Elkhart Brass ELKHART PRESSURE-MATIC VALVES - Manual (Page 4)

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this pressure reduction ratio will tend to decrease with increase of flow rate through the valve. This behavior
results due to friction loss through the valve.
B. Valve Type Selection
To determine the correct type (bonnet) for each Pressure-Matic® valve in the system design, please use the
following steps.
1. Determine the standpipe or sprinkler riser residual pressure for each valve location. This is
the inlet pressure at each valve under design flow conditions. In order to accurately determine
these pressures, complete water supply data will be required, including results of municipal
supply flow test, and the pump performance curve. The Pressure-Matic® inlet pressure will be
equal to the sum of the pump discharge pressure and the municipal supply pressure at the design
flow rate, less piping friction loss, and elevation loss.
2. Turn to the appropriate valve performance chart (Figs. I through VIII), based on valve size
and body style. The valve flow range for each chart is indicated in the lower right corner of the
chart. Be sure to use the correct chart for the designed flow rate through the valve.
3. Locate the valve inlet residual pressure on the vertical axis of the chart and draw a line from
this pressure horizontally across the chart.
4. Locate the desired valve outlet residual pressure on the chart horizontal axis and draw a
vertical line from this pressure across the chart.
5. From the intersection of the inlet and outlet pressure lines constructed in (3) and (4) above,
move horizontally to the nearest valve performance curve (actually straight diagonal lines). This
will be the appropriate valve for the chosen location.
EXAMPLE:
The residual inlet pressure at a straight pattern sprinkler system floor
control valve is 275 psi at a design flow demand of 280 gpm. The desired
residual outlet pressure is 120 psi. On the appropriate chart (Fig. III) it is seen
that the intersection of the residual inlet and outlet pressure lines fall very close
to the performance curve (straight line) for the "DE" valve. Therefore, the "DE"
valve would be chosen, and would provide an actual residual outlet pressure of
125 psi.
6. Determine the valve static inlet pressure. This will be the sum of the municipal supply static
pressure plus the pump churn pressure, less elevation loss.
7. To determine the valve static outlet pressure, refer to the appropriate static chart (Fig. IX or
X). Locate the valve static inlet pressure on the vertical axis of the chart. Follow across to the
appropriate valve curve (straight line) and drop down to the horizontal axis to read valve outlet
static pressure.
EXAMPLE:
For the valve in step (5) above, the static inlet pressure is 290 psi.
Follow the 290 psi inlet pressure line across the chart horizontally to the "DE"
curve. Read the outlet static pressure of 153 psi on the horizontal axis directly
below the point of intersection.
NOTE:
If static outlet pressure is found to exceed the maximum outlet pressure allowed by NFPA 13 or NFPA
14, it will be necessary to re-select a valve type to the left of the originally chosen type