Omega HHP360 Series User Manual page 34

Remove the batteries by pulling the positive side first straight out
of the battery compartment. Note the positive (+) and negative (-)
battery polarity markings at the bottom of the compartment, as
shown here.
To install the four batteries: 1) Make sure polarity of battery
matches the markings in the compartment. 2) 1st place the (+) end
of the battery into the bottom of the battery slot. 3) Then push in
(-) end of the battery until it is seated in the bottom of the battery
slot. The battery compartment has stand offs molded into the side
of the compartment. When a battery is installed with the polarity
reversed, the stand offs prevent the negative battery terminal from
contacting the positive terminal in the battery compartment. The
unit will not power up when a battery is installed this way. Should
this happen, simply reverse the battery to align the polarity.
With the batteries secured in the battery compartment, replace the
compartment cover. The cover has only one correct alignment.
The "WARNING "
DO NOT OPEN IN EXPLOSIVE ATMOSPHERE
statement on the battery cover must be visible and aligned in the
middle of the manometer case. To secure the cover, torque the
screws clockwise to 1.6-1.8 in-lbs. Do not over tighten.
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