Component enhancements are reported to improve the operating efficiency of a line of desiccant dehumidifiers used by air-handler manufacturers, design-build contractors, and building owners and managers. The DHS Series 4000 DryHandler from Air Technology Systems Inc., Desicair Div., Frederick, Md., integrates with new or existing air-handling equipment to treat humidity loads associated with process, ventilation, or make-up air. Improvements include new bearings that require no maintenance and FDA food-grade lubrication in the sealed ball bearings. An extruded dual-lipped peripheral seal prevents air from bypassing the desiccant. Two-ply, PTFE-faced air seals prevent mixing of reactivation and dehumidified air. Models range from 750 to 24,000 cfm and come in single or double-wall cabinet construction. Bypass sections for sensible air requirements handle up to 100,000 cfm. All models include the company's H-Trac capacity control, as well as reactivation energy-conservation controls.