The control valve is the the key to any treatment system. Whether the system is a cabinet water softener, a commercial or industrial water softener or a backwashing filter system, all of these systems require a control valve. The valve is typically mounted above the vessel in most systems. These are mainly automatic in operation and control the various phasas of the treatment process. In a water softener the cycles or phases typically are backwash, brine pick up, fill and fast rinse. The duration of these different parts of the cycle depend on the hardness, the capacity of the system and the media being used. The larger the system, the longer the cycle times necessary. The control valve completes these various parts of the regeneration cycle dependent on the programming. Once programmed the valve will automatically carry out the commands in the program. The trigger for regeneration can be either based on time or volume of water treated. The most efficient method of water softening utilises a volumetric system which monitors the volume of water being used to determine when regenerations are required. Time control is more suited to filtration where the only regenerate used is water and perhaps air. Typically there will be a small premium for the volumetric or metered water softener control valve. The pay back period is generally less than one year’s salt saving and the reduction of water used for regeneration will make this shorter again
A device installed as part of a water system through which water flows for the purpose of removing turbidity, taste, color, iron, or odour. Filters can be loose media beds in vessels or cartridge -type devices and filter media can be used for mechanical, adsorptive, neutralising or catalyst / oxidation filtration processes.
Filter and water softening systems typically utilises a control valve as previously covered. These control valves are mounted onto pressure tanks generally referred to as Vessels. These have a threaded “neck” with a squared shoulder to receive the control valve to provide a seal.
A vessel is designed to contain the pressure of the water system and typically consist of a PTFE liner which is then wrapped in a coating of GRP to ensure rigidity and the ability for ” cycling” which refers to the raising and lowering of pressure which occurs many times each day.
Regeneration is the term given to the process of renewing or rejuvenating the media. Any system for water treatment will have an optimum capacity whereby it will perform to it’s best, but beyond which the performance falls away. This is true of water softeners as well as filter systems. This is referred to as the capacity of the unit. Once a water softener or an automatic filter unit reaches it’s capacity it is necessary to regenerate so as to renew it’s ability to perform it’s function. In the case of a water softener this involves the use of Brine made up of water and salt. This regenerant is used to displace the contaminant ions deposited on the ion exchange resin during the service period. These contaminants are washed away to drain and replaced with sodium ions ready to return to service. Water softening resins are designed to exceed 900 regenerations. This means that if a water softener regenerates 3 times per week then you can expect beyond six years resin life. This is a minimum, so if the softener only regenerates twice per week you can see that the life of the resin should exceed ten years.
After the regeneration the control valve goes into Service position:This is the normal position for a control valve. It means that the raw water is entering the control valve and passing through the media bed, being treated and going to service as demanded.
In the case of larger water softeners you would typically have a vessel with a control valve mounted on top. Beside this you would have a salt bin. These allow for the storage of two or more bags of salt in the salt bin, so the brine tank only requires filling less often.
Backwash:Water softeners and filtration units backwash as part of the regeneration process. Backwashing is to reverse the flow of water through the vessel. This is done internally and is used to wash to drain all of the contaminants the filter unit has trapped during it’s service period. This allows the unit to go back into service refreshed and ready to start from scratch and extends the life of the filter media. Water enters through the inlet connection and flows through the vessel in the reverse direction from the service flow. This water then runs to drain so it doesn’t enter the house.
Fast rinse: This is the position of a control valve typically before it returns to service. In this position the water is running through the media in the direction of the service water but is being sent to drain.
Salt consumption: The rule of thumb is that the larger the softener is, the more salt efficient it is. This also applies to water consumption. A large water softener, of 20 – 25 litres volume of resin will only require to regenerate maybe every 7,10 or 14 days. Because of the height of these units the brine is being drawn through a taller column of resin. This means that the brine is utilised to it’s maximum efficiency and marginally less salt is used in comparison to a cabinet softener with a shorter column of resin. The same can be said of the water used.
With all water softeners the phases of the regeneration are the same. With a larger softener the frequency of regenerations is reduced. This means that even though the various stages are longer for a larger unit they are still more efficient due to the reduction of regenerations needed