Laidlaw B-G
A Full Service Boiler Guard

Why Boiler Treatment?
Minerals and other contaminants are in all city water systems, wells and other common sources of process water.

Just as these dissolved solids are left as "scale" on the bottom of a pan when water is boiled off, so is scale left on tubes and plates of a boiler as the water is converted to process steam. As scale forms on tube walls, it takes more and more heat to penetrate the scale. This means increasingly higher fuel costs. It also leads to overheating the tubes which can ultimately cause costly damage - costly for repairs and lost production.

Another problem with water in boilers is corrosion. Oxygen in the water sets up iron corrosion. Gases are driven off in to the lines which will recombine with the condensed steam to form weak but corrosive acids in the lines.

The primary function of the B-G Boiler Guard treatment is to change the composition of the water so that it is no longer harmful to either the process or the equipment.

How Boiler Treatment Works
Untreated water with mineral salts dissolved in it comes in contact with the tube walls. Heat is applied through the tube wall into the water causing it to evaporate or boil off. The dissolved mineral salts are left behind on the tube.

Instead of allowing this salt laden water to come in contact with the tubes, the B-G Boiler Water Treatment combines with these salts to form other salts (magnesium and calcium hydroxide) which do not dissolve in water. Because they are immediately insoluble in water, they drop out as a precipitate or sludge. This sludge is in turn removed from the boiler by regular blow-down.

Insoluble salt formation is not the end of the B-G function, though. If the sludge is not further treated, it could drop out in the form of a heavy cake, which would be difficult to remove by blow-down. B-G prevents this by inhibiting caking. B-G promotes formation of a mud type precipitate that is easily removed by blow down.

Gas in the form of iron pitting oxygen and carbon dioxide, dissolved in the boiler water, is the prime source of corrosion. As the water heats up to a boil, carbon dioxide is driven off with the salt into the lines. As the gas cools off, with the steam that condenses into water, the two combine into a mild yet corrosive (carbonic acid). This will corrode lines and plates if allowed to form. B-G combats corrosion in two ways: B-G keeps boiler water on the alkaline side. This reacts with or neutralizes the acids so they form into harmless non-corrosive salts. It also inhibits oxygen corrosion. Secondly, B-G contains oxygen scavengers (sulfites) which scoop up free oxygen that comes into the system with the feed water and converts it into harmless water soluble salts before the oxygen has a chance to be driven into the team chamber and lines.

Regular use of Laidlaw B-G can give years of extra trouble-free service from your boiler.

Laidlaw Chloride Control
As steam is formed and carried away from the boiler, the dissolved salts stay in the boiler water. As more steam is used more raw water with dissolved salts is introduced into the boiler. More steam is driven off leaving more dissolved salts behind in the boiler water. In this way the concentration of salts and other contaminants is built up in the water left behind in the boiler.

Part of these salts are dropped out of the water by boiler treatment in the form of sludge.
Other harmless water soluble salts stay dissolved in the water. Among these salts is chlorides. Common table salt is a chloride - sodium chloride.

These chlorides are easily analyzed and can thus be used as a measure of all the contaminants introduced into the boiler. It is therefore a gage for proper blow-down procedures.

If city water for instance has 15 parts per million of chlorides in the water, and the boiler contains 150 parts per million, this indicates the boiler water has turned over or concentrated 10 times. There are 10 times as much chlorides in the boiler as in the water that feeds it. This means there are 10 times all other contaminants introduced into the boiler water too; we know this, even though we have not measured them, because they came in with the chlorides. Some of these contaminants are precipitated out by B-G and are building up in the bottom of the boiler. Others are staying dissolved in the water.

A good rule of thumb is a 10 X concentration to be kept in the boiler water.
Laidlaw offers a test kit with B-G, at no extra charge. The test kit is easy to use and easy to understand with just a little practice.

The Laidlaw B-G Test Kit analyzes the dissolved chlorides in the boiler water. By periodic tests, it can be determined by the cleaner himself if his blow down schedule is proper, without having to wait several weeks for an analysis to come back from a factory somewhere.

Also included with the Test Kit is a pH indicator solution. pH is a measure of acidity or alkalinity. Boiler water should be kept above a pH of 10 (alkaline) to insure protection against oxygen corrosion.

Example of control - if there are about 10 times more chlorides in the boiler water than there are in raw feed water, that is OK. If the pH is maintained about 10, that is OK. You can be pretty well sure that your blow-down rate and B-G additions are about right.
If, on the other hand, the chlorides are high and the pH is high it indicates too much boiler compound is being added and/or not enough boiler water is being blown down.
If the pH is below 9.5 to 10, there is not enough corrosion protection present in the water and more compound is needed, especially if the chlorides are about right.
If chlorides are low, that is about 5 to 8 times more than raw water, too much boiler water is being blown-down. This wastes heat and compound. Decrease the amount of blow-down.

A regular sample may still be forwarded to Laidlaw Corporation for a complete analysis and recommendation.

copyright 2000 Laidlaw Corp.