Control Flow Roof Drain Calculation

The above sizing data is offered as a guide only.

Control flow roof drain calculation. Sizing quantity and location of raintrol roof drains are separate and distinct procedures from those for regular roof drains. Smith raintrol metered flow rate roof drains are designed to provide this control. This house is 2000 square feet 50 x 40. Required roof drainage flow rate in gallons per minute 0 0104 x rainfall rate x roof area.

Now that we know where the water will drain to we can begin to calculate how much water will run off to each drainage zone. The control flo weir is linear functioning with integral membrane flashing clamp gravel guard and poly dome. The zurn z105 15 diameter control flo roof drain for dead level roof construction has a dura coated cast iron body. Tables 1 and 2 are computed for a proportional flow weir sized for 10 gpm per 1 inch of head.

This house has four downspouts one at each corner of the house that equally drain the roof runoff. Calculate drains needed. The full flow capacity of a drain is not realized until the water reaches approximately 2 5 above the inlet in a four inch drain and 3 5 in a six inch drain. Zurn manufactures the control flo roof drain for dead level roof construction.

First we will divide the roof into drainage areas. This table is based on zurn s roof drain vertical requirement for horizontal roof areas at various rainfall rates table. 2 flow control roof drains may be installed provided a the maximum drain down time does not exceed 24 h b the roof structure is designed to carry the load of the stored water c one or more scuppers are installed not more than 30 m apart along the perimeter of the building so that. Roof drains zurn plumbing products groupspecification drainage operation 1801 pittsburgh avenue erie pa 16502 phone 814 455 0921 fax.

Factors which affect proper roof drainage are deck slope drain size and placement of drains. The result is the number of drains needed. Take the roof s total square footage and divide by the total square footage handled by one drain. Smith used a multiplier of 0 0104 in these calculations to convert inches of rain fall per hour into gallons of water per minute per square foot resulting in the following formula for calculating roof drain flow rate.

Z105 control flo roof drain. The roof drain selector along with tables 1 and 2 allows the engi neer to select control flo drains and pipe sizes for most applications.