The first picture looks like a flip top stack cover, the others all look like pan plugs. The flip open stack cover gets bolted onto the top stack pipe and is then opened and closed by pulling a rope or small cable from the ground. I use 1/16" or maybe it was 3/32" SS cable. One to pull it open and one to close it.
The first one I had of that design had a stop at just past the balance point and an operating arm in proper orientation to work properly. Pull on one side it opened, pull on the other and it closed. The one I now have was welded wrong and I was going to remove the control arm and weld it the way it should be and add a stop but then I decided to just use the operating cables. I pull the one to open and the close cable is attached to a fixed point to stop it barely before the balance point. I then hook the opening cable to hold it in position. To close it I just unhook the open cable and lower the flip cap. That worked so well I never saw a reason to remove the cap and change the weld on the operating arm.
Some use ropes and they hang down over the edge of the roof, my cables are fed thru holes I punched using an 8 penny nail from below, the open cable comes down on one side of the base stack and the other comes down on the opposite side of the base stack.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.