There is sometimes confusion about whether our air nozzles have an American or a European thread. Or both?
The following overview explains what the (optional) NPT and BSP connections are all about.
If you are still unsure whether our products will fit your system, we will give you individual advice – just call or send us an email!
American nozzles for our customers in Europe
- First things first: we supply almost all our air nozzles with a European BSP inch thread (British Standard Pipe, Whitworth thread).
- A tapered NPT inch thread (National Pipe Thread) is of course also available on request.
- To make ordering easier for you, the part numbers in our shop carry the prefix BP, for example BP1230. This is how we identify all variants with a BSP thread, so there can be no mix-up.
- Please note: if you order an EXAIR product without the BP identifier, from us or elsewhere, it will probably be supplied with an NPT connection! In the USA, where the nozzles are made, NPT is the standard version.
NPT or BSP – no problem!
- Many of our nozzles with a “BP” part number have a factory-machined BSP thread. These include most of the vortex tubes, our cabinet coolers and some of the air nozzles.
- If an EXAIR product is made without a BSP connection, the matching compressed air adapter is always included in the scope of delivery.
- Our adapters have two male threads (NPT and BSP) and can be mounted on the compressed air line with standard fittings.
1/4″ Eputec compressed air adapter with one NPT and one BSP male thread
BSP male thread vs. female thread
A BSP male thread is a tapered, cone-shaped inch thread from the R thread group, known in English as BSPT (T = taper). For the thread standard, please see DIN 2999 at: http://www.gewinde-normen.de/kegeliges-whitworth-rohrgewinde.html
A BSP female thread is parallel, in other words a G thread, also called BSPP (P = parallel). See DIN ISO 228 (DIN 259) at: http://www.gewinde-normen.de/whitworth-rohrgewinde.html
Proper sealing is always important!
Whether BSP, BSPP or NPT, it is always advisable to wrap sealing tape all the way round the thread. To a certain extent, this compensates quite well for the differences from a metric G thread.
Problems with connections between BSPT and NPT and metric or other thread types (for example on “soft” plastic pipes) arise when they are screwed and unscrewed repeatedly. This damages the threads and leads to leaks.
And what does metal-to-metal sealing mean?
A metal-to-metal seal joins two metal surfaces into a tight unit without the use of additional sealing materials. It is often used where high temperatures or pressures occur, because metal is highly resistant and durable.
Tapered threads seal without additional sealant, because the male and female threads wedge into each other when tightened.
Parallel threads need aids (O-ring, washer) to ensure a tight connection.
These compressed air adapters are made from a copper-zinc alloy (brass).
Depending on the specific requirements, different materials are suitable for metal seals:
- Stainless steel is highly resistant to corrosion and high temperatures.
- Copper offers good thermal conductivity and resistance to many chemicals.
- Aluminium is light and corrosion-resistant, but less heat-resistant than stainless steel.
- Nickel alloys withstand high temperatures and aggressive chemicals.
To learn more about thread types in general, we recommend this site: www.gewinde-normen.de.
For any questions specifically about compressed air connections, our Technical Customer Advice team will be glad to help.
You can find the English version of this article here: BSP or NPT threads: Always a good connection