LMI RFP Series, Instruction Manual, Page: 4 / 12

4
III. PROGRAMMABLE DIVIDER AND PUMP CALCULATIONS
The following information is provided to enable you to understand the calculations necessary to properly adjust your
RFP flowmeter. In the steps below you will calculate:
A
- Required pump output
B
- Maximum output of metering pump
C
- Percent output required from pump
D
- Stroke knob setting on pump (strokes per minute)
E
- Divider number
1. DETERMINE METERING PUMP OUTPUT (GPH*)
• Be sure the metering pump selected is an LMI A7, B7 or C7 type pump. These pumps are equipped with an external
input jack for use with RFP flowmeters.
• When using the A7, B7 or C7 pump with an RFP flowmeter, the speed control knob function is bypassed and taken
over by the divider unit. The speed of the pump is controlled automatically, based on the flow of the water through the
flowmeter. On the LMI A7 pump external mode is accomplished by turning the speed knob fully counter clockwise. On
B7 and C7 pumps, a switch is provided to place the pump in the external mode.
• Be sure the pump's pressure rating exceeds the system pressure by a minimum of 20%. For example, if system
pressure equals 100 psi, the pump rating should be 120 psi or greater.
• Use this calculation to determine output in gallons per hour (
GPH*
).
Example Results:
Select an A77 pump with .42 GPH* max. output at 140 psi. (Use the pump selection
guide.)
Example A:
X
70
(GPM *)
4
(PPM *)
5.25
(% solution expressed as a whole number)
=
53.33
X .006
=
.32
Percent concentration of pumping solution
(expressed as a whole number)
Desired concentration
(in PPM* )
=
X
.006
=
(Required pump
output in
GPH* )
X
Max. flowrate of water through
flowmeter (in GPM *)
(A)
(A)
(B)