4-2.3 Design Criteria; 4-2.3.1 First Branch Flow Split - Kidde Fire Systems ECS Manual

4-2.3 Design Criteria
The complexity of two-phase flow formulas does not allow for any simple method of manual
HFC-227ea calculation. For this reason, the flow calculations and design criteria described in
this manual have been programmed into a flow calculation software program.
The latest version of the flow calculation software program is the only
calculation method to be used with Kidde ECS System equipment. No other
CAUTION
calculation method is accepted by Kidde.
The system designer must become thoroughly familiar with the latest version of the Flow
Calculation Software User's Guide 06-236272-001 to determine the proper procedures for
applying the input parameters to the Kidde computer program. There are a number of
limitations to these input parameters which must be observed if accurate results are to be
obtained. Most of these limitations are in the program. However, there are certain restrictions
that must be addressed by the system designer before applying the input data. The following
paragraphs describe the essential design parameters and design limitations which must be
considered.
4-2.3.1 First Branch Flow Split
To assure accuracy of the flow calculations, there are various agent flow limits. The
maximum% agent in pipe for all systems is 80%. There is a limit on the allowable percent of
agent prior to the first tee. When these conditions are not met, the computer displays a
warning. It is then up to the system designer to correct the piping volume to the first branch
split. For example, when reading Figure 4-1, in order to achieve 60% agent in pipe, a minimum
of 8.3% agent is required prior to the first tee. When this condition is not met, the computer
displays a warning. It is then up to the system designer to correct the piping volume to the
first branch split to meet this design requirement (see Figure 4-2).
Figure 4-1. Percent Agent Before First Tee as a Function of Percent Agent in Pipe
06-236115-001
Limits: % of agent in pipe and % of agent
before first tee. (As computed by "FLOW",
do not use for manual computation.)
35%
30%
25%
20%
7.9%
15%
10%
5%
0%
0% 10% 20% 30% 40% 50% 60% 70% 80%
% OF AGENT IN PIPE
4-9
Design and Installation
33.6%
8.3%
October 2014