The Myth of Pressure Regulators

[Jon Fong / Flat Cat Gear]

FWIW, I have had both the BRS3000t and the Fire Maple 300t flames lift off of the stove and go out while using new canisters.  I happened to be doing some full throttle testing and noticed this limitation.  My 2 cents.

[Roger Caffin]

Yeah, new canister, 30/70 mix, flat out: lift-off possible with quite a few stoves I would imagine.
There’s a moral there somewhere.

Cheers

[Olivier A]

I have a Primus Tupike dual burner stove where the regulator is on the stove, not on the LPG tank. The advantage is that regardless the gas vapor pressure, the pressure at the stove is constant and there is no flame lift off even at the highest valve setting.

I can see an advantage when the regulator is at the stove side : only one regulator, i can switch between the LPG tank, or small butane / propane canisters, or a small pure propane canister, and i need only adapters, not many regulators.

An inconvenient, not too much for stoves but more for catalysis heaters, is that some hoses can release oils specially when used at high pressure and can obstruct the heater. Using a regulator at the tank side in this case reduce the pressure and can solve partially the problem (the best solution is to have a hose that does not release oils). It seems that this hose release problem is because of some chemical additive to make it more flexible. Release free hoses are more rigid unfortunately but are the recommended ones to avoid problems. Another option is to add a filter just before the heater, not a very good option i think as this filter need to be changed every couple years.

Anyway, this is not probably a problem with portable stoves, as they are using short and small hoses that do not seem to release any contaminants and stoves are much less sensitive than heaters.

In the end i think that a pressure regulator for a small portable stove is overkill for cost, long term reliability and weight reasons. More it is probably very difficult to manufacture in a DIY project.

Manufacturers like to make things difficult to copy.

[Roger Caffin]

We have had reports of a few strange hoses over the year, including one which seemed to crumble and shed bits of ?rubber? into the jet.
I use PFA tubing: it is flexible, light, tough, gas-proof and takes up to 250 C. Not cheap, but you should not take risks with LPG anyhow.

Cheers

[Olivier A]

An inline gas pump between the canister and the stove would be more useful than a regulator. It could pump gas out of the canister in liquid feed during extreme cold weather. Then marketing guys could advertise something really working.

Such a system would make multicombustible stoves even more useless; except when gas is not available.

[Jon Fong / Flat Cat Gear]

I have recently been testing a lot of stoves and frankly, I am pretty impressed with the micro-regulated stoves. The regulation lowers the overall pressure ranges and it seems to make the flame control very precise and makes it difficult to blast like a beast. Yes, with practice you can have similar control with just a needle valve (like the BRS 3000t). That being said, I find that the micro-regulated stoves are pretty forgiving for novice users and overall require less brain cells to operate.

Let’s agree to a couple of things first, a pressure regulator
Will not inherently increase fuel efficiency
Will not allow you to extract more gas from, a canister
At cold temperature 3 C to -1 C all canister stoves are probably going to have a problem

Given Randulph’s conclusions
You should be able to boil 2 cups of water in under 4 minutes. In that time range, the output pressure and therefore the output power should be relatively constant
Most people cook at relatively normal temperatures (20 C) and the adiabatic impact would be minimal at that temperature and burn duration.

So, this has been an interesting article for me. One of the reasons is that I am actually well versed in pressure regulators and in fact have a patent for a negative pressure regulator for inkjet printers. Pressure regulators are pretty well documented, and the Soto version seems very typical. With respect to the actual engineering, it appears that the Soto regulator works are design. Randulph’s conclusion read very differently than the attached graphs. The first 4 are in alignment with a standard pressure regulator

The Soto Micro Regulator Stove seems to be fitted with a regulator that limits the maximum gas flow to a level corresponding to an output of 2,6 – 2.8 kW.

As long as the pressure in the gas canister is higher than a certain threshold level, the Soto Micro Regulator stove burns with this constant output.

When the pressure in the gas canister drops below this threshold level, the output of the Soto Micro Regulator Stove also starts to drop.

The duration of the period of constant output depends on the ambient temperature, as well as the size of the gas canister and the composition of the gas. At room temperature and with a large (445 g) gas canister the period of constant output has been measured to up to 45 minutes. For small gas canisters (125 g) at room temperature a period of constant output of 10 – 15 minutes has been measured.

One thing that was missing in the article and tends to show a bias is the chart showing the 445 g gas canister running at a constant output for nearly 45 minutes at room temperature. To me, that demonstrates that micro-regulation does indeed function correctly at nominal conditions. Is micro-regulation useless? Not so much. Is it worth the extra $$$? Maybe for someone who doesn’t want to think much about stoves and how they operate. I am pretty pleased with both the Pocket Rocket Deluxe and the Soto Windmaster, but the primary reason is the wind robustness. Micro-regulation comes with the design, and I find it useful. My 2 cents.

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