bubble tester pipe size

[GUMPY]

2 hours ago, blackrose said:

 

Every time you want to test the system? Sounds like that might get expensive.

The only time I wanted to test my gas system after fitting a new cooker my local examiner said "here take my tester and DIY you know how its done"

 

[blackrose]

2 hours ago, cuthound said:

 

You can get lpg monitors to fit in the bilges and/or use your highly sensitive nose to test for gas leaks.

 

https://www.force4.co.uk/department/safety/fire-gas-safety/gas-fume-alarms.html

 

Yes, you certainly can, but bubble testers, lpg detectors and smelling for gas are not mutually exclusive options. One can have all 3 so it's not a choice between them. If one smells gas or a lpg alarm sounds, then it might be useful to have bubble tester as a quick way of testing the system. 

1 hour ago, Loddon said:

The only time I wanted to test my gas system after fitting a new cooker my local examiner said "here take my tester and DIY you know how its done"

 

 

Lucky you for having an examiner who's willing to lend you his equipment. I don't but I've still tested my gas system plenty of times. 

[mrsmelly]

1 hour ago, Loddon said:

The only time I wanted to test my gas system after fitting a new cooker my local examiner said "here take my tester and DIY you know how its done"

 

I use the number one smelling implement, never failed yet. System was tested last week for the MOT and boat passed first time without me doing any prep whatsoever to anything. Surely a bubble tester is just another weak point in a gastight system?

[cuthound]

3 minutes ago, mrsmelly said:

I use the number one smelling implement, never failed yet. System was tested last week for the MOT and boat passed first time without me doing any prep whatsoever to anything. Surely a bubble tester is just another weak point in a gastight system?

 

I completely agree, and you have to look at it to see if you have a leak, whereas the nose is always on duty.

[blackrose]

19 minutes ago, mrsmelly said:

I use the number one smelling implement, never failed yet. System was tested last week for the MOT and boat passed first time without me doing any prep whatsoever to anything. Surely a bubble tester is just another weak point in a gastight system?

 

Why would it be a weak point? Only if you're incapable of making a gas tight joint I suppose... Besides it's inside the gas locker.

 

I fitted 2 bubble testers to my dual lpg systems about 13 years ago and never had an issue. They quickly helped me to determine which system was leaking when I smelled gas once. Turned out to be a factory made joint on the back of my Morco water heater, not one of mine.

 

Anyway, the choice is simple. If you don't want one, don't buy one! They are not obligatory.

Edited December 14, 2019 by blackrose

[Iain_S]

3 hours ago, Loddon said:

Why bother with one just get a proper examiner who is qualified to do gas.

 

Good luck finding one north of Hadrian's wall!

[Guest]

On 09/03/2019 at 14:51, Guest said:

Indeed. Ours were so tight I feared shearing something off on our new tester. I think the sealer used glues them in. I bought two adaptors from Midland Chandles that could be fitted over the existing stubs. These worked very well.

just a thought, but if these are parallel female fittings screwed on to the “stubs” which are the ends of the compression fittings usually fitted, you have connected 2 parallel threaded fittings together. While this won’t fail BSS, correvt practice for marine LPG threaded fittings is to use BSPT fittings, the T being taper.
 

So best this is not replicated ?
 

 

[Alan de Enfield]

1 hour ago, watchfuleye said:

While this won’t fail BSS, correvt practice for marine LPG threaded fittings is to use BSPT fittings, the T being taper.

I doubt the majority of BSS examiners would even know what to look for, or, see the difference  - maybe that is why its not a requirement.

[Chewbacka]

3 hours ago, watchfuleye said:

just a thought, but if these are parallel female fittings screwed on to the “stubs” which are the ends of the compression fittings usually fitted, you have connected 2 parallel threaded fittings together. While this won’t fail BSS, correvt practice for marine LPG threaded fittings is to use BSPT fittings, the T being taper.
 

So best this is not replicated ?
 

 

And more than one turn of ptfe tape, but if they are parallel thread, it will need more than one turn or it will leak.  But amount of ptfe is not a BSS examination point.
However it will be interesting to see what the BSS examiner makes of the joint ‘design’  (assuming it is noticed) as it exceeds the number of components allowed in a joint as specified in the BSS private boat check list section 7.8.4.  

“• must be made with a minimum number of individual components.”

”NOTE – the minimum number of components is usually interpreted as two.”
 

So if noticed, I think it should be a fail.

 

Edited December 17, 2019 by Chewbacka

[blackrose]

6 hours ago, watchfuleye said:

just a thought, but if these are parallel female fittings screwed on to the “stubs” which are the ends of the compression fittings usually fitted, you have connected 2 parallel threaded fittings together. While this won’t fail BSS, correvt practice for marine LPG threaded fittings is to use BSPT fittings, the T being taper.
 

So best this is not replicated ?
 

 

 

Perhaps I'm wrong but my understanding is that if a parallel female fitting is screwed onto a tapered male stub that still equals a tapered fit? It's not usually tapered to tapered is it?

2 hours ago, Chewbacka said:

And more than one turn of ptfe tape, but if they are parallel thread, it will need more than one turn or it will leak.  But amount of ptfe is not a BSS examination point.
However it will be interesting to see what the BSS examiner makes of the joint ‘design’  (assuming it is noticed) as it exceeds the number of components allowed in a joint as specified in the BSS private boat check list section 7.8.4.  

“• must be made with a minimum number of individual components.”

”NOTE – the minimum number of components is usually interpreted as two.”
 

So if noticed, I think it should be a fail.

 

 

It's inside the gas locker so the "minimum number of components" requirement doesn't come into it does it? I though that requirement was only on the low pressure side - outside the gas locker? 

Edited December 17, 2019 by blackrose

[Alan de Enfield]

7 minutes ago, blackrose said:

Perhaps I'm wrong but my understanding is that if a parallel female fitting is screwed onto a tapered male stub that still equals a tapered fit? It's not usually tapered to tapered is it?

 

It would appear that to be built RCD complaint :

 

 

6.5.8 All threaded connections required to ensure gas tightness of the system shall be of taper pipe thread
type conforming to ISO 7-1 or fittings conforming to EN 1949, with sealants conforming to EN 751-2 or
EN 751-3. Sealants shall be applied to the male thread only, before assembly.

 

Suggesting that a parallel fitting of any form would be non compliant

[blackrose]

11 minutes ago, Alan de Enfield said:

 

It would appear that to be built RCD complaint :

 

 

6.5.8 All threaded connections required to ensure gas tightness of the system shall be of taper pipe thread
type conforming to ISO 7-1 or fittings conforming to EN 1949, with sealants conforming to EN 751-2 or
EN 751-3. Sealants shall be applied to the male thread only, before assembly.

 

Suggesting that a parallel fitting of any form would be non compliant

 

I'm not an expert on these matters by any means, but to me it seems intuitive that if you screw a tapered male thread into a tapered female thread (of equal tapers) then what you've actually done is produce a parallel fitting joint! Surely what you want is one parallel fitting and one tapered?

 

Happy to be a fool for 5 mins...

Edited December 17, 2019 by blackrose

[Alan de Enfield]

6 minutes ago, blackrose said:

 

I'm not an expert on these matters by any means, but to me it seems intuitive that if you screw a tapered male thread into a tapered female thread (of equal tapers) then what you've actually done is produce a parallel fitting joint! Surely what you want is one parallel fitting and one tapered?

 

Happy to be a fool for 5 mins...

I also am no 'gas expert' (expert = a drip under pressure) but Google suggests that both male & female should be tapered.

 

Tapered threads help make better seals. The male and female threads compress and wedge themselves together. As a result, these connections are stronger and leak resistant.

 

 

This first step will help you eliminate a number of possible thread types, as well as explain the method of seal.  For a parallel thread in port application, the fitting will usually seal at the top of the thread by means of an O-ring or seal.  With a tapered thread, the fitting typically seals via metal-to-metal wedging of the threads.  It is also possible for some tapered males to thread into certain parallel female threads, however, there are many variables involved so caution should be taken.  Sometimes a thread sealant is applied prior to installation to reduce instances of leakage on tapered threads.

[WotEver]

11 minutes ago, blackrose said:

 

I'm not an expert on these matters by any means, but to me it seems intuitive that if you screw a tapered male thread into a tapered female thread (of equal tapers) then what you've actually done is produce a parallel fitting joint! Surely what you want is one parallel fitting and one tapered?

 

Happy to be a fool for 5 mins...

Logic certainly agrees with you, but I don’t know either. Where’s @Mike the Boilerman when you need him?

Ahh, perhaps Alan’s post clarifies the matter. 

Thinking more about it, two tapered threads can’t be parallel as one will try to climb the other, and they’ll lock up. 

[Alan de Enfield]

2 minutes ago, WotEver said:

Logic certainly agrees with you, but I don’t know either. Where’s @Mike the Boilerman when you need him?

Ahh, perhaps Alan’s post clarifies the matter. 

Thinking about it - surely a taper fitting going into a parallel female will only contact on fewer threads than a taper/taper.

The first (say 3 or 4 ) threads will be on a taper a smaller diameter than those further up the taper so will not actually engage in anything ?

[WotEver]

Just now, Alan de Enfield said:

Thinking about it - surely a taper fitting going into a parallel female will only contact on fewer threads than a taper/taper.

The first (say 3 or 4 ) threads will be on a taper a smaller diameter than those further up the taper so will not actually engage in anything ?

Yup, I agree, having expended a few grey cells thinking about it properly. 

[Alan de Enfield]

1 minute ago, WotEver said:

Yup, I agree, having expended a few grey cells thinking about it properly. 

 

[blackrose]

Yes, I guess so. But do you have a picture of a tapered thread into a parallel fitting Alan? ?

 

Edit: I was joking but I found one: So I still stand by what said above except that I concede that a tapered to tapered works and probably seals on more threads. However, (and I know it's only a drawing) the fact that the tapered to tapered bolt is screwed in all the way down tells me that the seal isn't that good?

 

Anyway, as long as the tapered male into parallel female forms an adequate seal then it should be fine. With some correctly wound gas PTFE as shown in photo previously I don't see any problem.

 

Edited December 17, 2019 by blackrose

[Alan de Enfield]

7 minutes ago, blackrose said:

Yes, I guess so. But do you have a picture of a tapered thread into a parallel fitting Alan? ?

 

Edit: Found one: So I still stand by what said above except that I concede that a tapered to tapered works and perhaps seals on more threads.

However, as long as the tapered male into parallel female is an adequate seal then it should be fine.

 

 

Yes - possible.

 

51 minutes ago, Alan de Enfield said:

This first step will help you eliminate a number of possible thread types, as well as explain the method of seal.  For a parallel thread in port application, the fitting will usually seal at the top of the thread by means of an O-ring or seal.  With a tapered thread, the fitting typically seals via metal-to-metal wedging of the threads.  It is also possible for some tapered males to thread into certain parallel female threads, however, there are many variables involved so caution should be taken.  Sometimes a thread sealant is applied prior to installation to reduce instances of leakage on tapered threads.

 

[Chewbacka]

1 hour ago, blackrose said:

 

Perhaps I'm wrong but my understanding is that if a parallel female fitting is screwed onto a tapered male stub that still equals a tapered fit? It's not usually tapered to tapered is it?

 

It's inside the gas locker so the "minimum number of components" requirement doesn't come into it does it? I though that requirement was only on the low pressure side - outside the gas locker? 

The lpg pipe work section of the bss does not state that it only applies to outside the gas locker, so I think one can assume to applies to all joints.  I hope I am wrong.

[bizzard]

Like any precision taper to taper fit I reckon the two components need to be a precision matched pair to seal the threads metal to metal properly without tape, and any old unmatched tapered female to male componants could well leak without tape, probably the reason why tapered to parallel are mostly used with tape. The matched tapered pair might be used on , say aircraft hydraulic systems or crucial things like that, I don't know.   However winding the tape on in the correct direction with a little tension is very important otherwise it might unravel and not penetrate down very far into the threads.

[J R ALSOP]

All good gas engineers use the yellow pack 1 wrap ptfe, plumbers will use the white thinner ptfe.

[blackrose]

2 hours ago, Chewbacka said:

The lpg pipe work section of the bss does not state that it only applies to outside the gas locker, so I think one can assume to applies to all joints.  I hope I am wrong.

 

Assume what applies? The minimum number of components rule only applies if that number has been exceeded, and if you need to add two components to fit a bubble tester inside a gas locker then I really think would be taking things to extremes for any examiner to apply that rule. The last BSS examiner who visited my boat said exactly that about one of my lpg joints where I'd needed to add a fitting. It's all about what reasonable to achieve a safe, gas tight system and as such there will always be an element of interpretation. But it's not about absolutes.

 

Perhaps I missed it but I haven't seen anything on this thread which shows that the BSS prohibits such joints either inside or outside the gas locker. Alan posted regs from the RCD but even they leave room for some ambiguity as they talk of "tapered connections" not tapered fittings and one could argue that the tapered male into parallel female fitting does constitute a tapered sealed connection as shown in the drawing above.

 

The BSS even shows this picture of a "highly recommended" bubble tester which includes a drawing of what looks like a flexible hose and a jubilee clip! ? If the BSS is recommending a hose/jubilee clip connection inside a gas locker then I think we may be over-analysing things here.

 

This is from the 2nd edition (2005) so it may have been updated.

 

 

 

 

Edited December 17, 2019 by blackrose

[Alan de Enfield]

19 minutes ago, blackrose said:

This is from the 2nd edition (2005) so it may have been updated.

The 2015 BSS simply states :

 

All LPG pipe joints must be compression fittings on copper pipework or
compression or screwed fittings on copper alloy or stainless steel pipework.

[matty40s]

2 minutes ago, Alan de Enfield said:

The 2015 BSS simply states :

 

All LPG pipe joints must be compression fittings on copper pipework or
compression or screwed fittings on copper alloy or stainless steel pipework.

However, rubber hoses are still acceptable in the gas locker....as rubber hoses run from gas bottle to regulator.