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Water Treatment For Open Recirculating Systems

Water Treatment For Open Recirculating Systems

There is nothing more important in the prevention of Legionnaires disease than correct water treatment.

This section contains the information you need, to have the very best water treatment operational for open, recirculating systems.

It commences with all the steps that must be taken to achieve the highest quality in any open recirculating system. Some of the features are…………

1.Routine Treatment Program

This tells you how to kill Microorganisms, including Legionella species which cause Legionnaires disease and prevent further growth. These microorganisms also actually worsen any corrosion and scaling and already present.

2. Corrosion Inhibitors

All the recommended ones are listed and their mode of action described.

3. Scaling And Fouling Inhibitors

Deals with conditions which favour scaling as well as sites in the water system which are particularly prone to the condition.

4. Scaling And Anti Fouling Chemicals

Again the way these work is described, also safeguards to take before using them.

5 Bleed Off Techniques

These describe the bleeding off to waste of a portion of the systems water.

These are almost always used in open recirculating systems

and are an absolute must.

Unfortunately poor techniques are often used and all too frequently there is an inadequate level of care and competency in using and maintaining good ones.

You will learn from this section how to attain the very best practice.

A.Manually Adjusted Bleed Off Valves

The problems with these are discussed.

B.Catcher Type Bleed Off

This is described along with its disadvantages

C.Combined Standard Dose Of Chemicals And Amount Of Bleed Off

The principle features of this approach to water treatment for open recirculating systems are given here along with details of inadequate function due to design.

6.Corrosion Rates, Coupons

These are a basic part of all good water treatment systems. In this section you will find instructions on their correct use and placement.

7. Cathodic Protection

This is a very valuable part of our corrosion prevention program in which a particular piece of an added special metal has no purpose other than to be preferentially dissolved on order to protect the metals used in the systems structure.

8. Deposition Coupons

These too, like corrosion coupons are a basic part of all good water treatment. Their use and correct positioning are described.

9. Biocides

Adequate water treatment for open recirculating systems demand the use of suitable biocides. There are no exceptions allowed to this rule. It is very important to be familiar with biocide use.

Their action in killing microorganisms and preventing re- growth is of vital importance in preventing legionnaires disease and other diseases.

There are other benefits from their use. Corrosion and bad odours are also prevented thus helping to maintain an adequate circulating water rate. They are subdivided into the oxidizing and non-oxidizing biocides.

10. Clean Systems

Unless a water treatment system is thoroughly clean it cannot be regarded as adequate. There is no priority higher than this.

The following headings are for sections describing these components of water treatment for open recirculating systems that are particularly important in achieving a thoroughly clean system……. Read Carefully

11. Silt Removal

Defines silt and how to remove it


Necessary to improve the wetting power of biocides

13. Bleed Lockout

This lessens chemical wastage thus helping to maintain an adequate level of residual.

This section also covers the use of the blowdown facility

14. Chemical Feeders Inhibitors

This key section describes the features of the best practice systems in which the chemical inhibitors are put into the water automatically by an electronically controlled pump which adjusts the amount of chemical and water required according to and activated by the conductivity level as measured by a conduction meter in the system.

15 Biocides, Oxidizing and Non-Oxidizing

To be used only in a suitable automatic dosing system

16. Dispersants

Essential for anti-fouling and scaling inhibition and by prevention they increase biocide affectivity

17. Best Water Treatment Practice For Cooling Towers

The basics of water treatment for open recirculating systems do not alter but there are additional features to consider in special applications. The following is an outline of those features which are detailed in the cooling tower section.

a.Design Requirements

Aim for minimal water loss, choose durable materials which are corrosion resistant. Consider carefully the pipe layout, and ensure ease of access to tower.

b.Building Specifications

Details of all plans and the actual installation must be formally approved and documented.

c. Choice of Water Treatment Company

A company selected must possess demonstratable competence and details of legal requirements in this regard are given in this section.

d.Hydrostatic Pressure Testing

For details refer to this section

e.Water company responsibilities for Each State Of Treatment

The right documentation for this is a must.

f. Pre- Treatment

This essential procedure must be carried out before commissioning. Omit no steps here.

g.Chemical Testing

Refer to section

h.Testing For Legionella (Legionnaires Disease) and other Microorganisms

An absolutely essential part of routine treatment.

i.Adherence to Chemical Procedures

As well as this summary’s contents there must be strict adherence to all recommendations. Described under the principal heading “Water Treatment For Open Recirculating Systems” The procedures are listed under headings 1-17 of this document.