Control Flow Roof Drain Calculation

Z105 control flo roof drain.

Control flow roof drain calculation.

First we will divide the roof into drainage areas. All roof openings whether they are at the roof drain or at the vent stack should be protected from vandalism. The sizing of roof drains must be large enough to quickly carry away all water entering the. Calculate drains needed.

Tables 1 and 2 are computed for a proportional flow weir sized for 10 gpm per 1 inch of head. Factors which affect proper roof drainage are deck slope drain size and placement of drains. Required roof drainage flow rate in gallons per minute 0 0104 x rainfall rate x roof area. Zurn manufactures the control flo roof drain for dead level roof construction.

Take the roof s total square footage and divide by the total square footage handled by one drain. This house is 2000 square feet 50 x 40. 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. 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 above sizing data is offered as a guide only. This house has four downspouts one at each corner of the house that equally drain the roof runoff. 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. Roof drains zurn plumbing products groupspecification drainage operation 1801 pittsburgh avenue erie pa 16502 phone 814 455 0921 fax.

This table is based on zurn s roof drain vertical requirement for horizontal roof areas at various rainfall rates table. Sizing quantity and location of raintrol roof drains are separate and distinct procedures from those for regular roof drains. 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. The zurn z105 15 diameter control flo roof drain for dead level roof construction has a dura coated cast iron body.

The result is the number of drains needed. Smith raintrol metered flow rate roof drains are designed to provide this control.