Contents:

The Systemsure water analysis test kit includes glassware and reagents to test water for pH value, dissolved iron, dissolved copper, chloride, total hardness and inhibitor concentration, together with an illustrated instruction manual.

General instruction notes:

For accurate results, rinse sample tubes with a sample of the water to be tested before carrying out tests, and rinse again with fresh tap water after use.

Drop Test Method:

The test should take between 10 and 30 drops of titrant to reach the end point. If outside this range, adjust the sample volume used, i.e. take a larger sample volume if less than 10 drops are used, and a lesser sample volume if greater than 30 drops are required.

NOTE: The multiplication factor will have to be altered accordingly.

---

• pH (acidity/alkalinity)
The pH of water is an indication of how acidic or alkaline it is. The scale runs from 0 to 14, with a pH of 7 being neutral. The nearer to 0 the pH value is, the more acidic and, conversely, the nearer the value is to 14, the more alkaline the water.

The corrosion rate of ferrous metals and copper becomes increasingly rapid as the pH falls below 6, and it is therefore important to ensure that all residues of acidic flushing chemicals are removed after power flushing.

Aluminium heat exchangers and radiators are prone to corrosion when the pH is less than 6, or above 8.5. Copper is adversely affected when the pH is above 9.5, as may happen when alkaline flushing chemicals or inhibitors are used, or when softened water is used to fill the system.

An electronic pH meter is also available (at extra cost). See right hand column.

• Dissolved Iron
Iron oxides, produced by corrosion in heating systems, have only limited solubility in water. Even heavily corroded systems will rarely contain more than 5 mg/l, at which level visible red or black iron oxide particles indicate that corrosion has already occurred and that the system should be power flushed.

Mains water often contains iron, although at levels of less than 1 mg/l. A test reading of more than 1 mg/l above the mains water indicates that corrosion is taking place (even though water drawn from the top of a radiator may be clear), and the system should be power flushed.

After power flushing, a dissolved iron level check can ensure that all flushing chemical has been removed from the system. If flushing chemical is still present then the dissolved iron level will be higher than that for mains water.

• Dissolved Copper
The presence of dissolved copper in system water, at a level of 1 mg/l or more, is indicative of corrosion problems and is associated with excessive use of flux when installing or repairing a system, and inadequate pre-commission cleaning.

Only low levels are usually recorded as the copper in solution tends to plate out onto steel and aluminium surfaces, causing localised corrosion and wasting (at ca. 0.5 to 1.0 mg/l), and pinholing at higher readings of >1.0 mg/l.

• Chloride Level
Most mains water supplies contain some dissolved chlorides, varying from ca. 20 mg/l upwards to 100 mg/l.

Chloride levels significantly above the mains level (more than 25 mg/l, or more than 50% higher) can cause pitting and corrosion of mild steel, particularly in areas of high stress such as bends and welds, and will reduce the performance of corrosion inhibitors.

High chloride levels are indicative of flux contamination of the heating system, which should be power flushed and the chloride level re-checked. It is important to check chloride level before and after pre-commission cleaning of a system to ensure that the process has been fully effective.

• Total Hardness
More than 60% of Britain, by area, has water classified as hard (expressed as more than 200 mg/l calcium carbonate). The harder the water, the more prone heat exchangers and calorifiers are to scaling up with limescale deposits.

Whilst soft water (expressed as less than 100 mg/L calcium carbonate) does not cause scaling problems, it tends to be more corrosive to metals used in heating systems.

If, when checking the hardness of system water, the hardness is much less than that of the mains water, then it is probable that scaling up of the boiler or heat exchanger has already occurred. Even when the hardness of mains and system water are apparently similar, scaling may also have occurred if the system has been frequently drained and refilled, or if a water leak has led to a continuous ingress of fresh water into the system.

Soft water produced by a water softener usually has a hardness value of less than 2 mg/l, but should not be used in central heating systems as it is more aggressive than even natural soft water, particularly to aluminium heat exchangers and radiators.

• Inhibitor Concentration
It is important to check the correct level of corrosion inhibitor in a system in order to ensure long term protection from internal corrosion, sludge formation, scale deposition and boiler noises.

The Systemsafe-DM inhibitor level test is used to check the correct level of Kamco inhibitor. The test measures the molybdate content within a heating system. A reading of 330 mg/l (ppm) molybdate equates to the optimum treatment level of 1% Systemsafe-DM by volume.

A higher value is not detrimental, but if the test indicates under-dosing, then the level should be brought up to the optimum by further addition of Systemsafe-DM.