Sunday, February 22, 2015

Liquid Fuel - Optimus SVEA

Advantages

  • No pump
  • Proven design
  • One piece
  • One moving part (the valve)

Disadvantages

  • Small fuel reservoir
  • heavy

Notes

  • White gas only
  • Integrated fuel reservoir
  • Pack weight (w/o fuel): 22.2 oz (629 g) w/cup, 19.6 oz (557 g) w/o cup 
  • Include "pot" extremely small
Originally introduced in 1955, this stove remains essentially unchanged. The only noticeable changes are the internal jet cleaner, valve angle, and the modifications to the valve key tool. The original valve had a downward angle from the stem. The new valve is perpendicular to the stem. I assume the change in angle is to facilitate the internal jet clean. The changes to the key are of little importance since the key is only used to turn the valve and has cut outs to fit the jet and hex nuts for maintenance.

I bought this stove for a couple of reasons.

First, this stove remains essential unchanged since 1955 and is still available today. How many stoves can boast that longevity. I just wanted one. Since I have more advanced stoves, I doubt that I will every carry this stove into the back country.

Second, this stove has no pump and bridges the gap from the simple alcohol stove, to the pressurized liquid fuel stoves. One of the drawbacks to alcohol stoves is their susceptibility to wind. Without pressure behind the flame, the flame moves around like a flame on a candle. One of the drawbacks to liquid fuel stoves is the pump. A pump failure is catastrophic. I have never had a pump fail, but it is a complex piece of the stove. The SVEA does not have a pump, yet works as a pressurized stove. As I do presentations to groups about backpacking, I like to have this stove that bridges the gap.

In the most simple terms, the SVEA uses heat from the burn to self pressurize. Like other liquid fuel stoves, you must prime the stove. The integrated fuel reservoir is heated with the priming, causing pressure to build. The burner is also heated converting the liquid to gas and allowing the stove to produce a good blue flame which perpetuates the process. Word of warning. The stem and valve get very hot and if you leave the key on the valve, that heat is transferred to the key. You will burn you fingers adjusting the flame! Always remove the key from the valve after making any adjustment.

The SVEA burner is the classic inverted bell similar to the DragonFly and Nova stoves.

The noise level is similar to the Nova stoves, which produce less noise than the DragonFly stove. The SVEA also has a "buzz" beside the classic jet engine sound.

The included aluminum "pot" is too small to be of any value other than a lid to the packed stove. Since there are not "parts" for the lid to hold in place, that does not even make a good reason to carry the "pot" as a lid.

One thing to note. The stove has performance issues with older fuel. With newer pressurize stoves you will probably not notice the performance difference using older fuel unless you use a stopwatch to time your boils. With the SVEA you will notice that the stove does not produce a consistent flame and tends to sputter. I discover this by accident. I had an old fuel container with a few ounces of fuel left in it that was several years old. I used that older fuel in the stove just after I purchased the SVEA. The stove performed so poorly that I was beginning to wonder if I had a bad stove, or if the "cult" like following of the SVEA was just that, a "cult". I finally dismantled the stove, cleaning the jet, the tank, and everything else I could find. I poured in new fuel, and the difference was night and day. The stove performed so well that I wondered what I had done that fixed it. I then had a thought about the fuel, so I swapped out the fuel for the older fuel. Stove went back to not working very well. Changed the fuel out again to new white gas, and I had a functioning stove that performed very well.

With newer and lighter stoves available to me, the SVEA has not yet made it into my backpack. My decision not to carry the stove is all about weight. The fuel reservoir carries enough fuel for a few nights, any longer trip length and you need to carry addition fuel. The extra fuel and bottle make the SVEA even less appealing because of stove and fuel weight. The SVEA performs as well as any other stove, and is uses about the same amount of fuel as my most efficient liquid fuel stoves. It is just heavier than the newer stoves.  For an overnight or for a weekend trip, the SVEA competes very well since no additional fuel bottle is required. Newer stoves require the fuel bottle which raise their weight to be comparable to the SVEA that does not require a fuel bottle (for short trips).

My use and testing show that the stove boils 2 cups (~500 ml) of water using a MSR Titan Kettle in 5 minutes using 2/5 oz. (by weight) of new white gas.

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