IBM System/370 Guide

The user must supply 30 gallons of cooled water per minute (45
0
to 60
0
F.> to the coolant distribution unit (CDU>, which is housed
in a stand-alone frame that also contains power and the power
distribution unit. Water is supplied to the CDU in pipes under the
raised floor. The chilled water entering the CDU is used to control
the temperature of the internal water that passes through the cpu.
That is, the user-supplied water does not enter the closed-loop system
of the cpu. (See Figure 10.10.1.> The CDU houses the necessary
controls to maintain the proper temperature in the closed-loop system.
The user must supply the controls to maintain the temperature of the
chilled water supplied to the CDU.
User-supplied
water
(45°- 60°F)
Coolant Distribution Unit
CPU
Figure 10.10.1. Conceptual flow of the water cooling system in the
Model 165
The use of water as the cooling liquid offers several advantages.
First, it is readily available. The chilled water normally supplied
for air conditioning is acceptable. Second, water offers safety
features. Low pressure is required and the cooling system can operate
at room temperature, thereby eliminating problems with condensation.
Last, a simplified circulation system suffices, with relatively few
moving parts and less exposure to leaks. Pipe components within the
cpu are separated easily, and the valved connections close off
automatically to prevent water from escaping.
12

IBM System/370 Specifications

General

Brand	IBM
Model	System/370
Category	Server
Language	English