- 1 cubic foot of resin = 30,000 grains of capacity
- 1 grain per gallon = 17.1 PPM
- Regenerate with 15 pounds of salt per cubic foot of resin. 1 gallon brine = 2.6 pounds of salt.
- Keep brine strength > 95% salinity.
- Brine strength and contact time during regeneration should be 30% for 30 minutes.
- Test daily. Know influent water make up quality.
- Know capacities, operating, and control characteristics of softener system.
- Know resin condition. Have routine sodium elution study performed.
- Keep brine tank salt at proper level. Ensure brine tank is not overflowing.
- Know regeneration schedule and necessary regeneration cycle times.
A Primer on Ion Exchange
Water softening water is the process of removing potentially scale forming minerals from a system’s make up water. These scale forming minerals consist primarily of calcium and magnesium. These minerals, commonly referred to as hardness, are naturally occurring and found, to some degree, in most water supplies.
The procedure for removing calcium and magnesium (hardness) involves the process of ion exchange. This process involves the exchange of calcium and magnesium ions in the water for sodium ions. The exchange process takes place on the surface of a media that we commonly term resin. This resin bed is also commonly called sodium zeolite, and cation exchange resin.
The resin is a man-made product of polystyrene and divinylbenzene in the form of beads, about the size of the ball on a ball point pen. The nature of the resin is such that it has a negative (-) charge. The resin when charged, or regenerated is laden with sodium ions which have a weak positive (+) charge and are attracted to and attach to the surface of the resin beads. As hard water runs over the resin bed, the calcium and magnesium ions, which have a positive (+) charge are attracted to the surface of the beads and the exchange of calcium or magnesium ions for sodium ions occur. The result is that the water is termed “soft,” due to the fact that the “hard” minerals, calcium and magnesium, have been removed and replaced with the sodium ion.
This process will occur billions of times while a softener is in use. After a period of time, based on the size of the water softener and the hardness of the incoming water, the resin will become saturated with calcium and magnesium and hardness will start to leak through. At this point, the softener must be regenerated with a brine solution in order to displace the calcium and magnesium ions with sodium ions and recharge the resin beads. Once a proper regeneration has occurred, the ion exchange (softening) process can start again.
When treating water, whether for a boiler or cooling system, one of the major objectives is to prevent the formation of scale and mineral deposits. By far, the single largest contributor to the formation of boiler and cooling system scale is hardness in the system’s make up water. Left untreated or improperly controlled, calcium hardness can combine with other constituents, such as carbonate, and form calcium carbonate (CaCO3). This is the most common form of mineral deposit found in boilers and evaporative cooling systems.
The addition of a water softener to your facility may be one of the most cost effective improvements you can make. By reducing or eliminating the hardness in the make up water, there are several cost savings to be realized. First, there is a savings in chemical treatment. When hard water is introduced into a boiler, the two ions that make up the hardness, calcium and magnesium, must be chemically addressed to prevent formation of the undesirable compounds calcium carbonate and magnesium silicate. This is accomplished by adding treatment chemicals that will react with the hardness ions and form compounds that are relatively soluble and will form a sludge that falls to the bottom of the boiler and be blown down. Most commonly you will see phosphate used to combine with calcium to form calcium phosphate and sodium hydroxide or caustic to form magnesium hydroxide. These compounds are more resilient to plating out of solution and coating the heat transfer surfaces of the boiler. Combined with some of today’s polymeric dispersants, these compounds will stay in a fluid state until blown down.
In this simple example, it can be seen that by eliminating hardness from the make up, you could reduce the chemical treatment demand for your system. However, it goes further than this. Because the formation of more desirable compounds, calcium phosphate and magnesium hydroxide, is not instantaneous, they do not fall to the bottom of the boiler as quickly as they form. Therefore, additional blow down is needed to control the level of suspended solidsthat these compounds become to prevent them from plating out and/or baking to the heat transfer surfaces. Additional blow down means more water, more fuel, and even more treatment chemicals go to drain.
Soft water in a cooling system allows for higher cycles of concentration by reducing the saturation index or scaling tendency of the system water. Higher cycles of concentration are accomplished by reducing the bleed off or blow down of the system. When bleed off/blow down is reduced, the required treatments are reduced accordingly, and there are significant savings to be realized in water and sewage costs as well.
Is a water softener cost effective for your system? Your Water Treatment Consultant can show you more specific details of cost verses savings pertaining to your system(s).
As can be gathered, water softening is the process of exchanging of Sodium (Na) ions (that are attached to the resin bead) for Calcium (Ca) and Magnesium (Mg) ions. Many problems associated with ion exchange are due to insufficient Sodium available for the exchange process to occur. This usually indicates a problem in the regeneration cycle that prevents loading of sodium ions on the resin bead.
All conventional Sodium Zeolite Water Softeners operate in the same basic fashion. Consequently, there are some flow characteristics that are shared by all units. In service, water flows from the top of the unit down through the resin bed and out. As the water passes over the resin, the exchange of sodium ions for the Calcium and Magnesium ions takes place. When all of the Sodium has been exchanged, Calcium and Magnesium starts to become present in the effluent water. When this occurs, we say the resin bed is exhausted and must be regenerated to release the hardness ions and reattach more Sodium ions to the resin so that the ions exchange process can begin again.
Let’s review the Regeneration Process. The first stage of regeneration is backwash. During backwash, the flow of water is reversed. Flow is from the bottom of the unit through the resin bed and out the top and to drain. Backwash is designed to lift and “fluff up” the bed and to remove any debris that may have been brought into the unit with the incoming water. Backwash also serves to remove any resin fines from the softener.
The next step of regeneration is the brining cycle. This is probably the most important cycle of the regeneration process. During this cycle, Calcium and Magnesium ions are stripped from the resin beads and Sodium ions are reattached. Most Water Softener problems occur due to insufficient or improper brining.
During the brining cycle, the water flows into the top of the unit, flows across the resin and out the bottom of the softener to drain. Brine, which is Sodium Chloride (NaCl) or salt dissolved in water should be pumped or educted into the unit at a rate that allows the resin bed to be exposed to a solution of 30% saturated brine for a contact time of 30 minutes. During this contact time, the resin is stripped of hardness salts (Calcium and Magnesium) and Sodium ions attach to the resin beads. When the proper amount and strength of brine has been in contact for the appropriate amount of time, the unit is then rinsed of excess Chloride.
A slow or brine displacement rinse is part of the brining cycle. In most instances, the unit will also have a fast rinse. It starts the softening process and prepares the unit to be returned to service.
Some Water Softener troubleshooting guidelines are:
1. Check the condition and quantity of the ion exchange resin. Over time there is a natural loss of resin that can be 3% to 5% per year. The resin is also subject to fouling from materials that do not readily rinse off. Iron and some organic materials can coat the resin and prevent it from working properly.
2. Ensure that the brine tank has the right amount of salt and water. The brine has to be saturated with salt to be useful. Measured with a salometer, the brine should read 95% or greater. One gallon of saturated brine contains 2.6 pounds of salt.
3. Make sure that during the brining cycle, brine is being introduced to the unit at the correct strength and contact time. Many problems are the result of insufficient brine strength and/or contact time.
4. Know the incoming water characteristics and system demand.
5. Each cubic foot of ion exchange resin, when properly regenerated, has the ability to remove a specific amount of hardness. Over time, the incoming water quality may have changed sufficiently to require a change in the regeneration schedule to ensure soft water continuously. However, as is often the case, over time the demand on the system may be more than the original design.
Identifying problems with a Water Softener sometimes requires no more than simply observing the regeneration process and making a few adjustments of procedural changes. Other times correcting a problem will require some specialized testing and checks. If you are experiencing difficulties with your Water Softener, contact your Water Treatment Consultant.
When updating your equipment, a few considerations should be made. All of these should be researched to determine what is best for you.
Price – This is put at the top of the list as it is one of the important factors, but continue on, and price will probably move down on your list.
1. What options would help me maintain more consistent programs – Biocide options, Flow Switches, Water Meter Read-outs, Dead band adjustability or given today’s technology, remote access through your computer.
2. Programmability – This is usually handled by your Water Treatment Consultant, but sometimes minor adjustments are made by plant personnel (i.e. Calibration and Inhibitor Feed Timer Adjustment).
3. Dependability – You get what you pay for. Some models are more reliable than others.
1. The adjustability of the pump. Some pumps have limited adjustment (i.e. 1 to 6 are your adjustments, other pumps have 1 to 100 speed stroke adjustments).
2. Pressure ratings. Your pump must have a discharge rating above your systems operating pressure.
3. Pump Output. Make sure your pump meets your needs. With a 30 GPD pump, your setting may be 10/10. If you had a 7 GPD pump, your setting would be 20/22 to yield the same feedrate. Try to get your pump to operate in the middle of its operating range.
1. Should be easily cleaned.
2. If system collects a lot of debris, maybe a motorized Ball Valve would best suit your needs.
1. Sample Time & Sample Interval Adjustability
2. Reliability of Controller
1. Ease of calibration
1. Location of installation sometimes determines what type of equipment you will use (i.e. some Towers have no usable wet taps, and a drop-in probe may need to be used).
As you evaluate replacing your control equipment, you can readily see that there are many considerations.
Pipe Diameter in inches (ID)
Wrought Pipe (iron, steel)
Extruded Pipe (Cu, Al, Plastic)
In many Water Treatment applications, electronic metering pumps are used. A common style of electronic metering pump has adjustments for the speed or frequency, the pump pulses, as well as the length of each stroke.
These adjustments are normally expressed as a percentage of maximum and are used to give the pump an infinitely variable output of its rated capacity. The pump settings are recorded as percent speed or frequency and percent stroke (i.e. 50% / 50%). Understanding these settings will give the operator insight as to the expected output of the pump at any given setting.
A common electronic metering pump output is 24 gallons per day (gpd) when set at 100% Speed and 100% Stroke. This relates to 1 gallon per hour of continuous operation or approximately 2 fluid ounces per minute. By adjusting the settings you are able to tune the pump, with a great deal of accuracy, to deliver the desired amount of liquid to a system or application. The flexibility of this type of pump allows the operator an opportunity to use the same style and model of pump for an infinite variety of applications and reduce repair or replacement parts inventory to one type from one source. Different delivery and pressure ratings are available as well as materials of construction to meet most application needs.
There is often confusion in the adjustment and setting of electronic metering pumps. This sometimes results in “chasing” a pump setting that will yield a desired level. The “trick” to mastering the adjustment of this type of pump is to look at each setting, speed or stroke as the percentage of maximum for each. For instance, a setting of 100% Speed and 100% Stroke on a pump rated at 24 gpd. should have an output of approximately 1 gallon per hour. The same pump with a setting of 50% Speed and 100% Stroke should yield an output of approximately ½ gallon per hour. The same pump with a setting of 50% Speed and 50% Stroke will deliver approximately ¼ gallon per hour. When adjusting this type of pump, keep in mind that each setting, speed and stroke, will affect the output proportionally.
A very common error in adjusting an electronic metering pump is to change both speed and stroke settings resulting in a final output that is twice the intended change. By way of example, assume a pump setting of 100% Speed and 80% Stroke on a pump with a rated capacity of 24 gpd. The system being treated is in a steady, stable state of operation and the product being delivered has a tested residual of 10 ppm. Assume further, the desired product residual is 5 ppm.
The 100% / 80% pump setting yields the following: 100% Speed = 1, 80% Stroke = 0.8, Capacity = 1 gallon (128 fluid ounces) per hour. Given this information, the pump would deliver 102.4 fluid ounces per hour (1 x 0.8 x 128 = 102.4). This feedrate is resulting in the 10 ppm residual mentioned above.
To reduce the product residual to the desired 5 ppm, the pump output should be reduced by ½. Given all other conditions remain stable, one approach would be to reduce the speed setting to 50% and leave the stroke setting at 80%. This yields the following: 50% Speed = 0.5, 80% Stroke = 0.8, Capacity = 1 gallon (128 fluid ounces) per hour. The pump would now deliver 51.2 fluid ounces (0.5 x 0.8 x 128 = 51.2 fluid ounces), ½ of the original delivery. Another approach would be to leave the speed setting at the original 100% setting and reduce the stroke setting to 40%, resulting in the following: 100% Speed = 1, 40% Stroke = 0.4, Capacity = 1 gallon (128 fluid ounces) per hour. 1 x 0.4 x 128 = 51.2 fluid ounces per hour of operation, again ½ of the original output.
It is important to remember that each setting, speed and stroke, is a percentage of the maximum for each and that by changing either, you will effect the output by a corresponding percentage. A common situation occurs when there is a desire to reduce the delivery of a pump, as shown above, and both settings are reduced by ½. The result would be 50% Speed = 0.5, 40% Stoke = 0.4, Capacity = 1 gallon (128 fluid ounces) per hour. 0.5 x 0.4 x 128 = 25.6 fluid ounces per hour of operation or ¼ of the original setting. This would yield a tested residual, from our example, of 2.5 ppm, 25% of the original setting.
The intent of this discussion is to help clarify common misunderstandings that are observed in day to day application of Water Treatment Programs. A better understanding of the operation of electronic metering pumps will aid in establishing and maintaining Water Treatment Residuals in the desired control ranges for optimum Water Treatment Program Results.
The use of non-chemical devices (NCD) to condition water systems for scale, corrosion, or fouling is not a new concept. In fact, it goes back to the days of the Civil war when NCDs were being patented for use on boilers to control scale. The idea back then, as now, was to exploit the human desire to get something for nothing.
Today, non-chemical devices are marketed in the same manner as soaps, detergents, and even toothpaste by stating that they are “new and improved.” The old system is outdated, but new discoveries and a new patent claim now makes these “new and improved” devices valid. Do not be intimidated by a patent claim or number. The United States Patent Office does not have the capabilities to authenticate a claim or even to verify the effectiveness of the device. The patent office will only determine if the device is original and unique.There have been many studies performed by universities, independent labs, NACE International, and even the country of Germany. In fact, Germany requires testing of all non-chemical devices. The test is designated W-512 and was developed in 1995. It seems that all these studies came to the same conclusion: there was no beneficial result in using a non-chemical device. It is interesting to note that a chemist who studied NCDs once stated that the United States government spent millions to develop the atomic bomb by splitting the atom, and now “gadget” manufacturers are trying to do almost the same thing for a few thousand dollars. The U.S. government should have saved their money and called on these people. Look at the money we could have saved.
Until the time comes that a standard test is in place and required by regulatory agencies and insurance companies to validate the non-chemical device, how can a buyer protect his equipment? There are a series of questions that should be asked by the buyer, and a vender should respond with factual information and not by just a series of testimonial letters. The buyer needs to follow a formal procedure of risk/benefit analysis. If this is not available, then the buyer needs to determine the possible savings versus the possible losses. If the buyer is comfortable with his findings and still wants to proceed, there are seven questions that should be asked of any vendor. The following questions were developed by NACE International as an appendix to their document 7K198, Publication Item Number 24195:1. How do you know the device is performing the function for which it was installed? What is the accepted standard method that determines the performance?
2. What means will be used to size the equipment or process? In other words, show the formula used to calculate the size of the unit that relates to the performance of the unit.
3. Under what conditions will the equipment or process perform the desired function as intended? Name the range of applications. Spell out the operational limitations under which it will not yield the desired results. What are the variables (e.g. fluid flow rate, heat load, etc.) that would cause the vendor to recommend a change in size or type of equipment?
4. Has an independent testing laboratory such as the National Sanitation Foundation or the German DVGW tested and approved the equipment or process for its intended use using a technically sound protocol?
5. Are there documented case histories of successful applications similar to the intended usage? The documentation should include flow rates, heat exchanger efficiencies, water chemistry, metallurgy, fouling factors, corrosion rate monitoring, and objective data before and after installation.
6. What are the cost of installation, maintenance, and operation of the equipment or its components? Are there any energy costs, extra water usage costs, and any wastewater treatment costs?
7. What is the expected mean time of failure for the product, what is and is not covered under warranty, and specifically, under what conditions is the warranty VOID?
Some additional items that we feel should be addressed in order to make a final decision are:
1. Does the vendor/manufacturer have sufficient product liability insurance? All water treatment chemical vendors have had to provide this coverage to their clients on a regular basis for years.
2. Is the manufacturer and its distributor registered to do business in your state? If not, they gain an unfair economic advantage by not paying their fair share of taxes and fees. Also, they can avoid litigation claims, if they occur, since they have no agents of record in that state.
3. What effect will the installation of the NCD have on the manufacturer warranty of the chiller, boiler, or associated equipment?
4. In order to describe what allows any diaphragm (Asco, for example) solenoid bleed valve to function, we need to understand all the parts and their purposes. The solenoid bleed valve consists of the valve body, a rubber gasket, a diaphragm (with a bleed and pilot home) a core, core spring, valve bonnet (a.k.a. top body), and a coil.
5. In the closed position, water enters the valve body, but cannot pass through it. The water is directed to the bottom side diaphragm, where it flows through the pilot hole. The water fills the top side of the diaphragm and pushes the diaphragm down to seal against the valve body. Line pressure is applied to the entire top side of the diaphragm and to the outer edge of the bottom side of the diaphragm. The differential pressure seats and seals the diaphragm and seals the valve closed.
6. When the valve is energized and called upon to open, the core is magnetically pulled up into the bonnet. This unseats the pilot home and water from the topside of the diaphragm flows through the valve body. This allows water to pass through the valve. When the solenoid de-energizes, the core spring pushes down on the core and re-seats the pilot hole. The topside of the diaphragm fills again and shuts off the water flow.
In order to describe what allows any diaphragm (Asco, for example) solenoid bleed valve to function, we need to understand all the parts and their purposes. The solenoid bleed valve consists of the valve body, a rubber gasket, a diaphragm (with a bleed and pilot home) a core, core spring, valve bonnet (a.k.a. top body), and a coil.
In the closed position, water enters the valve body, but cannot pass through it. The water is directed to the bottom side diaphragm, where it flows through the pilot hole. The water fills the top side of the diaphragm and pushes the diaphragm down to seal against the valve body. Line pressure is applied to the entire top side of the diaphragm and to the outer edge of the bottom side of the diaphragm. The differential pressure seats and seals the diaphragm and seals the valve closed.
When the valve is energized and called upon to open, the core is magnetically pulled up into the bonnet. This unseats the pilot home and water from the topside of the diaphragm flows through the valve body. This allows water to pass through the valve. When the solenoid de-energizes, the core spring pushes down on the core and re-seats the pilot hole. The topside of the diaphragm fills again and shuts off the water flow.
|Valve Does Not Open
||Check power to coil, replace if defective
||Pilot Hole Plugged
||Clean pilot home, replace diaphragm if necessary
||Valve Bonnet Will Not Allow Core to Rise
||Clean and ensure smooth operation of core
||No Water Pressure on Valve
||Open valves to solenoid
|Valve Constantly Leaks Water
||Debris Between Diaphragm and Valve Body
||Close bypass valve
|Valve Does Not Close
||Core Does Not Close Pilot Hole
||Replace missing core spring, clean debris blocking pilot hole
||Bleed Hole in Diaphragm Clogged
||Clean bleed hole
||Diaphragm too Stiff to Seal Against Valve Body
||Clean or replace diaphragm
These are a few possible problems that cause bleed valves not to operate properly. If problems with your valve persist, contact your Premier Water Treatment Consultant.
From time to time we come upon systems where the conductivity and inhibitor levels are low. Troubleshooting this condition usually involves the following procedure:
First, a visual inspection of the bleed valve is made to ensure water is not passing by the valve. If water is passing by the bleed valve, then a repair is in order.
Next, the water level in the tower is checked to ensure it is below the overflow pipe. If it is not, adjustment to the float should be made.
Finally, if possible, compare the make-up meter reading to the bleed meter reading. This ratio should be comparable to your system’s cycles of concentration (i.e. 300 mmhos in the make-up to 1200 mmhos in tower equals four (4) cycles of concentration). If the make-up to bleed meter ratio is higher than the cycles of concentration, uncontrolled water loss is occurring. The most common causes of uncontrolled water loss are bleed valve malfunction and an overflowing tower.
There are a couple of ways to check for tower overflow other than minute to minute observation. One way is to place a crumpled paper towel into the overflow pipe and inspect the paper towel each morning to see if it is wet. If it is wet, overflow has occurred. Another method is to place a “drop-in” tablet toilet bowl cleaner (Vanish blue is preferred) under the overflow pipe. This would need to be checked daily, and if there is blue dye around the drain, the tower is probably overflowing.
Remember, the tower water level should be kept at least four (4) inches below the overflow stand pipe at all times (including at shutdown) to keep unchecked water loss to a minimum.
For additional help in tracking down water loss, contact your Water Treatment Consultant.