A closed fluid system has been developed and implanted in several hundred humans, internationally, which restores urinary control to incontinent patients. The low pressure system consists of activating bulbs, three types of low pressure valves, and an artificial inflatable cuff which constricts the urethra and regulates the flow of urine. The system is constructed, principally, of silicone rubber. The system is described mathematically as a set of interactive Kelvin-Voight response models with pulse-like forcing which controls cuff pressure. Spike pressures in the cuff due to repetitive pulses supplied to activating bulbs reduce asymptotically to steady-state pressure levels which control incontinence but do not induce tissue necrosis at the urethral pressure site. Computer simulation of the system has reproduced physical response to permit system characterization.