1. Location of the vent pipe: It should be installed at the high point or corner of the drainage pipe to ensure that the drainage system can effectively discharge gas and maintain normal ventilation.

2. The height of the vent pipe: it should be higher than the height of the drain pipe by a certain distance to avoid negative pressure when draining, which may lead to the backflow of sewage or odor.

3. Diameter of the ventilation pipe: it should be in accordance with the specification requirements, generally not less than 1/2 of the diameter of the drainage pipe.

4. The material of the vent pipe: generally use the same or similar material with the drain pipe, such as plastic or cast iron.

5. Connection method of the vent pipe: the connection with the drain pipe should be sealed in a reliable way to ensure that the gas will not leak or enter the drain pipe.

6. Protection of the vent pipe: Anti-backflow devices should be installed to prevent rainwater or foreign objects from entering the vent pipe and affecting the ventilation effect.

7. Exit location of the vent pipe: the exit should be far away from windows, doorways, air conditioning vents and other locations to prevent odors from entering the room.

In short, the installation of the ventilation pipe of the drainage pipe should comply with the above provisions to ensure the normal operation of the drainage system and the ventilation effect.