydraulic line	Hydraulic tee fitting
Blank off an unused port	Hydraulic blanking plug or hydraulic blanking cap
Connect through a panel or bracket	Hydraulic bulkhead fitting
Improve sealing on a compatible connection	Hydraulic bonded seals and O-rings

8. Need Help Finding the Right Hydraulic Adaptor?

Flowfit also supplies other hydraulic adaptor options including female to female adaptors, swivel adaptors, bulkhead fittings, tee fittings, cross adaptors, blanking caps, ORFS adaptors, JIS adaptors, hose tail fittings, bonded seals, compression fittings, banjo bolts and stainless steel fittings.

Tip: Before contacting us, take photos of both ends of the fitting and note any measurements, thread markings or machine details.