solely as a manual valve assembly in which a user such as lab technician rotates the rotatable valve 130 of the valve assembly 146 by turning a knob 150 or by any other suitable mechanism as with the motorized valve assembly 102 the rotatable valve 130 of the valve assembly 146 can be removed and replaced with a rotatable valve having different size wells to dispense a different amount of dcm powder into the flask 142 per each rotation the valve assembly 146 can further include a counter 147 such as a mechanical or digital counter as known in the art that counts the number of rotations of the rotatable valve 130 and can be automatically or manually reset to zero after the desired amount of dcm powder has been dispensed as further shown the valve assembly 146 can include a non porous rubber or plastic sleeve 148 to allow for mating with the mouth of the flask 142 furthermore the valve assembly 146 or the sleeve 148 can include an inlet tube 152 to allow water or other liquid to be manually or automatically fed into the flask 142 as the rotatable valve 148 is being manually or automatically rotated the valve assembly 146 and the system in general can be automatically or manually agitated to allow the dcm powder to more freely fall into the valve assembly 146 and thus more freely into the flask 142 accordingly the system shown in fig7 also provides an efficient and sanitary system for dispensing dcm powder into a container while avoiding waste and contamination of the surrounding area due to dusting and exposure to dcm powder inhalation due to dusting while this invention has been particularly shown.