Inlet Grate Flow Capacity Calculator
Selecting and specifying the proper type of inlet grates for drainage is an important part of a stormwater management design plan. EJ manufactures many different types and sizes of inlet drainage grates to meet your design needs. Please use our flow calculator as a tool to help you find the best EJ grate solution.
The flow capacity of any inlet grate in a sump or ponded condition is a function of the depth of water over the grate and the open area of the grate. For this calculation, the orifice equation is used.
At water depths less than 4 inches an inlet grate acts as a weir to incoming flow and requires different analysis to determine flow capacity. For this calculation, the weir equation is used.Orifice Flow Calculator Weir Flow Calculator
Important Note: The orifice and weir calculators do not compensate for any reduction in flow capacity due to clogging by debris. This adjustment may vary and is left up to the discretion of the specifying engineer.
In traveled portions of roadways, inlets should be placed at low points and along slopes. The inlets placed along slopes are intended to reduce inlet bypass and to reduce or eliminate ponding which can be a hazard to traffic. Maximum allowable ponding varies between specifying bodies.Sinusoidal and Vane grate flow characteristics
It is generally accepted that vane grates are more efficient than standard bar grates when capturing water that is moving across them. Sinusoidal and vane grates have greater efficiency due to better directional flow characteristics. Sinusoidal and vane grates typically allow less water to bypass the grate. Please note that if a vane grate is installed improperly (i.e. backwards) the grate will have poor flow characteristics, while sinusoidal grates accept water equally in either direction.