Water aggressiveness evaluation and optimized lining choice

This document provides details about the aggressiveness factors, evaluation indicators of raw water, or inlet water of ductile iron pipe system and relevant lining information applicable to ductile iron pipes, fittings and accessories used in water mains and distribution system. This document is intended to serve as a tool for estimating the properties of certain water and their effect on internal linings of ductile iron pipes, fittings and accessories used in water mains and distribution system which are specified in ISO 2531, ISO 16631 and can be used to decide the most appropriate protective measures to ensure long term durability of pipeline. It is not always possible to definitively determine the aggressive parameters of certain water, and fully considered by limited test and evaluation. Therefore, the history information of the evaluated water, experiences of local water works can be taken for reference. The aggressiveness evaluation of water can be carried out before determining the internal lining materials of certain pipeline, and the evaluation and relevant tests can be done by qualified laboratories and engineers. Water that leads to high-level scaling in the pipeline is believed aggressive. Drainage and waste water are not in the scope of this document, the internal protection of drainage and waste water can be recommended by pipe suppliers.

Évaluation de l’agressivité de l’eau et choix optimal des revêtements intérieurs

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TECHNICAL ISO/TR
REPORT 4340
First edition
2022-06
Water aggressiveness evaluation and
optimized lining choice
Évaluation de l’agressivité de l’eau et choix optimal des revêtements
intérieurs
Reference number
ISO/TR 4340:2022(E)
© ISO 2022
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ISO/TR 4340:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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Published in Switzerland
© ISO 2022 – All rights reserved
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ISO/TR 4340:2022(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 Water aggressiveness evaluation ...................................................................................................................................................... 2

4.1 Normal internal corrosion mechanics ............................................................................................................................... 2

4.2 Internal protection of ductile iron pipe ............................................................................................................................ 2

4.3 Water aggressiveness evaluation for ductile iron pipe system................................................................... 3

4.4 Main corrosive aggressive factors ........................................................................................................................................ 3

4.5 Water evaluation indicators and their trigger value ............................................................................................ 4

4.5.1 Langelier saturation index (LSI) .......................................................................................................................... 5

4.5.2 Ryznar stability index (RSI) ................................... .................................................................................................. 5

4.5.3 Calcium carbonate precipitation potential (CCPP) .............................................................................. 5

4.5.4 Larson ratio (LR) ................................................................................................................................................................ 6

4.5.5 Aggressive index (AI) ..................................................................................................................................................... 6

4.5.6 Evaluation chart .................................................................................................................................................................. 6

5 Sampling and testing .......................................................................................................................................................................................7

5.1 Sampling ....................................................................................................................................................................................................... 7

5.2 Testing ............................................................................................................................................................................................................ 8

6 Optimized lining choice based on water evaluation ...................................................................................................... 8

7 Steps for water aggressiveness evaluation and optimized lining choice ................................................8

Annex A (informative) pH .............................................................................................................................................................................................. 9

Annex B (informative) Relevant test standards ...................................................................................................................................12

Annex C (informative) Type and characteristics of water-related concrete corrosion .............................18

Bibliography .............................................................................................................................................................................................................................19

iii
© ISO 2022 – All rights reserved
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ISO/TR 4340:2022(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 5, Ferrous metal pipes and metallic fittings,

Subcommittee SC 2, Cast iron pipes, fittings and their joints.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
© ISO 2022 – All rights reserved
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TECHNICAL REPORT ISO/TR 4340:2022(E)
Water aggressiveness evaluation and optimized lining
choice
1 Scope

This document provides details about the aggressiveness factors, evaluation indicators of raw water, or

inlet water of ductile iron pipe system and relevant lining information applicable to ductile iron pipes,

fittings and accessories used in water mains and distribution system.

This document is intended to serve as a tool for estimating the properties of certain water and their

effect on internal linings of ductile iron pipes, fittings and accessories used in water mains and

distribution system which are specified in ISO 2531, ISO 16631 and can be used to decide the most

appropriate protective measures to ensure long term durability of pipeline.

It is not always possible to definitively determine the aggressive parameters of certain water, and fully

considered by limited test and evaluation. Therefore, the history information of the evaluated water,

experiences of local water works can be taken for reference.

The aggressiveness evaluation of water can be carried out before determining the internal lining

materials of certain pipeline, and the evaluation and relevant tests can be done by qualified laboratories

and engineers.
Water that leads to high-level scaling in the pipeline is believed aggressive.

Drainage and waste water are not in the scope of this document, the internal protection of drainage and

waste water can be recommended by pipe suppliers.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 2531, Ductile iron pipes, fittings, accessories and their joints for water applications

ISO 16631, Ductile iron pipes, fittings, accessories and their joints compatible with plastic (PVC or PE)

piping systems, for water applications and for plastic pipeline connections, repair and replacement

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 2531 and ISO 16631 and the

following apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
© ISO 2022 – All rights reserved
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ISO/TR 4340:2022(E)
3.1
scaling

dissolvable salts, residues of water pipeline inner surface reaction and other solids deposit on the inner

surface of pipeline components, which will reduce the cross-sectional area and increase the head loss

Note 1 to entry: Scaling is sometimes also harmful to water quality and pipeline service life. The scaling process

is normally related to the water chemical stability, temperature, flow rate, inner surface roughness of the pipeline

component.
3.2
corrosive water

type of water which attacks metal component (pipe, fitting, accessories) without an internal coating

Note 1 to entry: The chemical reactions produce ferrous and then ferric hydroxides, forming nodules and

tuberculation, which eventually reduce the component’s cross-sectional area and significantly increase head

loss, reduce the service life of metal pipeline components.
3.3
water aggressiveness
propensity to react with materials containing calcium such as hydraulic binders

Note 1 to entry: Depending on the chemical analysis, mineral content, pH and temperature of the water, three

cases can occur:

— Water in calco-carbonic equilibrium does not attack or deposit calcium carbonate at a given temperature.

— Scaling water tends to deposit calcium salts (carbonates, etc.) on the pipeline components’ inner surface.

— Aggressive water can attack certain components of cement mortar containing calcium (lime, calcium silicate

and calcium silicoaluminate).

Note 2 to entry: Normally, ductile iron pipe components are supplied with linings, and cement mortar linings

are the standard internal protection, so aggressive water and water aggressiveness are mostly used in this

document. But the reaction with uncoated metal surface is also considered and described in some parts of this

document.
4 Water aggressiveness evaluation
4.1 Normal internal corrosion mechanics

Internal corrosion mechanics of ferrous pipeline system have been studied for decades, according to

the state of art, major pipeline internal corrosion problems can be traced to the stability of calcium

magnesium carbonate system and iron system in the water. The status and the change of stability of

these systems can lead to the deposition and dissolvement of carbonate and ferrous compound, which

is the major reason of lining failure, red water, yellow water, scaling and related secondary corrosion.

The stability of calcium magnesium carbonate system and iron system are complex systemic ion

balance problem related to multiple positive and negative ions, and highly related to water temperature.

Considering those factors one by one is not a good way to get comprehensive information of the water

aggressiveness, those factors are a united system and can be considered systematically.

Many indexes and indicators are concluded to evaluate the aggressiveness or stability of water.

4.2 Internal protection of ductile iron pipe

Ductile iron pipes are normally supplied with internal linings. There can be some special applications

without internal linings. Linings are believed an effective way to protect the pipe when they are used

appropriately. It is possible to categorize all existing linings as isolation barriers (polymeric linings),

active protection (cement mortar lining), or their combination (cement mortar lining+seal coat). Cement

mortar linings are standard internal protection of ductile iron pipes, and currently, most of ductile iron

pipes are lined by cement mortar lining.
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ISO/TR 4340:2022(E)

Other linings or internal protections can exist or can be developed as the updating pursue of water

quality and pipeline service time.

Suitable lining choice based on water aggressiveness evaluation is beneficial to ensure the durability of

lining protection in the long term and reduce the negative effect on water quality.

4.3 Water aggressiveness evaluation for ductile iron pipe system

Ductile iron pipes and fittings are used at any part of the water distribution system. They will influence

other pipeline sections by the flowing water and be influenced as well. The interaction of ductile iron

pipe and water can be considered based on the stability of calcium magnesium carbonate system and

iron system. The interaction of water and cement mortar can also be considered at the same time.

In this document, multiple indicators with comprehensive consideration of aggressive factors based

on calcium magnesium carbonate system, iron system, and also the interaction of water and cement

mortar material are used to evaluate the aggressiveness of water.
4.4 Main corrosive aggressive factors

4.4.1 The pH value: the pH value of water is a measure of the concentration of the hydrogen ion

+ +

concentration (H or H O ). The pH scale ranges from 0 to 14. Values less than 7,0 are considered

acidic, values greater than 7,0 are considered alkaline, and 7,0 is considered neutral. Drinking water pH

values typically range from 6,0 to 10. At higher pH values, there is less of a tendency for metal surfaces

in contact with drinking water to dissolve and dissociate, which is why pH adjustment is a common

component of an effective corrosion control treatment strategy. Maintaining a consistent target pH

throughout the distribution system is always critical to minimizing lead and copper levels at the tap

and minimizing discoloured-water complaints, even if other corrosion control methods are employed.

Another important consideration with regard to pH is its impact on other water quality parameters.

It plays a significant role in the carbonate balance in that it impacts buffer capacity and dissolved

inorganic carbon (DIC) concentrations. It also influences other corrosion-related parameters, such as

oxidation–reduction potential (ORP) and corrosion inhibitor effectiveness.

4.4.2 Alkalinity: alkalinity is the capacity of water to neutralize acid. It is the sum of carbonate

2– – –

(CO ), bicarbonate (HCO ), and hydroxide (OH ) anions and is typically reported as milligrams per

3 3

litre as calcium carbonate (mg/L as CaCO ). Waters with high alkalinities tend to have high buffering

capacities or a strong ability to resist changes in pH. Low-alkalinity waters are less able to neutralize

acids or resist changes in pH.

4.4.3 Total dissolved solids/ionic strength: total dissolved solids (TDS) can have an impact

on corrosion, though the effect can be less than other corrosion-related parameters. High TDS

+ 2+ 2+ – 2–

concentrations are generally associated with high concentrations of ions (e.g. Na , Ca , Mg , Cl , CO ,

SO ) that increase the conductivity of the water. Corrosion is an electrochemical reaction in which

electrons from the anodic surface are transferred to the cathodic surface. The increased conductivity

resulting from high TDS concentrations increases the ability of the water to complete the electro

chemical circuit and conduct a corrosive current.

If sulfate and chloride are major anionic contributors to the TDS, the TDS is likely to show increased

corrosivity toward iron-based materials. If the TDS is composed primarily of bicarbonate and hardness

ions, the water will probably not be corrosive toward iron based or cementitious materials but can

probably be highly corrosive toward copper. Low-TDS waters can also be corrosive and increase lead

solubility. Low-TDS waters often have a strong tendency to dissolve (corrode) materials with which

they are in contact in order to reach electro neutrality. Uniform corrosion is an electrochemical process

in which the water solution in contact with the cathode provides the chemicals to accept the electrons

donated by the pipe wall. The pipe wall, acting as an anode, then releases the oxidized metal ion to

the water. Water has a limited capacity to accept dissolved species. Thus, although high-TDS waters

have many electron receptors, low-TDS waters have the ability to accept a large number of anions and

cations, resulting in a subsequent dissolution of existing pipe scales and corrosion of pipe surfaces.

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ISO/TR 4340:2022(E)

TDS is a surrogate for the ionic strength of a solution. The ionic strength is a measure of the force of the

electrostatic field caused by the presence of ions in a solution. More simply, the presence of anions and

cations in solution increases the conductivity of the solution and can increase corrosion unless offset

by passivating layers on the pipe surface. It is possible to determine the ionic strength as shown in

Formula (1).
I=2,5×10 ×TDS (1)
where: I = ionic strength; TDS = total dissolved solids concentration, in mg/L.

4.4.4 Dissolved inorganic carbon: DIC is the sum of all DIC-containing species and is one of the most

critical parameters for controlling internal corrosion. It includes dissolved aqueous carbon dioxide

– 2–

gas (CO or H CO ), bicarbonate ion (HCO ), and carbonate ion (CO ) in a particular water, and DIC

2 2 3 3 3

is usually expressed as milligrams per litre of carbon (mg/L as C) or milligrams per litre of calcium

carbonate (mg/L as CaCO ). Although DIC and alkalinity are similar, they are not the same water quality

parameter. DIC varies according to water temperature, pH, ionic strength, and alkalinity.

4.4.5 Hardness: hardness is a characteristic that represents the presence of dissolved multi-valence

cations, primarily calcium and magnesium, in water and is reported as an equivalent concentration of

calcium carbonate (CaCO ). Hardness can be taken into consideration when corrosion control is selected

and implemented because it can create scaling problems within the treatment plant, distribution

system infrastructure, and customer plumbing. In this regard, hardness is an important parameter to

be considered in developing a corrosion control program and evaluating the amount of pH adjustment

that is permissible without causing scale problems.

4.4.6 Dissolved oxygen: dissolved oxygen (DO) can play important roles in both corrosion reactions

and metals release. Oxygen can serve as an electron acceptor in the corrosion cell, allowing for metal

oxidation at the pipe surface and release of ionized metal species into the water. Thus, new metal

surfaces that are exposed to water containing DO will corrode faster compared to anaerobic water.

4.4.7 Oxidation–reduction potential: ORP, also frequently referred to as redox potential, is a

measure of water’s capability to oxidize and is reported as electrical potential (volts, V, or millivolts,

mV).

4.4.8 Metal ions and anions: it is possible to indicate metals in water as total metal and dissolved

2+ 2+ 3+ 2+ 3+

metal, dissolved metal ions such as: Ca , Mg , Fe , Mn , Al . Their dissolvement balance affect

the water quality and scale formation. Some metal ions are regularly monitored deal to their effect

on human health such as lead, they are normally limited in local water quality specifications. Some

anions are highly related to the crystallization corrosion of concrete, their mechanisms are introduced

in Annex C.
4.5 Water evaluation indicators and their trigger value

Water aggressiveness is evaluated by comprehensive indicators. Normally, two equilibrium systems are

considered for ductile iron pipe internal protection: iron equilibrium system and carbonate equilibrium.

As ductile iron pipes are normally supplied with cement mortar linings, the aggressiveness of water to

cement material can be evaluated.

In this document, five indicators can be used to evaluate the water aggressiveness. Their calculation

and trigger value are showed in 4.5.1, 4.5.2, 4.5.3, 4.5.4, and 4.5.5. Other water evaluation indicators or

scaling tendency indicators are possible.
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ISO/TR 4340:2022(E)
4.5.1 Langelier saturation index (LSI)
LSI=pH-pH (2)
where:
LSI is the Langelier saturation index;
pH is the pH value;
pH is the saturation pH (the calculation of pH is shown in Annex A).
s s
The indications for the LSI are based on the following values:

LSI <0 water is under saturated with respect to calcium carbonate and has a tendency to remove

existing calcium carbonate protective coatings in pipelines;

LSI = 0 water is considered to be neutral, neither scale-forming nor scale removing;

LSI >0 water is supersaturated with respect to calcium carbonate and scale forming can occur.

4.5.2 Ryznar stability index (RSI)
RSI=2pH -pH (3)
where:
RSI is the Ryznar stability index;
pH is the pH value;
pH is the saturation pH (the calculation of pH is shown in Annex A).
s s

RSI is normally used together with LSI; they are based on the same thermodynamic hypothesis.

RSI <5,0 heavy scale will form;
RSI = 5,0~6,0 light scale;
RSI = 6,0~7,0 little scale or corrosion;
RSI = 7,0~7,5 corrosion significant;
RSI = 7,5~9,0 heavy corrosion;
RSI >9,0 corrosion intolerable.
4.5.3 Calcium carbonate precipitation potential (CCPP)

The CCPP predicts both tendencies to precipitate or to dissolve CaCO and quantity that can be

precipitated or dissolved. It is also known as calcium carbonate precipitation capacity (CCPC).

The CCPP is defined as the quantity of CaCO that theoretically precipitate from oversaturated waters

or dissolved by undersaturated waters during equilibration.
2+ 2+
CCPP=100*([ Ca ] —[Ca ] ) (4)
i eq
Unit: mg-CaCO /L.
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ISO/TR 4340:2022(E)
where:
2+ 2+
[Ca ] —[Ca ] concentration of water sample, in mol/L;
2+ 2+
[Ca ] —[Ca ] concentration of water in CaCO equilibrium status.
eq 3
CCPP = 0~4 no scaling or little scale CCPP = 0~-5 slight corrosion
CCPP = 4~10 light scale CCPP = -5~-10 corrosion
CCPP = 10~15 heavy scale CCPP ≤ -10 heavy corrosion
CCPP ≥ 15 very heavy scale

CCPP is not suitable for hand calculation. It can be calculated by software or determined by experiments.

4.5.4 Larson ratio (LR)
−−2
     
LR= Cl + SO / HCO (5)
() −
     
Unit: mol/L

LR shows the effect of anions in water, which is significantly related to iron-equilibrium and

aggressiveness to cement materials.
LR <0,5 non corrosive water;
LR = 0,5~1 slight corrosion;
LR >1 corrosive, bigger value, heavier corrosive.
4.5.5 Aggressive index (AI)
AI =pH+lg (Ca*Alk) (6)
where:
Ca is the hardness, in mg-CaCO /L;
Alk is the total alkali, in mg-CaCO /L.
AI shows the aggressiveness to cement material.
AI <10 heavy aggressive;
AI = 10~12 aggressive;
AI >12 not aggressive.
4.5.6 Evaluation chart

The following chart can be used to evaluate the aggressiveness of certain water sample. The way to

evaluate water stability of certain water sample is shown in Table 1.
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ISO/TR 4340:2022(E)
Table 1 — Water stability evaluation chart
Evaluation Indication Water sam- Calculation Evaluation
index ple name result conclusion
LSI LSI <0 water is under saturated with respect to
calcium carbonate and has a tendency to remove
existing calcium carbonate coatings in pipelines;
LSI = 0 water is considered to be neutral, neither
scale-forming nor scale removing;
LSI >0 water is supersaturated with respect to
calcium carbonate and scale forming can occur.
RSI RSI <5,0 heavy scale will form;
RSI = 5,0~6,0 light scale;
RSI = 6,0~7,0 little scale or corrosion;
RSI = 7,0~7,5 corrosion significant;
RSI = 7,5~9,0 heavy corrosion;
RSI >9,0 corrosion intolerable.
CCPP CCPP ≤-10 heavy corrosion;
CCPP = -10~ -5 corrosion;
CCPP = -5~0 slight corrosion;
CCPP = 0~4 no scaling or little scale;
CCPP = 4~10 light scale;
CCPP = 10~15 heavy scale;
CCPP ≥15 very heavy scale.
LR LR <0,5 water is not corrosive;
LR = 0,5~1 slight corrosion;
LR >1 corrosive, bigger value, heavier corrosive.
AI AI <10 heavy aggressive;
AI = 10~12 aggressive;
AI >12 not aggressive.

If the evaluation results of LSI and RSI are contradictory, CCPP can be considered to get correct indication of the

carbonate equilibrium status in certain waters.
5 Sampling and testing

Water is changing all the time. Natural water source can be affected by seasonal changes or other

environmental changes. Those changes can be considered.

Temperature is important for sampling and testing. Water temperature change affects the solubility of

salts. The current or estimated pipeline service temperature can be considered during the sampling and

testing. Also, the temperature change leaded by seasonal changes or weather effects can be considered.

If there are more than one water sources used, they can be sampled, tested and evaluated separately

and the worse one can be considered for ductile iron pipe internal protection solution.

Relevant ISO standards for water sampling and testing of certain parameters are listed in Annex B.

5.1 Sampling

Representative and adequate water samples are critical to the aggressiveness evaluation. It is possible

to follow national water sampling standards, regulations or routine. The water sample can be raw

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ISO/TR 4340:2022(E)

water from water source, or the inlet water of ductile iron pipes, decided by the location of ductile iron

pipe in the pipeline system.
5.2 Testing

Basic parameters and supplemental parameters are listed in Table 2. It is possible to follow national

test standards if they exist. Basic parameters are needed to finish the evaluation indicator calculation,

and supplemental parameters can help to get better understanding of the water aggressiveness. Other

parameters can be added depending on the case study.

Historical data are important to understand the water quality change. For certain water sources, local

water works can have historical data.
Table 2 — Water aggressiveness evaluation parameters
Basic Supplemental
Temperature Iron (total and solve)
pH NH
Hardness Sulfide
Total alkalinity Dissolved oxygen
Cl Disinfectant residual
Conductivity/TDS
HCO
6 Optimized lining choice based on water evaluation

Based on the evaluation results of indices given in 4.5, it is the manufacture’s responsibility to give

suggestions for suitable lining.
7 Steps for water aggressiveness evaluation and optimized lining choice
The following steps are normally conducted:

1. Collection of historical data of certain water sources, with the consideration of seasonal changes

and local specific properties, if any.

2. Making of a sampling plan and determine the sampling time, location, capacity, etc. when water

temperature and content show periodical changes according to the historical data. Sampling can be

done separately at representational time or at the worst status for the pipeline internal protection.

3. Testing the samples according to the aggressiveness parameter chart and paying attention to the

difference between the test temperature and the original water source temperature. Test results

can be corrected accordingly if necessary.
4. Calculation of the evaluatio
...

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