NRV Head Dimensions

Hi BD
I want to fix my old stove and I need to get the NRV out of the pump tube to replace the old rotten pip. I tried to buy one of those NRV wrenches from S. Korea and, then, from the UK, but those sellers don’t seem to be able to ship overseas due to COVID-19. Can you tell me the dimensions of the NRV head, please?
TIA, Old Stove Guy
Hi, Old Stove Guy
Sure. You bet. Here are some photos. All measurements in millimeters. This is a genuine Sweden-stamped and Swedish-made NRV. The dimensions are proper for the vast majority of NRVs in stoves out there. Be aware there are a few stove companies that vary from this style. Optimus, Primus, Radius, Svea/Sievert and Enders all use this style of NRV.
P2070106.jpgP2070108_2.jpg
Length
P2070110_2.jpg
Width
P2070112_2.jpgP2070113_2.jpg
Depth
P2070114_2.jpg
Head diameter (just for interest)
Iif you are a home hobby sort, it’s probably easiest to take a steel bolt just under the inside diameter of your pump tube, cut off the threads with a hacksaw, and then cut a slot just slightly undersized in the end of the cut-off bolt with the hacksaw. Clean the cut to exact dimensions with a file. The end will look like the end of this more polished out-of-production NRV wrench made by now-retired and out-of-sight tool maker Stu Burgess in England: (In other words, you can’t get these any more.)
P2070115_2.jpgP2070117_2.jpg
If you are more of a machinist, maybe have a vertical mill, you can use a 4mm end mill with two passes in your mill and make a closed end wrench like this:
P2070118_2.jpgP2070120_2.jpg
The closed-end wrench just above is an original Optimus wrench for marine stoves. The advantage of the closed end wrench is that it won’t do this in use:
P2070125_2.jpg
I tried to make this one up from a bolt recently to fit into a specialty off-brand stove whose NRV head is down inside a pocket in the end of the pump tube. That’s a rare stove and you don’t have that concern.
The failed example I show directly above is made from a too small diameter bolt. So, try to keep your bolt as large in diameter as you can to avoid the sides bending out like this. More material gives better support.
Lastly… here are some unsolicited pointers:
  1.  – the best way I’ve found to remove NRVs is to put the wrench upright in a vise, put the stove over the wrench, then use strong downward force on the tank to keep the wrench head on the NRV head so it doesn’t skip off the end of the wrench. I demonstrate the technique in this section of one of my YouTube videos: https://youtu.be/2LKsxIYCTko?t=226
  2.  – tighten the NRV just slightly/gently before trying to untighten. This may help to break the brass-to-brass bond if there is no NRV head washer present
  3.  – if you chose to use penetrants… it will do no good at all to put the penetrating oils down the pump tube. The NRV is air and liquid tight sealed inside that pump tube. Instead, use a small brush and reach inside the tank through the fuel filler to apply penetrant to the outsides of the pump tube where it will run down the tube and get into the exposed threads of the NRV that are hanging out at the end of the threaded pump tube end block. That is where you want penetrating oils to assist.
Hope that helps. Good luck!
BD

Heat & Air Clean Regulated Burners?

Hi BD
Is it possible to “heat and air clean” the carbon and other crud from a regulated burner using compressed air and a torch?
Thanks!
Burner Guy

Hi Burner Guy
Thanks for your question! Yes! Absolutely, you can clean regulated burners using the manufacturer approved heat and air cleaning method. Like all burners, you’ll want to disassemble the burner, removing the jet, the spindle and the spindle nut.
But, you’ll need to close off the spindle opening.
So how to block the opening at the spindle? What I did was take a spare spindle nut and silver braze a cap on the open end. I just used a slip of brass sheet over the open end and machined it round after the brazing. But, you could leave it rough and all and it would still do the job. 

Once threaded into the spindle housing, the modified spindle nut will direct the air through all parts of the burner and out the jet.

Hope this helps!

(PS – Before anyone asks… yes, this is a very odd burner and is somewhat rare. It was close to hand from a long-term stove project I’m working on. So, yeah, it looks a little different from your everyday standard regulated but the idea is still the same.)
BD

Stove Part Supplier Links

Here’s a list of stove part suppliers that I’ve used or know about. As I think on it, I may add more, so check back frequently. This list is current as of June 2020. These suppliers tend to come and go in many cases. If I’ve listed your outfit and you don’t want to be listed just let me know in an email. If you find a dead link or if you know of a link I should add, please let me know by emailing: bd@berniedawg.com and I’ll try to add, update or remove it as required as soon as possible. Thanks!

USA:
EU
UK:
Australia:
South Korea:
Taiwan:

Which Cap for a “Multifuel”?

Hi BernieDawg
I  have  a  short  question  about  the  bernie dawg silencer caps. Does the Omnifuel Cap fit to the Multifuel Burner?
Best regards,
Stove Guy
Hi Stove Guy
Thanks for your questions.
I’m not sure from your question which “Multifuel burner” you are meaning. Primus has made several different stoves they have called the “Multifuel”.  And, Trangia has sold two different types of “Multifuel”-named burners. All this makes things confusing if you don’t go by model numbers or full product names.
Sooo… I’ll cover them all. Sometimes “short questions” need long answers. Sorry about that. This is a bit complicated, so please read through this carefully.
Omnifuel 3289
The OmniDawg cap is for the Primus Omnifuel 3289 stove.

Omnifuel 3289

Trangia X2 Multifuel 750001 Burner made for Trangia by Primus – current production
The Trangia X2 Multifuel 750001 burner is made for Trangia by Primus, but it is made in a way so that it is not as powerful a burner as the Omnifuel. It looks like an Omnifuel, but it’s less powerful because of the reduced power jet supplied with the X2 for use with the preferred fuels (isobutane canisters and white gas). This is also a very expensive burner for what it is. You can usually find used or even new Omnifuel stoves for less than the cost of the greatly overpriced X2. You’ll also retain the precision control and simmering using an Omnifuel due to its spindle control (absent on the X2).

For the reduced power Trangia X2 Multifuel burner, the PolarDawg silent damper cap works best using isobutane canisters and white gas due to the smaller jet supplied for those fuels. The DragonTamer is a pretty good second choice for these fuels. Trangia makes it pretty clear in their product manual that isobutane canisters and white gas are the fuels of choice for this burner. If you intend to use kerosene with this burner (I discourage this fuel for this burner), then the supplied same-size-as-the-Omnifuel (0.28mm) jet that comes with the X2 will need to be used. This turns the burner back into a simmer-disabled Omnifuel burner, so you should use the OmniDawg cap if you decide you absolutely must use kerosene.
Some clever stove users have changed out the jets on their Trangia X2 Multifuel burners so that the X2 runs the same jets as the Omnifuel. For example, using a 0.37mm jet will let you run the X2 burner with white gas at the same power as the Omnifuel. Using a 0.45mm jet will let you run the burner with isobutane at the same power as the Omnifuel. If you intend to do that, it may cause melting of your Trangia windscreen surrounds if you are not careful and attentive. But, using the more powerful jets makes the X2 more like the Omnifuel, and a OmniDawg cap would be the right one to use. If you use a 0.25mm jet with kerosene (not recommended), thereby reducing the output of the burner, you can use the PolarDawg or the DragonTamer. Confusing isn’t it?
Caution! I do not recommend the use of a re-jetted X2 with an OmniDawg cap with the Trangia 27 sets as the small size of the surrounds puts the surrounds too close to the flame. Trangia 25 sets are okay… if you are careful.
Trangia Multifuel Burner 780001 made for Trangia by Optimus – discontinued product
The original Multifuel 780001 burner sold by Trangia was made for them by Optimus and is a stripped-down Nova burner. There are “fins” inside the burner bell of this burner.
The proper silent cap for this burner is the Dawg-A-Nova cap.
Primus 328894 and 328896 Multifuel
The newer 3288 (correctly termed the 328894 or the newer 328896) Multifuel is a reduced feature (no stove-side control spindle) Omnifuel-based stove. Sort of a Omnifuel “lite” stove.

Multifuel 328894 or 328896

For a bit more money you can get a real Omnifuel and the additional cost is well worth it for the control spindle. Because the Omnifuel is also much more popular, you can even commonly find new Omnifuels at discount for prices well below the retail cost of the 328894 or 328896 Multifuel. The 328894 or 328896 Multifuel comes with a reduced size jet set compared to the Omnifuel. While the Omnifuel has 0.45mm, 0.37mm and 0.28mm jets for isobutane, white gas, and kerosene, respectively, the Multifuel comes with 0.37mm, 0.32mm and 0.28mm jets for those fuels. This is why the Omnifuel produces 3000 watts of power while the Multifuel only produces 2700 watts of power. If you plan on mostly kerosene use, get the OmniDawg for this stove. If you plan on white gas or isobutane and intend to use the correct jets for the Multifuel, then you need a slightly less powerful cap like the DragonTamer or the PolarDawg to match up with the lower output of the Multifuel.
You can also “cheat” a bit if you are planning on using white gas by using the 0.37mm jet that came with the Multifuel for white gas. This will increase the white gas flame output and let you use the OmniDawg cap just like with an Omnifuel stove.
Sorry that this is a bit confusing. Primus is marketing a strange beast with the Multifuel. Your best bet is to bypass the odd Multifuel stove and go directly to the full-featured, award-winning, and more powerful Omnifuel.
Primus Himalaya Varifuel 3278 and Multifuel 3288 – discontinued product
These are two long discontinued stoves from Primus that I am often asked about. Both stoves feature small diameter burner bells and smaller jets than the Omnifuel.

Both stoves, the Varifuel 3278 and the Multifuel 3288 work well with the Minicap, either with or without legs. I recommend the Minicap with Legs if you are only planning on using the Minicap with one of these Primus stoves. If you would like the flexibility to use your Minicap on other small self-pressurizing stoves like the Optumus 80, Radius 42, or Svea 123/123R, then I recommend the Minicap without Legs.

Sorry for any confusion this may cause. Primus and Trangia haven’t been kind to us in naming so many stoves as a “Multifuel”. I hope my post will enable you to select the right cap for your stove.
Happy Camping!
BD

Stuck NRVs??

Hi BernieDawg
I have this great old Primus 100 stove that I’m trying to fettle. I’ve got the NRV loosened up, but it seems to be stuck in the bottom of the pump tube and won’t drop out of the tube. It’s hung up somehow. It wiggles around and is loose down there at the bottom of the pump tube. I wonder if there’s some gunk in the tank that’s hanging it up?
What can I do to get it free?
Sincerely,
Stuck and perplexed
____________________________

Hi Stuck

Well… I think this might make a good blog topic actually, because I get this question and this issue fairly frequently. And, don’t feel bad – it’s common and it happens to me, too. Here’s how I handle it.
1. best thing is to buy a tool which can solve 75% of these sort of stuck NRV issues. What you want is an “ear forceps” aka an “alligator forceps”. They come out of Pakistan (for reasons I don’t understand) for pretty cheap. They are stainless steel. And they help you with other tank related stuff, say reaching into a tank to retrieve something, or at the end of the pump tube in case a rotted leather pump cup gets stuck down there. Check pricing on eBay, but here’s a screen shot of a pair I picked at random just so you can see what I’m talking about:
The larger one is about 6.5″ long and is a great size for pump tube and stove tank work. But, you can get them a lot longer, too. It was selling as a Buy-It-Now with free shipping for only $6.50.
2. next thing is to take your little flashlight and peer into the tank. Is it all black and gooey in there? If it is, then your idea about gooey stuff being on the end of the NRV barrel is probably right. Here’s how to fix that and clean your tank, too. Get a gallon of acetone at Home Depot, Lowes, or wherever. Fill the tank with it. Let it soak (plug the openings with some paper toweling to control evaporation). If you want to get really industrious, you can add some BB’s to the tank and shake it around. Pour out the acetone into a metal or glass container through a coffee filter for reuse – you can reuse it on many tanks. Shake out the BB’s, or use a magnetic pen tool to remove them. Rinse the tank with just a splash of acetone and you should be good to go. Acetone dissolves the black gooey crud (dried kerosene). It will dissolve the gooey crud on the end of the NRV barrel and then it should pop right out. This should take care of another 20% of the problems.
3. two other issues can cause the NRV to hang up in about 4% of cases.
a. there can be a little burr of brass where the vent hole in the side of the NRV barrel was punched in the barrel. You can use your alligator forceps gripping the NRV head with an unscrewing motion (like you are unthreading the NRV) to “unscrew” the burr past the opening in the pump tube end plate. Do it with the pump tube opening facing toward the floor to allow gravity to assist you. Use a little 400 grit wet dry sandpaper or a small file to remove the burr once you’ve got it out so it doesn’t give you problems again.
b. the other problem comes about from using lead NRV head washers. The lead will expand outward when the NRV head is tightened down, sometimes into the opening for the NRV head threads. This can hang up the NRV. Alligator forceps should help you to get it out, again with that unscrewing motion. Consider to switching to HDPE (#2 plastic) NRV head washers. You can punch them from the lids of food containers, so they are cheap to make and they almost never cause these hang-up problems. They last forever, too.
4. Lastly… for that final 1% of stubborn NRVs… if you have compressed air… set the air output to about 40 psi. Hold a rag in your hand over the pump tube opening to catch the NRV. Install the vent screw and apply a little compressed air into the burner mount opening with your thumb over the filler opening. Pop! Out shoots the NRV into the rag in your hand. These can shoot across the shop if you don’t use a rag to catch it and be difficult to fine otherwise.
Hope that helps!
Happy camping!
BD

A Nifty Borde Pot Stand

I’ve had this little Borde stove for some time. But, it came without a pot stand. I put this pot stand together from stainless steel sheet. The sheet is 0.032″ thick. The legs are from stainless steel tube 1/4″ in diameter. The pot support rods are 5mm stainless steel rod. All the stainless is 304. I made 1/4″ long plugs of some of the rod which I TiG welded into the ends of the pot support legs. The 1/4″ tubing legs are silver brazed to the sheet sides. The stand forms a triangle about 5″ long per side.

After all the fabbing work was done, I gave the whole thing a polish up to make it look pretty. You can see the stand in use in a YouTube video at my BernieDawg Cinema channel: https://youtu.be/I_GQG8TbO_s

It works great and folds down small. A-OK by me. You can click on the images for bigger views. Maybe this will give you some ideas or inspire you to try to make something for your stoves. Gear-building is fun!

Primus 100 Silent Cap?

Dear BernieDawg
I found a great old Primus 100. It works well and is very nice. But, how can I make it more quiet for use in camp in the early morning ? Thank you for your help!
Noisemaker
 –
Hi Noisemaker
The Primus 100 stoves are among my favorites. A silent damper cap can make your stove quieter, and also generate a better fuel/air mix for efficient burning.
 –
 Best choice is a Primus 4010 silent damper cap. They work super awesome on the 100s.
Base-Camp in England had some of the 4010’s a while back, but they’ve sold out of them now. Watch for a possible (though unlikely) return of the 4010 at Base-Camp sometime in the future, or ask around to some of the stove forums. Perhaps someone there would sell you one of their extras.
 –
Another good choice for a Primus 100 silent damper cap is to fab up a cap adapter I call a spigot plate. I’ve made lots of these over the years. It’s a great newbie brazing project for anyone who wants to work on stoves.
 –
Basically, you take a round piece of sheet metal with a hole in the center and braze a short piece of 5/8” diameter tubing to the middle.

OLYMPUS DIGITAL CAMERA

OLYMPUS DIGITAL CAMERA

The spigot plate holds the inner cap centered, and the outer cap settles around the inner cap.

OLYMPUS DIGITAL CAMERA

OLYMPUS DIGITAL CAMERA

You can make the diameter of the sheet metal base to fit either the first or the second ledge in the lipstick burner bell and then just use a regular cap set with the stove.

OLYMPUS DIGITAL CAMERA

OLYMPUS DIGITAL CAMERA

Good luck on this project. It can be done with hand tools and an electric drill. You don’t need specialized tools.
Happy camping!
BD