Steam consumption of Simpson Strickland Quad

[dhic001]

Hi guys,
Does anyone know the steam consumption figures for the Simpson Strickland AB size quad (3 + 4 + 5 1/4 + 7 * 4, 500rpm, 250psi and 20ihp)?
I'm sure there is a way of calculating it, but I don't know how to do it!
Cheers,
Daniel

[barts]

Hi guys,
Does anyone know the steam consumption figures for the Simpson Strickland AB size quad (3 + 4 + 5 1/4 + 7 * 4, 500rpm, 250psi and 20ihp)?
I'm sure there is a way of calculating it, but I don't know how to do it!
Cheers,
Daniel

http://www.steamboat.org.uk/user.php?id=62027 suggests that this engine has slide valves, which would not last long at
250 psi, I think. I would be surprised if this engine could do better than 12-15 lbs/ihp-hr.

- Bart

[dhic001]

The quads do have slide valves, but they seem to last ok, despite the pressure. I've felt heavier reversing levers on engines that run on much less pressure than this one. Remember Simpson Strickland built a lot of these engines running at these pressures, so they knew what they were doing.
Daniel

[dhic001]

Interesting figures there, which explain why that vessel is always crawling around. These engines were rated for 20IHP at 250psi, or 14IHP at 175psi. They will certainly not like much less than 175psi, otherwise there will be no steam left by the time it reaches the last cylinder.
Daniel

http://www.steamboat.org.uk/user.php?id=62027
- Bart

[fredrosse]

A double expansion Compound should run at 150 PSI, Triple Expansion 185 - 220, Quad should have at least 250 psi. These initial pressures would be needed to get higher efficiency, and to get some useful work out of the LP cylinders. Higher initial pressures were normal in locomotive practice, often well over the numbers quoted above, even for single expansion locos.

[dhic001]

That is correct Fred, although Simpson Strickland did state that they were very happy running quads at 175psi, and their compounds were designed for 140psi. However they did consider the pressure difference from 175 to 250 made quite a difference, in the case of this engine 6ihp.
Daniel