Step 1: Determine the gender, male or female
If the thread is on the outside of the pneumatic fitting, it is a male thread; if the thread is on the inside of the fitting, it is a female thread.
Step 2: Determine if the threads are straight (parallel) or tapered
Several thread designs exist:
National Tapered Pipe (NPT)
National Straight Pipe (NPS)
British Standard Pipe Taper (BSPT), also known as R thread
British Standard Pipe Parallel Pipe (BSPP), also known as G thread
Metric, tapered or straight
Step 3: Determine the thread pitch
The thread pitch defines the distance from the peak of one thread to the next. It may be expressed in some tables as an inch or mm measurement from thread to thread, or in other tables as to how many threads fit into a one-inch distance.
Step 4: Determine the thread diameter
Use calipers to measure the OD of male threads, or the ID of female threads (Figure 5). Take this measurement at the largest diameter of the thread, female fittings measured at the first thread and male fittings measured at the last thread.
Step 5: Determine the fitting size
Compare data obtained in steps 1 through 4 with charts like Figure 6, to identify the fitting size.
Avoid downtime by being prepared
Because pneumatic machinery can be very reliable, some facilities may not carry adequate spares. But with the right tools and knowledge, determining fitting and tubing types and sizes isn’t all that tough. Measurement accuracy is of utmost importance as many of the thread diameters and pitches are very close to each other but not interchangeable. With the right information and a good supplier website, you can quickly order the parts you need to resume production. If you still have any questions, you can contact us.