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Thread: Barb Sizes Explained

  1. #1
    Administrator coolmiester's Avatar
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    Default Barb Sizes Explained

    OK let try and take away some of the guess work out of Barb sizes.

    Firstly the UK standard of BSP (British Standard Pipe) and under the heading of BSP fall two commonly used standards, BSPT the T standing for Tapered Thread and BSPP the P standing for Parallel Thread.

    BSPT barbs should always be married up with a BSPT hole thus acting like a plug and all threads working against each other forming an even bond, and to make totally water/air tight wrap the barb 3 or 4 times with PTFE tape:-

    \ /
    \ /

    Otherwise if you put a tapered barb into a parallel threaded hole you are literally relying one thread doing all the work:-

    \ /
    | |

    And also BSP (UK standard) are not interchangeable with NPT (USA standard) as the actual pitch of the thread is different - BSP being 55 degrees and NPT being 60 degrees so be careful trying to squeeze BSP into NPT holes (especially brass into plexi) and vice versa otherwise you could end up doing this……………see below pic of 1/4" BSPT thread barb being forced into a 1/4" NPT hole.

    Note: This isn't to say that mixing Parallel, Taper, BSP and NPT thread can't and shouldn't be done as on many occasions it can be done successfully but nevertheless doesn't mean because it works it is correct and care should always be taken!




    When choosing a Barb or Fitting there are three sizes which need taking into account.

    a] Hose Tail (OD) Size
    b] Thread Size
    c] Diameter (ID) Size



    a] The Hose Tail Size commonly called OD or Outer Diameter is pretty much self explanatory for example on a 1/2" Hose Tail the measurement is taken form the widest overall diameter of the hose tail (see pic below)



    b] The Thread Size is much more complicated to calculate and also to comprehend as on first inspection bears no resemblance to measurement as you would have thought.
    So to keep this as a simple guide it is easier to assume that in most basic water cooling set-ups fall into two categories and then obviously the various consequence sizes of both, usually in variants of inches and not metric:-

    BSP (British Standard Pipe)
    and
    NTP (American Standard)

    In the pic below you can see a 1/4" NPT Thread Chrome Barb against a 1/4" BSP Thread Brass Barb and the thread pitch /\ doesn't actually marry up due to the pitch of the thread being different and as most people will not have the necessary instruments to measure thread pitch, trying to explain the complicated procedure of measuring the thread size whether BSP or NPT will be left at this stage but a general rule of thumb is to consider most British and European manufacturers use 1/4" and 3/8" BSP and most American use mainly 1/4" NPT
    To find a more comprehensive view on measuring thread sizes you may want to Google it and look for a chart which will equate the number of threads into a measurement!



    c] Finally, Inner Diameter or commonly called ID is also self explanatory and is the overall widest inner diameter of the barb which can be measured and seen in the pic below.
    This size can vary from each individual manufacture and comes down how wide they have milled the inner bore in the production stage.
    The inner Diameter measurement is very important in terms of flow rate and a larger Inner Diameter will be less restrictive than a smaller one.
    Remembering that on a 1/2" set-up called such by the Inner Diameter of the hose and Barb Hose tail size can have the flow rate dramatically reduced by the use of a very narrow ID Barb diameter.



    Anyway, I hope this may help take away some of the confusion that these fittings seem to inevitable create but remember it is only a small guide outlining and identifying some of the basics on these small yet very confusing fittings.

    Thanks
    Last edited by coolmiester; 02-04-2006 at 06:11 PM.

  2. #2
    Junior Member coldspot's Avatar
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    Thumbs up Barbs and Flow

    The Wall thickness is way to much for our set-ups so I did this little "Barb Mod".
    Way better flow

    Enjoy

    l8r
    Attached Images Attached Images
    Last edited by coldspot; 30-08-2005 at 03:20 AM. Reason: Bad and wrong grammer

  3. #3
    Member The Boy Riley's Avatar
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    Default

    I can understand the thread sizes, but if I want to get 1/2" barbs, do i use 1/2" tubing, because its supposed to be a tight fit yea? wouldn't i use 3/8" tubing, so it is tight, then the clamps. Bit of a noobish question, but I am.
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  4. #4
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    1/2 barbs for 1/2 hose (7/16 hose for even better flush fit), but please find a more appropriate place to post than guides!

  5. #5

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    Only just seen this guide, thats exactly what my dad had told me, and hes an engineer,

    top stuff.


    Manktelow

  6. #6
    Administrator coolmiester's Avatar
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    We seem to have had a lot of people getting confused lately with all the different types of barbs and in particular which barbs fit their particular hardware.

    Im not 100% sure why this is but one reason could be that there is a lot of second hand hardware kicking around these days which doesn't always come with their intended barbs fitted so its left to the new owner to source new ones.

    Anyway, this Barb Sizes Explained Guide is really handy and gives a good insight into which part of the barbs individual measurements equates too - so please give that a read as more often than not it will answer most questions.

    Having said that i've just taken a picture of the most common barbs used with most hardware on our site which should help identify which barb is right for your hardware.

    Things have become much easier since Danger Den took it upon themselves to start using the European standard of 1/4" thread (G1/4) though unavoidably there is going to be a transition period while the production of new blocks enter circulation and older stock or second hand blocks are still doing the rounds so we can't write off the older 9/16" thread Hi-Flow barbs just yet.

    As you can see from the picture, starting on the right is the Alphacool G1/4 Thread to 1/2" Hose Tail which is also available in 3/8" Hose Tail and even smaller 8mm Hose Tail and will fit most European things such as Alphacool, Innovatek, XSPC and can also be used with the new Danger Den gear including HardwareLabs Radiators though its recommended to use their own Perfect Seal Barbs if possible.

    Second is XSPC version of the G1/4 Thread to 1/2" Hose Tail. These are presently only available in 1/2" Hose Tail but i have heard that a 3/8" version will be available soon.

    Next is Danger Dens new offering, the Perfect Seal which again is available in either 1/2" or 3/8" Hose Tail and has a G1/4 Thread so can be used with pretty much most European hardware such as Alphacool, Innovatek, and XSPC.

    Finally is the older Danger Den Hi-Flow Barbs which again are available in 1/2" or 3/8" Hose Tail but has a bigger 9/16" thread so only fit their earlier hardware and are not interchangeable with their newer Perfect Seal.

    Anyway without going to in depth for fear of confusing people even further (including myself) i'll stop there but hope this might help out.

    It might be an idea to make a list of all hardware and which barbs they use if anyone's feeling really board which could be added here and turned into a sticky :smile:

    Note: 10/10/06 Since writing this things have changed again and Danger Den are now dropping the G1/4 Perfect Seal Barbs in favour of the new G1/4 Hi-Flow Barbs which look exactly the same as the Hi-Flow Barbs pictured below (right hand side) but now have a G1/4 thread so essentially they are interchangeable with most other G1/4 thread hardware but not with hardware that uses the 9/16" thread.

    Last edited by coolmiester; 10-10-2006 at 11:37 AM.

  7. #7
    Administrator coolmiester's Avatar
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    Just to clarify another recurring issue with Perfect Seal and Hi-Flow Barbs as many people on receiving 3/8" Perfect Seal Barbs automatically think they have been sent 1/2" Hose Tail as the.

    They are named Perfect Seal as the Hose Tails are oversized causing a perfect seal between the barb and hose.

    Below is a picture of Danger Dens most common barbs to show the difference in hose tail sizes - all are G1/4 thread and with the outside diameter measurement of the hose tail is indicated in mm to try and avoid confusion.

    3/8" Hi-Flow (10.5mm) >>> 1/2" Hi-Flow (13mm) >>> 1/2" Perfect Seal (15.5mm) >>> 3/8" Perfect Seal (12mm)


  8. #8
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    Just wanted to say thanks, this helped me greatly

    Flubster

  9. #9
    Junior Member pandaking's Avatar
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    Default Difference between bsp and g?

    So from the first post where you talk about BSP and NPT, to the next post where you mention G what is the difference between the too.

    Is G the same as BSP, or NPT or is it completely differant.

    Thanks

    PS. Also might be worth deleteing the other users posts or addding all your info into the fist one so it's all together...

  10. #10
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    Just what I was looking for, this guide has helped me along nicely

    Thanks

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