The beads are barely loose with just some slight movement and there is some resistance to flow if your trying to push a lot of air through it. However most pcp compressors dont have that much intake air flow. for example, on a Yong Heng compressor i would pull all the small red plugs out of the bottom when filling and you should have plenty of air flow with little if any restriction. Just put the plugs back in when your done.
As for the dimensions, they are available in 3 different hights as you can see in one of the pictures, 4,6,8 inches roughly. Diameter is about 3.8 inches, and the bottom is threaded 1 1/4 NPT. The internal pipe diameter is about 0.9 inches. Inlet holes are 0.4 inches.
Effectivness,
So many variables and I don’t want to make any outlandish claims. For my use, if I had to guess based on water from the moisture trap/seperator and other things I’ve observed, 70-90% reduction in water from the drain. I have a small(yong heng) prefilter before my large gold filter on the discharge. I used to get some dampness on the small pre-filter. Now with the 6 inch gearbox breather installed I find NO noticeable moisture in the pre-filter. My compressor is on the slow side, so the silica has some time to do it’s job. A higher capacity compressor may not get as good of results but, I’d be interested to hear what others results are.
John