24 blood outlet port 26 and hanger 28 turning next to fig2 which shows the reservoir schematically in a first blood collection step with blood b shown entering inlet 14 upon the imposition of a vacuum v through vacuum port 16 inlet 14 is connected to a blood source and vacuum port 16 is connected to a suitable source of suction compartments 20 and 22 are in fluid flow communication both compartments being under vacuum through a central opening through which the blood flows into compartment 22 for collection compartments 22 and 24 are sealed off from one another by means of valve 30 which forms a fluid tight seal between the two compartments valve 30 is held closed by spring 32 which is under compression causing the seating of the valve and sealing of a central opening between compartment 22 and 24 also shown in fig2 is lever 34 engaging elongated member or rod 36 the upper portion in this view being coupled to the lower portion by spring 38 spring 40 and valve 42 being supported by member 36 additionally provided are filter 44 used for gross particulate removal and foam reduction and baffle 46 which serves to divert blood away from vacuum port 16 to keep blood from exiting through the vacuum port there is furthermore provided a port 48 which can serve to selectively pressurize compartment 24 as shown by p pressurization p can be achieved by using a sphygmomanometer bulb a pressure gauge and tubing all of which are not shown communicating with port 48 pressure is preferably maintained from about atmospheric up to about 200.