water tube boiler

[Matt]

hello everyone,

I'm just starting my third year on my engineering degree, and this year we have to do an individual engineering project. I've got a few ideas, and one of the is to build a lady Ann with a water tube boiler, and compare it's performance with a regular lady Ann.

so my question is, has anyone ever tried building a water tube boiler in 16mm scale.

[DaveWatkins]

I have not heard of a water tube boiler in our scale. I suspect water capacity and hence duration would be low unless you were to fit a water pump. How about flash steam? That is point a gas torch down the middle of a coil of copper tube, with a non return valve and water pump on one end and the other end connected to the steam chest?

[Matt]

I have not heard of a water tube boiler in our scale. I suspect water capacity and hence duration would be low unless you were to fit a water pump. How about flash steam? That is  point a gas torch down the middle of a coil of copper tube, with a non return valve and water pump on one end and the other end connected to the steam chest?

Interesting idea.

At the moment, the idea I've got is a 3 drum boiler like the yarrow marine boilers, scaled down and shaped to fit inside a Lady Ann boiler casing, with water tanks and an axle pump from djb. the idea is to use as many commercially available parts as possible (roundhouse frames and running gear, most of the boiler fittings other than the actual boiler itself, ect), to reduce costs and simplify construction. I still need the go ahead from the course leader, but I've spoken to the head of department (who fortunately is also a railway enthusiast), and he's okay about it.

[TonyW]

Archangel built a few locos with water tube boilers in the 1970s...
http://www.archangel-works.com/renov-02.html

[Wobbly Wheel]

It all depends on your definition of a water tube boiler, would a 'smithies' type count?

I have built a small yarrow boiler, though not for a 16mm engine, but for a boat and while it produces a lot of steam, as you'd expect, the most time consuming part was the casing and insulation.

I had expected it would suffer from foaming / priming, but it didn't.

The space available for the three drums in a 2" diameter casing and its water capacity might be problematic.

As another designer found locomotives and water tube boilers are not easy to get to work - no names but its 'hush hush'.

[Matt]

It all depends on your definition of a water tube boiler, would a 'smithies' type count?

I have built a small yarrow boiler, though not for a 16mm engine, but for a boat and while it produces a lot of steam, as you'd expect, the most time consuming part was the casing and insulation.

I had expected it would suffer from foaming / priming, but it didn't.

The  space available for the three drums in a 2" diameter casing and its water capacity might be problematic.

As another designer found locomotives and water tube boilers are not easy to get to work - no names but its 'hush hush'.  8)

Yeah, i heard about Gresley's efforts, that's partly what gave me the idea.

at the moment it's just in the idea's stage, although the yarrow boiler idea is the one which i want to go with.

[The Denying Dutchman]

I have not heard of a water tube boiler in our scale. I suspect water capacity and hence duration would be low unless you were to fit a water pump. How about flash steam? That is  point a gas torch down the middle of a coil of copper tube, with a non return valve and water pump on one end and the other end connected to the steam chest?

For flash steam boilers stainless steel is recommended and even stainless steel doesn't last long.