The Ben Ain Build

[Bunkerbarge]

For those of you who have already seen this on other forums, I apologise but there may be some amongst you who will find it interesting.



The Ben Ain Build


One: Planning and Preparation

As with a lot of projects this one actually started off quite by accident.  I was having a look through a Model Boat magazine one day when I saw an advert for a Mountfleet Models Kit.  I didn’t even know at that time that Mountfleet were so close to me so I gave them a ring and Frank Hinchcliffe kindly invited me around to have a look at what he had to offer.  At the time he was using a local shop as a storage place for his prototype models and he allowed me to browse the contents of the shop while he stood by and answered any questions I had.  I was amazed at the collection of models which I had never really paid much attention to in the past and didn’t even realise that such kits of ships existed.  I left with a bunch of leaflets of all his models and took them home to study.  I made my mind up that for my first ship build a kit was the best way to start as I had limited time for building and I didn’t want to start as a beginner by trying to make a hull from scratch.  A fibre-glass hull sounded ideal with white metal fittings, all the wood and accessories you may require a set of plans and an instruction book.

I laid out all Franks leaflets on the floor and eventually narrowed it down to the Osprey or the Ben Ain, both of which appealed to me as a subject and were about the right size I wanted to build.  The Ben Ain won the day as she was built at Manchester Dry Docks and could have been plying her wares across the Irish Sea at the time my Father was sailing out of the Manchester Ship Canal as a Second Mate with Manchester Liners.  This gave me a strong bond with the ship which I always find helps with a model, especially one which was going to take such a long time to build and enthusiasm may falter along the way.

I drove back over to see Frank, purchased the kit and took it home with a grin on my face.  As is always a good idea I did a complete inventory of the contents and read the instruction booklet a few times.  I had to then start planning the basics of the kit and one idea that was developing in my mind was the fact that I wanted a steam coaster model to be powered by steam.  Not only did I not have a clue about building such a kit but I didn’t have much of a clue about model steam plants either so I was certainly in for a steep learning curve.

One of the first things was to think of how I wanted the steam plant to work as this has a direct impact on the internal layout. I knew that I wanted a boiler feed tank so that I could pump up the boiler with feed as it was consumed so that meant I had to include a feed tank in the construction. As I wanted to balance the weight of the boiler and engine at the aft end and I wanted as much space available as possible I decided to make the feed tank in the bow.  Another convenience of having the tank here is that it can easily be connected to the accommodation vent cowls for filling and venting the tank, making the arrangement as user friendly as possible on the side of the pond. The tank was made of polystyrene sheet, or Plasticard, which should give suitable water resistance and was easy to work with and I included internal frames to reduce the free surface effect of the water. I also decided that to resist the effects of the steam plant and help to keep the inside of the hull clean I would paint it with a cream paint finish which serves the purpose of being easy to wipe clean. I used a radiator paint to resist any heat effects of the boiler and put a total of three coats on to smooth out the fibre glass internal finish. After the initial bath trials I estimated that about 30-35 lbs of ballast was going to be needed so I manufactured two steel plates, 16cm x 16 cm x 8mm thick, drilled through with a large number of 8mm holes to allow resin to flow through, and laid them in the bottom of the hull. This area was dammed with the three wooden bearers, that were to take the brass mounting plate in the main hold, and completely encased in resin so that the brass base plate had something to screw to when it came time to fit.

My vision of the finished boat was that it would look weathered and as realistic as possible from the outside but when it is opened up this will contrast with the insides, which was to be the gleaming pristine polished brass and copper steam plant. That was the theory anyway. To help with this effect the outside of the hull had rivet detail added on the plate work, which would add tremendously to the eventual weathered effect of the hull I was going to attempt. I tried to emulate the correct rivet arrangement as used on real coasters of the time and used thick gel superglue to create the rivets. Riveting the hull took me most of my spare time for a week with regular rests to regain the feeling in my hands and I decided to follow the original plate details already moulded into the hull with a realistic period double row riveted pattern.

One thing I also decided very early on was that the ply wood overlays did not give the most realistic of effects with the grain being visible across all the planks so all decks, hatch boards and bridge woodwork were going to be made from individual planking.  This proved to be very time consuming when compared to using the overlays but the effect is well worth the effort.   I planked the deck using lime strip wood and finishing off with a mixture of weatherproof PVA glue mixed with black powder paint. The resultant mix was rubbed into all the caulking and sanded down to give the overall deck finish. The deck was then coated with three coats of satin yacht varnish and rubbed down between coats.  The foredeck being the first planked deck I had ever made leaves a lot to be desired in many ways but I still think it is an improvement on the printed ply overlay.

I actually started off the construction with a pretty basic mistake, based mainly on a lack of experience, when I fitted the kits plain bushed stern tube as per the instructions.  A subsequent conversation with a number of people in the business made me realise just how much better a proper stern tube fitted with sealed roller bearings would be so, before I got too far down the line, I drilled out the old tube and fitted the new one in it’s place.  I was lucky that it didn’t cause any major problems to do this and I learned very early on to plan better!!

[Bunkerbarge]

Two: Designing the Steam Plant

The next step in the project was to decide just how the main components of the steam plant and it’s auxiliaries were going to be located and secured in the hull and how the model may have to be modified or redesigned to accommodate them.

The individual components were placed in the hull in numerous arrangements until I decided on the final design with the separator tank on one side and the gas tank on the other side in the main hold.  The propulsion assembly is a John Hemmens unit and came complete with the optional base plate. Unfortunately the base was too wide to get the plant into the hull and it quickly became apparent that the boiler needed to be as far astern as I could arrange. The best solution was to make a new brass base plate, which had a step in it, and put the engine at a higher level than the boiler. This was so that the boiler could be located as low as possible for centre of gravity considerations, and yet positioned the engine at the correct shaft height. Of course it must be borne in mind right from the start that the boiler and engine must be removable after the model is finished so this also dictated the configuration of the components and the size of the base plate made for the boiler and engine. I also fitted a new stern tube with proper ball bearings on the recommendation of John Hemmens and purchased a double universal joint for the shaft to ensure that any misalignment was taken care of.

What was also obvious was that no matter how far astern I was going to be able to get the boiler I was not going to get the boiler flue to line up with the models funnel. The angled funnel makes me smile every time I think of it. I was walking around one of the scrap metal stores on my ship one day toying with ideas when I knew I needed to look into the possibilities of what I could do with the funnel. I had brought the brass ring from the boiler top with me so I had an internal diameter. I came across a piece of old refrigeration system copper pipe, which fit but it had been used as a paint stirrer however I thought it would be good enough to have a play with.

I designed the cuts I thought I would need to generate the offset I wanted whilst maintaining matching surface areas for silver soldering and a resultant vertical funnel with a 1 cm offset. I cleaned up the pipe, cut it, silver soldered it and polished up the final piece. At the end of that trip I took it home to see how it would do and was absolutely amazed to find that my 'test' piece fit perfectly as regards amount of offset and the height of the offset.

I also noticed that the offset gave me the perfect opportunity to fit the exhaust pipe from the separator which I particularly wanted to run up the inside of the funnel rather than outside as is more normal. The engine exhaust then comes out of the funnel which looks a lot more realistic and the exhaust from the separator is heated by the exhaust from the boiler which helps to prevent it condensing and spraying dirty water on the model. So I took the funnel back to the ship the next time and made the exhaust pipe and fitted it inside the funnel. These will both need cutting to length when the model funnel is finally fitted. So the funnel evolved from a scrap test piece of copper pipe that had been used to stir paint!!

All that huge space that I started off with very soon became eaten up with the components of the plant and a great deal of thought and care went into where they were going to be placed from an access, stability and trim point of view. The port side tank is the exhaust separator and was sized to give about half of a full boiler capacity. This would be the normal amount of water that I will want to use before filling the boiler again so filling the boiler and emptying the separator can take place at the same time. On the other side of the boat is the gas tank. One of the biggest problems that modellers seem to find with steam boats is the fact that the gas tank cools down considerably when the gas is being used. This can get to the point where the gas pressure drops so much due to the reduced temperature that the burner suffers and the boiler does not generate enough steam to power the engine. I wanted to avoid this so a couple of ideas that I developed as the bits went into the hull included using a gas pressure regulating valve on the tank, warming the tank from the nearby separator tank through a copper strap or heat sink, and using a Cheddar Models gas control system to maximise the gas supply to control the boiler pressure. More about this as it goes in later.

I also decided to use a brass base plate to mount all the hardware in the main hatch.   This gave additional ballast and a suitable base to drill and tap to fit all the gear in with stainless machine screws. Also the finished feed tank with sight glass and outlet valve was fitted into the bow and the arrangement for the pump, gas valve and servo, batteries and switches was finalised.
The next stage of the construction was to fit the major parts of the steam plant to the base and then work out the details of the rest of the installation. The boiler and engine assembly was fixed to its own removable brass base and this was tested through the hole in the Quarterdeck many times to ensure that this going to be removable.  Pipe connections and fittings were arranged to allow easy access to disconnect and remove the unit which ended up possible although not exactly easy.  The base is held down by brass machine screws that are set in resin in the bottom of the boat and I made a weir across the hull to try to contain any water leaking from the engine and the stern tube which could then be easily removed when the boat comes in for a fill.

The alternatives with the feed water system was to use an engine driven pump with either a controlled or a manual three way valve that can fill the boiler or return to the feed tank or a manual pump connected up to the boiler. As I was apprehensive about sapping power from the engine I went for the manual pump option so I will have to bring the boat along side to fill the boiler. This isn’t a bad thing as I will have to bring it in anyway to empty the separator tank and I am hoping for a duration between fills of about 25-30 minutes, which should prove to be convenient enough.

Also worthy of note is that the construction of the kit would have allowed me access to the internals through the forward hatch and the aft accommodation block only. This would have been quite restrictive to operate and considerably more difficult to remove items when the model is finished. To greatly help this I followed the advice of John Hemmens and I am making the entire bridge section removable as well. This makes for considerably more thought as regards the construction of the bridge and its locating means but will be well worth it in the long run.

Any steam plant seems to have one or two inherent challenges, the most irritating seems to be the fact that the gas in the on board tank cools as it evaporates to the point where it cools the tank itself. This has the knock-on effect of slowing down the evaporation rate of the gas and hence the flame in the boiler reduces. This affects steam production and the whole thing slows to a halt. The cooling of the gas tank is directly proportional to the rate of gas use so the obvious starting point is control that use. For this I purchased a Cheddar gas control valve, which controls the release of gas to the burner depending on boiler pressure. This means that if the engine is not being used much the burner shuts down to a pilot flame and conserves gas.

Another main factor in this effect is when the boiler is brought up to pressure in the first place. This obviously requires the burner to be on full for a considerable amount of time so when the boat is first put in the water the gas tank is already cooling down. To get past this I have made a valve arrangement on the gas tank, which enables the initial pressure raising to be done with an external tank. When the boiler is up to pressure and the gas control valve is operational then I change over to using the on board tank prior to putting the boat in the water so the on board tank hasn’t started to cool.

A final modification that I decided would be worthwhile was to transfer heat from the separator tank to the gas tank. I made a copper strap with a saddle piece which sits neatly between the two tanks.  The outside surfaces are insulated maximising the transfer of heat from the hot separator to the cooler gas tank. I hope that this will warm the gas tank enough to ensure excess pressure, which will then be controlled by a Cheddar pressure regulating valve. As soon as the plant is in operation the separator becomes quite warm so there is a good supply of excess heat.  This also has the added advantage of cooling the separator tank which should also help to condense the exhaust.

The final points to note are the separate batteries for the radio gear and the Cheddar Gas Control Valve as interference could be an issue with the valve and the servos for the ruder and engine control.  Consequently I have a battery for the gas valve and lighting and a battery for the receiver and control servos.

[derekwarner_decoy]

Hi PD's & a very good looking steam kit Bunkerbarge... but one or two points I have collected   on the way

a) having the gaz tank on the stdb side will dictate that you will lose approx 100 gms of stdb side weight in approx 30 minutes, where as you will make up only say 30gms or ml of oily water on the port side

b) not sure if anyone has mentioned but the gaz tank MUST be removed for each fill or the result is that more dense gaz will lay in the bilge area &  :boom

c) with your Chedder gaz regulator & gaz control valve I suspect you may get some 45 minutes run time

So even thou she is not a paddler  :nah keep us posted as many  :gather enjoy the steam story  

[Bunkerbarge]

Thanks for the reply decoy.  In answer to your points:

1) The model will displace 15 kg when completed so the loss of 100 gms on the stbd side and the addition of 30 gms on the port side will have little affect on the trim or stability of the model.  The feed tank in the bow holds about 500 gms of water and the differrence between full and empty is negligible on the trim.

2) The gas tank is filled while inside the model from an external connection.

3) I am working on a 30 minute cycle.  That gives me the opportunity to empty the condenser, top up the boiler from the feed tank and top up the gas tank.

Sea trials soon to follow.

[derekwarner_decoy]

Hi PD's.....Bunkerbarge....I would be VERY interested in understanding your planned gaz filling   scenario

Is your Cheddar gaz control valve [regulator] boiler pressure piloted? - I have a French ANTON gaz regulator and am in the same situation as you found space wise - in Decoys gaz compartment [FWD hold]... I have the gaz tank, the regulator & steam/water pilot isolation valve , a gaz isolation valve [remote from the tank], a 10 Bar 1" gaz gauge & a 3 Bar 3/4" gauge & space is at a premium  :rant with the removal of the tank for a refil

Your John Hemmens gas tank is very similar to my ACS supplied  unit, however Sandy from ACS explained to me on PD's some years back the function of the additional lines to your de-oiler being that you can blow down your lubricator to the seperator [de-oiler] with a little residual steam pressure

[Bunkerbarge]

Three: Initial Trials

I decided that before I started in earnest on the model itself the next stage was to get the hull on the water and see how it performed.

I set up a temporary servo for the rudder and the engine controller, lashed them to the back end of the hull and set about getting the plant ready for its first dip in the water. The test tank (bath) proved stability and trim were all set and test runs on the bench with the boiler and engine seemed to indicate that the plant was going to work OK. The things I didn’t know, of course, was how it would perform as regards endurance and reliability when pushing over two stone through the water with the hydrodynamics of a breeze block!

The first part of the process was to conduct tests on the plant outside the hull with all the elements in use. The initial idea was to complete the technical aspect of the model before continuing however what I didn’t realise was how much the steam plant was going to develop as the ideas generated.  Although the bench tests indicated that the plant was going to work it was going to be a completely different situation with the boat in the middle of the pond and actually using steam to drive it.

A calm day was required as the decks were not fitted at this stage so it was with a certain degree of trepidation that I raised steam on the side of the pond until the Cheddar gas valve started to work then after a radio check and a test run I placed it in the water.  What a moment to stop and reflect.  All that time and effort concentrated within a fibre glass hull and sat very precariously on the water.  I pushed the throttle very slowly forward and she inched ahead for the first time.

Initial things that were immediately apparent included just how remarkably powerful the Richmond engine is. The ship is capable of way above scale speed if required to get out of trouble but it was also noted that when up to full speed it took quite a distance to stop it again!! It also proved to be extremely manoeuvrable due to the substantial rudder, large prop and the very controllable engine. I was extremely pleased with the propulsion set up and just how controllable the whole thing was. The Cheddar gas valve worked superbly and was heard controlling the burner according to the demand of the engine.

Another thing that soon became obvious was the issue with the cooling of the gas tank. Even with raising steam on an external tank and using the Cheddar gas valve the tank still started to cool and affect steam raising capabilities. This was what led me to think of the heat exchanger and a Cheddar pressure regulating valve but more of that when it gets fitted.

I also noted that the engine tended to leak steam more than I was happy with so a bit of careful investigation was required there. The steam seemed to leak from the regulating valve faces and the oscillating cylinder faces so this would need some attention at a later date.

All in all I was very impressed with the steam plant and the handling of the model on the water. It is certainly as easy to manoeuvre as an electric model but does require a lot more attention to maintain this. I have had many discussions with many other modellers over the last couple of years regarding steam plant and the same issues seem to be the cause of most of the frustrations. I am certain that many modellers are put off by the fact that steam requires a lot more input and attention and I am convinced that a great number of steam engines have been confined to the back of the modelling cupboard as they have proved to be too much trouble.

So with the model working pretty much as I had wanted with just a couple of additions to make to the plant it was time to turn my attentions a bit more to the model itself.

[Bunkerbarge]

Hi PD's.....Bunkerbarge....I would be VERY interested in understanding your planned gaz filling   scenario

Is your Cheddar gaz control valve [regulator] boiler pressure piloted? - I have a French ANTON gaz regulator and am in the same situation as you found space wise - in Decoys gaz compartment [FWD hold]... I have the gaz tank, the regulator & steam/water pilot isolation valve , a gaz isolation valve [remote from the tank], a 10 Bar 1" gaz gauge & a 3 Bar 3/4" gauge & space is at a premium  :rant with the removal of the tank for a refil

Your John Hemmens gas tank is very similar to my ACS supplied  unit, however Sandy from ACS explained to me on PD's some years back the function of the additional lines to your de-oiler being that you can blow down your lubricator to the seperator [de-oiler] with a little residual steam pressure

In answer to your points:

1) It is not a planned gas filling scenario, I have been using the idea for a few outings now.  In the gas outlet pipe from the tank I have fitted a "T" branch with an additional isolation valve.  Connected to this valve is a clear plastic hose.  This serves two purposes.  The first is that when the boiler is being brought up to pressure initially rather than start to cool the on board gas tank I raise steam from an external bottle connected to the hose with the "T" branch valve open and the normal tank valve closed.

When steam is raised and the Cheddar valve has started to operate I shut the "T" branch valve and the external bottle valve and open the on board gas valve before reigniting the boiler.

The "T" branch also allows me to fill the on board gas tank, by connecting the external gas bottle, opening the "T" branch valve and the tank valve and closing another isolation valve on the burner I can raise the external gas bottle, invert it and watch the liquid gas drain into the on board tank.  This seems to me to be a far safer and more convenient method of filling than the typical tank filling valve and bottle connection that seems to spray gas and liquid everywhere and you never know just what has gone into the tank.

2) The Cheddar gas control valve uses boiler temperature to control the gas valve which simply turns up full on demand or down to a pilot setting when the boiler is up to pressure.

3) John Hemmens was developing a new gas tank with an internal heating coil, to be connected to the exhaust steam but I haven't spoken to him for a few months so I don't know how this is developing.

4) My lubricator can be blown down with steam pressure into the condenser/seperator tank.


As Cheddar no longer manufacture the Gas control valve I would be interested to hear what your thoughts are on the Anton regulator.  My next project will require some form of gas control valve so I am looking at the possibilites at the moment and the Anton one looks promising.  Which one do you have as they seem to make a number of alternative arrangements?

[derekwarner_decoy]

Hi PD's ...& your .jps  :kewl of Ben Ain on the water so soon look great  Bunkerbarge

I am a little lost  :ohno in that my ACS gas tank has [like most others] a Schrader type tyre valve which requires mechanical force to open & to permit the gas entry....I do not understand how remote gas pressure can achieve this or to refill the onboard tank from an external supply

With respect to ANTON, yes they manufacture four versions of gas control valving [1=OK, 1+3= better, 1+2= good, 2+4=best]  :?:

...I thought the French translations were confusing :rant  but not as much as when I wrote & spoke with Fabrice but ended up with the V72 version

With my rate of build on PS Decoy it may be some 12 months before I understand how the V72 functions

[Bunkerbarge]

Derek, I am not filling it through the Schrader valve, read the explanation above again.  I am filling it through the gas outlet valve.

I hate those Schrader valves and haven't come across one yet that reliably opens and allows you to fill the tank easily without spraying liquid and gas everywhere.  I am filling mine through the gas discharge line that goes to the burner.

As for the speed of the build, don't be misled, those pictures are a couple of years old.  The model is a bit more progressed from that as you will see when I upload the remaining posts over the next few days.

Thanks for the notes on the Anton valves.

[Bunkerbarge]

Four: The Main Deck Structure

After the internal arrangement was settled and all items fitted into the hold and the ideas for the construction of the removable bridge was finalised it was time to fit the first deck.  The main deck was prepared as a unit with longitudinal and transverse stiffening and was test fit to the side battens already glued to the hull at the correct height.  A clamping arrangement was made to hold the hull sides in along the deck and the deck was glued into place.  Before any other items were placed onto the deck the plating detail was added by cutting up pieces of cartridge paper to a scale 6’ x 2’ then adding a flush rivet detail along the edges before sticking them on to the wooden deck.  

The foc’s’le bulkhead was next which proved to be a bit of a challenge as the foc’s’le deck is at a slightly steeper angle than the main deck so the further forward parts of the bulkhead were actually slightly higher than the aft sections.  I discovered that I was able to carefully thread the unit into position once completed, by flexing the deck, and so it was constructed to ensure that there were no gaps when fitted.    I tried another riveting technique with this bulkhead as I wanted to match the kit supplied butt strap rivets.  I fitted individual pin heads along the plate seams, which proved to be very effective, matched the butt straps perfectly but took forever.  In the absence of actual drawings I tried to think about how the area would be constructed and scribed the plate lines accordingly. Almost certainly curved plates would be separate from straight plates and an appropriate plate size was considered as again about 6 ft by 2 ft. One of the doors was left open to give the area a bit of interest so the rear was boxed in to maintain the watertight integrity.  After the forward ports and lighting was installed the bulkhead was glued into place against some transverse supports.  

Next it was the bulwark stays that I wanted to modify.  The kit suggests cutting triangles of ply but all the pictures and references I could come up with indicated either a flat bar or an angle iron to support the bulwarks.  I went for a flat bar with angle iron attachment at the deck and the bulwark.  The bar being made out of trimmed down deck planks and the angle iron made from plastic extrusion section.  This looks very much more realistic and is quite typical of the construction methods used at the time.

The anchor windlass was made according to the instructions and was finished in a semi-gloss black with a light degree of weathering. One point of interest is that I wore away the paint on the winch warping ends to look the same as a real unit. This is where experience of real ships pays tremendous dividends, as I have been lucky enough to see first hand how things look with normal wear and tear and how they weather over the years. I did a similar thing with the bollards, which will be finished with a crewmember and some realistic ropes as a finishing touch.

The next big item to tackle on the main deck was the hatch cover.  First the coaming was built around the insides of the opening and then the kit instructions were followed to make the box unit to fit over it.  When it came time to fit the ply overlays however for the hatch boards I again decided to make mine out of strip wood and also use recessed hand holds which I had seen on a number of reference pictures.  To achieve this I had to drill a hole in the boards at either end so I set up a jig on the tool post of my modelling lathe, put a new sharp wood drill into the chuck and went through the pile of boards, individually cutting a nice neat hole in either end of them.  This hole will be blanked at the back to make it appear as though it is a recess in the plank and a metal bar will be glued across it for the handle.  Once I had the basic box construction finished I moved on as the intention was to provide a cover for the hatch opening for further trials.  My nerves were not up to another venture onto water with an open hull!!  The cover will be eventually fitted with a small fan, taken from a PC, which will draw air through a ‘cargo’ of rock chippings and blow it through the hull to provide fresh air for the boiler burner and cooling for the internals.  The workings for this, including the battery, will all be held completely inside the hatch cover.

[derekwarner_decoy]

Hi PD's..... ..it is in fact the ANTON V71 gas regulator that I have..my statment above was incorrect   :

V68 =  VANNE COUPE GAZ RADIO =  65,00
 
V69 =  VANNE COUPE GAZ AUTOMATIQUE =  70,00

V70 =  VANNE COUPE GAZ AUTONOME = 140,00
 
V71 =  REGULATEUR SIMPLE MEMBRANE = 80,00
 
V72 =  REGULATEUR DOUBLE MEMBRANE = 120,00

If you take the time to view the WEB  :computer links from the ANTON site...  you will find some steam launch engine sets with what appear to contain a V70 AND a V72  .......a bit beyond  me  :music

[sandy_ACS]

   

Hi PD's,

OK lets sort out a few errors......

Derek suggests: -

I am a little lost  in that my ACS gas tank has [like most others] a Schrader type tyre valve which requires mechanical force to open & to permit the gas entry....I do not understand how remote gas pressure can achieve this or to refill the onboard tank from an external supply

The refill valve on my gas tank, and that of John Hemmens, does not utilise a Schraeder tyre valve, or anything remotely like one.
The valve used is a purpose made type, specifically for refillable gas tanks/lighters, and is made by RONSON.

It is unique in that it is bi-directional... i.e. self venting.

This type of valve is fitted in a recessed chamber on the top of the gas tank, the depth of which is specific to the particular vessel.. and is chosen so as to allow the free venting of excess gas (liquid) when the level reaches a pre-determined level.
This is very important, since a gas tank must never be filled totally with liquid gas, but rather some free gas space must be left to allow for expansion.

Providing the correct re-fill adaptor is used, and pressed firmly into/onto the refill valve then filling will be trouble free.
When liquid gas begins to exit, oround the extremities of the valve, then the tank is filled to the correct level.

This must be done with the gas control valve on the tank fully closed otherwise the liquid level can rise all the way to the top of the tank.
It should also be done with the gas tank removed from the model, otherwise the escaping (vented) liquid gas will form a gas layer in the bottom of the model hull... which could very easily ignite when the burner is next lit.... thus destroying your precious model.

Bunkerbarge: -

Firstly, welcome to the mad house, although I'm not sure you have chosen wisely...  :music  :nah    and secondly the BEN AIN is looking so very nice indeed.

I read, with interest, your proposed/chosen method of re-filling your gas tank and, whilst I agree it would work, the biggest problem I can foresee is.... YOU CAN VERY EASILY over fill the tank, since it cannot vent at the desired/correct level.
This can easily lead to liquid gas being allowed to reach your burner which, not being of the pre-heated type, can, and would flare up, possibly with dire results.
I would seriously recommend you re-consider this method, as I would hate for you to have a nasty accident.... losing a beutiful model would be bad enough... but a personal liquid gas burn injury,.... you do not want to even think about going there.

Anton gas valves.... as Derek has listed: -

Hi PD's.....  ..it is in fact the ANTON V71 gas regulator that I have..my statment above was incorrect  

V68 = VANNE COUPE GAZ RADIO = 65,00

V69 = VANNE COUPE GAZ AUTOMATIQUE = 70,00

V70 = VANNE COUPE GAZ AUTONOME = 140,00

V71 = REGULATEUR SIMPLE MEMBRANE = 80,00

V72 = REGULATEUR DOUBLE MEMBRANE = 120,00

The first of the above (V68) is an RC controlled gas regulator valve and can be used to replace (or in addition to (in-line with)) the valve fitted to the gas tank (or the disposable canister).
Usefull to some degree, but difficult to get feedback from a model out on the lake.... best used for complete shut down in the event you run out of water...especially if no gas regulator is fitted....

 V69 and V70 are automatic gas shut off valves... these will completely shut off the gas to the burner when the pressure in the boiler drops below a pre-set level (adjustable) say 20psi, which would normally only occur if the water level in the boiler was depleted.
Both of these valves are NORMALLY CLOSED, at pressures below the pre-set level. In order to light your burner, with the boiler cold, or at low pressure after a large re-fill, then a by-pass arrangement must be employed to over-ride the valve whilst pressure is raised.

The V69 is the more simple version and would require an additional external bypass valve to be fitted, whilst the V70 is the more complex version which has a built in, lever operated, bypass arrangement.


The V71 and V72 are pressure controlled gas regulators, which, just like the Cheddar gas control valve, will automatically alter the burner level depending upon boiler pressure.
The control range is adjustable and will give full power to the burner at a low set point and will shut the burner down to a small flame level at the high set point.... the burner does not go out... unless you set the low flame level to low.    :sob

If fitting both types,(say a V69 followed by a V71) then the set levels need to be carefully chosen.... in that the low shut off pressure for the V69 must be chosen to be well below the low pressure point for the V71.

Ok chaps, I think that about covers it.

Keep happy.

Best regards.

Sandy.   :vacat  :computer  

[Bunkerbarge]

Firstly I would just like to say how much I appreciate your in depth detailed and knowledgeable reply.

I understand your concerns with filling the tank the way I describe but I sort of backed myself into a corner with my design.  The gas tank is not removeable as it is screwed down to the brass base plate so I have no option other than to fill it in the boat.  I went for this arrangement to enable the raising of steam with an external tank and the transfer of heat from the seperator to be designed and included in the knowledge that I would have to fill the tank in the model.

I understand the concept of the Hemmens tank but remain concerned that the valve discharges liquid when the tank is up to the required level so I decided I did not want to fill through this.  My alternative also has dangers in so far as the tank could be completely filled with liquid and hence supply liquid to the burner and it could hydraulically lock causing overpressure problems.  Currently to overcome this I make a point of discharging through the filling line, outside the model, until I am confident that only gas is being emitted but I have been thinking about modifications to the arrangement to improve it.  One possibility is an additional valve on the tank and line to the hull,  just cracked open while filling.  When liquid is seen at the outlet I know it is time to stop filling and the level is where the valve is located and the excess will be vented outside the hull.

Possibilities and I know these are all to overcome the problems I have made for myself but I am hoping that an awareness of what is going on with the arrangement will keep it safe.

Thanks again, I appreciate you thoughts and input.

[malcolmbeak]

For the past 20 or so years I have been using a gas container fixed in my launch. As the photo shows, I have a level gauge fitted so I can see how full it is. You will also see a pressure regulator. This drops the presure to around 10psi. On the fore deck you can see the samson post which is the on/off valve, and just visible ahead of that is a coil of "rope" that covers the filler valve. This is a screw on valve, and the only leakage is a very small puff when disconnecting.


Malcolm

[sandy_ACS]

 

Hi Pd's,

Bunkerbarge... Thank you for your appreciative response to my last post.
I was a little concerned that you may have taken some of the content the wrong way, which was not the intention.

As most PD's, who know me, are aware, I am not given to harsh criticism, other than, perhaps, in fun/banter, since in my mind it serves no useful purpose, but rather my intention is always toward awareness, safety and the safe use of such potentially dangerous materials.

If, in passing on my small amount of hard earned knowledge, it saves someone from making a potentially dangerous mistake, and perhaps prevent a nasty accident then I have at least helped in some small way.
 
Clearly, from your last post, you are aware of the issues.


I think you are on the right lines with your thinking, i.e. adding an extra valve and discharge pipe to vent off the escaping gas/liquid at the required level..... one possible way of doing this would be to replace the RONSON type filler valve with a standard, good quality, 90 degree stop valve, preferably one with gas grade o-ring spindle seals, and which had a short extension pipe fitted into the part screwed in to the tank.... the length of this could be adjusted to suit the desired level.... say 3/4 full.

I accept that this would require re-tapping the bush to 1/4" x 40tpi, which would then prevent the replacement of the original RONSON valve... but I would think that once fitted then any future use of the gas tank would use the new method anyway, so not really a problem.
The outlet of the valve could then have a suitable pipe fitted to vent outside the hull, which could be changed to suit different models.

The other alternative is, as you suggested, to fit an extra bush to the tank however, this would mean much more major surgery on the tank, which would also then need to be re-pressure tested and re-certified.



Malcolm.... what a lovely steam launch.... is it your own design.

A very elegant solution to the gas tank problem... and one which resolves all of the above issues. Presumably this is also one of your own designed units... would it be possible for you to post some additional details on the screw on filler valve you used, as I am sure there are many PD's that would find this useful.

Ok chaps, thats my lot for now.

Keep happy.

Best regards.

Sandy. :computer