I have recently started custom machining heavy duty CPVC wide mouth mason jar lids for our generators, they are all one piece construction an have a 1/2" thick top surface that is drill and tapped for the terminal connections and hose barb connections, These also have high temperature gaskets under the lid and create a 100% seal.
I have recorded 1 to 1-1/2 liter per minute with my 316L stainless steel plate design.
Check out my website @ www.hydro-extra.webs.com