Braithwaite Water Tanks/Towers

I know there's a wealth of knowledge on this forum so I'm hoping people can give me some good advice.

How many railways have built the sectionalised Braithwaite water tanks? We are looking to do it at the Spa Valley but obviously need to build the base and more importantly the foundations.

Now I know foundations will differ from site to site and be based on soil conditions, but what sorts of foundations and bases did people build?

Any help and advice is gratefully received as it's always better to learn off others rather than reinvent the wheel again.

Many thanks

Matt

 

The NYMR have fairly recently extended the one at Grosmont. I don't have any info, but Ploughman on here might able to at least point you in the right direction.

 

Don't know if it was Braithwaite or not, but the Bluebell built a new, brick-base water tower at East Grinstead, so presumably have suitable calculations. From memory, the tank capacity was 18 cubic metres, i.e. 18 tons of water, which I make to be a little under 4000 gallons.

Tom

 

Welsh Highland Railway have built them at several stations on steel frame supports.

 

I studied this problem several years ago; I recall a few points. First, the concrete foundation is not just to support the tank, but also to stop it getting blown over if it happens to be empty in a gale. Secondly, if you nail a batten cut at 45 degrees inside the top of the shuttering then you will get a neat chamfer to the top of the concrete slab.

I have a `1940 Royal Engineers field manual which gives the height of the tower at the outlet as 2ft above the tallest tank inlet on any engine in the railway plus 1ft per 200 ft of pipe run to the column.

 

As the weight of a tank full of water is not inconsiderable you will need the services of a suitably qualified structural engineer/ architect. Although you may have permitted development rights to avoid planning permission This will not exempt you from the building control requirements. These particularly apply if the structure is near your boundary or a residence / place of work. To obtain the permission you will need to show your plans and calculations to the satisfaction of the local authorities engineer.

This isn't the sort of thing you want to get wrong so probably not suitable for a diy approach.

 

Interesting. Does it give the diameter of the pipe to the water column or make any further allowance for bends in the pipe?
Also does it give any indication of the flow rate that could be achieved with this formula?

 

You seem to be starting at the wrong end! Before you design anything you need to get answers to fundamentals. First fundamental is how much water do you want/need and how frequently. If you only need to fill up once a day, that is vastly different from every 45 minutes Second fundamental is how big is your mains supply and what will it deliver or how much has it got to deliver. That, in association with the first fundamental wil ldetermine the size of the tank.Third fundamental is how quickly do you need/want to fill the loco. That will determine size of outlet pipework and how high the tank needs to be.

 

The RE manual seems to have been designed to give rules of thumb for inexperienced young officers in the middle of a desert, it did not give detailed explanations or encourage further questions. It did give rules for estimating the size of tank. It also gave instructions about how to improvise a water tower from scaffolding, planks and a tarpaulin and specified 6" pipes. The design for an improvised water crane used two lengths of 6" gas pipe slotted into a sleeve of 9" gas pipe, packed around with rope and grease to make a swivelling seal and with the lower 6" pipe and the bottom of the 9" pipe all encased in concrete, interesting but I don't intend to try that one.

Thinking about the general proportions of say, a GWR parachute tank, I would think that a 6" delivery off a good size tank would fill, for example, a 1200 gallon austerity tank jolly quickly. One day I hope to prove it. Meanwhile I have seen a very nice new Braithwaite tank on a steel tower at Cheddleton.

In other sections of the book it describes how short bridge girders were to be improvised by bundles of rail tied up with fencing wire.

 

The manual sounds interesting could you post the title please?

 

The copies i have are titled Royal Engineers Pocket Book
Issued 1967 and another for 1979
Would not normally be available to public due to Restricted classification, but possible at a military auction or outlet.

Railway bridging and water towers had disappeared from the pocket books by the 1967 issue.
More concentration on Roads and Airfields than previously instead.

 

I have worked on various Braithwaite type tanks for water projects. One of mine in sat with legs either side of the equator. (It was going to be a few metres north but when we worked out where it was, we just had to shift it...). And to preempt the inevitable question, the water still does swirl round the outlet (and to pre-preempt my fellow pedants I know that is a myth!).
I would like to reiterate the point made above - this a very heavy tank up in the air: you need to design it properly for wind loading, and get someone to design a proper slab foundation. Some people put the legs on individual pads but you will end up with differential settlement issues.

 

For the foundation, you must get proper calculations for all credible scenarios eg full of water, empty, wind loading (from different directions) etc. I am not a civil engineer so cannot give more details than telling you to consult experts.

For sizing of the pipework take a read of http://aquaforall.org/wp-content/up...vity-based-water-schemes_publication_2014.pdf . I assume that any pipework from the tank will be as short as possible to minimise pressure loss and therefore tank height. But to do all this you need to know what flow you need into the tender. Simple calculation from the capacity of water needed to how long your timetable allows to fill. But remember trains can run late and have less time than the timetable! For the size of the tank you can easily set up a spreadsheet to simulate the tank level. You need to know the filling rate (either from mains or an R.O. plant) and then the discharge rate. If you are by a loco shed you may be filling a few locos in a morning one after another, so the tank would need to be bigger.

I suggest you come back on here with a philosophy of how you want to size your tank and we can comment and give advise. You may find you have forgotten something.

 

The point about galas is very valid. The NYMR has just doubled the capacity of its Grosmont shed tank because it regularly ran dry at galas when several locos were wanting water in a short period. it was further complicated by the fact that the delivery pipe actually went up hill slightly so, once the tank was empty, the syphon action was lost and you had to wait until it was fairly full before the supply was re-established.

 

If Spa Valley are buying the sections direct from Braithwaites then I am sure they would be able to recommend a civil engineer that could do the required loading computations.

 

From the design work done at RVR Robertsbridge for the yet to be installed new water storage tank we have to use shot blast and painted Braithwaite tank panels as apparently the water produced from a R.O. plant and galvanised plate dont mix!

 

That surprises me, because I would have thought that in general water produced by an RO plant would be relatively pure and therefore be safer with galv plate than tap water is. Galvanised plate doesn't cope well with conductive liquids such as salty or hard water, or the output of the type of water-softening plants that add further chemicals to the water.

 

Is it that the water is first softened and then goes through the osmosis membrane?
Though I'm surprised any residual salt wound be an appreciable problem. Are there
special circumstances or simply any likelihood of holes in the membrane?
And there are certainly circumstances where you might well use a Braithwaite
tank for seawater to get a fire fighting supply.

 

Demineralised water is very corrosive. You normally use Stainless steel for demin water. You can use carbon steel, but only after the water is deaerated. Deaeration normally takes place after demineralisation.

 

Gents,
As always food for thought that I had not even thought about. Thanks for the advice to date.

As I said I was putting the discussion out there to see how we can start going about building this. We certainly want to get this done once and done right!

To answer a few questions, the tank will be based at our depot at Tunbridge Wells. Currently the supply to the tank is small so we are looking at a high capacity, otherwise I think we would just continue with our current tank. We are starting to look into an alternative supply purely for the tank itself.

On a normal day we currently fill Austerity type engines and fill a tank of that size on approximately an hourly basis, a run-round can take approximately 15-20 mins including watering. We are currently operating around a 20 min run-round.

Like the NYMR, we want a greater capacity to supply multiple locos on steam galas etc.

Please keep firing the questions at me and it will hopefully trigger the memory etc.

Thanks again chaps.

Matt