Making the switch(?) OR acting as the Dive Tribes "Crash Test Dummy"

[QuarterMaster]

I'm REALLY digging Butane. I figure all you lady boys out there can't wrap your head around the word as it's associated with lighters and torches. But again, that can of Propel you're so endeared to has the SAME FLAMMABILITY rating!

See this attached SDS!

I have spoken.

[QuarterMaster]

Big badda boom!

Has any "Propel" boats exploded in the past 25 years of use? Bute and Propane has the SAME safety level.

[QuarterMaster]

How about the Green gas used by airsoft/paintballers.

Dude,

Your onto something.

Took a moment, but I realize what this is...Airsoft folk use it. So why can't we?

See attached SDS for this, aka PROPANE!

This DOES have silicone oil added, at least the Airsoft Green Gas. Lube'll do ya good(?)

Parts relatively inexpensive and available.

I'll do some analysis and get back. This GBB (Propane) vs Butane in cost.

BTW, in the end if the worry of it's use (no different from Propel) has me sitting alone at the far end of the pond.

I'm VERY ok with that.

[Bob Gato]

From what I can find butane is a little cheaper than propane but propane is easier to purchase in quantity A barbecue bottle will last you 5 years. ..
..." Pumped a lot of 'tane ( butane) down in New Orleans... Big wheels (paddle) keep on turning ...proud Mary keeps on burning ( the burners under the boilers) rolling on the river..." Fuel for thought...
.. I think I would go with the propane a little higher operating pressures better operation in cooler weather whenever 900 MHz gets figured out, you'll also get better operation at two atmospheres.

[QuarterMaster]

From what I can find butane is a little cheaper than propane but propane is easier to purchase in quantity A barbecue bottle will last you 5 years. ..
..." Pumped a lot of 'tane ( butane) down in New Orleans... Big wheels (paddle) keep on turning ...proud Mary keeps on burning ( the burners under the boilers) rolling on the river..." Fuel for thought...
.. I think I would go with the propane a little higher operating pressures better operation in cooler weather whenever 900 MHz gets figured out, you'll also get better operation at two atmospheres.

Just to be clear, burning or explosion is NOT a factor, if it is EVERY can of "Propel" is just as suspect.

So we can dispense with the flammability concern, because you have it already.

Now I've done the math.....

Capt. Redboat wins!

Source: AMAZON	Base Cost/Unit	Total Grams	Cost per Gram	Density g/cm3	Cost/CC	Expansion Ratio	gm used for 1litre (1kcm3) Ballast Tank	Cost per Blow	# of blows per unit purchased
CO2 (10 Cartridges)	$16.99	160	$0.11	1.25	$0.13	535	1.869158879	$0.25	85.6
Propel (1 Can)	$29.70	368	$0.08	0.91	$0.07	306	3.267973856	$0.24	112.608
Freon (3 Cans)	$43.58	1020	$0.04	1.24	$0.05	274	3.649635036	$0.19	279.48
Ronson Lighter Butane (3 x135 ml cans)	$22.95	405	$0.06	0.6	$0.03	233	4.291845494	$0.15	94.365
Airsoft Green (12 x 13.5 oz)	$110.00	4791	$0.02	0.58	$0.01	274	3.649635036	$0.05	1312.734

So, buy more, save more. But is it really about the $$? That's up to you, as is everything here.

As safety is the same regarding Propel, Butane, and Propane, that mitigates the flame fear as Propel is the same. YOU just don't equate Propane/Butane = Propel in Flammability safety, period.

All this being said, I'm liking the Butane/Airsoft (propane). I'd really like to verify the stored pressure of the Airsoft. From the article below, it's up to 100psi (based on Propane numbers). I'm digging the 25psi of Butane. We could co back to PVC holding tanks for it, provided they're UV stabilized. Though thicker walled than Cu (precluding smaller boats), anyone can tap and glue SCH40 PVC.

The following is the article I basing this on. Note, it's a single source, one data point, of information. Let's find more to back it up.

Analysis complete.

LPG stands for Liquefied Petroleum Gas.

Basically it is a natural by-product of the process of separating hydrocarbon products such as petrol from crude oil in the ‘cracking plant ‘ at petrochemical refineries.

It can also be found in its natural state under the sea or under the ground, generally in the same location as oil fields. How a gas cylinder Works


An LPG cylinder / bottle is a pressure vessel around 2-3 mm thick made of mild steel.

A ‘full’ cylinder is never actually full of liquid, space is left to allow for expansion of the liquid and for the compressed gas. So cylinders are normally filled up to a maximum of between 80 -87%

When the valve is opened, gas is pushed out by the internal pressure and there is a subsequent pressure above the liquid. The liquid draws heat through the wall of the cylinder from the outside atmosphere and begins to boil, just like boiling water, but instead of steam, it is gas vapour that is produced.

As the process of conversion to gas continues, the level of the liquid goes down. When the valve is closed again, or an appliance switched off, then the pressure inside will rebuild up to the same pressure as the liquid, irrespective of how much remains inside the cylinder. Properties and Characteristics of LPG

AS A LIQUID

• It is always stored under pressure.
• It has a very high rate of expansion in the cylinder.
• It is both odourless and colourless in its natural state.
• It ‘boils’ at low temperatures.

AS A VAPOUR OR GAS

• The liquid will expand to over 240 times its’ own volume.
• It is heavier than air.
• It has low limits of flammability.
• It has a very low viscosity and is very searching.
• It is lighter than water.
• It can be used at high or low pressures
• It has a higher calorific value than natural gas.
• It has a higher gas/air ratio than natural gas.
• The products of good combustion are harmless.

Properties and Hazards of LPG


At a liquid temperature of 15 ⁰C or 60 F the following pressures would be expected inside a cylinder.

Butane = 20 – 25 p.s.i approx. 1.5 bar

Propane = 100p.s.i 6.9 bar

It would be almost impossible physically and financially, to store LPG entirely as a gas, due to the amount and size of storage containers required. So it is liquefied and kept under pressure to reduce volume. As a liquid, it has a high rate of expansion


Cylinders and tanks are never completely filled with liquid; it varies by cylinder size between 80 to 87 percent of capacity, to allow for expansion in varying air temperatures outside or instances of other manmade heat sources being placed nearby. Even though expanded the weight of liquid in the cylinder will remain constant. As a liquid it is odourless and colourless in its natural state.


It can be described as having the ’colour’ of water sometimes discoloured but still clear. When released as a gas it has no smell, refineries have to-by law- add a stenching agent to it usually Ethyl mercaptan, to give it that distinctive ‘cooking cabbage’ smell. It boils at low temperatures


Butane boils (produces gas) at temperatures down to -2 ⁰C or 28 F

Propane boils at temperatures as low as -42 ⁰C or 44 F

Both products draw heat from the air outside, through the walls of the cylinder / tank to aid vaporisation. As long as the air temperature around the cylinder remains above the ‘boiling point’ of either product, then vapour should be produced.

Butane can be affected by cold weather, and in deep cold winter months could result in very poor pressure to appliances.

Propane, with a much lower boiling point, should not be adversely affected in the British climate.

Excessive demand from appliances to both products stored in cylinders could result in poor performance as the boiling liquid can only produce certain volumes of vapour by cylinder size.

It is always prudent to match installations with the correct size or amount of cylinders to do the job properly. The liquid will expand over 240 times its volume as a gas.


One litre of Butane liquid will produce 233 litres of Butane gas.

One litre of Propane liquid will produce 274 litres of Propane gas.

Only a small amount of liquid escaping will produce a large amount of flammable gas, it is therefore very important that cylinders are stored -and used -in an upright position to prevent liquid entering any valves or pipe-work.

That is why cylinders should never be moved whilst attached to working appliances in case liquid enters the pipe-work causing large amounts of gas getting to the burner heads. As a Gas it is heavier than air


Butane and Propane both have a specific gravity greater than air, Propane half as much again and Butane twice as much. Which means that if released into the atmosphere, it will sink down to the lowest level available; basements, drains, ducts etc. and it will continue to gather in low levels for a long time, until eventually reaching a flammable mixture. LPG has low levels of flammability


Which means it only takes a small amount of gas in the air to produce a flammable mixture and create a fire or explosive hazard.

Which is why, unlike natural gas installations which have a small degree of tolerance to gas leaks, ALL LPG installations MUST be gas tight. LPG has low viscosity and is very searching


Butane and Propane as either gas or liquid have very low viscosity, so it flows very easily and can penetrate even the smallest break in an installation, it will also react with oil based products which will result in leaks.

This means that it is very important not to use such jointing compounds as used in natural gas installations for an LPG one. Only such compounds as Calorie etc. should be used. Every joint and connection in an LPG installation should be thoroughly tested for soundness. LPG is lighter than water


Lighter by half as much again, which means whilst it will sink in the air it will float on water, down streams, along drains and sit on pond surfaces.

[QuarterMaster]

One last thought...

25psi, too low????

NOT unless you dive to 18.3m (60ft) where it can't overcome water pressure at depth. 10x my Test Depth (deep submergence)

[B800Kaluga]

Firstly, Thank You for doing all of this research and math on behalf of the community, I have been lurking around the forums for some time now, and I really appreciate the work you do!

I have two things that bug me with regards to the use of Green Gas in RC subs. First is that Green Gas is very temperature dependent. As someone who played a lot of airsoft, Green Gas is very finicky and inefficient in cool environments and since subs are in water, my concern is that you would get far less blows that you have calculated. When I used Green Gas in my airsoft gun, I would have a really low BB velocity and if the ambient temperature was less than 50F I couldn't shoot all 30 BBs on a single load of gas. We call this the "cool-down effect", and this is why I switched over to CO2/HPA for my airsoft guns. CO2 is much less temperature dependent and because of that I would regularly get two 30 BB loads off of one 12g CO2 cartridge even during the winter months. Since gas cools when is allowed to expand you have a negative curve as far as temperature and pressure go, which will give you less and less gas expansion. Cooler gas means less pressure and depending on the size of your ballast tank which is in your case is fairly large, since you're running a 1/48 boat it means that after even one ballast blow the gas will be at such a low temperature and also at a low pressure due to the temperature that you may not be able to blow again. This leads me to my second issue with Green Gas: Icing.

From what I have read about the USS Thresher disaster, part of the reason that she was lost was because there was moisture in her high pressure ballast lines which then froze solid when the crew tried to conduct an emergency blow. Since Green Gas container would cool off quickly during a ballast blow, my concern would be that the valve or line would freeze solid during a blow. 80.12 Cu in is quite a large ballast tank by any description. So during a blow, you having have to push that much water out means you're going to need a lot of gas just to fill the ballast tank much less build up the pressure to push the water out. That will require a very long blow, and a blow of that duration will cause a significant drop in pressure and temperature, which combined with the inherent moisture may cause your ballast valve/line to freeze. Being unable to blow ballast due to a frozen line/valve may not be the end of the world, and if I recall from Bob's YouTube video about your SSN-591 you run a 2.4GHz setup, which means that you're near the surface at all times. I'm also going to guess that your submarine is also ballasted so that if your ballast tank is full, the sail is partially out of the water, which may not make this a concern at all.

Here is a video of a Green Gas airsoft gun being fired, which illustrates the above statements I made . Listen to the rate of fire drop and watch the ice that forms on the magazine as they fire; the test starts at around the 4:33 mark. https://www.youtube.com/watch?v=UvduADSzoEc

[redboat219]

Going back to CO2, the guys playing with RC warships use CO2 powered BB guns to sink opponents. Maybe you can get in touch with the group in Texas and ask them for some advice. https://ntxbg.org/

[redboat219]

[QuarterMaster]

Firstly, Thank You for doing all of this research and math on behalf of the community, I have been lurking around the forums for some time now, and I really appreciate the work you do!

I have two things that bug me with regards to the use of Green Gas in RC subs. First is that Green Gas is very temperature dependent. As someone who played a lot of airsoft, Green Gas is very finicky and inefficient in cool environments and since subs are in water, my concern is that you would get far less blows that you have calculated. When I used Green Gas in my airsoft gun, I would have a really low BB velocity and if the ambient temperature was less than 50F I couldn't shoot all 30 BBs on a single load of gas. We call this the "cool-down effect", and this is why I switched over to CO2/HPA for my airsoft guns. CO2 is much less temperature dependent and because of that I would regularly get two 30 BB loads off of one 12g CO2 cartridge even during the winter months. Since gas cools when is allowed to expand you have a negative curve as far as temperature and pressure go, which will give you less and less gas expansion. Cooler gas means less pressure and depending on the size of your ballast tank which is in your case is fairly large, since you're running a 1/48 boat it means that after even one ballast blow the gas will be at such a low temperature and also at a low pressure due to the temperature that you may not be able to blow again. This leads me to my second issue with Green Gas: Icing.

From what I have read about the USS Thresher disaster, part of the reason that she was lost was because there was moisture in her high pressure ballast lines which then froze solid when the crew tried to conduct an emergency blow. Since Green Gas container would cool off quickly during a ballast blow, my concern would be that the valve or line would freeze solid during a blow. 80.12 Cu in is quite a large ballast tank by any description. So during a blow, you having have to push that much water out means you're going to need a lot of gas just to fill the ballast tank much less build up the pressure to push the water out. That will require a very long blow, and a blow of that duration will cause a significant drop in pressure and temperature, which combined with the inherent moisture may cause your ballast valve/line to freeze. Being unable to blow ballast due to a frozen line/valve may not be the end of the world, and if I recall from Bob's YouTube video about your SSN-591 you run a 2.4GHz setup, which means that you're near the surface at all times. I'm also going to guess that your submarine is also ballasted so that if your ballast tank is full, the sail is partially out of the water, which may not make this a concern at all.

Here is a video of a Green Gas airsoft gun being fired, which illustrates the above statements I made . Listen to the rate of fire drop and watch the ice that forms on the magazine as they fire; the test starts at around the 4:33 mark. https://www.youtube.com/watch?v=UvduADSzoEc

First off, thanks for stepping out and speaking up. My point is that there has always been a lot of speculation vs facts discussed on message boards. (80/20 rule. Your experience is invaluable.

Roger that. Higher pressure is likely related to the cooling effect but I'm not comfortable with the working pressure. Granted Airbrush/Freon is in the neighborhood, but I would want to go down, not UP given the choice.

In 105F, Propane Tanks can reach 180 psi. That's not unusual here in northern Texas during the summer!

See Understanding Proper Propane Tank Pressure!

If it weren't for the 3 cases of Freon I bought just before the pandemic, I'd lean towards Butane.

12 Cans 1 Case Johnsen's R134a AC Freon R-134a Car Auto A/c Refrigerant 12oz

Late 2019, I got them for $64.99 Case from the Louisiana dude on Ebay.

Today he lists at $135.00.

Thank god Gasoline or Milk never rose that quick.

I purchased two filler valves for Butane. I plan to make a modular pressure tank, and modify the refit on my test platform SHARK.

Stay tuned.

[QuarterMaster]

Going back to CO2, the guys playing with RC warships use CO2 powered BB guns to sink opponents. Maybe you can get in touch with the group in Texas and ask them for some advice. https://ntxbg.org/

You go Capt Redboat!

You know, I read about these guy's when I first moved down. Shied away because it's really not my Cup o' Joe. Their running pond is near where I go in Carrolton. They're having a meet the 17th.

The Clippard regulators look interesting!

On Mission...

[redboat219]

The BB guys have a system to negate any freezing from the expanding gas

[QuarterMaster]

Ask, and thou shall receive! BUT, you still have to ask....


---------- Forwarded message ---------
From: Vac-U-Boat <philpace@vac-u-boat.com>
Date: Sat, Jun 3, 2023 at 2:35 PM
Subject: RE: Homebrew Beverage 150psi regulator
To: Ed Tordahl


Ed,
In my experience, Combat Warship folk will run their ships maybe 1 day per month and not overhaul their regulators until the end of the season. Then, usually just a disassembly and cleaning/lubing.
Quality of materials depend on the price of the regulator.
150 psi is the goal as that is the max pressure to be used in the bb guns the ships carry.

I utilized the homebrew regulators because they were small and inexpensive. Better quality non-adjustable 150psi regulators are available for our hobby.
My ships were the smallest ones and size/weight was important. $25 for a homebrew vs $100 for a better one was a factor as well. The smallest class of ships generally have only 1 cannon where larger classes can have 5 or 6 and need the added volume of the more expensive regulator.

I even assembled a rebuild O-ring kit for the latest version of the homebrew one because they weren’t available.

150psi keg chargers are harder to find due to better lower-pressure models being developed.

A couple of years ago, the homebrew regulators changed, for the better for your use. Every few years, a new, different looking model comes out.
They used to be adjustable up to 150psi. Those models are still available. But they were very jumpy when adjusting to the lower pressures that someone would need to “charge” their keg of homebrew beer. An easier to adjust lower PSI model came out. Most of them on Ebay or Amazon are the lower pressure models. 0-60 psi. and recently 0-30 psi. They are much more reliable when dialing in lower 5 to 15 psi pressures needed for beer.

Search co2 keg charger 0-30, or co2 keg charger 0-60.

During use, the core of the regulator is pressurized so water won’t enter the heart of it.
Under the adjusting knob, there is a shaft that puts pressure on a spring inside the upper part of the unit where it isn’t pressurized. Water can enter there but does little harm to the large steel spring.
An O-Ring could be placed on the brass shaft of the knob to reduce water intrusion.
Or, just coat the spring with a synthetic grease or Vaseline.

In the new design 0-30psi one below, note the three holes in the sides of the different sections. The bottom one is a vent hole that releases gas as you unscrew a co2 cartridge for safety. The top one may just be an opening/vent to the unpressurized adjustment spring location to release pressure should the spring’s seal fail.
The middle section’s hole may be another safety vent for over pressurization failure.
The original version had no vent holes and probably wasn’t as safe as the new ones.
The vent holes may allow some water to enter non-pressurized areas but could be covered with a dab of grease without blocking them.

The one below is the newest of the models. Different than prior versions as it has sharp edges in its profile. I haven’t handled one of these.
Each time a new version comes along, it has more safety features and more durable components than the one before. For $16, I’d get one of the new ones and take it apart.
You may find a stainless steel adjustment spring in it. Later versions did away with custom seals and utilize standard O-rings making them rebuild able.

The gauge isn’t sealed and water will fill it. In my application, I removed the gauge and the brass/plastic snaplok adaptor, plugged one side and put a hose adapter on the other side. I adjusted it with a separate, larger, more accurate pressure gauge.
If you have room for the gauge, leave it on. It should hold up for quite a while.

2 tips. Screw in the CO2 cartridge upright, so some gas may escape as it is pierced but any liquid CO2. Set in the sub with the co2 cartridge at an up-angle to keep liquid co2 out of the regulator for a more constant pressure. Regulators are better at regulating gas pressure but not liquid which can expand past the regulator’s opening causing pressure to jump around.

Does this help?
Phil

[redboat219]

Just sharing this minor downside to using CO2.
Not sure if Propel has the same property.

https://youtube.com/shorts/rDdt5Owt9bs?feature=share

I doubt if your ballast tank will collapse but water will gradually fill your tank as more and more CO2 diffuse into the water. You may need some occasional squirts of CO2 to maintain waterline.

[QuarterMaster]

Just sharing this minor downside to using CO2.
Not sure if Propel has the same property.

https://youtube.com/shorts/rDdt5Owt9bs?feature=share

I doubt if your ballast tank will collapse but water will gradually fill your tank as more and more CO2 diffuse into the water. You may need some occasional squirts of CO2 to maintain waterline.

THAT's what my LPB is for. When I manually surface (w/o the mast up) I give a quick burst, then complete the blow with the LPB.

I also hit the LPB to top off once and a while. I found rolling in a heavy sea state losses more air out the bottom.