Hello everyone .. I'm beginning a fettle on a Petromax 821 and wanted to replace the c/v seal . But the problem I have is the c/v isn't a standard slotted one it's a square shaped on the top . Would anyone know how to remove this ...if there's a special tool ? Thanks very much..Ernie
@Ernie, there is a special tool but many of the shop-bought ones aren't as good as they are made out to be and you will be better off making your own. It's actually not too difficult. For more information type Primus type NRV into the search bar (top right of this page), the result will explain things better than I can.
@Ernie my optimus is the same - as I suspect are many similar lamps. I simply filed a slot in a peice of alloy round bar I had lying about. They are not normally too tight. Chris
Your definition of too tight must be different from mine. I have had some where aluminium would not have worked. Use a steel bar and file a 5mm slot in the end. I still havn't tried it, but what I am planning on doing is using a socket extender (1/2") and filing a slot in that. That way you can use a socket T handle to give extra purchase.
I've made one for my Primus nrv from a cheap T-bar socket wrench. Sawn off the socket end and cut a fitting slot on the solid end. It wasn't perfectly fitting to the NRV but it worked without damaging the brass.
The 821 is an excellent little lantern. It boxes way above its weight class in terms of light output. Certain parts are becoming very hard to find though, especially upper vaporisers and ceramic burner caps. It is supposed to use the same slotted NRV as the 829 etc. The Brite-Lyte NRV will fit and work. The newer aftermarket Primus style NRV's have less screw thread than the originals or the Pmax types and may damage the threaded hole in the pump tube when you tighten it up.
Thanks very much everyone for the replies ! I am going to order some seals and a new NRV from Britelyt Co . I'm also going to have a hand at making a tool for the NRV ..it doesn't look to hard and I have a few extra 3/8 socket extensions I can sacrifice one for a good cause. Thanks very much again ...Ernie
Hello everyone .. So I managed to get the NRV out of the lantern with a piece of square stock I made a slot in and it worked great . Here is what I have ..it looks like the old seal is cork so I assume that's original to the lantern . Im thinking all I have to do is order a new pip and I'm good to go ..correct ?? Thanks very much...Ernie
Good to hear you've home-made something that works. Cork pips were often found in older NRVs. Cork is pretty resistant to a wide variety of solvents and fuels. Not all 'rubbers' are fuel-resistant. Viton wasn't available yet in those days. Some Buna-N or Nitrile might work ok.
Edit: for a fast fix: turn the cork pip over, use the backside. This also works for rubbers pips/seals, as long as they are intact. The continues indentation by the spring pressure makes them leak in combination with drying out. Or completely wrong: pull the spring further out a little... This doesn't work for cork but may for rubber. Off coarse all besides cleaning the seal.
Also, no need to destroy any sockets. Just find a bolt of appropriate width, cut and file to fit the NRV and tube length. A spanner/socket will then fit on the end of the bolt
