Thread info required for the TEMU hydraulic pressure tester

[GreensandsParticipant @greensands]

 

I have recently purchased a hydraulic pressure pipe tester from TEMU to carry out some local boiler leak testing which I gather has been used for this sort of work and is certainly a cheap (and cheerful) tool for the job. The free end of the 1m length of pressure pipe is fitted with what I think is a standard pipe fitting measuring typically 20.5mm O/d but of unknown thread pitch. To be of any use for model engineering purposes a reducing adaptor needs to be made up and screwed onto the existing fitting but before cutting metal I would like to have confirmation of the thread specification and any advice that can be offered which may be of help. All help and assistance much appreciated.

[Andy StopfordParticipant @andystopford50521]

1/2″ BSP – 14 TPI, used the world over for plumbing threads, though quite often with rather loose tolerances.

[bernard towersParticipant @bernardtowers37738]

do you need to make an adaptor ehen you can cut that one off and fit your own?

[GreensandsParticipant @greensands]

Yes, i am coming around to that conclusion myself as the simpler and neater option to an adapter which would  be otherwise too chunky. The ideal arrangement would be to crimp the new fitting to the hose but not having a crimping tool I would probably end up using a suitably sized circlip.

[JasonBModerator @jasonb]

The Temu listing actually says 1/2″ twice which confirms what Andy said.

Hopefully a Jubilee clip rather than a Circlip.

[Andy StopfordParticipant @andystopford50521]

The way I did mine was to buy one of those braided flexi-hoses for connecting kitchen taps with a small (1/8 BSP I think) male thread on one end and a female 1/2 BSP on the other to connect to the test pump. I then made a small adaptor to screw into a convenient bush on the boiler with a 1/8 BSP female thread to attach to the existing hose end.

The advantage of doing this is that the existing hose is short and rather inflexible, and it’s just a real nuisance to attach to the boiler. You can get 500mm long flexis and they make it all much more manageable. And you can still use it for testing your plumbing.

By the way, the pressure gauge on mine was reasonably consistent, but read about 20 psi low.

[JasonBModerator @jasonb]

Do be careful using tap connectors for this. They are often only rated to 10 bar which could easily be exceeded if doing a twice working pressure test on a copper boiler

[Nigel Graham 2Participant @nigelgraham2]

Note those tap-connectors shrouded with braided, very fine stainless-steel wire are not really designed for frequent flexing, contact over edges and so forth, and consequent broken strands are very hard to see but very effective thorns.

How do I know…?

Ouch!

 

(You could add an outer sleeve of non-adhesive heat-shrink sleeving but I’d still heed Jason’s point about their pressure rating first.)

[colin branniganParticipant @colinbrannigan54160]

I bought one recently for pressure testing my Marston Sunbeam rocker box oil feed, ran it at 30 psi and then adjusted the the oil drips to suit. I cut off that 1/4 BSP fitting replaced it with 1/8 BSP, for the price it works well.

Colin

[noel shelleyParticipant @noelshelley55608]

From what has already been said it is a standard BSP fitting and from the measurement given 1/2″. Adaptors are available at a local hydraulic suppliers in a vast range of combinations. 1/8″ BSP is just over 3/8″ od. As this illustrates BSP is the commonest pipe thread, the world over. The likely hood is that the other end is also BSP may be 3/8″x19 and an ordinary single or double reinforced hydraulic hose will make a good replacement. For model engineering threads just buy an over size adaptor, machine down and rethread to suit. Adaptors are available in brass, stainless and mild steel.

NOTE The thread sizes are nominal bore NOT outside diameter.

If your near me I can help with fittings or pipe – N Norfolk.

[GreensandsParticipant @greensands]

What sort of adjustment is provided by the hex headed screw seen at the bottom of the gauge?

[Martin of WickParticipant @martinofwick]

hex headed screw seen at the bottom of the gauge?

…is the pressure bleed off.

Also, as Jason says the pressure gauge is best treated as an indicator not an accurate reading. Can be replaced with gauges available cheaply on line to suit your requirement but you ay need an adapter.

On mine the thread to the the gauge is measured as 1.5mm x14mm, as is the connection to the tube from the pump.

 

 

[GreensandsParticipant @greensands]

In what circumstances is the pressure bleed off screw used?

[Martin of WickParticipant @martinofwick]

Okay, so you pump up your test item to 250 bar and it holds perfectly.

Then you bleed of the pressure to atmospheric in order to be able to disconnect the item (or precisely set whatever other pressure you want to test). Unlikely you would be able to unscrew the connector threads under pressure (not generally recommended and not really safe).

[noel shelleyParticipant @noelshelley55608]

The more expensive version of a proof pump has 2 valves, one isolates the pump from the system leaving the pressure gauge in circuit, the other is the relief valve, as the name implies it relieves the pressure.  Noel.

A word of caution ! These pumps can easily burst ordinary plumbing equipment Etc a friend of mine borrowed mine and blew up an oil cooler like a balloon. Above 2 bar go easy, unless rated for mains pressure and even then much above 6 is sailing into danger.

[Howard LewisParticipant @howardlewis46836]

20.8 mm = 0.818″ which looks like a slightly undersize (truncated?) 1/2 BSP (0.825″) and 14 rpi, Whit Form thread, not 60 degrees., as already said previously.

Where pipework is concerned, think of BSP fittings and Imperial sizes, not Metric.

Even the EU use BSP fittings, although they call them GAZ, and probably work in decimal Metric sizes, as you have done.

Howard

[duncan webster 1Participant @duncanwebster1]

6mm blue nylon airline pipe has a working pressure of 33 bar

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