Another good find Steven, I think you are pointing us to our answers. I assume you noticed the air valve by the base mounting flange in that Marine Engineer photo.
See Marine Engines and Boilers.... , Gustav Bauer, Germany 1905 pg 622 http://www.archive.org/details/marineenginesan00donkgoog (go to the HTTP files and right click/save target on the PDF to get past Google’s limits) The supply water goes to a 3/4” nozzle at the bottom of the 6” ash discharge pipe. The water pressure disappears at the nozzle and becomes velocity. So the air valve can relieve air under heaped ashes, maybe supply air to be dragged along by the water so as to draw the ashes in and possibly it drains residual water from the ash pipe.
In time order we have: -Horace See’s, USA. Appears to have just dumped the starting water to the bilge or maybe it’s just back draining the ash pipe. -Howaldtswerke, Germany and Schaffer & Budenberg, England. Added a fast acting pilot operated valve. It has a surge bottle and a throttling bolt on the return line to the sea or the pump. -Olympic dumped the start up water overboard. With guidance from the Ceramic’s boiler room cross section I think Olympic’s drawings are also hinting at a fast acting starting valve standing next to the ejector. If it allowed flow in both directions then it could help with the dust too -Ceramic has the fast acting starting valve, presumably of See’s design, and the repositioned starting discharge hints at taking the dust control further. -Britannic went to bottom expellers.
It sounds like ejectors were a successful solution to getting the ashes out of the boiler room but difficulties persisted with what happened after that.