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This blog addresses the third question in ‘How to Determine the Appropriate Regulator‘ as part of our ‘Choosing the Correct Regulator’ series: What type of porting? NPT or BSP?
There are many options for port sizes for a pressure regulator. Generally, port size will be dictated by the flow requirements in a particular application. Then there are different types of threads. The two main thread types are NPT and BSP. Here are the main differences between NPT and BSP threads:
Identifying the size of a thread is sometimes important when trying to find a replacement regulator. Please note that the OD of the thread on a 1/2” NPT port is not 1/2”. It is closer to 3/4”. We have a table of the thread OD for the 4 most popular thread sizes.
NPT Thread | Outside Diameter |
1/4” | 0.533” |
3/8” | 0.668” |
1/2” | 0.832” |
3/4” | 1.043” |
1” | 1.309 |
Some regulators have different port size options. The smaller port size options can be the choke point for the airflow. If the larger port sizes are used, the choke point becomes the internal valving in the regulator.