Brochure

Gastite Division, Titeflex Corporation
1116 Vaughn Parkway / Portland, TN 37148
800.662.0208 / www.gastite.com / [e-mail]
18
April 2015
Section 3: System Configuration
Sizing for a Hybrid System (one that includes both rigid pipe and CSST) is accomplished by using the longest run method to
determine the appropriate pipe size for a given load and run length. Each segment of the piping system uses the appropriate
sizing table for that particular piping material. is procedure is shown in Examples 6 & 7.
Summation Method:
An alternative sizing method is the Summation Method which considers a summation of the pressure losses through each
section of piping. is procedure is utilized for the designer whose requirements are not satisfied by the previously described
methods. e summation method can be used for system pressures and pressure drops other than indicated in the sizing
tables for longest run. is method allows full use of the maximum flow capacity of CSST. In this fashion, a designer can
minimize piping size (or maximize flow capacity) with greater accuracy in more complicated arrangements. e summation
method is shown in Examples 8 & 9.
3.1.7 Modifying an Existing System
FlashShield™ fittings transition from CSST to pipe thread (NPT) and may be run in conjunction with all other approved fuel
gas piping (iron pipe, polyethylene tubing, copper tubing, etc.). When adding appliances to an existing system the installer
must verify whether the existing system, upstream of the lines to be added, can support the additional load.
A retrofitted line, even when properly sized, added to a system that can’t support the additional load, can adversely effect all
the other appliances in the system.
When the existing system will not support the additional load several installation options exist. A new trunk line(s) can be
run replacing the under-sized system upstream of the retrofitted appliances. A dedicated trunk line can be run from the gas
source to the new appliance. e system pressure may be elevated, thus increasing the allowable pressure drop, after which
the existing trunk lines may afford sufficiently higher flow capacity to handle the existing and new appliances.
If the piping is visible or the existing run lengths are known, the entire system can be resized using either aforementioned
sizing method (Longest Run or Summation). e system shall be resized with an appropriate sizing table based on the
affordable pressure drop. When the piping is not visible or accessible for measurement, approximated lengths should be
rounded up.
3.2 Sizing Procedures and Exercises
3.2.1 Sizing Examples
While the following examples show typical applications of the sizing methods they do not address all of the system
configurations in which they can be used. In general, Longest Run and Summation can be used with any pressure or system
configuration (series, parallel, dual-pressure, hybrid, etc.).
e following exercises illustrate various design layouts, pressure drops and sizing methods. To further highlight the differences
in methods and designs, examples 1-8 use the same appliance layout and load.