Primus no 25 advice.

Hi all I'm new to stoves and having a problem lighting my primus 25 stove, is there a part missing like a tube in the burner or is the flame spreader wrong, advice appreciated. Thanks.

 

Hi @Steve Sanderson It looks like you are missing the inner burner cap #4678 , which sits on top of the vaporisation chamber and under the outer burner cap.



Best Regards,


Kerophile.

 

Thank you kerophile i forgot to ask what is that part 4268 used for.

 

#4268 is an auto-igniter. It saves a match every time it is used.

The self-igniter is a pilot-light device which clips on one of the burner tubes so that the bell end of the tubular igniter is dipping into the spirit bowl and the top end is near the top of the burner.

The bell end contains a small piece of asbestos wick and the spirit vapour rises up the tube and establishes a pilot light at the top of the burner.

When the spirit in the spirit bowl is almost exhausted there is still a good flame from the top of the igniter tube, so when you pump air into the fuel tank the kerosene vapour exiting the jet is readily ignited...saving you a match!

Burmos: pilot lighter

Best Regards,
Kerophile.

 

Thanks very much I had no idea what it was used for .

 

@Steve Sanderson Hi further to @kerophile post the outer cap you have seems to be a 4205 for a no 5 burner as it has 4 rows of holes whereas outer. 4206 has 6 rows of holes . Those inner and outer caps are quite rare . One solution would be to fit a number 5 size burner for which you already have the outer and inner caps are readily available . This would get your stove up and running till you can source 4206 and 4678 caps. I have a number 10 which also takes that burner (4140) and used a Liberty medium outer cap which also fits and has 5 rows of holes.

 

Hi, here is an extract from an old post where I list the detailed dimensions of the burner caps from some common silent burners:

Primus No.4 stove;
Inner Cap = 33.5mmOD, but lip at bottom extends to about 35mm diam. Centre hole diam.= 16.3mm, Height = 14.5mm
Outer Cap = 38mm OD, but about 40mm on lower lip. Height at max, the top is domed, = 24mm. 5 Rows of holes.


Primus No.5 stove;
Inner Cap = 39.5mmOD, 42mmOD on bottom lip. Centre hole diam. = 16.4mm. Max Height = 16mm
Outer Cap = 44.6mm OD, 47mm on bottom lip. Max. Height = 26mm. 4 Rows of holes.


Primus No.6 or No.25 (# 4142)
Inner Cap = 44mmOD, 45mmOD on bottom lip. Centre hole diam. = 16.4mm. Max Height = 20mm.
Outer Cap = 49mmOD, 52mmOD on bottom lip. Max Ht = 26mm. 5 or 6 Rows of holes.

 

Sorry if stating the obvious, but it's not very clear (although just noticeable) from the drawing:

Most silent burners have a tube surrounding and extending upwards from the central hole, the inner cap locates around this. The 4140 burner has not, so the 4678 inner cap has this tube attached instead, which locates in the centre hole in the burner. Just visible in the illustration above.

As this goes against the majority of silent burner practice, spares are few and far between.

Hope this clears any remaining doubt, if indeed there was any!

 

Primus No.10 - 1939

 

Well I am still confused (it doesn’t take much) by which burner(s) a no 25 takes . In kerophile’s first post the illustration shows #4140 for No 25 and #4142 for No 6 & No 8 but the cap dimensions post says No6 and No 25 (4142)?

 

The part numbers are very rarely marked on Primus burners......

 

Hi all thanks for the advice, I have got my primus working with an inner cap ,and a improvised tube from an brass outside tap will this be OK.

 

Flames looks A-OK. Well done.
(I hope that inner tube can take the heat?)