The Different Types of Fittings: A Complete Guide
Fittings Guide
Discover all the types of fittings for your air ride system and learn how to choose the right components for a reliable and leak-proof installation
Why Is Choosing the Right Fittings Crucial?
When assembling an air suspension system, choosing the right fittings is just as important as the hoses. Each type of fitting has its advantages, disadvantages, and specific applications.
📌 Important Point
An air ride system can have the best components, but if the fittings are not suitable or poorly installed, air leaks can occur and compromise the entire system. That’s why it’s essential to understand the different types of fittings available.
Standard Thread Sizes
Here are the four most common thread sizes in air ride systems. Measurements are taken at the outer diameter of the thread.
💡 Measurement Tip
Most people don’t have a caliper with inch graduations. So we measured the threads and created these visuals to help you. The displayed values are approximate (± 1/100) and serve only as a reference to identify your fittings.
G1/8" ~ 9.5mm
Thread diameter 9-10mm
G1/4" ~ 12.8mm
Thread diameter 12-13mm
G3/8" ~ 16.4mm
Thread diameter 16-17mm
G1/2" ~ 20.5mm
Thread diameter 20-21mm
🔧 Need Help?
If you measure a similar size but the fitting doesn't fit, it may be due to different threading standards. Feel free to contact us with your measurements; we are here to help!
The Different Types of Fittings
Push In
Quick and simple installation
Push-in (or push-to-connect) fittings are the easiest to use. Simply insert the hose into the fitting for it to lock automatically.
⚠️ Attention Point
It is crucial to cut the hose perfectly straight with a tube cutter to avoid leaks. A slanted cut compromises the seal.
✓ Advantages
- Ultra-fast installation
- No tools required
- Easy disassembly (press the button)
- Ideal for frequent modifications
✗ Disadvantages
- Less reliable in the long term
- Risk of leakage if cut incorrectly
- May loosen with vibrations
Screw-On
Superior reliability and sealing
These fittings use a clamp system that creates an "olive" around the hose, ensuring maximum sealing. Commonly supplied in Airmext kits.
💪 Installation
1. Slide the clamp onto the hose
2. Insert the hose into the fitting
3. Tighten the clamp firmly
⚠️ Do not overtighten to avoid cracking the hose
✓ Advantages
- Very reliable and leak-proof
- Good vibration resistance
- Proven system
- Excellent value for money
✗ Disadvantages
- Longer installation time
- Requires tools
- Risk of cracking if overtightened
Hard-Line Olive
For permanent installations
Used for rigid pipes (copper, stainless steel, aluminum), these fittings offer the best sealing and a clean professional look.
🔧 Installation
1. Cut the pipe straight
2. Deburr inside and outside
3. Slide on the sleeve then the olive
4. Insert into the fitting
5. Tighten the sleeve firmly
✓ Advantages
- Maximum reliability
- Professional appearance
- Extreme durability
- Long-lasting
✗ Disadvantages
- Complex installation
- Requires skills
- Hard to modify
- More expensive
Male and Female Fittings
These fittings allow you to connect your system to the tank, solenoid valves, and other components
🔌 Connection Types
Male and female fittings come in various shapes to suit your installation:
- ➤ Straight Fittings: For straight-line connections
- ➤ 90° Fittings: For 90-degree angles, useful in tight spaces
- ➤ T Fittings: To split a line into two
- ➤ Y Fittings: Alternative to T fittings for certain configurations
📚 The 3 Major Thread Families
There are three main threading standards for air ride pneumatic systems. Each has its own dimensions, angles, and sealing methods:
- 1. NPT/NPTF: American standard, 60° tapered threading
- 2. G (BSPP): British/European standard, 55° parallel/cylindrical threading
- 3. R (BSPT): British/European standard, 55° tapered threading
NPT fittings (US Tapered)
National Pipe Thread - American standard with 60° tapered threading. Sealing is achieved by tightening the tapered thread.
🔧 Technical Characteristics
• Angle: 60°
• Type: Tapered (taper 1:16)
• Origin: American standard
• Standards: ANSI/ASME B1.20.1
🔐 Installation
Even though the tapered thread provides some sealing, it is strongly recommended to use PTFE (Teflon) or Loctite thread sealant to guarantee 100% perfect sealing.
✓ Advantages
- Very common in the USA
- Sealing by tightening
- Solid assembly
✗ Incompatibility
- ⚠️ NOT compatible with R or G
- Requires specific adapters
G fittings (Parallel EU)
BSPP - British Standard Pipe Parallel - European standard with 55° cylindrical/parallel thread. Sealing is done by O-ring.
🔧 Technical Characteristics
• Angle: 55°
• Type: Cylindrical/Parallel
• Origin: British/European standard
• Standards: ISO 228-1, BS EN ISO 228
⭕ Sealing
Sealing is ensured by O-rings that compress when tightened. The thread itself does NOT provide sealing; it only holds the parts together.
✓ Advantages
- European standard
- Sealing by O-ring
- Easy to disassemble/reassemble
- Replaceable seals
✗ Points of Attention
- Check the condition of O-rings
- Replace seals if worn
R fittings (Tapered EU)
BSPT - British Standard Pipe Tapered - European standard with 55° tapered thread. Also called PT. Sealing is done by tightening + PTFE.
🔧 Technical Characteristics
• Angle: 55°
• Type: Tapered (taper 1:16)
• Origin: British/European standard
• Standards: ISO 7-1, BS EN 10226-1
🔄 Designations and Compatibilities
• R: Tapered male thread
• Rp: Cylindrical female thread (for R)
• Rc: Tapered female thread (for R)
• Also called: BSPT, PT, BS 21 (old standard)
🔐 Sealing
Sealing is ensured by a PTFE (Teflon) coating on the thread. The tapered R thread can screw into a cylindrical Rp or tapered Rc female thread.
✓ Advantages
- Very common in Europe
- Reliable sealing
- Compatible with Rp and Rc
- Often pre-Teflon coated
✗ Incompatibility
- ⚠️ NOT compatible with NPT
- Different angles (55° vs 60°)
⚠️ WARNING: NPT ↔ R/G incompatibility
NPT and R/G threads are NOT compatible with each other!
Even if the dimensions seem close, the thread angle is different:
- ✗ NPT = 60° (American standard)
- ✗ R/G = 55° (British/European standard)
If you need to connect NPT with R or G, you MUST use a specific NPT ↔ BSP adapter. Forcing the assembly will cause leaks and could damage the threads!
🛡️ Pro Tip: Always use Loctite/PTFE
Whether for NPT, G, or R fittings, using a sealing product is essential:
- ✓ For NPT and R: PTFE tape (Teflon) or thread Loctite
- ✓ For G: Check the condition of O-rings + Loctite as a supplement
A small leak can drain your system and leave you stranded at the worst moment!
Thread Diameter Chart
Quick reference to identify your fittings
| Designation | Diameter (mm) |
|---|---|
| NPT STANDARD (USA) | |
| NPT 1/8" | ~9.5 mm |
| NPT 1/4" | ~12.8 mm |
| NPT 3/8" | ~16.4 mm |
| NPT 1/2" | ~20.5 mm |
| G / BSPP STANDARD (EU - Parallel) | |
| G 1/8" | ~9.7 mm |
| G 1/4" | ~13.2 mm |
| G 3/8" | ~16.7 mm |
| G 1/2" | ~20.9 mm |
| R / BSPT STANDARD (EU - Tapered) | |
| R 1/8" | ~9.7 mm |
| R 1/4" | ~13.2 mm |
| R 3/8" | ~16.7 mm |
| R 1/2" | ~20.9 mm |
Installation Tips
🛠️ Installation Checklist
Before Installation
- ✓ Check thread size compatibility
- ✓ Prepare all your tools (tube cutter, wrenches, Loctite)
- ✓ Clean threads and contact surfaces
- ✓ Check the condition of O-rings
During Installation
- ✓ Cut hoses straight with a tube cutter
- ✓ Apply Loctite on male/female threads
- ✓ Tighten firmly but without excessive force
- ✓ Follow torque specifications if indicated
After Installation
- ✓ Test the system under pressure gradually
- ✓ Check each fitting with soapy water
- ✓ Tighten again if necessary after the first test
- ✓ Re-check after a few days of use
⚠️ Common Mistakes to Avoid
- ✗ Cutting hoses at an angle (main cause of leaks)
- ✗ Do not use Loctite on threads
- ✗ Over-tightening fittings (risk of cracking)
- ✗ Mixing NPT and G fittings without an adapter
- ✗ Do not test the system before use
