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Hi, It depends on your system layout and your needs. You should generally locate any drier upstream of any pressure regulator because they are more effective there due to the change in dewpoint with respect to line pressure. For example, a dewpoint of 60°F at 100 psig is the same as a dewpoint of about 40°F when the pressure is reduced to 40 psig. That is also equivalent to a dewpoint of 10°F at atmosperic pressure. It is always better (and easier) to remove moisture at the highest pressure possible because of the higher dewpoints there. If you have multiple stations in a shop distribution system, the preferred location is near the compressor at the beginning of the distribution system such that a single unit can serve all stations. If, on the other hand, you only have one station it would be best to locate the drier next to the station (but still upstream of the station regulator) to reduce the moisture load on it. That presumes that you have a significant length of piping upstream between the compressor and the station that is properly pitched and drained, either manually or automatically. Hybrid systems can also be put to good use if your system is complex, with multiple stations, where perhaps only one has unique needs relative to the others. For such a system, a main drier (usually refrigerant type) is installed near the compressor to serve all stations and a different type, usually dessicant or deliquescent, is installed at the special needs station (also upstream of the station regulator). I doubt that coiling hose in ice water would solve your problem. Hose is typically used downstream of any pressure regulator where the cooling advantage is less due to the dewpoint situation as mentioned above. Hose is usually rubber which is a poor conductor of heat. Couple that with the fact that the line velocity is higher due to the reduced pressure. This results in a lower residence time in the hose and further limits heat transfer and condensation. In addition, coiling hose in a water bucket usually does not allow for good drainage and subsequent removal of moisture from the system. Whatever moisture is condensed in such an arrangement is likely to be carried along in the airstream and could result in slugs of water droplets at your end use point. Now if you were talking about coiled copper tubing in ice water, located upstream of your station regulator and arranged such that the coil is gravity-drained to a low point where the collected water could be drained out of the system, you'd be in much better shape. That is basically a poor man's equivalent of a refrigerated drier and can be quite effective. I don't know what your present system looks like but you might want to consider installing a good run of metallic piping between your compressor and your station, even if you only have one station. A section of copper fin tube typically used in hot water baseboard heating systems can usually be put to good use in such a run of piping, provided it is all properly pitched to a low point drain where collected moisture can be removed. Portable, single stage stage compressors, with marginal-to-inadequate capacity for the need, using relatively small storage tanks and with built-in regulators at the compressor are the worst culprits for moisture problems. If that is your case, you should first look into bypassing your compressor-mounted regulator and plumbing your air to a metallic distribution system with a wall-mounted station regulator located where your greatest usage is likely to be, preferably a good distance away from where the compressor is located.  Rod
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