8.1 General Requirements
8.1.1 The opening size and design head series of service gates，emergency gates and bulkhead gates the hydropower station should meet the requirements in the Specification for Design of Steel Gate in Hydraulic and Hydroelectric Engineering，SL74.
8.1.2 The types of gates shall be selected after techno-economic comparison according to operational requirements of gates，position and size of orifices，upstream and downstream water levels，operating water head，hydrological，sediment and debris conditions，types and capacities of hoists，manufacturing and installation technology and workmanship，material supply，and maintenance and overhaul conditions，etc.
8.1.3 The minimum net distance between two gates or between the gate and the trash rack shall meet the requirements for concrete strength and seepage prevention in the gate slot，layout and operation of hoists，installation and maintenance of gates and hydraulic conditions，and should not be less than 1.5m.
8.1.4 If the back side of a submerged gate cannot be sufficiently ventilated，air vents shall be arranged at the top of the orifice immediately downstream of the gate，and the upper edge of the air vent shall be separated from the hoist chamber and be higher than the check flood level.Protection facilities shall be installed at the orifice.
8.1.5 According to the working nature and operational requirements of the gates，a pressure equilibrium facility should be installed for emergency gates and bulkhead gates.If a filling valve is used for pressure equilibrium，its operation shall be linked with that of the gate hoist，and a small-opening limit switch shall be installed on the hoist.
8.1.6 The top of an emersed working gate shall have a free board of 0.3-0.5m，which cannot be used for reservoir regulation or extra storage.(https://www.daowen.com)
8.1.7 Anti-corrosion measures shall be taken for gates，trash racks and auxiliary equipment depending on water quality，operating conditions，installed position and structural types，which shall meet the requirements in Specification for Anticorrosion of Hydraulic Steel Structure，SL105.
8.1.8 Gates shall not be under the static pressure of ice.Measures against the static pressure of ice shall be taken respectively according to local temperature，sunshine and water level variation of the reservoir（fore bay），which may include the use of a submersible pump，compressed air bubbles，digging ice ditch or other methods to separate gates from ice layer.If gates might have to bear a part of static ice pressure，checking calculation of their strengths shall be conducted.
For gates that need to be operated during ice period，not only shall the water stop be as tight as possible，but also temperature insulation or heating measures shall be taken so that the gates and gate slots would not be frozen.
8.1.9 Hoist chamber，protective cover，overhaul room or overhaul platform，gate chamber or deposit slot should be installed according to the requirements for normal operation and maintenance of gates，trash racks and hoists，.
8.1.10 For hoisting equipment of gates，screw type，fixed winch type，platform type，gantry type or hydraulic type shall be selected respectively after techno-economic comparison of the type，size，number of openings and operational requirements of the gates.The design of hoisting equipment shall meet the requirements in Design Code for Gate Hoist in Water Resources and Hydropower Projects，SL41.
8.1.11 For submerged bulkhead gate and emergency gate that are to be opened in static water after filling and pressure balance，the devices for monitoring water levels should be installed both in front of and behind the gates.
