My experience is limited mostly to Swedish and Norwegian made stoves, and I guess I am a bit of a paraffin burner. So here I am talking about traditional brass paraffin stoves, and by pip I mean the seal in a None Return Valve normally at the bottom a pump tube. I have been trying to get a pip material timeline straight in my head, and by now it looks about like this. I am not at all sure this is right and there are wide overlaps and lots of uncertainties. Stoves can be tampered with, so I have tried to rule those out in this rather unscientific little study. This is of course also a part in the big jigsaw – “How old is the stove?” It would be interesting to hear if others have information/experience/ideas on this subject. First came cork; cork is a good material and works well. It works best wet so give a dry cork pip some time to soak after filling the tank. When I was a kid there was a farmer come blacksmith come tractor mechanic come stove fettler whom – I later have understood – had cork pips on paraffin in a small medicine bottle. Then there is a black rubber material. A twenties or Thirties Primus No 96 or No 210 can have this type of pip. It is normally worn from the pump action, and is hard and need replacing. Next in line – I do not know what it is or when this appears – Thirties? Forties? - is a lighter colored kind of rubbery material. The color can be closer to a greyish or brownish white, some are also a bit maroon (this color variation may come from the fuel). This material might look and feel OK but looking in a magnifier there is a lot of small cracks in it and it will leak and need replacement. These do not get worn as much (as the previous black variant), from the pump action. When poking it out of the pip holder this feels granular (a bit like sand) and can disintegrate when given a little squeeze. I poked one of these out of a Radius Ltd No 20 last week. It seemed to be OK at the first test fire, but because of the small cracks there was a small leak. Then next in line we have a “normal” black rubber pip – nitrile? - and sometimes in the Fifties (I think) the molded one piece pip (going directly onto the spring, need no pip holder) appears. Both types I guess are the same material and will be hard and need replacement. This type does not have as much wear on them as the earliest black pip. All the way a stove will have a black rubber filler cap seal (I think cork where used in the early days), but at some point one figured out this lighter colored material were better for pips – Why? SRV pips are much the same, I have a petrol blow torch with a cranky SRV where the pip is more on the maroon color side and with lots of superfine cracks in it – leaks and sometimes with a little flame. Synthetic rubbers were made way back, but I do not know much about application in stove seals back in the day. Now days we have viton with good resistance to fuels and wear, and it stays soft for a long time. There is a variation in types of viton as well, but more on that some other time – perhaps … Comments anyone? Thanks, and all the best, e
I have been thinking that above mentioned material is leather. I have never done gasket nor NRV pip from leather, but I have been thinking that in extreme cold (below -30°C/-22°F) it might be safer solution than rubber pip(Viton or Nitrile)
Hi, have a look at this thread and the links within it. https://classiccampstoves.com/threads/primus-nrvs-brass-cap-and-dumb-bell.31845/#post-323463 Because NRVs and NRV pips were/are replaceable parts you have no way of knowing if they are original to a stove. I decided that the catalogue listings were a more reliable way of tying Pip-type to date. I was studying Optimus stoves at the time so my post relates to that make. However, I do believe that those few European stove manufactures still in business all adopted the one-piece pip or "cone" in the 1960s Optimus was still using cork NRVs in the late 1950s and seemed to change directly to the one-piece "rubber" cone in the 1960s, with no simple rubber pip in between. Interesting post so I hope other members will comment. Best Regards, Kerophile.
I have been using leather for making pips for a couple of years in two or three of my stoves with no problem. I'll let you know in 70 years or so how they worked out in the long term. Same conditions apply to cork, leather likes to be kept wet. Not such a big problem over a couple of years but I'd be leather would harden up and need soaking after a dozen years or so. Stan
In some of my oldest stoves NRV's I found cork pips. I just turned them upside down and they still are good after half a century. Certainly the best material, but as a natural material not suitable for machine made mass production, but if you search carefully in a ordinary bottle cork for the best parts.... If not successful, don't worry, you have won a bottle of wine. I LOVE CORK PIPS !!! Radler
Hi, I also like cork NRV pips and have many stoves well over 50 years old still running with their original cork pips ( some I have just turned over). If you do want to make your own cork NRV pips, please remember: 1. To use good quality pure cork, not cork composition with a thin layer of good natural cork on the bottom surface. 2. Punch out your pip on the long axis of the bottle cork. There is a "grain" in cork just as there is in wood, and if cut with the grain running vertically through the bottle cork or pip it will not seal, but leak. Best Regards, Kerophile.
For cork pis, I learned an easy way to revitalize them: just drop the pip still within its brass holder in a boiling water pot. turn off the stove below the pot and wight until the water is cold, and voila the pip is like new. The trick comes from British Seagull manual, and is related to cork piston of fuel tap of the outboard.
Few years ago I got an old Optimus 00 Patent with a leaking NRV. Whatever I tried, I did not got the NRV loose. After reading about cork pips, I took a chance that it was the original cork pip in the NRV and filled the tank with kerosene and pumped a little so I was sure there was kerosene at both sides of the leaking pip. After 1-2 weeks in kerosene, the pip was revitalised and has worked ever since.
@Afterburner Nope not leather it is a rubber material, just a bit different from the black rubbers. A similar type of rubber that cracked and granulated where used in floats for fishing gear, I think after WW2 but my timing is uncertain, but they where still around in the late sixties early seventies. Those had fabrics in them for shape and strength (like a tyre). Similar buoys where also made of black rubber – you could tell when they broke and you could see the inside. The outside where worn and grey on both. All the best, e
Having read through countless posts here on taking out the NRV of various stoves, I finally summoned enough courage to have a go at my Primus 210 (Høvik Verk). It went surprisingly easy. To my astonishment, I found that the pip was made out of cork. I'm rather new to these stoves, but surely, that would probably be the original pip from when the stove was made? Wouldn't a replacement have been made of rubber or some other material? The lead gasket seemed in good shape, and it was not stuck. From what I understand Høvik Verk produced the 210 under license from 1953ish to the early 60s? The pip was completely worn flush with the brass pip cup.
@Jarngard If the original pip works after a soak in oil, it should be fine. You can replace with pure cork or Viton. Cheers Tony
I too use cork pips as much as possible. They can even come to the rescue on old stoves where Viton proves too hard to get a good seal. I have never yet had a new or good old cork seal fail in use, even in extended use. But like Spiritburner I have been very wary of composite cork materials. One version which I have found to work successfully, however, is automotive cork gasket sheet specifically graded as fuel and oil resistant. The 'rubber' element in the best quality fuel resistant cork gasket sheets I presume must be something similar to Viton. I have used pips made of this grade of gasket sheet for as long as 10 years + without having one fail so far or react adversely to immersion in paraffin.
@Tony Press Aye, I'll give that a go. I put the old cork pip in some mineral oil. It looks intact, just seems a bit worn down. It is perfectly flush with the top of the pip cup. I thought it was supposed to be a bit "taller" than the cup itself? I've ordered a Viton pip, so most likely I'll be replacing the cork one.
Hello All, Has anyone tried cutting from viton rope? See below link. Black Fluorine Rubber solid Round Sealing Strip O-ring Seal Cord Dia 2mm-15mm | eBay
@Jarngard I always have my pips slightly proud of the cup, rather than flush. But if the face to which the pip is to make contact is narrow flush will work. Tony
@sefaudi I cut the slices from the O-rings Viton. It is not easy to cut evenly, but you can always sand with sandpaper. For the SRV in my PT-2 I also cut slices from O-rings. ( thicker ones)
