Adapters & Couplings for air suspension

In this category, you’ll find all types of air fittings and adapters you may need to complete your air suspension system. At DDESIGN, we offer a complete range of nipples in common sizes. Typical products include push-to-connect (PTC) fittings, also known as quick-connect fittings, adapters for joining different hose sizes and fitting types, T-fittings, Y-fittings, and bulkhead fittings.

• 1/4
• 3/8
• 1/2
• 6mm
• 10mm

What is NPT measurement?

NPT originally refers to a type of thread used to join pipes that carried liquids, gas, steam, or hydraulics. This was done with adapters at the ends that connected two pipes together. Because the thread was made conical, it could seal by itself simply by tightening. This meant there was no need for a flat surface with a sealing washer or O-ring - the thread itself would seal. Well, “seal” might be an overstatement; it was soon discovered that achieving a perfect seal was difficult. Over time, engineers experimented with different thread angles and found that thread sealant is needed for a completely tight fit. That’s why thread tape is almost always used on this type of fitting.

Nowadays, we most often encounter this type of fitting when building air suspension or other pneumatic systems in cars and similar applications.

How do I measure my NPT fittings?

So why isn’t a 1/2-14 NPT thread exactly 12.7mm in outer diameter? 
The reason is that the size designation is based on the pipe size. An adapter labeled 1/2 is designed for a pipe or hose that has an outer diameter of 1/2 inch. For the pipe to fit inside the adapter, the adapter itself needs to be slightly larger (to allow for material thickness). Therefore, a 1/2-14 NPT fitting has an external diameter of 21.3mm on a male thread (MNPT).

Read our guide here on how to measure your air fittings or ports on your air springs.