There are many products offered in the marketplace that are appropriate chemical formulations for your wood boiler. The formulation for Treatment Solution 101 has been carefully chosen by the founding water treatment professionals of Wood Boiler Solutions, LLC based on providing the best product for the application given attention to cost, safety, testability, etc. Here is what you are going to find out there so that you can have the information to get the protection value you are paying for. This comparative information allows you to be confident with your purchase. Ask questions before you buy! To keep it simple we are going to compare ferrous (iron) inhibitor packages. Any product worth buying will also have a yellow metal (copper, brass) inhibitor and some degree of mineral scale preventative package so make sure you ask if it is not stated. We manufacture all that we sell. We know what we are selling. We support others in the industry, although competitors, that are providing application appropriate products and sound advice.
Nitrite (Sodium Nitrite) Excellent anodic (i.e. magnetite film or barrier forming) ferrous inhibitor. Price is right, especially for performance capability. The most common appropriate ferrous inhibitor in the wood boiler market offered by reputable manufacturers. Testing is inexpensive, easy, and accurate. Biodegradable and relatively safe to handle. Can be prone to degradation by microbial activity in a dirty system. Nitrite is many times formulated with Molybdate and Silicates which is fine and good. Nitrite is not an "oxygen scavenger". Some products list sodium nitrite or nitrite and then state that they contain an "oxygen scavenger". Incorrect terminology. Besides such chemistry (nitrite and a true oxygen scavenger) in solution is impossible. You do not want a product that contains oxygen scavenging chemistry. Treatment Solution 101 DOES NOT rely on Nitrite alone to inhibit steel corrosion. Nitrite is a "secondary", traceable component of the formulation.
Molybdate (Sodium Molybdate, Molydenum) Capable anodic ferrous inhibitor when combined with another . Very expensive and as a raw material the price is fore casted to only increase. Most Molybdate testing is expensive and requires some degree of expertise or very expensive equipment. Molybdate is a heavy metal and therefore is not biodegradable. It has been negatively publicized by US environmental groups in recent years for use in water treatment. Needs to be used in conjunction with other anodic inhibitors both because of its cost and to enhance its performance. Typically it is combined with Nitrite. Its best quality is that it is very traceable as it is prone to little interference.
Chromate Environmental concerns and regulations make this no longer an option.
Silicates Used nearly all of the time in combination with Nitrite or Molybdate, not as a stand alone inhibitor. Testing for silicates is more or less unavailable for the end user. Not generally considered a stand alone inhibitor for performance reasons but it is very viable as a component of a combo formulation (which most effective formulations are combinations as you may have gathered).
Phosphate Used very seldom in anodic formulations as a primary inhibitor due to weak performance in film formation and thermal stability. They are, although, included in many products to some degree as a good hardness precipitating and dispersing agent in the prevention of scaling deposition.
Azoles Included in almost every GOOD formulation but not primarily as a ferrous inhibitor, although they function quite well. They are included because of their excellent yellow metal (copper and brass) inhibiting qualities.
"Organic" Chemistries These formulations are more suited for industry because their use and application require a certain degree of expertise not suited to the wood boiler owner and that goes for the testability of them also. You test and control typically with "OP" or Organo Phosphonate. Rarely found if at all in this industry although the chemistry is more than applicable.
Last and Least: Sulfite (Sodium Sulfite, Bi-Sulfite, Meta Bi-Sulfites) Based Products ie "Oxygen Scavenger" Much to our surprise these products are out there and you may be using them. Many claim their products have them when they don't. These formulations are designed and applicable to steam boilers and are not suited for wood boilers. Sodium Sulfite or Meta Bi-Sulfite is an oxygen reducing agent, hence its descriptive nick name "Oxygen Scavenger", which means it scavenges oxygen and reduces it to a harmless non corrosive state. Sounds great-but wait. The reduction by-product is sulfate (sulfite + oxygen make sulfate) and unless this by-product is purged from the system (ie steam boiler blow down) it will accumulate in the system, reach a threshold and actually accelerate corrosion when too much of it is "floating" around in your wood boiler. Yes, ACCELERATE CORROSION! Sulfates will also form deposits inside your boiler. So unless you are routinely/continually blowing down (purging) your wood boiler you are actually accumulating a problem within your system. With all this said, here is the other side of the story. Sulfite is "consumed" on contact with oxygen and unless your boiler is in a vacuum you will have to continually monitor and add sulfite to keep up with "scavenging" the oxygen. Oxygen is present in all water (yes all) at all wood boiler operating temperatures, and the colder the water the more dissolved oxygen content, the higher the temp the more oxygen is catalyzed or enhanced to corrode. So that means hot water has a lower concentration of oxygen than cold water, BUT that oxygen, although less in concentration, is more harmful in aiding the effects of pitting and corrosion. Fall start-up is especially hard on improperly treated systems. Summer storage temp of water allows for high Oxygen content and then when you pour the heat on with start-up the same Oxygen just sizzles with enhanced hunger for metal. Claims that such "Oxygen Scavenger" products treat 200, 400, or more gallons may be true...treatment that lasts for about a week or two. After that you have a boiler full of harmful by-product and the oxygen is also right back in business with all the "scavenger" exhausted. Sulfite is used all the time in water treatment.....for steam boilers....not systems such as that with your wood boiler. That goes for an open or closed type system. Wrong chemistry!! Most of these products will indicate a maintenance level (control limit) of 20-60ppm "oxygen scavenger" or state "oxygen scavenger" to give you an indication of what you are buying if the sulfite based ingedient is not listed on the bottle, paperwork, etc. in the first place. Some "sellers" of supposed wood boiler chemicals use "oxygen scavenger" in their description and they don't really have a scavenger based product. What this really means is they don't know what they have! THESE ARE THE PRODUCTS WHICH FILL YOUR BOILER WITH BLACK SLUDGE-DRAIN AND FLUSH YOUR SYSTEM WITH PREP SOLUTION 102 BEFORE STARTING ANOTHER TREATMENT PROGRAM!
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