There have been occasional questions posed about which is more important: depth or diameter? Sometimes it's both. But for the fixed size (discounting inflatables) nozzles, it does often does cum down to the combination. However, for nozzles of similar length, the larger diameter of each nozzle means more displacement (more volume). I have also opined that for some of these nozzles, I do take into account the volume displacement of the nozzle itself because the nozzle volume can be significant.
In a separate offline discussion, I was discussing how to take these volumes into account and although I had for a couple of my nozzles, I hadn't made that measurement for my collection of my most used nozzles. I took a large pot, filled the pot to overflowing, and inserted each nozzle, in turn, into the water up to the safety flange displacing the water volume. The center bore of the tube is open and allowed to fill just like it would be inside me. After dipping the nozzle all the way in, I withdrew the nozzle and refilled the the pot back to the full level. So, without further ado, here are the displacement volumes of some of my favorite nozzles:
- Model B: 300 ml
- DBLBL-3XL: 550 ml
- SNCMAX3: 750 ml
- Priapus: 1100ml
Since these nozzles have limited customization options that would affect displacement volume (solid/open bore diameter), the displacement volume will be similar within each model. For the first three, the increased diameter has the greatest effect on displacement volume. For the Priapus, the combination of great depth (17.5 inches) and larger diameter greatly affects the displacement volume. So, for the full insertion of the Priapus, 1.1 liters of my colon volume are already occupied before any enema solution flows in.
The colon tubes are somewhat different because there are customization options like the tip characteristics and retention ball size and characteristics, that the actual displacement volume will depend upon the configuration.
- CT75-36 (36-inch long, 1-inch diameter, smooth tip, and 2.5 inch diameter retention ball): 700 ml
- CT75-52 (52-inch long, 1-inch diameter, smooth tip, and 2.0 inch retention ball): 760 ml
- CT122-32 (32-inch long, 1.66-inch diameter, smooth tip, and double 2.5 inch diameter retention balls): 1200 ml
My larger enemas have mostly occurred (at first) with one of the first two colon tubes. My first times over 5.5 liters and over 6.0 liters were with these tubes. Since they are not large diameter tubes, the enema occupies the same relative location of the tube and the "real volume" is the liquid and the nozzle volume. The last colon tube inserts all the way beyond the splenic flexure. The tube diameter is large enough to essentially fill my colon all the way to the flexure. Most of the liquid fills my transverse and ascending volon first before trying to expand my descending colon, Sigmoid, or rectum to hold more liquid volume. So, yes, the size does have some effect on the total volume that can be taken.