Reviewer Information:

Name:	Mark Roberts
Age:	33
Gender:	Male
Height:	6’1” (185 cm)
Weight:	180lb (82 kg)
Email address:	mroberts AT biol.sc DOT edu
City, State, Country:	Columbia, SC, USA
Date:	07/05/2004

 
Backpacking Background:
    I have been backpacking since I was about 15 years old.  A lot of early outdoor experiences, however, involved canoe camping.  Because of that, I rarely took the weight of my camping equipment into consideration.  I have been trying to break that habit since I was about 25 and am finally starting to get better at it.  I am not an ultralight, and probably not even a light, backpacker but I do try to buy the lightest equipment that I can find.  Since I have really only had a decent income for the last few years I am slowly replacing my old, cheap, heavy gear with bright, shiny, fancy, light new gear.  My typical excursions are long weekends (3-4 days) but they sometimes go longer.  My wife and I hike together a lot with our two dogs and are hoping to build up to much longer hikes sometime soon since our first child was just born in May 2004.  Most of our nearby hikes are either in the Congaree National Swamp or the on the Foothills Trails of the Appalachian Mountains, so our hiking conditions can vary considerably.

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Product Information: 

Manufacturer:	Primus
Year of Manufacture:	2001
URL:	http://www.primus.se/
Dimensions:	6.5" x 3.5" x 3.4" (165 x 88 x 86 mm)
Listed weight excluding pump:	11.5 oz (326 g)
Listed weight including pump:	15.1 oz (428 g)
MSRP:	$99.95 (US)
Measured weight of stove:	13.4 oz (378.8 g)
Measured weight of pump:	4.69 oz (132.9 g)
Measured weight of storage bag:	0.78 oz (22.3 g)
Measured weight of tools:	0.58 oz (16.5 g)
Output:	2,800 - 3,000 W (10,000 - 10,500 BTU/h)
Listed boil time for 1 L of water:	3.5 - 4.5 minutes

The MFS was part of the Himalaya line of Primus products.  However, the Himalaya part of the name has since been dropped from all of the Primus products.  Fortunately, the MFS continues to be produced sans the Himalaya tag as one of Primus' "Expedition" stoves. It was the first multi-fuel stove and has won numerous awards.  It purports to be capable of burning almost any liquid fuel as well as LP gas canisters.  Of course, to burn any of the liquid fuels one must have a canister to put the liquid in.  If I am using liquid gas I carry it in an MSR canister which weighs 131.3 g (4.6 oz) or 264.2 g (9.3 oz) including the pump that must also be carried.  Primus also makes a liquid gas canister but I have no experience with it.  The stove has a built-in preheating system that is designed to allow the stove to function well even in very low temperatures.  It sports 3 folding legs that are connected to the pot supports - all three of which have a serrated pattern on them.  When fully opened, the pot supports create a 7" (17.8 cm) diameter area to rest pots on.  The stove also comes with a tool kit to help disassemble the stove and clean it.  It also comes with a different sized "jet nipple" (hole through which the fuel flows) for certain fuels like kerosene and diesel fuel.

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Field Review:

I have owned the MFS since January 2002 and it has served me faithfully on many trips and power outages since then.  I have only used either LP gas canisters or white gas as fuel sources and have yet to have a clog.  Since the MFS is a 'remote' stove (i.e., the fuel source is attached via a hose rather than directly to the stove) it is equally stable using either fuel type; and it is quite stable.  The three rigid legs provide plenty of secure support for the stove and since it is not sitting on top of a LP gas canister, it has a relatively low profile, adding to its stability.  The three serrated pot rests are quite rugged and prevent pots from sliding around on the stove. 



The MFS is particularly easy to light when combined with a LP gas canister.  Simply screw the adjustment knob, which sits at the end of the fuel hose, directly to the canister.  It threads easily and it seats firmly.  When the knob is opened to release fuel a match is used to light the fuel at the stove.  As with many stoves, it is necessary to light the stove at a low fuel flow and then increase the flow.  When the knob is fully opened the MFS produces a hefty amount of heat as well as a hefty amount of noise.  It is a very noisy stove using either fuel source.  To turn the stove off, simply tighten the adjustment knob. 



Using liquid fuel with the MFS stove is slightly more complicated but works more smoothly than the old Coleman white gas stove my father had from the 1960s.  I hadn't really planned on using liquid fuel with my new stove unless I had too.  However, after playing with the stove a little, white gas has become a very viable option.  It burns clean and hot and is readily available.  And, with the MFS, it is relatively easy to use.  White gas (or any liquid gas for that matter) is stored in an approved gas canister into which the Primus aluminum pump has been screwed.  In recent models this pump has been replaced by the "ErgoPump" which is made of both aluminum and composite materials and which Primus claims is easier to use.  The fuel canister can be stored in this fashion for the entire trip or even longer.  When ready to use the fuel, simply connect the adjustment knob to the pump.  Next, pressure must be created by pumping about 15 strokes.  The pump itself has two easily read labels on opposite sides of the pump; one says "On" and the other says "Off".  Once enough pressure is built up, the pump is turned so that the On side faces up.  The adjustment knob is then opened up ever so slightly so that some fuel will rush out of the canister and onto the "priming pad" which is then lit.  It is easy to overdo this step and have way too much fuel on the priming pad.  This can result in a very large flame and an unecessarily long priming time.  Once the fuel on the priming pad has almost burned out, turn the adjustment knob open and start cooking; it will light right up.  When done using the stove, simply turn the pump over so it reads Off and let it burn itself out.  This step gets rid of excess fuel that is still in the line.  Once it burns out, turn everything off and it is then possible to remove the hose without any gas leaking.  This takes a little practice to get the hang of and I somehow almost always manage to get some gas on me, but it isn't overwhelmingly difficult.  Obviously, the LP canister is the much simpler method.

The adjustment is easy and smooth.  The stove can be adjusted down quite low although I don't know if it would count as a 'simmer' like many people seem to desire.  I am typically just boiling stuff so a simmer is nearly useless for me anyway.  However, there is a wide range of fuel settings although anything above about halfway is incredibly loud.  When done with the stove it folds up and stores in the included Primus storage sack.  The folded size of the stove is approximately 3.25 in x 3.25 in x 6.75 in (8.25 cm x 8.25 cm x 17.15 cm).

The listed boil time for 1 L (33.8 oz) is 3.5 - 4.5 minutes.  To test this claim, I used a 1.5 qt (1.4 L or 48 oz) aluminum Revereware kitchen pot with a copper bottom and a 6 in (16.2 cm) diameter.   I conducted the test with both Primus LP gas (60% butane, 25% propane and 15% isobutane) and white gas.  My location is at 332 ft (102.2 m) above sea level so I decided that the boiling point would be the point at which the water reached 100 C (212 F).  Water temperature was measured using a standard 12 in (30.5 cm) laboratory thermometer that was held in the water without touching any part of the pot itself.  Boiling time for the white gas does not include the priming time.  All volumes were measured using a 500 ml (16.9 oz) graduated cylinder and all weights were determined using a triple beam balance.   The ambient temperature was 26.5 C (79.7 F) and the water temperature was 25 C (77 C).  Only distilled water was used.



The tests show that to actually reach boiling temperature takes quite some time, especially with the LP gas. However,  I probably would have turned off the water at around 70 C (158 F) if I were in the field.  At this point I noticed small bubbles and it was more than hot enough to rehydrate food.  Interestingly this is around 3.5 - 4.5 minutes. When in the field, I have never thought that it took too long for this pot to boil water.  Actually, I have always felt that it was a very hot stove, even with the LP gas. 

To further compare the two fuel methods under field conditions, I conducted a boiling test using 450 ml (15.21 oz) of water in an MSR 475 ml (16.06 oz) StowAway pot.  Everything was done exactly as in the first test.  This test was repeated once to ensure accuracy. 

		White Gas	LP Gas
Test 1	Gas used	13.2 g (0.47 oz)	11.6 g (0.41 oz)
	Time	187 s	214 s
Test 2	Gas used	13.5 g (0.47 oz)	9.6 g (0.34 oz)
	Time	176 s	203 s
Average Time:		181.5 s	208.5 s
Average Gas Used:		13.4 g (0.47 oz)	10.6 g (0.37 oz)
Total Capacity:		419.4 g (14.8 oz)	225 g (7.9 oz)
Total Potential burn time:		1:34:40.8	1:13:45.6
Total Weight:		683.6 g (24.1 oz)	301.9 g (10.6 oz)
Total # boils:		31.3	21.2

Total capacity is simply the total amount of gas that each type of canister can hold.
Total potential burn time is the time that the stove could run continuously based on the average time and gas used.
Total weight was the actual weight of both the fuel and the canister.
Total # of boils is the number of times that 2 cups of water could be boiled.


The most notable result is that, once again, white gas boils water much quicker than LP gas but it also consumes more gas in the process.  In addition, the white gas in its canister with the required pump weighs more than double what a LP canister does but does not offer twice the number of uses.  There is no clear cut answer as to which fuel is 'better' but the beautiful part of this stove is that anyone can experiment and decide for themselves since either gas can be easily used. 

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PROS:

1. Easy to use.
2. Very stable.
3. Relatively light if using just LP gas.
4. Very reliable.
5. Very sturdy.
6. "Boils" water relatively rapidly.
7. Can use almost any fuel.
8. Serrated pot supports to keep pots in place.

CONS:

1. Relatively heavy if using white gas.
2. Loud as heck at full tilt.

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Summary:    

I really love this stove.  It is the multi-tool of stoves.  I have used it over and over again without so much as a small hiccup out of it.  I am extremely pleased with the quality of the product and how reliable it has been.  One thing that can be most startling is just how loud this thing really is.  Of course, that takes up only 15 minutes or so out of a day so it really isn't that big of a deal for me.  Those who are looking for the lightest or smallest stove that money can buy should probably look elsewhere as this stove is not ultralight; of course, it isn't gargantuan either.