FLOOR DRAIN SIZING AND LOCATION |
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| The location, number and size of floor drains are all important
factors in the design of a drainage system. Proximity of the drain to the source of water
is important, as well as the grade, so that water on any floor area naturally flows to the
drain. The number of drains must be considered based on anticipated volume and
proximity. In any case, local and national codes should be followed for drain sizing and
placement. The size of floor drains is important as it affects the number of drains required and the amount of water which can be efficiently drained. As a general reference, floor drains should be sized to handle an overflow condition of water that may be discharged onto the floor. The chart below illustrates water outlets and the demand (GPM) requirements for a drain.
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HOW TO CHOOSE A FLOOR DRAIN |
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| Given a piping system with a
designed flow rate, an appropriate floor drain can be readily selected. Factors such as
flow rate, length of horizontal pipe, and pipe size are some of the predominate factors
upon which the selection of a floor drain depends. These factors are the first to be
considered because together with a floor drain, they fulfill the purpose of a drainage
system, which is to carry all water efficiently from the floor. Also to be considered is
the maximum head and buildup of water on the floor. This value can range typically up to
2" depending on pipe size or any other design consideration of the particular
application. Based upon a specified
flow rate and head, the grate open area of the required drain can be calculated using the
following equation: The equation can be easily arranged to
solve for ‘A’: Click here for: Flow/Area Calculator. (Microsoft Excel required.) Pipe size and open area of grate should be one of the first specifications decided on, in the selection of a floor drain, because they are most important in fulfilling the requirements of the specified flow rate and drainage system. However, additional criteria exists in selecting the most appropriate drain. The type of connection, either Inside Caulk (IC), Threaded (IP), No-Hub (NH), Neo-Loc (NL) or Spigot (SP) needs to be chosen. Backwater valves are useful to reduce drainage backup. Sediment buckets can filter out of the water flow such items as leaves, jewelry, hair, paper and dirt, which can cause the drainage system to clog. Depending on the purpose and location, an extra heavy, heavy, medium or light duty drain may be selected. Extra-heavy and heavy-duty drains are useful in places where heavy and medium size trucks are being operated. Medium duty drains can be used where there is lighter vehicle traffic. For pedestrian traffic and bicycles, light duty drains may be used. The type of material chosen is important for corrosion characteristics, as well as for blending into the surroundings. The top shape (round, square, rectangular, etc.) and finish should be selected in accordance with the surrounding environment. In areas where pedestrian traffic is the norm, floor drains with heel-proof grates should be used. Heel-proof grates are designed with 1/4" wide slots or 5/16" square openings to provide a relatively secure surface. The heel-proof feature, if available, is contained in the Engineering Specification of that product. |
