Ian, have you tried on of these? They are easy to make from a piece of hex bar. One end of the bar is bent at about 45 degrees, the other is straight so you can always get a good fit into one of the six holes.
Looks like one of the apprentice tests the old boys from Vickers Scotswood works used to talk about: take a square of 1/2" plate and a 6" long piece of round bar: then, using hand tools only, put a hexagon shaped hole through the plate and convert the round bar to a hex that will pass through the plate as a sliding fit in all orientations
Resurrecting this older thread. I have just dismantled an original No3 and found to my surprise the same restrictor plate as mentioned in previous posts but with gauze as well, completely clogged with what I suspected was some kind of asbestos so it was removed and under a running tap just in case! Then put in the ultra sonic cleaner which sorted gauaze and plate beautifully This was on a 1914 stove so either it was a replacement burner or Primus had been fitting restrictor plates as early as that? This one is with the plate top recessed to fit nearer the jet than the riser tube.
@nmp Thanks for reminding me if this thread. I had forgotten about it. There was no obvious restrictor in the two burners of my Primus No. 3, but when it gets a bit more light here in Tassie, I’ll check to see if there’s any evidence of the burners having had restrictors or “inside” threading. Cheers Tony
I’ve checked my Primus No. 3 burners. The wrecked one that came with the stove is threaded inside the burner to accommodate a threaded restrictor. The spare burner that I fitted to the stove, and which seems to burn well, is not threaded inside the burner, and has a blob of casting brass or brazing inside the burner tube. Here is the burner running without a restrictor. Cheers Tony
I got my No 3 running tonight had some good green flames to start that settled to a blue flame with orange tips the pulsing was evident until I turned it down fairly low. Very noisy! I was running it with the restrictor and mesh in.
@lgh371 Hi despite reports from others on here (and respect to them) i have found if you run the primus no3 burner without a restrictor you run the risk of a fire due to the amount of pressure through the burner pipes
makes sense, Primus would not have gone to all the cost and effort of developing anf fitting those restrictors without good reason. And there would have been users then who would not have taken the care members here do now to consider and regulate tank pressures!
