A couple of "gaz" questions!!!

[steamydave]

Hi,

I have a couple of camping gaz questions.
Firstly – how much yellow flame is OK?! I know the gas shouldn’t burn with a yellow tip, but is any yellow acceptable? I’ve noticed that the camping gaz burns well, but on occasions there is a yellow tinge to the flame. Also if a breeze catches the burner, there is often yellow in the flame.
Because my drive is at quite a slope, the gas doesn’t always come out of all the “holes” in the rose (the ones higher up). The ones that do work are often yellow. The others usually catch up eventually, or I give the rose a gentle puff, and it makes the flame “chase” around the rose.
I presume as more gas/air ratio is coming out of the lower ones, that’s why they are yellow, and the upper ones have all air!

Secondly, is it OK to attach the gas hose from the regulator directly onto the tube on the bottom of the hob unit using jubilee clips, or should the hose connect to a brass nut type connector, and the hob connect to the other end of the join with olive joints – if you know what I mean.
I bought the Smev 911cv unit along with a generic fixing kit, so I have all the parts, but wasn’t sure how many of the bits I required. For example, the kit cam with an in-line fuse holder and fuse/wire, but the hob has peizo ignition! The kit came with copper tubing, so I assumed the nut joints were for connecting the flexi hose to the ends of the copper pipe.

Any ideas?

Dave

[Derek]

Hi Dave

Use one of these to connect the rubber pipe

or these if you are fitting on a bulkhead

The flame shouldn't be yellow but if the wind blows it around it may flare a bit. It will have a yellow tinge though. I think it may be a bit of a Smev thing, my cheap suitcase stove burns much better than the Smev in the Romahome ever did.

Is it a new regulator? May be worth trying another known good one. It can also take a little time to get all the air out of the system, maybe that is the problem. You can also get a duff batch of gas, that has been known.

[steamydave]

Thanks Derek.

What goes on the end of the metal pipe under the hob?

Thin it might be a Smev thing too. The burner doesn't have an air hole as such, the whole head has gaps at the base where the air is sucked in, so no blockage there.

Its not a major "yellowness". Just that I'm not that used to gas cooking to know what looks right or not. I'll try and take a photo or video to show.

Dave

[jayjay]

Should be a blue flame mostly. If it's all yellow in places, you could have a problem and you might need to alter the air/gas ratio. It may just need 'burning in' for a while until all the parts have got nice and hot. Aslo check your gas bottle isn't running out, this can affect the burn quality as well.

[steamydave]

Thanks,

I'll take a photo or two and see what you all think.

The regulator is new, and the whole unit is only a year old - and not used much yet.

I might have not left the burners running long enough.

The cylinder was new too - don't think its low.

I have a carbon monoxide alarm which doesn't seem to worry about it, and I cook with the sunroof open, and usually the door ajar slightly.

Dave

[jayjay]

If the unit was second user and has been used to cook food on, try taking off the burners and soaking them in hot soapy water for an hour, then wire brushing (or old toothbrushing!) the jets, they could be burning yellow because of muck/fat in them.

Also could just be that, as it hasn't been used in a while, the air just needs to blow through and out the jets (which will burn yellow) before the gas comes through properly. Sounds like you just need to leave it on for a bit longer. My rings blow out at first until the gas starts coming through properly the fist time I use it at the beginning of the season.

[Graham]

If the unit was second user and has been used to cook food on, try taking off the burners and soaking them in hot soapy water for an hour, then wire brushing (or old toothbrushing!) the jets, they could be burning yellow because of muck/fat in them.

Also could just be that, as it hasn't been used in a while, the air just needs to blow through and out the jets (which will burn yellow) before the gas comes through properly. Sounds like you just need to leave it on for a bit longer. My rings blow out at first until the gas starts coming through properly the fist time I use it at the beginning of the season.

Jayjay your technical knowledge and good ideas astound me at times. I think we should have a "Ask Jayjay" section , thanks for your helpful contributions to this forum.

[Twolitre]

jayjay is right about the possibility of dirty jets, but jets should never be wire brushed or "poked" through. The hole (orifice) is very carefully sized on manufacture and must not be damaged.
Yellow in the flame can mean too little air OR too much gas. The size of the flame may be a clue.
Many if not all units have a means to alter the air flow. On the older units often just a screw with a lock-nut in the tube to the burner. Screwing it in or out varies the air flow to remove yellowness from the flame, but if the jet is partially clogged it will result in a small flame. Many of us must be familiar with Bunsen Burners. It is the same principle, but rather more refined.
Yellow in the flame indicates less efficiency and incomplete combustion, producing toxic gases.
Jim.

[steamydave]

Thanks all.

I think I might be being just over cautious.

When I had my bongo which had been converted professionally, I took it for granted that everything was as it should be.

However, on a self-build, you start to get worried at the slightest knock or squeak!!!

Dave

[jayjay]

Jayjay your technical knowledge and good ideas astound me at times. I think we should have a "Ask Jayjay" section , thanks for your helpful contributions to this forum.

Its because I spend a lot of time on t'internet and reading up on things! Usually when I need to know for myself!

[Graham]

Its because I spend a lot of time on t'internet and reading up on things! Usually when I need to know for myself!

Well I do that but then I forget what I learnt. Old age catching up.

[Derek]

What goes on the end of the metal pipe under the hob?

Our Smev was one of these and it used a standard compression fitting


like this


I suspect your flame is OK, the low pressure flames are not very fierce, I tried to get some more air into the burner on our Smev but the design wouln't allow it.

[jayjay]

jayjay is right about the possibility of dirty jets, but jets should never be wire brushed or "poked" through. The hole (orifice) is very carefully sized on manufacture and must not be damaged.

Jim.

Of course you're right about the jets, you shouldn't poke them. What I meant to say was that you can wash the little holes out and give them a brush, the ones on the burners.

So that sentence should read:
f the unit was second user and has been used to cook food on, try taking off the burners and soaking them in hot soapy water for an hour, then wire brushing (or old toothbrushing!) them (as in the top bits where the flames exit), they could be burning yellow because of muck/fat in them.

You know, like you do on a gas cooker from time to time. thanks for pointing that out, Jim.

[steamydave]

Hi,

Here are some photos of my flames! Some ok, then the yellow tips - quite beautiful really. Low power seems less of a problem. Am I getting excited about nothing?!
The last picture shows the burner dismantled. The gas appears to shoot up the tiny hole in the centre brass nut, passed the rose (drawing air in from under as the rose sits on the "feet", hits the ceramic disk on top, and gets deflected in all directions between the rose and the disk. Quite inspired design I thought! No small holes to get mucky.

Dave

[Derek]

Yep, fine, no yellow tip would be nice but flame may improve as the burner warms up. It may burn slightly differently with a pan on the trivet