Patent ID: 8337474

Claim:
A patient treatment device, comprising: a reduced pressure therapy device, comprising: a housing with vacuum chamber, the vacuum chamber comprising a longitudinal axis, and a non-circular cross-sectional shape transverse to the longitudinal axis; a sliding seal configured to sealably slide within the vacuum chamber along the longitudinal axis, the sliding seal comprising a non-circular cross-sectional shape transverse to the longitudinal axis; and a substantially constant force spring mechanism contained within the housing and attached to the sliding seal and to the housing; wherein the vacuum chamber further comprises a longitudinal window region configured to view the sliding seal; wherein the housing comprises a rear cap with a spring assembly covering the proximal opening of the vacuum chamber, and wherein the constant force spring mechanism is attached proximally to the spring assembly of the housing; and wherein the sliding seal further comprises seal indicia that are not visible through the longitudinal window region.