Gas Locker - material

[ChattingLil]

Hello

I'm replacing the cover on my gas locker.

When I had the gas checked last year, the engineer said that the gas locker should be made of flame retardant material, or of the same material as the boat. I don't want to use GRP (mainly because i have no idea how to approach that in terms of obtaining, cutting and shaping), so I was hoping for some other recommendations. It's nothing fancy, just a trapeze shaped flat piece with a hole cut it in for the hatch way to put the bottled through.

Thanks
Lisa

 

[richardabeattie]

I'll be shot for saying this but I am under the impression that, if and when a gas bottle leaks into the gas locker and the gas then ignites, it's not a flame you are looking at but a bang! So perhaps there's not a lot of point in the lid being flame retardant!

I am about to regret pressing the continue and submit buttons!

 

[sailorman]

mine is grp & plywood as are most boats

 

[leomagill]

Aliminium sheet is a good easy option, my gas locker is all 1.6mm ali sheet with drain at the bottom to outside.
As I recall lpg is very picky about it's mixture to actually explode and fairly rare to get ignited at just thr right time, that said best not to find out.
If the fire cannot reach the bottle regulator and hose why would it leak in the first place.

 

[ChattingLil]

Thanks Leomagill

I'd appreciate advice on cutting aluminium to shape .... I have general DIY tools, but nothing that I can think off that would cut neatly through alumnium.

Sailorman - my previous (and rotted) cover is of plywood and I can see it lasted a long time. However, seeing as I do need to replace it I thought I might as well be compliant with what the gas man said!

 

[BlueLancer]

Re cutting Ali, very easy use a jigsaw with suitable blade. Clamp Ali to a board when you cut it, this prevents it bouncing from the vibration. When cut file edges, seal joints and pop rivet together,or screw on to plywood frame. Good Luck .

 

[Anthony]

I believe the combination of ali and steel (i.e. the gas bottle) are not approved together explosive atmospheres in industry, somthing to do with a high spark risk when the two move against each other.

A quick google has revealed:

Mechanically generated friction sparks. The combination of materials and speed determine the effectiveness of the ignition source. For example 4.5 m/s steel-steel friction with a force greater than 2 kN is an effective ignition source. The combination of aluminium and rust is also notoriously dangerous. More than one red hot spark is often necessary in order to have an effective ignition source.

from http://en.wikipedia.org/wiki/ATEX_directive

I am not an expert, so maybe it doesnt apply, but would make me think twice....

Personally I would prob go with making it in marine plywood and cover / line in GRP.

Ants

 

[VicS]

I suggest wood (ply ) lined with fire resistant GRP. Or buy a GRP locker.

Make a wooden box and lid a bit larger than needed. Line with Fire resistant resin and glass mat.. Point is it must be gas tight hence the grp lining to make sure there are no leaky joints. At least thats how I understand it.

(Mine is just a well made plywood box)

Joints are a problem with metal lockers. Pop riveted panels are not acceptable.

I suggest you read part 7 of the Boat Safety scheme for all the details.

http://www.boatsafetyscheme.com/downloads/BSS_Guide_chap7.pdf

Fire resitance is to keep fire out, not to contain it!

 

[Twister_Ken]

I doubt the lid needs to be gas tight if the locker opens on deck where gas can 'fall' overboard. If the locker were internal to the boat I'd see why, but that would be a dodgy installation in the first place.

 

[ChattingLil]

It's hard for me to explain, but the locker is part of the design of the cockpit - almost cut into the transom. GRP on top (under the seat), to the rear, to the sides and underneath with a self drainer. It's just the 'front door' that needs replacing! Hence a flat piece of something, with a hatch cut into it. The gas man was happy with the location and the self-drainer, but just advised to have a fire retardant front piece put on.

Thanks for all the advice above - and the link to the boat safetry Scheme leaflet. Very interesting!

 

[VicS]

[ QUOTE ]
I doubt the lid needs to be gas tight

[/ QUOTE ] It only has to be gas tight to a point above the HP parts of the system I think you will find so lids IIRC do not have to be gas tight anyway! Its all in the Boat Safety Scheme.

 

[Seanick]

The point of covering a ply gas locker or front with GRP is to INCREASE its FIRE RATING from OUTSIDE the locker, and to make the locker gas tight, and drain overboard.
By the time a fire reaches a gas bottle one should be off the boat!

Vic S is right to state fire retardent resin.

The reason one has a gas locker, is that the most likley point in the gas system that may leak is the regulator to bottle connection, which may be made in a hurry, to get the tea on!

 

[kenspratt]

I found this website by calor very useful for making my gas locker.

http://www.calormarineshop.co.uk/installation/marine_gas_locker.htm

And to be fair all aspects of the gas system. O f course it goes without saying that once it is completed i will have it tested and approved by a suitably competent person.