Hi everyone! I live on a sailboat …and have been using a Primus 535 and also an Optimus 535 for the majority of my cooking for about 3 years. I ALWAYS unscrew the cap after each use to release the pressure …but , I was just wondering if anyone knows if this is necessary?????? Can I just leave it pressurized?? thanks Jonny
Hello Jonny, I have a Primus 535 Kerosene Burner, and can state that it is possible to leave it pressurized. I do so when using it for camping, and have had no issues. It must be said though, that it is a prudent measure to release pressure for longer-term storage, if only to rest the seals etc. I don't necessarily empty the stove, as it is used several times a year. If it was to be left for more than a year, I'd be inclined to empty the tank and use the kero elsewhere. Routine and regular maintenance will ensure that it performs well when needed. All in all a great stove. Other, more learned gentlemen will no doubt offer sage advice, and you will have many opinions and theories to choose from. There is much to be learned from them, so watch this space, huh!!! Best regards, Mike.
Hello Jonny Its a question of safety. If the Valve is leaking or gets open for some reason, liquid fuel would sort through the jet until the tank is empty. If it is the kerosene version, you will have a mess or maybe provisions made unusable. If you have the meth version, meth will vaporise and you may have vapours exploding in the worst case. On a boat I would not take the risk of a fire and always release pressure. In a house and with the kerosene version I would not release pressure all the times. By the way a very famous marine stove! Best Regards Radler
If the stove is in good operating condition you can leave it pressurized. If it leaks or there is a chance of a leak then releasing the pressure is a good idea. There are instructions for this stove in the Reference Library and they say "put out by turning knob fully to right." If releasing the pressure were necessary the instructions would say so. Especially if it were a safety issue. They do not. Ben
Thanks Mike! I agree , I would release pressure when leaving the boat for a while …. maybe every other week or so.
Thanks Radler! Yes! I LOVE the 535. I have one with the pot rail accessory as well as a gimbaling setup that I haven't installed yet. I rescued it from the trash heap at an old Chandlery a few years ago …bulletproof.
Thanks Ben. I read the instructions …actually for the Optimus version …..and I agree that it would most likely say so.
I do not agree with Ben in this point. The 535 is a historic European product. We have here a different culture about instruction sheets. US Instructions are made for full size ignorants in our opinion. (Due to the US habit of grotesque claims for compensation, not because US people are much more ignorant than we are) The European tradition is based on common sense, so we don't write what seems self-evident to most of us. The absence of a warning must not be interpreted as an allowance in our tradition. The second point is that a instruction leaflet only says how to operate a stove. The rules for safety aboard of a ship are a different range. Regards Radler
I wish that were the case in the United States as well. The fear of product liability lawsuits leads to instructions that are crammed full of unnecessary safety warnings as you say. Turning the knob to put out the stove seems self-evident. Yet this is included in the instructions. Reaching over still hot burners and unscrewing a fill cap (that can't be seen) thereby releasing the pressure to avoid a safety catastrophe is less self-evident. This too would have been included in the instructions if it were a normal part of the operating procedure. Releasing the pressure after each use is being overly cautious. There's nothing wrong with being overly cautious on a boat but it isn't necessary. Neither is disconnecting the batteries before going to bed at night to avoid the possibility of an electric spark igniting your boat. You can do it to be overly cautious but it isn't necessary. Ben
Well, Radler, with all respect-- a truly half-baked statement! As a "full-sized ingnorant" ("full-sized", at least, I cannot dispute!), I have always been gratified by the old Primus and Optimus instruction sheets; the one with the little fellow and the very detailed lighting instructions. They are very valuable. I take it, though, that those were designed strictly for the overseas market? "The second point is that an instruction leaflet only says how to operate a stove." This is similar to our tradition; general advice for the larger issues of life, maritime or terrestrial, we also seek in other places.....
Thanks for that railer …but , I'm not sure I agree. I THINK the 535 was made with boating in mind ( I'm sure someone will correct me if I'm wrong!) I think that if the stove is in good shape , and the seals are good , it should be fine pressurized for a week at a time (one fill up). Then again …I am not sure!
With my 535 alco and 155 kero I always release the pressure after the use. I just want to be sure that if there is a leak not too much fuel would come out from the stove/tank.
Gents, one important thing has not been discussed here; when these instructions were printed, 50 odd years or more ago, these stoves were NEW! Now, 50+ years later we are talking about OLD equipment, no matter how well looked after. One rule: "Better be safe than sorry" applies!!! Best regards, Wim
I have a boat and an Optimus 535 (though not on the boat). The question of how far to go with safety precautions is an individual matter. One seaman might throw out a third anchor, disconnect the batteries, set an anchor alarm, and assign over night watches. Another might use a single anchor and call it good. In the end you should do whatever it takes to get a good night's sleep. If that means releasing the pressure in your stove then that's what you should do. These days a lot of sailors have propane stoves on their boats. For safety the propane tank is usually mounted outside the cabin. While much more dangerous than alcohol or kerosene these propane stoves are typically shut off at the burner. Sailors don't go out onto the deck to shut off the propane tank after each use. Ben
Don't know about you, but if I had a boat with a propane stove I would make immediate plans to swap it out for something safer -- propane in the bilges is no joke! In the meantime, I would shut it off at the tank after every use. I might very well leave a kerosene stove pressurized between uses, especially if I was the only one on the boat. ....Arch
I'm with you. I used to have a little gimbaled propane stove that took the small Coleman propane cylinders. It had a mount on the deck where I could use it to make coffee in rough conditions. Then I would take it off and stow it below decks. That is until the day when I found my cabin full of propane fumes. I haven't used it since. Good thing they add ethanethiol to propane as an odorant. I might have blown myself up! Still, I see a lot of boats in the harbor with propane tanks mounted on deck plumbed to stoves inside. One man's reasonable safety precautions are another's unnecessary pain in the ass! Ben
