Lehr Propane Outboards

[Adelie]

I thought the pressure of a propane cannister was temperature dependent.

If the engine accepts 1lb cans, that tells me the engine probably has an internal regulator and the connection will be at tank pressure and then it will be stepped down to whatever the engine wants.

[Taro]

That might be. I would assume just a guess that this is a low pressure unit when it uses those 1 lb cans. But then again when looking at the hose its pressed fittings. Like hydraulic hoses etc. Normaly here in Denmark hoses for the barbeque are just propane hoses with those metalbands you thigthen with a screwdriwer. Dont know what they are called in english

[Adelie]

The pressure inside a 1lb can is going to be the same as the pressure inside a 40lb tank as longs as they are at the same temp, that's a physical property of the propane.

Since they screw the cans straight into the motor there is no room for a regulator to adjust pressure in the cans so there must be one on the motor unless it uses ambient pressure of the propane.

There is no reason for a tank to have a regulator on it that might not provide the correct pressure and would require a different plumbing path from inlet to cylinder so it almost certainly follows the same plumbing path which means it goes thru the same regulator as the 1lb can or there is no regulator at all.

There might be pressure problems if Butane or CampingGaz were used but those probably use different sized threads so they can't accidentally be used.

[Taro]

Actually there is a universal gas for the smaler units. Works both on propane and butane as it is universal gas. That might work.

One other question i have does the lower unit on the 2.5 hp. More exactly the waterpump use the same parts as the known brands. The impeller. Keep seeing Tohatsu mentioned along with Lehr. Is lower unit the same? Would be much more easy to find a impeller locally then. Parts for Lehr seems to be in either US or China.

[HopCar]

Adeline is correct. Pressure in a propane tank is temperature related. At normal temperatures the pressure is about 145 pounds (~10 bar). The tanks are sold about 3/4 full of liquid propane and about 1/4 full of gaseous propane. As the gas is let out the pressure drops and the liquid propane boils releasing more gas and maintaining the pressure.

I think with the extreme pressures you’re talking about it must be natural gas not propane.

[Taro]

Its probaly Butane im talking about is it is sold here in Denmark for barbeques, weedburners etc in up to 22 lbs containers. Not Propane as the 2.5 hp is using. That might be it.

[Taro]

Just checked its actually Propane allso in the large 22 lbs containers

[HopCar]

Originally Posted by Taro

Its probaly Butane im talking about is it is sold here in Denmark for barbeques, weedburners etc in up to 22 lbs containers. Not Propane as the 2.5 hp is using. That might be it.

Butane, that makes sense. Don’t think you can run a Lehr on that, but I’m not sure.

[HopCar]

Originally Posted by Taro

Just checked its actually Propane allso in the large 22 lbs containers

Now it’s getting confusing!

[Taro]

Just found out most of the small bottles of gas is actually Butane here in Denmark. Then there is this universal gas allso sold in 1 lbs bottles. Then there are the big containers 5,10, 22 lbs that is Propane for barbeques etc

[Taro]

But think ill visit the local big gasdealer tomorrow. Hes selling ll sorts of things running on gas. No outboards though. He might know what types i can use with what kind of adapters, hoses etc.

[pbiJim]

First of all, there are two basic types of propane service here in the US. They are liquid & gas.

If liquid is fed to the machine, then a vaporizer (heater) is the first place that the propane goes. It is usually followed by a mixing valve, which is similar to a carburetor.

If gas service is used, then a pressure regulator is the first place that the propane goes. In this case, the liquid propane needs to boil off into a gas form inside the cylinder. A small cylinder will run colder than a large cylinder. The surface area of the liquid inside the cylinder & the temperature of the propane limits the rate at which gas can be produced.

Equipment that needs a large amount of gas, needs to be fed from a large tank (cylinder). Equipment that uses a very large amount of gas, will use liquid service & a vaporizer.

Gas BBQ grills use gas service straight out of the cylinder, which is why they have the valve at the top of the cylinder when in use. A forklift will normally use liquid service, which is why they have the cylinder laying on it's side, rolled in a certain orientation. The same cylinder can usually provide gas or liquid service, depending on which way it is tilted or rolled.

This is one source for disposable 1-pound "coleman" cylinders - https://www.amazon.com/Evergreen-Far...s%2C326&sr=8-2
$40 gets you 4. This is not the best deal.

There are also refillable versions, like this one from Flame King - https://www.amazon.com/Flame-King-Re...%2C1714&sr=8-3
$35 gets you 2 reusable cylinders.

You would need a fill adapter to fill them yourself from a larger propane cylinder. Here is one such adapter for $20
https://www.amazon.com/MEFUN-Propane...zcF9hdGY&psc=1
When filling from a BBQ tank, you turn the BBQ tank upside down, to get liquid to flow out of it, into the smaller cylinder. You don't fill the small cylinder all the way to the top. Normally 80% is the limit. This allows space for expansion in warm weather. Refilling before the little tank is 100% empty & putting the little tank in the freezer before filling it, makes the fill go much faster.

My links are from Amazon. I don't know if they deliver in Denmark or not.