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Sodium Sulphite (sulfite) with Catalyst Powder

Product Description | Product Application | Product Notes| Product DOSE
Catalyzed sodium sulfite for corrosion prevention. Generally speaking, sulfite is not present in natural water.  In boiler feedwater conditioning sodium sulfite is fed to a boiler to remove dissolved [+] Read More...
Other Equivalent Brand

Catalyzed sodium sulfite for corrosion prevention

Short Description:
Removal of oxygen using commercial sodium sulfite and a catalyzed sodium sulfite makes great difference . After 25 seconds of contact, catalyzed sodium sulfite removed the oxygen completely. Uncatalyzed sodium sulfite removed less than 50% of the oxygen in this same time period. In a boiler feedwate
Generic Name:
Catalyzed sodium sulfite for corrosion prevention
Sodium Sulphite (sulfite) with Catalyst Powder
Sodium sulfite anhydrous is a white granular material with the chemical formula Na2SO3 It is primarily used in pulp and paper industry. It is used in water treatment as an oxygen scavenger agen [+] Read More...
Using Procedure:
Dose of Sulfite  can be controlled by this method :::  Because it readily reacts with oxygen to form sulfate, sulfite is not usually found in natural water systems. In its most common form, sodium sulfite, i [+] Read More...
The use of untreated water in a boiler can cause scale buildup and corrosion. Treating the boiler water with chemicals - known as boiler feed water treatment - will increase the life of the boiler and reduc [+] Read More...
Technical Specifications:


Test Results


Molecular Weight  126.05
Bulk Density  1.3 – 1.5 kg/dm3
Sodium Sulfite, wt %
Sodium Sulfate, wt % 
Max. 1
Moisture, % 
Insolubles, %  0.03max
Sodium Chloride, ppm  50max
Iron (Fe), ppm 3max
Heavy Metals, (Pb) ppm  10max
Selenium, ppm 2max
Arsenic, ppm 1max
PH of 5% Solution (@ 25° C) 9.5-10.6
Ca/Mg NH40H Inso. % 0.50max
Alk. as Na2C03 % w/w 0.15max
Water insolubles (other than Iron compounds) % by wt.
Max. 0.25

Oxygen Control

Chemical Oxygen Scavengers. The oxygen scavengers most commonly used in boiler systems are sodium sulfite, sodium bisulfite, hydrazine, catalyzed versions of the sulfites and hydrazine, and organic oxygen scavengers, such as hydroquinone and ascorbate.

It is of critical importance to select and properly use the best chemical oxygen scavenger for a given system. Major factors that determine the best oxygen scavenger for a particular application include reaction speed, residence time in the system, operating temperature and pressure, and feedwater pH. Interferences with the scavenger/oxygen reaction, decomposition products, and reactions with metals in the system are also important factors. Other contributing factors include the use of feedwater for attemperation, the presence of economizers in the system, and the end use of the steam. Chemical oxygen scavengers should be fed to allow ample time for the scavenger/oxygen reaction to occur. The deaerator storage system and the feedwater storage tank are commonly used feed points.

In boilers operating below 1,000 psig, sodium sulfite and a concentrated liquid solution of catalyzed sodium bisulfite are the most commonly used materials for chemical deaeration due to low cost and ease of handling and testing. The oxygen scavenging property of sodium sulfite is illustrated by the following reaction:

2Na2SO3 + O2 ® 2Na2SO4
sodium sulfite   oxygen   sodium sulfate


Theoretically, 7.88 ppm of chemically pure sodium sulfite is required to remove 1.0 ppm of dissolved oxygen. However, due to the use of technical grades of sodium sulfite, combined with handling and blowdown losses during normal plant operation, approximately 10 lb of sodium sulfite per pound of oxygen is usually required. The concentration of excess sulfite maintained in the feedwater or boiler water also affects the sulfite requirement.

Sodium sulfite must be fed continuously for maximum oxygen removal. Usually, the most suitable point of application is the drop leg between the deaerator and the storage compartment. Where hot process softeners are followed by hot zeolite units, an additional feed is recommended at the filter effluent of the hot process units (prior to the zeolite softeners) to protect the ion exchange resin and softener shells.

As with any oxygen scavenging reaction, many factors affect the speed of the sulfite-oxygen reaction. These factors include temperature, pH, initial concentration of oxygen scavenger, initial concentration of dissolved oxygen, and catalytic or inhibiting effects. The most important factor is temperature. As temperature increases, reaction time decreases; in general, every 18°F increase in temperature doubles reaction speed. At temperatures of 212°F and above, the reaction is rapid. Overfeed of sodium sulfite also increases reaction rate. The reaction proceeds most rapidly at pH values in the range of 8.5-10.0.

Certain materials catalyze the oxygen-sulfite reaction. The most effective catalysts are the heavy metal cations with valences of two or more. Iron, copper, cobalt, nickel, and manganese are among the more effective catalysts.
Removal of oxygen using commercial sodium sulfite and a catalyzed sodium sulfite makes great difference. After 25 seconds of contact, catalyzed sodium sulfite removed the oxygen completely. Uncatalyzed sodium sulfite removed less than 50% of the oxygen in this same time period. In a boiler feedwater system, this could result in severe corrosive attack.

The following operational conditions necessitate the use of catalyzed sodium sulfite:

  • low feedwater temperature
  • incomplete mechanical deaeration
  • rapid reaction required to prevent pitting in the system
  • short residence time
  • use of economizers

High feedwater sulfite residuals and pH values above 8.5 should be maintained in the feedwater to help protect the economizer from oxygen attack.

Some natural waters contain materials that can inhibit the oxygen/sulfite reaction. For example, trace organic materials in a surface supply used for makeup water can reduce speed of scavenger/oxygen reaction time. The same problem can occur where contaminated condensate is used as a portion of the boiler feedwater. The organic materials complex metals (natural or formulated catalysts) and prevent them from increasing the rate of reaction.

Sodium sulfite must be fed where it will not contaminate feedwater to be used for attemporation or desuperheating. This prevents the addition of solids to the steam.

At operating pressures of 1,000 psig and higher, hydrazine or organic oxygen scavengers are normally used in place of sulfite. In these applications, the increased dissolved solids contributed by sodium sulfate (the product of the sodium sulfite-oxygen reaction) can become a significant problem. Also, sulfite decomposes in high-pressure boilers to form sulfur dioxide (SO2) and hydrogen sulfide (H2S). Both of these gases can cause corrosion in the return condensate system and have been reported to contribute to stress corrosion cracking in turbines. Hydrazine has been used for years as an oxygen scavenger in high-pressure systems and other systems in which sulfite materials cannot be used. Hydrazine is a reducing agent that removes dissolved oxygen by the following reaction:

N2H4 + O2 ® 2H2O + N2
hydrazine   oxygen   water   nitrogen


Because the products of this reaction are water and nitrogen, the reaction adds no solids to the boiler water. The decomposition products of hydrazine are ammonia and nitrogen. Decomposition begins at approximately 400°F and is rapid at 600°F. The alkaline ammonia does not attack steel. However, if enough ammonia and oxygen are present together, copper alloy corrosion increases. Close control of the hydrazine feed rate can limit the concentration of ammonia in the steam and minimize the danger of attack on copper-bearing alloys. The ammonia also neutralizes carbon dioxide and reduces the return line corrosion caused by carbon dioxide.

Hydrazine is a toxic material and must be handled with extreme care. Because the material is a suspected carcinogen, federally published guidelines must be followed for handling and reporting. Because pure hydrazine has a low flash point, a 35% solution with a flash point of greater than 200°F is usually used. Theoretically, 1.0 ppm of hydrazine is required to react with 1.0 ppm of dissolved oxygen. However, in practice 1.5-2.0 parts of hydrazine are required per part of oxygen.

The factors that influence the reaction time of sodium sulfite also apply to other oxygen scavengers.  Rate of reaction as a function of temperature and hydrazine concentration. The reaction is also dependent upon pH (the optimum pH range is 9.0-10.0)

Popular Oxygen Scavengers
Catalyzed sodium sulfite Na2SO3  60 kg drum, 91% anhydrous powder
 Must be dissolved in water to give a 3-5% solution.
Catalyzed sodium metabisulfite NaHSO3 
The liquid of  25 wt% sodium metabisulfite solution Tends to react with atmospheric oxygen over time. More acidic than ammonium bisulfite.
Ammonium bisulfite NH4HSO3 :  37 wt% solution of NH4HSO3 is selected for use due to ease of handling. However, ammonium ion does provide an additional food source for bacteria. 
Calculation of Oxygen Scavenger Requirement
Use the following steps:
a) Calculate the mass of oxygen in solution.
b) Multiply the mass of oxygen in solution (a) by the feed ratio.
c) Add additional 20 mg/liter in excess.
d) Take into account the concentration of the oxygen scavenger in the supplied chemical.
For Example:
How much ammonium bisulfite (37%wt concentration) will be required to treat 10,000 liter of water containing 8 mg/liter of dissolved oxygen?
 [(10 x 10,000 liter x 8 mg/liter) + 10,000 liter x 20 mg/liter] / 0.37
(feed ratio x volume x oxygen content) + (volume x residual scavenger concentration) / concentration
 = (800,000 mg + 200,000 mg) / 0.37
 = 2,702,703 mg
 This is approx. 2.7 kg of 37% wt. ammonium bisulfite
 Assuming a specific gravity of 37 weight % ammonium bisulfite is 1.185  = 2.7 kg / 1.185 kg/liter = 2.3 liters of ammonium bisulfite to be injected. 
Sodium Sulphite (sulfite) with Catalyst Powder
Sodium Sulphite (sulfite) with Catalyst Powder
Packing Size:
25.00 Kg.(PWD)
Available Packing Size:

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