Culligan Smart Controller HE DF 12 Installation, Operation, And Service Instructions With Parts Lists page 43

Example Calculations for Diaphragm Pumps.
This section contains a more detailed description of the Controller programming that will allow the use of other pumps,
flow meters, and valves.
Alternate chemical dosing pumps may be used with the system.
Type 1 Chemical Dosing Pump (Diaphragm Pump)
The Diaphragm pump performs as follows:
• The pump delivers a specified volume of chemical each time the pump receives a dry contact closure.
• The pump must be able to accept a signal that changes from OPEN to CLOSED, with a duration of closed time that
is at least 0.1 seconds, and then returns to OPEN.
Detailed Calculations for a Type 1 Chemical Dosing Pump
In this section we first assume the following:
• Peak service flow rate = 30 gpm
• The flow meter k-factor = 28.5 pulses per gallon
• Controlling a Type 1 dosing pump which is rated at 30 gpd that operates at up to 125 strokes per minute
Example 1
• The flow rate is constant at the peak service flow rate of 30 gpm
• The k-factor is 28.5 pulses per gallon
The meter will then generate 30 gpm x 28.5 pulses/gallon = 855 pulses each minute.
When the service flow is at this level, we want the dosing pump to be running 100 percent of the time. We know, for this
particular pump, that it operates at 125 strokes per minute when it is delivering its rated capacity of 30 gpd. To operate at
this rate, it will need to be set to:
• At 125 strokes per minute, the pump strokes once every 60/125 = 0.48 seconds.
• The meter pulses 855 times per minute or 855/60 = 14.3 pulses per second, or 14.3*0.48 = 6.9 pulses every 0.48
seconds.
If we set the Controller to count the incoming meter pulses and command the pump to stroke once every 7 pulses, it will
keep the dosing pump running at 100% capacity or 30 gpd.
If the service flow rate is:
• 30 gpm x 1440 minutes/day = 43200 gallons per day
then the dosage is 30/43200=0.0006 gallons dosed per gallons of service flow.
If the service flow rate slows down to 10 gpm:
• There are 285 meter pulses per minute, or 4.75 pulses per second. At that rate, it will take 7/4.75 = 1.5 seconds to
receive 7 pulses and command the pump to take a stroke.
• Each minute the pump would stroke 60/1.5= 40 strokes. At this rate, the pump would be delivering 40/125*30 gpd =
9.6 gallons per day of chemical.
• The amount of service flow per day would be 10 gpm*1440 minutes/day = 14400 gallons, so the chemical dosing
rate is 9.6/14400 = 0.0007 gallons dosed per gallons of service water—basically the same ratio as when the sys-
tem was running at 30 gpm service flow.
In this example, a new stroke will be sent by the pump at a rate of up to once every 0.48 seconds. For this reason, it is
important that the duration of the "on-time" stroke signal is not longer than 0.48 seconds or the pulses might start to over-
lap. The duration of the dry contact closure stroke signal is set from the Controller using the Aux5 On Time setting. A good
choice for the pulse duration is to choose around half of the shortest time between pulses. In this example, a good choice
for on-time would be 0.2 seconds. The Controller can be programmed to pulse for as short at 0.1 seconds—it is important,
however, to make sure that the stroke signal you are providing is not shorter than the minimum length pulse that can be
detected by the chemical feeder pump.
The Diaphragm pump can accept pulses as short as 0.01 seconds.
• The Aux 5 setting should be 7 pulses
• The Aux 5 Out Active setting should be 0.2 seconds
Cat. No. 01024514
Installing Accessories 39