Hach DR1300 FL Manuel De L'utilisateur page 10

Section 4 Install the batteries
Explosion hazard. Incorrect battery installation can cause the
release of explosive gases. Be sure that the battery is of the
approved chemical type and is inserted in the correct orientation.
Install the four supplied AA alkaline batteries. Refer to
Figure 3 Install the batteries
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W A R N I N G
Figure 3.