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[logoman]

Hello steam friends,
I'm having a problem with my Hemmens plant, which may be caused by a couple of compounded problems.

It doesn't look like i can get the boiler up to steam. After ten minutes with the burners on full, i'm barely reaching 20psi on the gauge, and I'm filling the boiler with boiling water.
The safety valve is not lifting, but the boiler will blow down it's entire contents. I've tried opening the steam valve to the engine and I soon get complete hydraulic lock in the engine.

After a few trials I've now burnt 300 grams fresh butane propane mix in the boiler, and have not seen anything over 30psi on the gauge.
I removed the poker burners and and checked the jets were clear, the burner looks like it is burning well when I tried it out side of the boiler.

faulty gauge? a problem with the burner?  This boiler is confusing me. 

[gondolier88]

Hi,

Just to be clear, are you saying the problem is with the boiler or the engine?

Where do you fill the boiler upto on the gauge glass?

Greg

[logoman]

Hi Greg,
I think the problem is with the boiler, but I'm not able to tell if the engine is functioning properly without being able to give steam at high pressure.
I'm filling the boiler 3/4 up the sight glass, I've tried a little more and a little less.

[SteamboatPhil]

Any chance of some pictures of the boiler / engine etc. has this problem just started after working OK or have you just got the plant ?
At a first guess it seems you have a blockage in the steam pipe to the engine, and you seem to be getting some sort of condensation in the steam delivery which is why you are getting the hydraulic lock.
Just a few guess's on my part, they might be of use.
Phil

[Bunkerbarge]

I would start by either changing the pressure gauge or better still having it checked for calibration if possible.  Then, if we are assuming the pressure gause is reading correctly and you are simply not getting pressure up on the boiler but using gas, then it could be a burner problem.  Try changing the jets and ensure that the jet tip is at the correct location with respect to the air holes in the tubes.  I'm assuming that the boiler has poker burners so they are the obvious things to try first. 

I suspect the condensate in the steam supply line is as a result of low pressure in the boiler so I wouldn't be concerned about the engine until we know the boiler is OK.  The burner will look OK outside the boiler but this does not mean that it is burning correctly when fitted.  Have you put your hand over the flue to feel any heat?  Is the flue blocked? 

Is the gas butane/propane 70-30 mix?

Just a few thoughts to consider.

[MONAHAN STEAM MODELS]

Another few things you may want to try are:

1) Inspect the fuel jets for damage. Such as someone trying to poke something through them to clean them at some point in the service career.

2) Sometimes jets become clogged with debris. The debris could be residue build up from the odorizer added to butane/propane. It can also be left over tiny drill chips from the machining process. Or it can be just plain dirt introduced into the system. To fix this, remove the jets from their holders and soak them in rubbing alcohol for a hour. Then carefully blow air backwards through the face of the jet to clear any debris. This is easily done with a small air compressor with a rubber tipped air nozzle that would damage the face of the jet. Jets can seem to be unclogged since fuel is flowing through them, but if there is any minuet obstruction inside the jet's orifice it can severely affect burner performance.

3) Check to make certain that the flame is burning at the burner itself and not burning in the smoke stack or just beneath it in the vertical flue.

4) The boiler should sound like it's roaring with the burners ignited and bunring at the burners themselves. This is especially true of most poker style burners. Would you say this is what you heard the last few times you ran your steam plant?

5) Check the fuel delivery line from the fuel tank to the burner for clogs. This is easily done by disconnecting the fuel line at the burner and quickly opening and closing the fuel tank valve. There should be lots a gas flowing out the line.

6) Try calling the manufacturer to give him a piece of your mind.   Just Kidding  

[derekwarner]

logoman....if it is a vertical boiler...the following should be possible

1. disconnect the boiler from the engine/vessel + gas supply
2. prepare the boiler with say 7/8 of the gauge glass full [use hot water]
3. place a cast iron plate on the kitchen stove hotplate [hopefully gas]
4. place the boiler centerally on the cast iron plate
5. ignite the stove hotplate
6. within a few minutes you should see bubbles appear in the gauge glass
7. within another few minutes the pressure gauge should confirm pressure buildup
8. maintain this & record or note the indicated value that the relief valve functions......

I used this same procedure to check & confirm the boiler functionality prior to purchasing a gas tank..........Derek

[gondolier88]

Hi,

Ok, you are correctly filling the gauge glass. The reason you get hydraulic lock will be that as soon as you open the valve you will lose all your pressure and you will be carrying the wettest steam imaginable into the engine, with little heat to boot.

The reason for this should be one of those pointed out so far, however you could also check they are the correct jets, it doesn't matter how much gas you put through, if they are over-aired or over-gassed they will not produce any real heat transfer.

Greg

[kno3]

It is possible that Hemmens adjusted their burners and jets for another gas mixture than what is commonly available today, and if you're using the 70/30 mixture it might not burn well. My Hemmens boiler had a disappointing performance with the original twin poker burners.
If possible, try using one of your Saito alcohol burners instead of the Hemmens burner and see if it performs any different.

[john hemmens]

 )The burner was designed to fire on gas that was available some 15 years ago and gas has changed somewhat since then. The plant is coming to me to check over and I expect all it needs is a burner to suit the gas currently available which I have in stock.

john hemmens.

[steamboatmodel]

)The burner was designed to fire on gas that was available some 15 years ago and gas has changed somewhat since then. The plant is coming to me to check over and I expect all it needs is a burner to suit the gas currently available which I have in stock.

john hemmens.

Mr. Hemmens,
Could you explain what has changed in the gas?
Regards,
Gerald.

[ian kennedy]

RE gas formulation

Its possible that the calorific value of the butane/propane mixed gas has changed and this in balance is causing the effect John mentions.

I too had issues with a clean and powerful burn and tried every commercial canister gas in my twin poker fired boiler, along with several jet size changes using 3,5,8 and number 10 gas jets and just couldn't get enough air into the mix to get a clean burn. All this was tested correctly using a gas analysis machine.

I designed my home made ceramic burner using a plumbing fitting and some expensive high temp ceramic plaque from a German company and now using a number 8 jet and cheap parasene 70/30 mix gas can raise 80psi in 8 Min's and maintain 50psi running two slide valve engines at full tilt. According to the gas meter readings i am getting a burn efficiency of 98% which is pretty good.

Ian

[logoman]

Thanks for all the help everyone, it is greatly appreciated.
One last time before i send the plant off to Mr Hemmens.
I have two new jets, a new pressure gauge, and a new can of Coleman branded 70/30 mix.

It does seem to me as if there is a shortage of oxygen preventing an efficient burn: the flame on the pokers looks like the gas pressure is too high ie, a better flame towards the end of the poker, and in places a gap between flame and poker.  The flame quickly moves to the top of the chimney when the gas valve is opened more.

[flashtwo]

Hello Miles,

I've noticed that you've been using a lot of expensive gas for testing.

For static testing I use a 13kg Calor Gas propane cylinder. The intial cost included the one off charge for the hose, hose clips and  regulator which came to about £35 (inc. del. and 17.5% VAT) and for the cylinder itself £56 (inc. del. and 5% VAT).

The cylinder charge was £21.4 for the gas and £30 for the cylinder refill agreement.

After the initial set up costs, the gas is much cheaper than the individual 460g cylinders - I think for a £22 refill you get the equivalent of about £150 worth of the 460g cylinders.

I know its not the 70/30 mix, but for static testing it is so much cheaper and less troublesome in keep having to buy the small cylinders.

Cheers

Ian.

[logoman]

The pr0bIem was staring me in the face

I had the burners instaIIed in the b0iIer with the inc0rrect attitude, b0th at tweIve 0'cI0ck, instead 0f ten t0 tw0

0k, s0 n0w the b0iIer is w0rking fine, unIike my keyb0ard 

There is a pr0bIem with the engine, and I'm up I0ading a vide0 t0 y0utube n0w, and wiII p0st in a few minutes,

Thanks Ian, I reaIIy c0uId d0 with saving s0me m0ney

[logoman]

http://www.youtube.com/watch?v=n9jBLl3a8os

[gondolier88]

Youv'e got a serious problem with the engine there!

My guess is the throttle valve is passing and equalising pressure on both sides of the piston- may be worth a strip down and check if there is excessive wear- I havn't seen inside one of these particular engines, but it may be case of replacing an O-ring.

Lovely plant though.

Greg

[MONAHAN STEAM MODELS]

Have you tried playing around with how far you allow the reversing valve travel. If you're allowing it to travel to it's extreme stopping positions, it may be over shooting the ideal alignment for the steam passage ways.

[logoman]

it feeIs Iike the vit0ns are chewed up inside the cyIinders, s0 i'II send the engine t0 J0hn f0r new 0nes,

[don galfur]

Hi logoman
    I too have a Max 4 in my latest launch. Similar problems were experienced. If you are using John's  80 grams tank ( or there abouts ) provided with the plant and drawing down with two say, number 5's, the refrigeration is extreme. The tank must be around room temp or better. This issue has been discussed numerous times in the forum. You have probably found this to be so. Proximity to the boiler is just not enough. I eventually used that tank as an expansion chamber supplied by a distant canister inverted to issue fuel as a liquid thereby displacing the expansion and chilling to where it could be nullified by the now heated refillable.
      But the real key to handling the constant problem of lack of heat and pressure was completely solved by getting more radiant heat from the burner and depending less on the flame conducting it. Alex and someone else discussed this very well a few months back. Nick Monahan suggested I check out one of the rail websites where they have grappled with this issue. One such site was very helpful. I suggest you experiment with this when you get the plant back. Use some fine stainless mesh and wrap  a first layer close to the burners.  A second one puffed out a bit further, maybe 4mm to create a two layer arrangement secured by pulling off one strand and using it to secure the layers as a thread. You will be amazed at the difference. I can now maintain 30 to 50 pounds with the Max 4 in my launch. Yeah, you have to cheat the system a bit because that great boiler is not in fact quite adequate to handle the plant. He made a bigger one for it as I recall. Try it.
Dave

[logoman]

Hello again Don, good to hear from you.

I do have the 80g tank, but I'm not using it yet, I'dlike to see a photo of your  twing tank stet up please.

you would need to take the burner holding cap from the flue to fit those mesh mantles, do you still use that cap or have you built soemthing else to hold the pokers?

miles

[logoman]

Greg, I think your guess is correct, there is something wrong with the throttle valve. I tested the engine on air and it ran quite well, so something is going on that is compounded by the hydraulic lock.

[don galfur]

       Hi Logoman
        When I get home tonight I'll re-size a few shots and get them out to you.
         Dave

[don galfur]

       

     Here you go Logoman,
          This should give you some better sense how to make/attach mantles. I should mention that the mesh is of two sizes: a fine mesh, like a paint filter, down first with a coarse mesh on the outer layer that really glows. The small mesh I bought form Small Parts here in the states and the other was just laying around. You don't have to modify the support for the tubes in any way. My first try was a bit too fat to fit in, so I tightened things up a bit and it slid in easily. A good side effect is that fuel consumption goes way down (hence chilling). The valve on the tank needs to be just cracked; a hundred gram canister lasted well over an hour.
          The double tank set up is a little hard to show but you can see the original tank with an extra red tube going under deck. That routes to the front hidden tank in the bow. It is a great engine in this boat.... so smooth !
Dave

[don galfur]

     


           And the burner shots which didn't make it on the last post.
            Dave