The present invention relates to novel nonpolymeric compounds and compositions that form liquid, high viscosity materials suitable for the delivery of biologically active substances in a controlled fashion, and for use as medical or surgical devices. A membrane dryer is inserted into the feed gas path to the concentrator absorbent beds, such that the moisture in the feed gas is directed to a part of the dryer exposed to the concentrator exhaust, thus achieving efficient operation of the membrane dryer with no loss of concentrator feed gas. A recirculation pump moves ink through an ink recirculation line connected to an ink reservoir.