NPT fittings

[daiking]

This water filter https://www.screwfix.com/p/bwt-high-capacity-water-filter-kit/16747 is described as having 3/4" NPT fittings, not BSP. Last time I tried this sort of thing, BSP fittings really did not work.

 

3/4" NPT fittings do not seem readily available let alone a coupler to 15mm pipe compression fitting.

 

What am I missing here?

[ProDave]

One of the reviews says "connected with flexible connectors" and another says "I have used Straight Tap Connector 15mm x ¾" Item Number 36420 and ptfe tape, no leak perfect "

[PeterW]

If you’ve not already bought it or fitted it then don’t bother - I took one back as it was rubbish. 

 

Replaced it with this and a pair of standard 1/2” to 15mm Tectite push fits for less than £20. 

[daiking]

On 9 November 2018 at 16:03, ProDave said:

One of the reviews says "connected with flexible connectors" and another says "I have used Straight Tap Connector 15mm x ¾" Item Number 36420 and ptfe tape, no leak perfect "

 

Past experience means I'm not willing to try fitting a 3/4" BSP to a 3/4" NPT again

 

On 9 November 2018 at 16:22, PeterW said:

If you’ve not already bought it or fitted it then don’t bother - I took one back as it was rubbish. 

 

Replaced it with this and a pair of standard 1/2” to 15mm Tectite push fits for less than £20. 

 

No I haven't yet, I had looked at some only options from water filter 'specialists' but will give that eBay listing a once over. I hope you can appreciate that to the untrained eye there is very difference between those products and buying blind off eBay by a laymen often ends in less than success as well. 

[Nickfromwales]

10 hours ago, daiking said:

 

Past experience means I'm not willing to try fitting a 3/4" BSP to a 3/4" NPT again

 

 

No I haven't yet, I had looked at some only options from water filter 'specialists' but will give that eBay listing a once over. I hope you can appreciate that to the untrained eye there is very difference between those products and buying blind off eBay by a laymen often ends in less than success as well. 

Cant ignore an educated recommendation though eh?  

[MikeSharp01]

The assumptions here need unpacking a bit perhaps.

 

When talking about BSP we usually assume parallel threads because the technical extra P (BSPP) is assumed while NPT does what it says on the tin (National Pipe Taper) has a tapered thread. To get a correct 'mating' you would need to use another NPT fitting. Tapered threads are designed, among other things, to seal themselves as they tighten with minimal packing while parallel threads usually need some additional sealing such an olive, a sealing face or washer. If you try and get an NPT (male) to mate with a normal BSP thread (female) it only meets at one place so is very challenging to seal and can split the female fitting. There is a NPS (straight) form as well but you don't see that about much. All the details can be found here: https://www.valvesonline.com.au/references/threads/ from Oz but as it is talking about the standards of two other countries I think it can be relied upon.

[PeterW]

10 hours ago, daiking said:

 

No I haven't yet, I had looked at some only options from water filter 'specialists' but will give that eBay listing a once over. I hope you can appreciate that to the untrained eye there is very difference between those products and buying blind off eBay by a laymen often ends in less than success as well. 

 

Try this - pipework in copper / Tectite at client request. 

 

 

Units are well made, Tectite male 1/2” connectors are wound with 2 wraps PTFE as this is brass into HDPE so can sometimes bite a little as the thread pulls in. Look to be machined threads in the HDPE head rather than moulded so they are better tolerance. 

 

Came with a 5 micron wound filter that will be replaced with a carbon block after commissioning. Dynamic balanced 3 bar across the build, no discernible difference in flow between hot and cold (hot unfiltered) 

 

They do them in 1/2”, 3/4” and 1” but the limiting factor is the flow rate through the filter itself so anything above 1/2” isn’t really necessary if it’s feeding a single tap. 

 

 

[daiking]

Wanted to have a look at this, this weekend but didn't get roundtuit. Just need a single filter for taking out the chlorine taste. Its only the kitchen feed which is the tap and the dishwasher. fortunately the washing machine is in the utility. Filter should last a bit longer that way.