The ornamental design for a gascylinder for medicalpurposes, as shown and described.
FIG. 1 is a right front perspective view of the gas cylinder for medical purposes.
FIG. 2 is a front elevational view thereof.
FIG. 3 is a left front perspective view thereof.
FIG. 4 is a right side elevational view thereof.
FIG. 5 is a left side elevational view thereof.
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines in FIG. 6 are included for the purpose of illustrating a portion of the gas cylinder for medical purposes that forms no part of the claimed design.