Gas Locker ( I feel a survey coming on!!)

[moomba]

This is fun. Let's do some fluids ...

My gas locker is 30cm deep. If it was half full of propane (density 1.88kg/m³) instead of air (density 1.22kg/m³) the additional pressure due to the 15cm column of propane would be (1.88 - 1.22) x 9.81 x 0.15 = 1Pa (near as dammit) = 0.01mb.

The drain pipe from my gas locker has an internal diameter of 15mm and is 0.3m long. I can't be bothered to do the calculation by hand, but using http://www.pressure-drop.com/Online-Calculator/ gives a flow rate of 0.5 m³ hour with that head. That's 0.94 kg of propane per hour.

Surprisingly high, to be honest.

Brilliant :encouragement:
we should all do this

 

[pcatterall]

This is fun. Let's do some fluids ...

My gas locker is 30cm deep. If it was half full of propane (density 1.88kg/m³) instead of air (density 1.22kg/m³) the additional pressure due to the 15cm column of propane would be (1.88 - 1.22) x 9.81 x 0.15 = 1Pa (near as dammit) = 0.01mb.

The drain pipe from my gas locker has an internal diameter of 15mm and is 0.3m long. I can't be bothered to do the calculation by hand, but using http://www.pressure-drop.com/Online-Calculator/ gives a flow rate of 0.5 m³ hour with that head. That's 0.94 kg of propane per hour.

Surprisingly high, to be honest.

And even higher if your drain was 'legal' ( 19mm I have read!)

 

[lw395]

This is fun. Let's do some fluids ...

My gas locker is 30cm deep. If it was half full of propane (density 1.88kg/m³) instead of air (density 1.22kg/m³) the additional pressure due to the 15cm column of propane would be (1.88 - 1.22) x 9.81 x 0.15 = 1Pa (near as dammit) = 0.01mb.

The drain pipe from my gas locker has an internal diameter of 15mm and is 0.3m long. I can't be bothered to do the calculation by hand, but using http://www.pressure-drop.com/Online-Calculator/ gives a flow rate of 0.5 m³ hour with that head. That's 0.94 kg of propane per hour.

Surprisingly high, to be honest.

It's significant, but it suggests you wouldn't need a very big leak for most of the gas to be leaving via the top.

 

[lw395]

And even higher if your drain was 'legal' ( 19mm I have read!)

But many are a lot longer than 0.3m.

 

[JumbleDuck]

It's significant, but it suggests you wouldn't need a very big leak for most of the gas to be leaving via the top.

True. I always leave my gas locker lid off or askew when using gas at anchor, on the grounds that any leaks will get out faster that way.

But many are a lot longer than 0.3m.

Also true. It was just an example. I also assumed a horizontal drain: anything which goes significantly down will suck faster, as a syphon.

 

[maby]

We agree on that.



Only if it's between 2.5% and 12.5% gas, of course.

Years a go a friend of mine was transferring liquid propane into an LPG powered Land Rover from 47kg bottle inverted with a chain hoist. The hose between the bottle and the car came undone and a wall of propane vapour moved steadily up the garage to the gas heater he was using to keep the propane warm, it being the dead of winter. The heater was between him and the door - all he could do was wait.

The propane reached the stove, was sucked in the air inlet and ... snuffed it out. Hooray for upper explosive limits!

Living near Buncefield, we had quite a spectacular and unforgettable demonstration of this on a rather larger scale!

 

[PetiteFleur]

Interesting debate. I have an open top grp locker in my cockpit locker. When I got the boat years ago I fitted a drain hose to outside, slightly sloping downwards, 12 or 15mm diameter from memory, fitted a test point, renewed all copper pipe and rubber hose, added a tap near the cooker and a removable plywood lid, and chocks in the locker to prevent gas bottles moving. Since then I've replaced the regulator with a 'marine' version and I was going to fit a remote on/off solenoid but not got round to it yet.

 

[moomba]

Interesting debate. I have an open top grp locker in my cockpit locker. When I got the boat years ago I fitted a drain hose to outside, slightly sloping downwards, 12 or 15mm diameter from memory, fitted a test point, renewed all copper pipe and rubber hose, added a tap near the cooker and a removable plywood lid, and chocks in the locker to prevent gas bottles moving. Since then I've replaced the regulator with a 'marine' version and I was going to fit a remote on/off solenoid but not got round to it yet.

very wise and sensible, I bought a coded boat that had just passed it survey again, and what you described is exactly what this boat has, a very good start for any gas installations. Why risk anything happening ,better to be over cautious than having a boat blow up.
I wonder if any one has checked their dates on their High pressure hoses

 

[rszemeti]

When we bought our boat we had a full survey. We did this, as it was our first boat, and we wanted to be sure that everythign was right.

Glowing survey, a few minor points, but, nothing to worry about.

What suprised me was the state of the gas locker. Apparently he missed this ... "minor item".

The gas bottle was on it's side, with nothing to tie it down with.
The drain hole is about 6mm diameter and 6" above the base of the locker.
The previous owner had cut a 4" diameter hole in the side of the locker, draining into the transom space/bilges.

My advice: don't bother with a survey, do it all yourself. You might miss something, but at least you will have checked most things.

 

[graham]

Euphonyx I fully agree Origo spirit stove is a safe option but it most certainly can produce carbon monoxide.

We have a 2 burner Origo, If we try to cook with washboards in the CO alarm will go off eventually.