APPLICATION METHOD (Continued)
Total Flooding (Continued)
STEP NO. 20 – Estimate the Nozzle Flow Rates
If all of the nozzles within the hazard area will have the
same flow rate, divide the Estimated Flow Rate for the Area
(Step No. 19) by the nozzle quantity (Step No. 18).
If all of the nozzles within the hazard area will not have the
same flow rate, perform a percentage calculation using the
volume protected by each nozzle divided by the total vol-
ume for the area and then multiply the Flow Rate for the
Area (Step No. 19) by the volume percent calculated previ-
ously to determine the flow rate for that nozzle. Complete
this procedure for each nozzle in the system.
If the design includes multiple levels of nozzles, remember
to include all nozzles on all levels in this step.
Complete this step for each area protected by the system.
Example
Computer Room
• 669 CFM (Estimated Flow Rate Per Area) ÷ 1 = 669 CFM
Nozzle Flow Rate
Subfloor
• 67 CFM (Estimated Flow Rate Per Area ÷ 1 = 67 CFM
Nozzle Flow Rate
STEP NO. 21 – Determine the Nozzle Locations and Lay
Out the Interconnecting Piping
Using a plan view drawing of the protected areas, locate
each nozzle and the cylinders. NOTE: Nozzles should be
located at the top of the hazard area, aimed downward.
Connect the nozzles with piping following the piping guide-
lines listed in the General Information Section and the
Installation Section. After all of the nozzles are connected,
lay out the piping to the cylinders and lay out the manifold.
Manifold layout limitations can be found in the Installation
Section of the Design Manual, including a manifold height
chart.
When laying out the manifold, remember that a center out-
let manifold will usually allow the use of smaller pipe sizes
for the horizontal legs of the manifold where the cylinders
are connected, especially if these legs are a single size. “H”
shaped manifolds are usually preferable to “end outlet,” “L,”
or “U” shaped manifolds. Center to center distances for the
cylinders will normally be 12 in. due to the spacing of the
brackets. It is normally recommended to keep the Pressure
Reducer as close to the manifold outlet as possible to
reduce the amount of Schedule 80 or 160 pipe required in
the system.
When selecting pipe schedules, keep in mind that the
manifold pressure should be assumed to be 2,900 PSI.
This will usually dictate the use of Schedule 160 pipe for
any size larger than 2 1/2 in. pipe if threaded fittings will be
used. If welded or “rolled groove” fittings are used in the
manifold, Schedule 80 pipe will be acceptable in most
cases for all pipe sizes through 6 in.
If the system is a “Balanced” system, review the pipe layout
to assure that all legs of the piping are equal in regards to
flow and fittings and that the maximum length of pipe for
the longest leg from the manifold to the furthest nozzle is
not more than 10% longer than the shortest leg from the
manifold to the closest nozzle.
If the system is an “Unbalanced” system, review the piping
arrangement for proper tee splits per the limitations listed in
the General Information Section and revise the piping
accordingly if necessary.
If the system includes Selector Valves, refer to the informa-
tion later in this section for assistance in laying out the pip-
ing for the Selector Valve manifold.
STEP 22 – Complete an Isometric Sketch of the Piping
Layout
Create an isometric sketch of the piping for use in inputting
the information in the INERGEN Designer program. After
the sketch has been completed, identify all of the pipe
lengths.
Identify and label all node points, manifold designators, and
nozzle designators. The first point on the manifold is con-
sidered as the inlet to the cylinder valve inside the cylinder.
The second point is considered as the outlet of the dis-
charge hose. This first section of pipe must always be
included in any system; therefore the flow calculation pro-
gram will include it automatically.
• Piping Node Points – Piping sections are numbered
starting at the inlet to the valve on the cylinder furthest
from the manifold outlet. Each point where flow increas-
es, direction changes, or flow splits marks the end of a
pipe section and the start of a new pipe section. Nodes
must be numbered numerically: 1, 2, 3, etc. Sequential
numbering is not required, however, it is recommended to
prevent confusion. NOTE: Anytime a tee is added to the
piping to take off pressure to operate a pressure trip or
pressure switch, a node point should be assigned and
the fitting should be entered as a coupling to address the
friction loss.
SECTION V
UL EX-4510 12-1-01 Page 5-8
Design
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