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Old 22 June 2011, 08:35   #1
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Adapting a pressure gauge for a SIB...

Been looking at gauges lately - I have the push on factory basic type with my Zodiac that shows a symbol for tube pressure and (HP) floor pressure rather than actual psi.

But as is common with these they only work when the pump is pumping (so the valve is pushed open).

However (experimenting last night), if you fit the gauge only then drop something like a wooden dowel in and plug with your finger...so the finger pushes against the dowel/valve - the air is released and blocked within the gauge by your finger giving a true constant reading.

Which got me thinking - the 'marine' gauges are of course overpriced (being 'marine').

Check something like this below:

http://cgi.ebay.co.uk/40mm-Pressure-...item3a6641ef7e

Looks strangely familiar to those at chandlers...

A certified gauge with the range required for a fiver - all that is required is to make an adaptor/plug with a protrusion inside to fit the two types of valve - one with the central sprung stem that is pushed in and the other with a smaller rounded stub to push against the rubber membrane thingy in the floor/keel.

I'll give it a go and post back results if anyone is interested...
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Old 22 June 2011, 10:14   #2
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Of course we're interested! This is RIBnet, we do 18 pages on drilling holes in things.

The Quicksilver setup is different however - the twistfit nozzle opens the valve and allows the pressure gauge upstream to show the tube pressure. There is a one way valve in the gauge itself so it works all the time.
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Old 23 June 2011, 08:23   #3
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Yup - I bought one of those exact gauges about 4 years ago and have used it ever since.

The (insulation taped) addition of a short piece of plastic tubing with a bar at the end (spare from a foot pump adapter) allowed pressure to be measured very easily when the tube was pushed into the valve.
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Old 23 June 2011, 10:01   #4
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Here's an update - received the basic gauge this morning after ordering yesterday afternoon, great service, went for this one at under 4:

40mm Pressure Gauge Base Entry 0-15 PSI AIR AND OIL on eBay (end time 20-Jul-11 16:25:01 BST)

And put the gauge together this morning, works an absolute treat, dead chuffed!

Here is the completed gauge next to the Zodiac floor/keel valve it fits:



I turned down a piece of PVC pipe to a taper so it fits the valve precisely, a couple of pieces of different diameter hose join the parts. A rounded 'prodder' (for want of a better word) is 'chemically metalled' into the tube at just the right position and depth to open the valve:



And in position:



Here checking the floor pressure:





And for reference this is the original Zodiac guage:



Obviously what I've made is to fit the Zodiac valves but with the right adaptor for your own valves it will work on any make SIB for a fraction of the cost of a 'marine' one. Makes a real difference having a proper gauge reading in 0.5psi increments rather than a 'guesstimate' pictorial gauge and of course being able to check the exact pressure at any time without getting the pump out especially in those 'leaving the boat in the sun' moments. All I need to do now is make a second tapered adaptor with central 'prodder' to fit the main tube valves.

A couple of observations - the Zodiac gauge reads under at the (LP) tube end and over at the (HP) floor end. Also, *importantly* when inflating the (small volume) keel to the recommended 3.4 psi - the difference between 2.4 psi and 3.4 psi is *less* than *one* complete up or down stroke of a typical stirrup pump!!

Similarily when you approach the correct 12 or so psi for the floor you have to take it easy. Again, all this shows how important it is to have a proper gauge and why perhaps so many people complain of flexy SIB air floors.
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Old 23 June 2011, 10:41   #5
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That's cool. It's very similar to the QS gauge. I've managed to get mine fitted into an inline inflation hose that I hook up to a large SCUBA cylinder for initial inflation, and a small one for on-water topups.
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Old 23 June 2011, 13:46   #6
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Old 23 June 2011, 14:21   #7
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Cheers chaps - made the adaptor for the tube valves - similar idea but a bit more 'Heath-Robinson' - does the job but I might re-do this - I needed one quickly for the weekend:





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Old 23 June 2011, 15:28   #8
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Very inventive Max!

I'm an obsessive pressure checker throughout days when the temperature changes and would really appreciate something that gave a permanent display of presure. I think you can get such a gauge for your Zodiac's main tube valves... it fits in with a bayonet to replace one valve cap. However my valves are a different type with a screw cap and I haven't seen anything to suit.
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Old 07 July 2011, 16:05   #9
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How the heck do i make the tubing bits?
(i'm not very creative)!
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Old 07 July 2011, 16:09   #10
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Quote:
Originally Posted by lawrence567 View Post
How the heck do i make the tubing bits?
(i'm not very creative)!
With anything that fits. At 11psi, you can use duct-tape for the joints
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