Abstract: A substantially sputtering-free low-profile low-restriction drain valve is used with a fluid reservoir having a drain opening. The drain valve comprises a valve body, a cap and at least one perforation-sealing member. The valve body has a tubular shank installed in the drain opening and defining a fluid ingress, and a tubular head portion generally coaxial with the tubular shank and defining a chamber in communication with the fluid ingress and having a cross sectional area larger than a cross sectional area of the fluid ingress. The tubular head portion comprises an inner transverse wall extending across the chamber and comprising at least one fluid flow perforation, and a distal end opposite to the shank. The cap is movably assembled to the distal end of the tubular head portion between open and closed positions. This cap defines a fluid egress which, in the open position of the cap, is in communication with the perforation to permit draining of fluid from the reservoir.