(a) Each refrigeration system must:

1. (1) Have enough capacity to maintain the cargo vapor pressure in each cargo tank served by the system below the set pressure of the relief valves under ambient temperatures of 45 °C (113 °F) still air and 32 °C (89.6 °F) still water with the largest unit in the system inoperative; or
2. (2) Have a standby unit with a capacity at least equal to the capacity of the largest refrigeration unit in the system.

(c) Each refrigeration system must:

1. (1) Have a heat exchanger with an excess capacity of 25 percent of the required capacity; or
2. (2) A standby heat exchanger.

(d) Where cooling water is used in a refrigeration system:

1. (1) The cooling water pump or pumps must be used exclusively for the system;
2. (2) Each pump must have suction lines from sea chests on the port and starboard sides of the vessel; and

3. (3) There must be a standby pump, that may be used for:

   1. (i) Non-essential purposes on the vessel; or
   2. (ii) Essential purposes on the vessel, if the pump is sized to simultaneously provide for the capacity requirements for the essential purposes and the refrigeration cooling water.