Nelsen Corporation 3900 NXT2 Manual

Operation & Maintenance Manual
3900 NXT2 Systems
© Nelsen Corporation Part# 3900NXT2 OPERATION MANUAL

Table of Contents
1INTRODUCTION
2 PRINCIPLES of ION EXCHANGE
2.1 Ion Exchange Softening Process
2.2 Quality of Effluent
2.3 Capacity of Ion Exchange
2.4 Regeneration Steps
3 INSTALLATION, LOADING & START-UP PROCEDURES
3.1 Installation of Equipment
3.2 Loading of Gravel & Resin
3.3 Start-Up Procedures
4 OPERATING & REGENERATION PROCEDURES
4.1 Normal System Operations
4.2 Multi-Port Valve Operation
5 OPERATING RESPONSIBILITIES
5.1 Operator procedures
5.2 Salt Specifications
6 TROUBLE SHOOTING
6.1 General
6.2 Reduced Capacity or Poor Effluent Quality
6.3 Increase Pressure Loss or Decrease in Flow Rate
7 SOFTENER SYSTEM DRAWINGS AND SPECIFICATIONS
7.1 Typical System 5 Duplex Interlock Unit Installation
7.2 Typical System 6 Duplex Parallel Unit Installation
7.3 Typical System 7 Duplex Alternating Unit Installation
7.4 Typical System 9 Triplex Alternating Unit Installation
7.5 Typical System 14 Twin Progressive Unit Installation
7.6 Specifications
7.7 Brine Float Setting
7.8 Commercial/Industrial Brine Tanks
8 SERVICE MANUALS
3900 Control Manual
NXT2 Service Manual
9 SOFTENER ADDENDUM
9.1 Sample – Water Softening Log

Foreword
The operating instructions contained herein are intended to serve as a guide for the operation
of the water softener equipment.
Since it is impossible to cover all operating contingencies and emergencies in a normal operating
manual, the operator should read the manual and become familiar with it contents. They should
also review the flow diagrams and vendor literature. This also should include all physical details,
and full knowledge of the location and function of the equipment.
The use of an operating logbook is recommended in order to provide a proper record of
performance. In the event of operational problems, such a record will prove invaluable when
“trouble shooting” the system. This log should include all pertinent flow rates, temperatures and
water characteristics. Equipment requiring maintenance or repair should be noted so that it can
be scheduled for service or repair.
Frequently, water softener equipment like other processes, develop their own distinct
characteristics. Design criteria outlined in this manual is based on many years of experience.
However, they do not preclude modifications due to “personality” of the system. Operators
should guide themselves accordingly and make any minor adjustments necessary for proper
operation of the system.

Section 1: Introduction
Long term, successful operation of any softening system depends upon the care and attention it
receives. Ordinarily, water treatment systems will provide uniform performance after the initial
start-up period. Total gallons between regenerations and treated water purity usually do not vary
appreciably over the life of the resin as long as the incoming water does not change.
This manual in intended to be a practical reference guide for operators. In view of the fact that
system performance can change very dramatically throughout the year, a discussion of “ion
exchange” theory is included in addition to basic information relative to equipment operation
and regeneration procedures. Thorough understanding of the simple chemical reactions will help
to determine if some equipment malfunction has occurred, or if the system is simply responding
to changing water conditions. For this reason, the operator and supervising personnel should
review Section 2, which defines terminology and simple chemistry associated with this system.
Ion exchange (softening process) is a reversible reaction. Ion exchange softening resins have
only a limited capacity for removing hardness (calcium & magnesium). If the volume of water
through the resin bed exceeds its capacity, hardness leakage will be detected in the effluent
water. Therefore, service runs must be terminated before hardness leakage occurs. When the
service run is completed, the resin is treated with sodium chloride (NaCl) to displace the hardness
and restore its capacity. This process is termed “regeneration”.
How completely softening can be accomplished depends upon several factors. The primary
influences are the incoming water, type of resin, and amount of salt. Equally important, secondary
influences are the concentrations and flow rates at which NaCl is introduced.

Section 2: Principles Of Ion Exchange
2.1 Ion Exchange Softening Process
In order to understand the softening process of ion exchange, it is first necessary to understand
the meaning of the terms which are used in the explanation. Hard Water, Cation Exchanger, and
Brine are defined below and used to show how the ion exchange process works.
Hard Water – All natural water contains dissolved impurities, but in widely varying amounts.
There is always a balance of cations (+) and anions(-), but in the softening process anions have
no effect. Water will be hard if it contains large amounts of calcium (Ca++) and/or magnesium
(Mg++) ions.
Brine – Salt which has dissolved in water. Completed brine (100%) saturation contains as much
salt as possible in water solution (26% to 27%). Salt – Sodium chloride (NaCl), when dissolved
in water splits up (ionizes) into sodium (Na+) ions and chloride (Cl-) ions.
Saturated Brine – Contains a large amount of Na+ and Cl- ions (concentration is over 200,000
ppm). When used to regenerate a cation exchanger, only the sodium (Na+) ions are used. The
chloride (Cl-) ions are washed to drain.
Cation Exchanger – A high-capacity bead form polystyrene sulfonate cation resin. These beads
have negative (-) electric charge, which attracts and holds the cations, which are positively (+)
charged (works like a magnet).
Softening Process – When the bead reaches the exchange capacity of Ca++ or Mg++ hardness
break through the resin bed will increase. The increase in effluent hardness will indicate that
the effective capacity of the cation resin has been reached. The cation exchanger must be
regenerated to restore it to its original capacity.
Regeneration – Brine is used to regenerate the cation exchanger to its original capacity. Sodium
(Na) ions attach to the resin beads forcing the calcium and magnesium ions to release from
the resin beads. Once the exchange has taken place the sodium ions are rinsed to drain. The
softener in now ready to remove hardness from the water.

2.2 Quality Of Effluent
If the hard water contains less than 500 ppm (about 30 grains) of calcium, magnesium and
sodium salts, all expressed as CaCO3, it will be found that the effluent from a softener will
contain an average of not more that 2 ppm actual total hardness (zero hardness by the soap
test). However, as the total cation concentration in the hard water increases above 500 ppm, the
average hardness in the effluent will also increase proportionately
The reason for this is that when the sodium salt - those present in the raw water plus those
formed by the exchange reactions - are present in high enough concentrations, they cause a
“back-regeneration” effect at the same time as the softening process is taking place. This effect
prevents as complete a removal of calcium and magnesium as would otherwise be possible.
It is often possible to reduce the average hardness in the effluent below normally expected
concentrations, by using a greater amount of salt than usual for regeneration. Normal Softening
Cycle - At the start of a normal softening cycle, the hardness in the effluent drops rapidly as
the residue of hardness ions left in the bed at the end of the rinse are forced out. The effluent
hardness reaches a certain minimum value and remains at approximately this concentration for
the major part of the softening run.
2.3 Capacity Of Ion Exchanger
The capacity for the removal of calcium and magnesium depends mainly upon the type of ion
exchanger which is used. It is further influenced by the amounts of hardness and sodium ions
in the raw water, and by the amount of salt used for regeneration.
Raw Water - The effect of the amounts of hardness and sodium ions in the raw water, is
expressed in terms of compensated hardness. The hardness of the raw water is considered
to be greater than it actually is for capacity determinations, whenever: (a) the total hardness is
greater than 400 ppm (as CaCO3), or (b) the sodium salts are over 100 ppm as (CaCO3). This
“greater-than-actual” hardness is referred to as compensated hardness.
Salt Dosage - The capacity, which will be obtained from a cation exchanger, is also determined
by the amount of salt used during regeneration. The grains of hardness, which can be removed
by each cubic foot of ion exchange, resin increases as more salt is used for regeneration.
At the same time, the efficiency of salt usage decreases with the higher regenerant dosages.
That is, a greater number of grains of hardness are removed for each pound of salt used at the
lower salt dosages, (and consequently, at the lower capacities). Thus, greater economy may
be obtained at the expense of the number of gallons of water softened between regenerations.

Calculation Of Capacity - To determine the capacity of any cation exchanger, follow the
procedure outlined below:
From the analysis of the raw water, determine the actual total hardness as the sum of the calcium
and magnesium concentrations expressed as CaCO3. If necessary, calculate the compensated
hardness in accordance with the formula given above.
Express parts per million (ppm) of total hardness as grains per gallon by means of the following
conversion formula:
PPM / 17.1= grains per gallon (gpg)
2.4 Regeneration Steps
Regeneration is a process by which ions are stripped from the exhausted resin bed and its ion
removal ability is restored. All exchangers, ranging from a simple water softener to a complex
mixed bed deionizer go through four basic regeneration steps. There may be variations in flow
rates; types of regenerating chemicals and regenerant concentrations but these general steps
are as follows:
Backwash - Water flow is reversed so that it passes upward through the resin bed. Flow rates
are sufficiently high to expand (fluidize) and to agitate the bed without washing large resin
particles out of the tank. This action relieves any compaction that may have occurred during
the service run. In addition, very fine resin fragments that can form during normal service are
washed to drain. Proper backwash is essential to good exchanger performance. A compacted
bed can develop high-pressure losses during service, which, in turn, can lead to flow channeling
problems.
Brine In - A brine solution is passed slowly through the resin, displacing the exchanged ions and
discharging them to drain. Proper control of flow rate and brine concentration is important to
insure high regeneration efficiency. The amount of salt that is used depends upon the allowable
hardness leakage for any given water supply and the desired resin operating capacity.
Displacement Rinse (Slow Rinse) - After all of the brine has been introduced into the resin bed,
water continues to flow at approximately the same low flow rate. This slowly displaces the salt
from the free space above the bed and from the void volume between resin particles, insuring
that it is utilized to maximum efficiency.
Final Rinse - The final step in regenerating is important in that it will displace any salt left in the
exchanger vessel prior to returning to service.

Section 3: Installation, Loading
& Start Up Procedures
3.1 Installation of Equipment
1. Before beginning installation, review the following instructions to familiarize yourself
with the general placement of the equipment.
2. The operating pressure is between 30 to 100 psi. If pressure is higher than 100 psi, then
a pressure regulator must be installed.
3. The operating temperature is between 35 to 100 degrees F.
4. Locate the equipment in the specified location. When setting the equipment, install on
level concrete pad if possible. Level equipment as required.
5. Equipment should be located near a floor drain. The floor drain should be adequate in
size to handle the softener backwash flow rate.
6. Interconnecting piping and shut off valves of equipment should be installed per local
plumbing codes by a certified plumber.
7. Unions to be installed in the drain line for cleaning of the backwash flow control. Do NOT
reduce the drain line pipe size, or install a manual shut off valve. Provide an air gap in
the drain line in accordance with local plumbing codes.
8. Before installing any flow meters, read the instruction manual on proper installation of
the sensor. Many flow meters must be installed in a certain way to operate properly.
9. Once installed close all manual shut off valves.
10. Brine tank should be located near the softeners, installed on a smooth flat surface. If not
the brine tank should be placed on a smooth piece of exterior plywood and level.
11. Once the brine tank has been set in place, remove the lid and check that the brine well
is in a vertical position. If the brine tank is equipped with a brine valve/float assembly,
remove and check to make sure the brine float setting is correct (See Section 7 – Brine
Float Setting). The float will have a certain setting depending on the amount of salt used
per regeneration. If incorrect adjust float to proper setting.
12. Place brine valve into brine well and set all the way to the bottom of the brine tank.
13. Fill brine tank with approximately 13-19 inches of water. The water level should be
approximately half to the height of float setting.

3.2 Loading Gravel & Resin
1. Before loading the gravel, check the lower
distributor for possible damage from shipping.
Making sure all laterals are in proper location.
Do NOT proceed with loading if any damage
is evident.
2. Once the distributor is checked out ok, plug the
end of the distributor tube with a PVC cap/plug,
clean rag or tape to keep the gravel and resin
out of the center of the riser.
3. Fill the tank approximately 1/4 -1/3 full of water.
The water will act as a buffer when loading the
gravel and prevent any damage to the lower
distributor.
4. Determine the amount of gravel and resin
required for each tank. When coarse, medium
and fine gravels are specified, add in that
order. Slowly pour the gravel into the tank. Try
to keep it as level as possible.
(Not all systems have multiple sizes of gravel)
5. Once the gravel has been loaded. Slowly pour
the determined amount of resin into the tank.
Try to keep it as level as possible.
6. Flush the tank opening with water to clean
resin beads from the top of the tank. Then,
remove the cap, plug, rag or tape from the
distributor pipe. Apply a light coat of approved
lubricating silicone to the top edge of the pipe.
(DO NOT USE PETROLIUM LUBRICANTS,
ie. Vaseline)
7. Finish filling the tank with water, up to the
top. This will eliminate air space and prevent
excessive air – head pressure when the water
conditioner is pressurized.
8. Once completed, lubricate the o-ring and
carefully install control valve, then secure the
top flange.
9. Keep power off until final checkout procedure
is completed.
1
4
5
3
2
6

3.3 Start-Up Procedures
1. Once the piping and installation completed, and with the mineral in the tank, proceed
with the following.
2. Open the manual by-pass valve. The manual inlet and outlet valves are to remain closed.
3. Plug electrical power of the main controller to a wall outlet (120v)
4. The main controller is a Fleck NXT2. The controller is now ready to be programmed.
See Section 8. Familiarize yourself with the proper manual, on proper wiring and
programming procedure for your specific controller.
5. Once the programming is completed, manually set the valve unit into backwash. Slowly
open the manual inlet valve. DO NOT OPEN INLET VALVE COMPLETELY. (Full flow
of water could cause loss of resin) Water will enter in the bottom of the mineral tank,
causing any air to expel from top to the drain. Continue to slowly fill until all the air has
expelled from the tank and only water flows to drain.
6. When only water flows to drain, open manual inlet valve completely and continue
backwashing until water is clear from any color.
7. Manually set the unit through regeneration one step at a time. When doing this make
sure the piston completely comes to a stop before proceeding to the next step.
8. Fill brine tank with proper amount and type of salt recommended.
9. Close the manual by-pass valve and open manual outlet valves. The system is ready
for service.

Section 4: Operating & Regeneration
Procedures
4.1 Normal System Operation
The system is designed for fully automatic operation. Service runs will automatically terminate
when an exhaustion end-point is reached.
Although it should not be absolutely necessary to observe every regeneration, Operators should
periodically witness a complete cycle to make sure that critical flow rates and steps have not
gotten out of adjustment.
Daily
Date and Time
Meter Reading
Outlet Hardness
Inlet Hardness
Inlet and outlet pressure gauge readings; calculated pressure drop
Record Salt Usage
Miscellaneous
All of this information can be invaluable in detecting if something is going wrong, or when trouble
shooting. High-pressure drop during the run can be symptomatic of buildup of suspended solids
on the bed or excess breakage of resin beads. Short runs or higher than normal effluent hardness
could be caused by resin fouling. This could be caused by malfunction during regeneration or
even a contaminated batch of salt.

4.2 Multi-Port Valve Operation
(See Section 8 – Fleck 3900 Control Manual)
Multi-port valve consist of Fleck 3900 multi-port double piston operated valve. The valve operates
with upper and lower piston that moves on a seals and spacer assembly. The upper piston is for
regeneration and the lower piston is for service. The piston moves to a certain location, which
determines the operation position of the unit.
SERVICE
During service flow, raw water passes through the valve and downflow through the softener up
through the distributor tube to service. Service flow continues until the water meter/counter has
signaled an end of run and will automatically switch service flow to the other unit and go into
regeneration.
REGENERATION
Based on 10 grains/gallon of hardness as CaCO3, approximately 3000 gallons of water per cubic
foot of resin in the softener can flow before exhaustion of resin.
BACKWASH
Raw water flow is diverted to pass down through the distributor tube and up-flow through the
softener. The water expands the bed scrubbing the resin beads and washing any entrapped dirt
out to drain. Backwash sequence lasts approximately 15 minutes.
BRINE AND SLOW RINSE
Raw water is directed through the ejector located at the multi-port valve creating a venturi action
in the ejector to draw the required amount of brine into the softener. The brine float air check
valve shuts off the brine flow when the preset draw down is reached. Raw water continues to
the drain slow rinsing the resin for the remainder of the cycle. Brine and slow rinse sequence
generally lasts 60 minutes.
FAST RINSE
Raw water passes through the multi-port valve down flow through the softener and out to
drain. This sequence removes all remaining brine from the resin and lasts 10 minutes. When the
regeneration cycle is completed and the softener goes back into service, raw water will backflow
through the ejector refilling the brine tank to its normal level. The brine valve float will control
water makeup level.

Section 5: Operator Responsibilities
Operator Maintenance
Long term, reliable system performance depends upon how conscientiously the equipment is
operated and maintained. Operator responsibilities should include the following recommended
practices:
1. Maintain Operating Logs - Operators should maintain close control of the process by
monitoring system performance daily. Effluent hardness, service run lengths and pressure
drop should be recorded. Since resins are subject to fouling, decrease in product quality
or run length could be the result of fouling. In addition to operating data, log notations
should include equipment design changes, or modifications in programmed times. This
information can be invaluable if trouble shooting is ever required.
2. Check Regeneration Flow rates - Check and adjust flows during regeneration on a regular
basis.
3. Institute, a Program of Preventative Maintenance - Setup a definite schedule for routine
maintenance. Typical recommended practices are: annual resin sampling and analysis;
and annual inspection, lubrication and/or replacement of diaphragms on all diaphragm
valves.
5.2 Salt Specification - Use Salt As Specified.
a. Type - Rock salt or evaporated salt
b. Color - White to grayish white
c. Composition - Not less than 98% sodium chloride, with a minimum of calcium and
magnesium salts; zero phenolphthalein alkalinity (Alkalinity P); no grease, fat, or oil
content
d. Fineness - Softeners using polyethylene brine tanks, with no gravel in the bottom, must
use an extra coarse grade of rock salt.
e. Solubility - The salt should dissolve rapidly without packing, to form a clear solution.

Section 6: Trouble Shooting
6.1 General
The most common system failures are either “poor water quality’ or “short service run. If the change in
performance occurs suddenly — i.e., within a couple of operating cycles, 9 times out of 10 these problems
result from:
a Insufficient regenerating chemical quantity,
b Poor control of chemical concentrations and/or flow rates,
c Over-running (over exhausted) resin beds during a service run
d Flow channeling because of a plugged or failed internal flow distributor.
If however, the change occurs gradually over a period of weeks or months, the problem is more likely due
either to a change in feed water mineral content or from fouling of the resins. Under any circumstance,
the importance of maintaining Operating Logs cannot be stressed too strongly. Study of the Log will
often reveal any trend that might be developing. In the case of fouling, periodic resin analyses are the
only way to identify such problems.
General guidelines that wilt assist in determining common operating difficulties are given below. Often
poor performance results because of one or more contributing factors. The recommended approach is
to go systematically through the list to see what symptoms apply and then to take corrective action.
6.2 Reduced Capacity Or Poor Effluent Quality
SOURCE OF TROUBLE POSSIBLE CAUSE CORRECTIVE ACTION
Change In Chemical Higher hardness Check hardness by
Composition Of in raw water chemical test. If it has
Raw Water changed, compute new
capacity and use new
meter setting
Softener Being Raw water has Check raw water hardness
Overrun Consistently more hardness and meter setting. Give
unit a “double regeneration
Meter setting is incorrect Reset meter per manual
Incorrect Chemical Test procedure in error Follow instructions carefully
Test Results
Chemicals for test Replace weak or
causing error contaminated test solutions
Meter Slippage Worn or damaged meter Replace or repair as necessary

Inadequate Using a weak (less than Recharge at required times
Regeneration 22 Be) brine solution Use salt which
meets specification
Use correct amount
of dilution water
Not using enough salt Check text for specified
amount. Use correct
saturated brine draw
(or pumpage)
Loss Of Ion Resin Surges during backwash Install pressure regulator
Replace lost ion
exchanger resin
*Fouling Of Ion Resin Oxidized iron (Fe) or If iron & manganese are
manganese (Mn) in oxidized form at source,
coating resin provide filter to remove.
If water supply is clear
when first drawn (Fe & Mn
are in soluble form)
eliminate any air leaks from
suction piping. Do NOT
feed chlorine or other
oxidizing chemicals before
softening the water
Organic matter (slime) Provide treatment to destroy
coating resin organic matter
Damage To Ion Resin High concentrations of Add reducing agent
chlorine (or other oxidizing (such as Sodium Sulfite)
agents) in water. or otherwise remove
Channeling - caused by:
1. Dirty or packed bed Backwash rate too low Adjust controller to
correct rate
Dirty inlet water or May require pretreatment
backwash water
2. Gravel hills, tipped bed Careless placement Inspect and probe bed
or potholes of supporting bed
Surges during backwash Install pressure regulator
Air in backwash water. Eliminate air leaks and
cause of surges
*NOTE: It is sometimes possible to restore a fouled bed to its original condition,
or very nearly so.

6.3 Increase Pressure Lose Or Decrease In Flow Rate
Dirty Or Packed Bed - See above for possible causes and corrective actions.
Restricted Flow – Obstruction in meter, piping or valves. Inspect and clean as required.

Section 7: Softener System Drawings & Specifications 7.1 Typical System 5 Duplex Interlock Unit Installation

7.2 Typical System 6 Duplex Parallel Unit Installation

7.3 Typical System 7 Duplex Alternating Unit Installation

7.4 Typical System 9 Triplex Alternating Unit Installation
2 Units in Service, 1 Unit is Standby