I by far prefer 5/16 drops and spiles on my 3/16 latrals. While it doesn't prevent back flow it radically minimizes it. The sap does not get pulled back into the tree as it does with 3/16 drops. The gasses pass the sap in the drop leaving cross contamination minimized, if not eliminated. While the gasses get pulled back into the tap hole the contaminated sap in the drop is left behind in most cases. The exception might be is there is a solid column of sap in the drop whice is very rare if ever.
Dave Klish, I recently bought 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.