A fluid collection vessel for drainage of body fluids includes a molded body with internal dividers constituting ports, baffles and subchambers, and a face plate that closes the body to form a suction-regulated multi-chamber vessel. The vessel has overpressure and underpressure protection, and cannot lose its fluid when tipped. The molded body incorporates novel valves and ports, and a wall structure enhances its utility for blood collection and monitoring. Dynamic fluid level is stabilized by diversion of fluid energy into a side chamber in the downstream region of the manometer column.