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blowpipe valve

Posted: Tue Oct 03, 2017 6:47 pm
by john
I really shouldn't have to ask this but will anyway because i'm very deficient in practical know-how. Regarding the blowpipe going into the bag do others find that once you've got the bag fully pumped up that the bag doesn't always hold properly and you have to keep pumping a little more just to keep the bag full before you've even started playing, and consequently have the same problem of having to pump more to compensate for lost air once playing? The bag i'm using is pretty well airtight so i think it might be a valve issue - would people recommend such remedies as rubbing vaseline onto the valve to try and make it hold firm inbetween bellows actions? any other suggestions? - thanks

Re: blowpipe valve

Posted: Tue Oct 03, 2017 7:57 pm
by bensdad
It is just as likely that the air is leaking through the leather itself, or through the seam, or rivets, or stitches, or whatever you have. Cork up all the apertures, blow it up through the blowpipe, and sit on it. It really should not deflate.

Re: blowpipe valve

Posted: Tue Oct 03, 2017 11:07 pm
by geoff wooff
Good advice there from Bensdad.

You should be able to tell if the Blowpipe valve is leaking because the Bellows will start to inflate by itself.

Some people have the habit of putting the 'hairy' side of the leather against the blowpipe.... this stops the typical 'clack' when the valve closes, or softens the sound, but if the leather is too hairy then it takes excessive pressure to form a seal and some blow back will occur. It should be possible to hear air leaking back through the valve.

And the leather of the valve can be porous. And the valve can be Upside Down or touching the side of the stock.

Whilst you have the whole thing apart, check each tube for air tightness... especially Regulators and Mainstock !

Re: blowpipe valve

Posted: Tue Oct 03, 2017 11:11 pm
by Pipewort
The bag should be 100% air tight.

As to the valve, check that it's hinge is on 'top' when the blowpipe is inserted into its stock. If it is not, it may move away slightly from one edge to leak a little.

Also that it is not fowling the sides of the stock, preventing it from closing completely.

Re: blowpipe valve

Posted: Wed Oct 04, 2017 1:33 am
by rorybbellows
The way to test the blowpipe specifically is to fully inflate the bag and then detach the connection to the blowpipe and dip the tip of the blowpipe into a glass of water. If bubbles are coming from the end of the blowpipe the valve is leaking.

RORY
PS be warned about sitting on fully inflated bags that have corks wedged into the holes, because of this I now have a one eyed dog.

Re: blowpipe valve

Posted: Wed Oct 04, 2017 5:53 am
by fiddlerwill
The trick I use to seal a valve, leather is to steam it and a spoon then use the hot spoon to press down hard on the steamed valve. This gives a good seal. Obviously the hinge needs to be the right way up , a bit of lip balm can help too on a valve that's dried up .
Doesn't require much in the way of steam. Just a moment or 2 for the valve and a bit longer for the spoon.

Re: blowpipe valve

Posted: Wed Oct 04, 2017 6:32 am
by An Draighean
john wrote:I really shouldn't have to ask this but will anyway because i'm very deficient in practical know-how. Regarding the blowpipe going into the bag do others find that once you've got the bag fully pumped up that the bag doesn't always hold properly and you have to keep pumping a little more just to keep the bag full before you've even started playing, and consequently have the same problem of having to pump more to compensate for lost air once playing? The bag i'm using is pretty well airtight so i think it might be a valve issue - would people recommend such remedies as rubbing vaseline onto the valve to try and make it hold firm inbetween bellows actions? any other suggestions? - thanks
Neither of my sets do that.

Have you checked to make sure that the hinge of the blow pipe valve is on top, so that gravity helps to close it?

Re: blowpipe valve

Posted: Mon Oct 09, 2017 4:11 pm
by john
thank you for all the responses, i'm going try the advice given and see how i get on