BSP vs NPT vs "PT"

- Will 1/8" NPT male thread seal in 1/8" BSP female thread. (I am aware of the flat/rounded shape and 60/55 angle differences between the thread types.)

- What is "PT" as regards to products mfd in China.

- Are there 2-3 UK or other sources for small BSP fittings. In particular, 1/8" BSP hex plugs.

I am located in Can where NPT is the norm. I can across a solenoid valve suitable for a project of mine - unfortunately, it has 1/8" BSP female ports as listed by most vendors. A few vendors offering the same valve describe the ports as 1/8" "PT".  So far, I have not come across an equivalent valve (2-position, 3-way) w/ NPT ports and a solenoid configuration suitable for the application in mind.

I have seen 1/8 "PT" Push-to-Connect hose fittings paired with the valves. These do not appear to meet my needs because: a) I don't know what PT thread is and b) I intend to use bespoke barb fittings (hex plugs drilled for 3mm OD brass tube.)

I have discovered one 1/8 BSPM - 1/4 NPTF adapter: the price is high for my purposes. Together with the matching NPT fitting, this arrangement is a deal-breaker.

Edited By Eddy Curr on 10/12/2019 19:53:59

Pitch of the two threads is also different so unlikely to fit NPT is 27tpi and BSP is 28tpi

I tried to edit the previous post several times, but the post text failed to display longer than momentarily before disappearing - seemingly a result of slow-to-load advertising banners. I'm all in favour of advertising - right up to the point where it bogs down the site and interferes with key functionality.

Anyway.

The previous content should say "... I CAME across ..."

Eddy you should be able to get 1/8BSP or G1/8 plugs from e-bay, just use ebay.com rather than ebay.ca which will tend to give mostly NPT results.

Hmmm. Different pitch, form and angle?

Probably nothing that additional PTFE tape and a bigger spanner can't fix, huh ?

Any forum vendors with a line of small BSP fittings that trade overseas ...

Thank you. Yes, I've had success w/ searches on eBay.co.uk in the past, too. Thought I'd ask about preferred vendors here as I've had pleasant dealings w/ the likes of Arceuro and others in the past, just don't know who carries such fittings.

G1/8 is a new term for me. Can you elaborate a bit?

Bit of hex brass stock and a little set-up. Given the same amt of time I've put into the BSP-NPT issue, I'd probably already be finished the 20 or so hex plugs.

Just seemed like there should be a readily available commodity: valve w/ NPT ports; easily-available BSP fittings.

Thank you. I'll get on with it ...

Correct Eddy!

NPT will be 60 degree thread form, while BSP will be 55 degree Whitworth thread form; as as you now know the pitch also differs.

By the sound of it you need more than just three for one solenoid valve? You would need a 1/8 NPT die (assumes that the valves have female ports ) and a 1/8 BSP tap to produce the female part of the adaptor.

Otherwise, i would advocate getting some hexagon brass bar and making your own adaptors, unless you want to go into mass production?

Howard

Comprehensive list of threads here on The Engineering Toolbox. I hope no-one expects a short simple list!

PT was a Japanese Industrial Standard thread. It's interchangable with BSPT.

PF was the JIS thread interchangable with BSPP (parallel), and later called 'G'

Dave

Edited By SillyOldDuffer on 10/12/2019 21:29:25

The "G" denotes Gas thread, interchangeable with BSPP

Phil.

Eddy

ISO 7 defines European pipe thread standards which as far as I can see copy the BSP 55 degree form, pitch and diameter. The standard prefixes the pipe diameter with a G. For example G5/8 is 5/8 BSP. This size is the European standard for a scuba diving cylinder exit port thread. A strange case of a non metric thread being an ISO standard.

So G 1/8 is 1/8 BSP by another name.

hth

Dave