Print this pageSiphonic Roof Drainage Calculations
John M. Rattenbury, P.E., CIPE,
LEEDap
Course Outline
This online course is intended to provide information on the design and hydraulic analysis of siphonic roof drainage systems using a pipe sizing software package. The course covers the set-up and calculation of two sample piping systems and discusses recommended design steps to arrive at efficiently designed drainage systems.
This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.
Learning Objective
At the conclusion of this course, the student will:
- Be able to lay out and dimension siphonic roof drainage systems;
- Become familiar with the process of calculating the capacity and performance of siphonic roof drainage systems;
- Understand the differences between traditional roof drainage and engineered siphonic roof drainage;
- Understand the calculation of major and minor energy losses;
- Understand how to estimate the pipe sizing of siphonic roof drainage systems for preparation of hydraulic calculations;
- Be knowledgeable of various terminology used in siphonic systems;
- Understand how to configure and adjust a piping system to achieve a satisfactory residual head using a single-drain system as an example;
- Understand how to configure and adjust a two-drain piping system to achieve satisfactory results for both residual head and imbalance;
- Be familiar with the selection of roof drains with respect to rainfall intensity and developed water depth;
- Understand the concept of cavitation and how calculations are used to avoid cavitation in siphonic roof drainage systems;
- Be familiar with the pipe, fittings and components appropriate for siphonic systems; and
- Be familiar with the adjustment of pipe stack sizing to control the residual head and static pressures of a system.
Intended Audience
This course is intended for plumbing engineers.
Benefit to Attendees
Attendee of this course will be able to lay out and dimension siphonic roof drainage systems.
Course
Introduction
The main objective of this course is to become familiar with the process of calculating the capacity and performance of siphonic roof drainage systems by selecting pipe diameters and adjusting pipe lengths and other variables using hydraulic analysis methods. The nature of performing these calculations and the multi-variable conditions of siphonic roof drainage design has made the use of computer software the “standard of care” in the industry. Although calculations were originally performed by hand during the onset of this roof drainage technology in the 1960’s and 1970’s before the availability of the microcomputer, the advent of the desktop computer and of software tailored specifically for siphonic roof drainage design has greatly decreased the time to dimension systems and has also increased the accuracy of design and overall reliability of installed systems. Therefore, this course will center on the use of a downloadable design platform (software) that the course participant can use to evaluate the calculation of sample systems and then retain for the design of systems in actual practice.
Course Content
The course content is in the following PDF file (737 KB):
Siphonic Roof Drainage Calculations
Please
click on the above underlined hypertexts to view, download or print the documents
for your study. Because of the large file size, we recommend that you first
save the file to your computer by right clicking the mouse and choosing "Save
Target As ...", and then open the file in Adobe Acrobat Reader.
You also need to download and install free software SiphoniTec for this course at:
SiphoniTec (by Jay R. Smith Mfg. Co.)
Course Summary
This course provides step-by-step procedures to set up and complete the process of calculating the capacity and performance of siphonic roof drainage systems by selecting pipe diameters and adjusting pipe lengths and other variables using hydraulic analysis methods.
Related Links
For additional information related to this subject, please visit the following websites or web pages:
ANSI/ASME
A112.6.9 "Siphonic Roof Drains"
ASTM
F 2021 "Standard Guide for Design and Installation of Plastic Siphonic
Roof Drainage Systems"
American Society of Plumbing
Engineers
Quiz
DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.
