How does the SRV on a radius 42 work?

Just acquired my first Radius 42. The type with the SRV on the tank and filler in the centre of the base:



Just been having a look at the SRV and I can't figure out how it works. It has a central screw protruding through the retaining cap:



Once the cap is removed there is part with a seal (which I can see needs replacing):



This screws down onto a spindle which attached to the base of the tank but is free to move up & down 2 or 3mm:



I can't figure out how this arrangement works. Does the SRV screw down tight onto the spindle? And then unscrew to release the tank pressure? Am I missing a spring somewhere?

Grateful for any advice or comments.

Best wishes,
Terry

 

Hey TD, on your 3rd picture, is the center part (round one) attached to the hexagonal piece? I would think if it is not attached, it works basically like the pump cup where when pressure builds up in that small chamber, it pushes down sort of a piston at the bottom of where the male threaded portion, pulling the center piece down and releasing some pressure. That is if the center piece is not attached to the hex nut. Acts more like a regulator to me. Otherwise, that would also puzzle me and needs to be disected by presscall (the man who may explain how it works)

I may add that looking at the cap fount collar, it may be removable for servicing otherwise am just as dumbfounded as you are

Ron

 

A parking place for a spare pump leather?

 

Hi Terry. I found this post.

https://classiccampstoves.com/threads/13412

and here. https://classiccampstoves.com/threads/13421

 

Hi

Instructions here

Couldn't explain it better myself.

My fettle here

 

Thanks Gary. I found another post on the patent.


https://classiccampstoves.com/threads/491

 

Rick
That's not the same SRV, that's what is commonly known as the "ugly" one.

Terry
Someone has been there before you, that leather bit shouldn't be there.
You need a spring and a nitrile/viton seal to fit inside the outer cap.

 

OOPs. My bad.

 

Looking at the link, I do not think it is the same cap as the ones posted on the links. This one is quite different in that it has a threaded shaft.

Ron

 

Would it be possible for someone who has a SRV like Terrys and knows the inner workings, to post a picture, or maybe just a simple drawing to outline the function?

I have the same model myself, and remember searching the forum for pictures a while back but didn't find any. As it is now, I've not taken it apart for fear of wrecking it. Running the stove without refurbishing that SRV feels so-so aswell.

 

Ron
Already been said.

The assembly is very simple spring over threaded shaft, screw on top hat, ensure seal is ok inside outer cap, screw this on and adjust as desribed in the instructions.
Simples.
http://www.taylorobrien.com/blog/?p=647

 

Hi Gary, thanks for the links. Not sure how I missed those instructions, I spent about 2 hours searching the forum for help!

So as I understand it, the thick leather gasket on mine should not be there? There should be a spring there instead?

There is an old seal inside the cap:



There is also a depression in the top of the hex nut, I suppose to allow it to bite into the seal in the cap:



The screw is then turned anti-clockwise to force the hex against the seal in the cap. But doesn't this mean that pressure from the tank will force the seal to become even tighter? Or are we looking at a fancy version of the Primus 71 style fixed pin? Where excess pressure in the tank causes the base to bulge and pull on the pin, thus releasing the pressure through the SRV cap? If so, what does the spring do? I can't see it's function, apart from holding the assembly in tension when slacked off. Presumably, the assembly must be slackened off to release/equalise the tank pressure and would rattle without the spring. Or am I way off course?

Sorry for all the questions, but it has me puzzled.

Best wishes,
Terry

 

Terry
Your thinking is sound i.e. a fancy Primus 71 style SRV.
It will work without the spring, I think it's there to lock the "top hat" in place so it doesn't rattle out of adjustment.
Once the SRV is set you don't touch it again unless it's leaking.
Once you get it running right I guarantee the 42 will become one of your favoutites.

 

Thanks Gary. I was concerned that the spring was vital to the safe function of the SRV. I've got a tin full of odd springs so I'm sure I've got one that will do the job. Next job is to winkle a wick in through the filler hole in the base as it came without one .

Regards,
Terry

 

Did a bit more fettling last night. Wick was surprisingly easy to do. Found a spring that looked about right for the SRV and replaced the seal in the cap with a viton washer:



I think that a previous owner must have had trouble with the SRV and decided to effectively immobilise it by installing a thick leather washer and screwing it down to block the vent. With a DIY flame spreader, it now goes like a stabbed rat:



Thanks to all for advice and help.

Best wishes,
Terry

 

Nice
Do you have a tin?
If not those British Army No.7 tins are a great replacement.

Gary

 

Hi Gary. Yes it has a tin. Best described as 'brown' but it is solid and will do the job OK. I don't plan on trying to restore it:



I took lots of pics during the fettle and will post a write up in the next few days.

Regards,
Terry