Control Flow Roof Drain Calculation

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.

Control flow roof drain calculation.

Sizing quantity and location of raintrol roof drains are separate and distinct procedures from those for regular roof drains. Read the full list of features and benefits. 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. This table is based on zurn s roof drain vertical requirement for horizontal roof areas at various rainfall rates table.

The zurn z105 15 diameter control flo roof drain for dead level roof construction has a dura coated cast iron body. The sizing of roof drains must be large enough to quickly carry away all water entering the. The above sizing data is offered as a guide only. Tables 1 and 2 are computed for a proportional flow weir sized for 10 gpm per 1 inch of head.

This house is 2000 square feet 50 x 40. All roof openings whether they are at the roof drain or at the vent stack should be protected from vandalism. This house has four downspouts one at each corner of the house that equally drain the roof runoff. Roof drains zurn plumbing products groupspecification drainage operation 1801 pittsburgh avenue erie pa 16502 phone 814 455 0921 fax.

First we will divide the roof into drainage areas. Required roof drainage flow rate in gallons per minute 0 0104 x rainfall rate x roof area. Smith raintrol metered flow rate roof drains are designed to provide this control. Take the roof s total square footage and divide by the total square footage handled by one drain.

Zurn manufactures the control flo roof drain for dead level roof construction. 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. 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. 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.

The result is the number of drains needed. The control flo weir is linear functioning with integral membrane flashing clamp gravel guard and poly dome.