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For Neutralising Acid Water and Remineralising very Pure Water

Ph Correction

When rain falls, the water has a naturally aggressive, slightly acidic nature. This water then dissolves chalk and/or metallic deposits present in the local rock strata which leads to contamination of the water. This results in ground and borehole water containing a number of elements that would not otherwise be present in mains water. These contaminants (such as iron and manganese) then cause problems when the water is put into use.


Acidic water results in corrosion of pipework, heating cylinders and equipment. Any iron and manganese present will result in poor tasting water, in addition to staining baths, basins and any appliances with which the water may come into contact.


A pH valve below 7 is considered to be acidic, and corrosion accelerates at pH levels below 6.5, with levels below 6.0 considered to be extremely aggressive. It is usually difficult to remove iron and manganese from acidic water, so often the first step in the process is to raise the pH.


The simplest and safest way to raise the pH is to run the water through a pressure vessel containing a bed of specially activated limestone. This is a mixture of calcium and magnesium salts, which are the salts found in waters of pH greater than 7.0. This limestone gradually dissolves increasing the pH level of the water. As the limestone dissolves, it will need refilling periodically. Refilling is straightforward as the media is inert and easy to handle.


To treat waters that are otherwise clean and pure, a basic up-flow system is all that is require. For water with iron, manganese or turbidity problems, an automatic backwashing downflow system will be needed to remove accumulated debris. Water with a pH below 5.0 is uncommon and is unsuitable for this type of treatment.


Specifying and Sizing

The contact time of the water with the pH correction media is important in achieving consistent results. The recommended maximum service flows for each system are shown in the Technical Details tables below.


For every 10mg/L CO2 present in the water, the alkalinity and total hardness will be raised by approximately 18 mg/L as CaCO3. For each 10 mg/L CO2 removed, there will be a consumption of approximately 12 mg/L of media.


System Management - upflow

Upflow 'manual' pH correction units are used for raising the pH of otherwise clean water, or for the re-mineralising of pure water produced by Reverse Osmosis or desalination. For water with significant iron and manganese levels an auto-backwashing or combination system will be required. Domestic units up to 13" include service flow controller and quick release couplings (QRCs) for ease of refilling. Larger industrial systems of 14" diameter and above use a top and bottom entry vessel for maximum flow. These do not include flow controllers or QRCs. With certain waters periodic manual high volume flushing will be needed in a 'manual' system to break up any Calcium Carbonate that has re-deposited onto the pH correction media bed. A manually operated flushing system can be incorporated into the unit at the time of manufacture. 


Technical details and model numbers - Upflow


pH  Correction Model FpH1054M FpH1248M FpH1354M FpH1465M Fph1665M FpH1865M FpH2160M FpH2469M
Flow rate
0.60 0.85 1.00 1.20 1.50 2.10 2.60 3.40
3/4" BSP 2" socket
Height (mm) 1455 1296 1445 1920 1920 1980 1860 2210
Diameter (mm) 270 315 335 370 410 510 560 620

System Management - backwashing systems

Backwashing systems include service and drain line flow controllers. 

NB Backwash flow per vessel is 1.5 times the service flow. Therefore when possible use two or more small units instead of one large one to reduce the pumping requirement. In areas of high media usage, special vessels can be supplied with an additional filling port eliminating the need to remove the backwashing valve during media replenishment.


Technical details and model numbers - Automatic backwashing systems

pH Correction
FpH1054 FpH1248 FpH1354 FpH1465 FpH1665 FpH1865 FpH2160 FpH2469 FpH3072 FpH3672 FpH4278
Flow rate (m3/hr) 0.60 0.85 1.00 1.20 1.50 1.90 2.60 3.40 5.30 7.70 10.50
B/W flow (m3/hr) 0.90 1.28 1.50 1.80 2.25 2.85 3.90 5.10 7.95 11.55 15.75
Connections (In/Out) 1" BSP 1" /11/2"
2" BSP
Height (mm) 1610 1460 1610 1890 1895 2020 1850 2210 2370 2450 2220
Diameter (mm) 270 315 335 370 410 510 560 620 770 930 1080


NB. To prevent damage to the vessel these filters must be protected from negative pressure from the drain or supply. A vacuum relief valve is recommended on the inlet supply and is supplied with all vessels from 370mm diameter upwards.


Special product features:

High efficiency British made media uses less mineral volume to correct pH than conventional systems. Replacement media is safe to handle and convenient.


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