What size for a gas vent hose?

[Mandarin331]

Looking at a gas locker vented via a hose leading from the bottom of a gas tight locker to a skin fitting. Can anyone tell me What should the internal diameter of the hose / skin fitting be as a minimum?

 

[charles_reed]

Looking at a gas locker vented via a hose leading from the bottom of a gas tight locker to a skin fitting. Can anyone tell me What should the internal diameter of the hose / skin fitting be as a minimum?

Mine has an id of 25mm, though I wouldn't presume to qualify this as a minimum.

 

[drew silverwitch]

The BSS requirements are 12 - 19 mm depending on the amount of gas stored, but the boat i have just had a survey done on has 25mm

 

[coopec]

This is something I have just completed on my boat. It looks like drew is on the ball but maybe Australian requirements are a bit more stringent.

LPG Cylinder compartments and lockers for boats
(clause 3.4.3(h) and figure 3.2)

The drain in the base of a cylinder compartment for a boat shall not be less than 19mm diameter.
(AS5601:2004 required a minimum diameter of
25mm)

http://www.esv.vic.gov.au/Portals/0...V - ASNZS5601_Road show_presentation_2014.pdf

 

[Stork_III]

BSS Scheme specifies 12mm minimum up to 18kg gas capacity and 19mm for 38 kg gas capacity, but recommends 19mm minimum for all cases.

See clause 7.3.6 http://www.boatsafetyscheme.org/media/180428/bss guide 2005 complete web.pdf

 

[Mandarin331]

Many thanks. >12mm it will be then as we only have a small gas bottle and I must admit to feeling reluctant to cut a large hole in the hull - which for a 19mm internal dia skin fitting I assume would be at least 25mm.

 

[Slycat]

Hi, I had a query on this too.

Is hose ok for the (unpressured) drain? Due to the shape of my boat fixed pipes would be awkward.

Also, what fitting are you using at the locker?

 

[lw395]

Hi, I had a query on this too.

Is hose ok for the (unpressured) drain? Due to the shape of my boat fixed pipes would be awkward.

Also, what fitting are you using at the locker?

Whatever you use, it needs to drain freely.
I've seen a few boats where the drain can form a 'sink trap' filling with water, so gas won't readily drain out.
It's often a problem with a sloping transom on an ex-race yacht.
I epoxied in an ali tube at the transom end and used a skin fitting for the locker base.
I think hose may be a good option, something rigid might get cracked.

 

[VicS]

Hi, I had a query on this too.

Is hose ok for the (unpressured) drain? Due to the shape of my boat fixed pipes would be awkward.

Also, what fitting are you using at the locker?

See the link to the BSS above.

The drain can be hose :

Best practice
We recommend you to fit, whenever possible, drain hose that
complies with a recognised standard such as ISO 7840 for fire
resistance or BS 3212 for LPG.

Lpg hose you should be able to obtain easily enough up to 13mm bore but you may need to use ISO 7840 fuel hose for larger sizes.

Be sure its well supported to give a continuous fall from locker to outlet with no low points that could become water traps

Skin fittings might be the best bet for the end connections