What is the requirement of fire alarm pull stations placement in Washington dc?

You must follow NFPA 72:

Chapter 17 Initiating Devices

17.14 Manually Actuated Alarm-Initiating Devices.

17.14.1 Manual fire alarm boxes shall be used only for fire alarm initiating purposes.

17.14.1.1* Unless installed in an environment that precludes the use of red paint or red plastic, manual fire alarm boxes shall be red in color.

17.14.1.2 Manual pull stations for initiating other than fire alarm shall be permitted if the devices are differentiated from the manual fire alarm boxes by a color other than red and labeling.

17.14.1.3 Manual fire alarm boxes shall be mounted on a background of contrasting color.

17.14.2 Combination manual fire alarm boxes and guard's signaling stations shall be permitted.

17.14.3 Each manual fire alarm box shall be securely mounted.

17.14.4 The operable part of each manual fire alarm box shall be not less than 42 in. (1.07 m) and not more than 48 in. (1.22 m) above floor level.

17.14.5 Manual fire alarm boxes shall be installed so that they are conspicuous, unobstructed, and accessible.

17.14.6 Manual fire alarm boxes shall be located within 60 in. (1.52 m) of the exit doorway opening at each exit on each floor.

17.14.7 Manual fire alarm boxes shall be mounted on both sides of grouped openings over 40 ft (12.2 m) in width, and within 60 in. (1.52 m) of each side of the opening.

17.14.8* Additional manual fire alarm boxes shall be provided so that the travel distance to the nearest fire alarm box will not be in excess of 200 ft (61.0 m), measured horizontally on the same floor.