Does the DR 3900 lid need to be closed during measurement?
Closing the lid when taking a DR 3900 measurement
Closing the lid is not required to take a measurement using the DR 3900 under standard lab lighting conditions. Many customers are able to use the 25 mL square glass sample cells without problem. When using TNT and TNT+ chemistries, the lid will not be closed, the light shield should be in place.