Fluid reservoir

A fluid reservoir comprising:

• i) a funnel portion (2) comprising an open angle in the range of 25° to 35°, wherein the funnel portion has a wide inlet for receiving fluid and a narrow outlet (3) for draining fluid at a constant flow rate, wherein the wide inlet has an inner diameter in the range of 0.40 to 0.60 inches and the narrow outlet has an inner diameter in the range of 0.10 to 0.20 inches;
• and
• ii) an attachment portion (1) in fluid communication with the funnel portion via the narrow outlet, wherein the attachment portion has a length in the range of 0.3 to 0.5 inches and an inner diameter in the range of 0.15 to 0.30 inches,
• iii) two flanges (4) positioned 180° from one another and adjacent to the narrow outlet, wherein the flanges (4) are attached to and stick out perpendicularly from the outer surface of the funnel portion by 0.10 to 0.15 inches such that the fluid reservoir directly twists or snaps into an orifice of a manifold and the flanges guide or lock the fluid reservoir into a stable and sealed position, wherein the fluid reservoir holds a maximum volume of about 2 mL, and wherein the fluid reservoir dispenses or drains fluid at a rate in the range of 2 mL/hr to 25 mL/hr.