IBM Rear Door Heat eXchanger V2 Installation And Maintenance Manual page 74

Note to service technician: The customer is responsible for disconnecting the
water supply and return hoses and draining the heat exchanger. If the hoses are
still connected, have the customer drain the heat exchanger by following the
procedure in "Draining the heat exchanger" on page 56. Disengage from the service
call until the customer informs you that the door is drained.
Statement 14:
CAUTION:
Goggles are needed for the procedure.
(L011)
Attention: Make sure that proper handling procedures are followed when you
work with any chemically treated water that is used in the rack cooling system.
Make sure that material safety data sheets (MSDS) and safety information is
provided by the water chemical treatment supplier and that proper personal
protective equipment (PPE) is available as recommended by the water chemical
treatment supplier. Wear safety goggles or other eye protection whenever you drain
or purge air from the heat exchanger.
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Rear Door Heat eXchanger V2: Installation and Maintenance Guide