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Boiler Water Oxygen Scavenger (Hydrazine Replacement)

Carbohydrazide Boiler Water Oxygen Scavenger (Hydrazine Replacement)

Accepta 2565 is a high performance carbohydrazide based boiler water oxygen scavenger that can be used as a direct replacement for hydrazine.

Accepta 2565 is scientifically formulated to provide outstanding protection from oxygen corrosion together with excellent feed water and boiler system passivation.

Accepta 2565 is an organic corrosion inhibitor used for scavenging oxygen and passivating metal surfaces.

Accepta 2565 is based on carbohydrazide and can be used as a direct replacement for hydrazine in any boiler without the associated safety hazards and handling precautions.

Accepta 2565 is based on volatile chemistry and so contributes no dissolved solids and minimal ammonia to the boiler system.

Accepta 2565 can be used in boilers of any pressure up to 220 barg, and can be fed into feed waters used for spray attemperation. Accepta 2565 can also be used for wet lay up of any boiler and non-drainable superheaters.

Important - Please note that Accepta 2565 cannot be used to treat boilers where steam produced will contact food or food products.

Accepta 2565 may be used in boilers where steam is used in the manufacture of paper and paperboard that might be employed for food contact purposes. It is not regulated as a hazardous waste or toxic pollutant.

Product Benefits

  • High performance carbohydrazide based oxygen scavenger giving outstanding protection from oxygen corrosion, plus feed water and boiler system passivation.
  • Improved safety - a direct replacement for hydrazine.
  • Used in boilers of any pressure up to 220 barg.

Product Properties

Appearance: Liquid
Color: Clear
Density: 8.5 lbs/gal
Specific Gravity @ 15°C: 1.02
Freeze-thaw recovery: None
Odour: Musty
Viscosity @15°C: 3.0 cps
pH (Neat)@: 8.0
Freezing point: -2°C
Volatile Organic Carbon (VOC) %: 0.00%
Measured VOC: Yes
Vapor Pressure @ 20°C: 12
Vapor Pressure @ 38°C: 32

*Full details of the product properties are available in the Safety Data Sheet. See below.

Application & Dosage Information

Total product dosage for Accepta 2565 is based on the sum of the dissolved oxygen level (23.0 ppm product per ppm oxygen) and the required product residual (1.0 ppm product per ppm residual).

The residual range for Accepta 2565 should be controlled between 0.8 and 1.2 ppm as product. The test is a feedwater control test and is not applicable to blowdown samples.

Feed this product neat. Diluting oxygen scavengers will cause loss of oxygen-scavenging ability. Diluted solutions of the product may not be stable.

Feed Accepta 2565 continuously. Any interruption in feed will result in corrosion in the feedwater system and possible tube failure in the boiler. To ensure consistent and adequate chemical feed, the pump speed should be set as high as possible and the pump stroke should be set as short as possible.

Accepta 2565 cannot be mixed with any other chemicals. Chemical additions to the formulation will result in extreme loss of oxygen-scavenging ability.

Feed Accepta 2565 to the storage section of the deaerator below the water line.

Dosage Calculations

Step 1

Determine: Feedwater oxygen levels (ppm)

Feedwater flow (ton.day-1)

Step 2

{Feedwater oxygen level (ppm) x 23} +  (1.0 ppm residual) = Total ppm Product

Step 3

Kg of Product required/day = (Total ppm Product (Step 2)/1000) x ton.day-1 feedwater

Step 4

Litres of Product required per day = kg.day-1 / 1,02 kg.l-1


Step 1

Boiler Pressure:         100 barg

Feedwater Flow:         11000 ton.day-1

Oxygen in the Feedwater:     0,012 ppm (No chemical present)

Step 2

Total Product dosage = (0,012 ppm O2 x 23) + 1,0 = 1,28 ppm

Step 3

Kg per day of Product = (1,28/1000) x 11000 ton.day-1 = 14,1 kg.day-1

Step 4

Litres per day of Product = 14,1 kg.day-1 / 1,02 kg.l-1 = 13,8 l.day-1

Consequences of Overfeed

Overfeed of Accepta 2565 will result in high levels of ammonia in the condensate system. This may be sufficient to increase the measured pH of the condensate system. The neutralizing amine dosage should not be reduced. This would result in inadequate protection of the condensate system (The combination of ammonia and oxygen in leakage are extremely corrosive to copper containing metallurgies.)

Overfeed will significantly affect the cost of the chemical treatment program.

Consequences of Underfeed

Underfeed of Accepta 2565 will result in serious oxygen corrosion to the boiler and feedwater system. The greatest damage will occur in the economiser or feedwater preheaters.

Oxygen corrosion will also increase iron levels in the feedwater.

Iron deposits will form in the high heat flux areas of the boiler causing tube failures.

Boiler Lay-up Dosage

1500 ppm as product should be the dosage for boiler lay-up procedures. This is 1.5 kilograms per 1,000 litres of boiler water.


The reaction rates of Accepta 2565 decrease substantially at lower pH values.

Do not use Accepta 2565 in systems with pH values below 8.5. Feedwater pH should be maintained in accordance with ASME guidelines.

Supplemental feed of Accepta 2565 in condensate systems is acceptable, but do not substitute for a condensate amine.

It is always advisable to carry out a 'Control Of Substances Hazardous to Health' (COSHH) assessment before use.

Testing and Control

Accepta 2565 does not interfere in the hydrazine test.

At sample point temperatures (prior to cooling) >260°C , the hydrazine residual test can be used for product applications. Multiply the hydrazine test result by 23.0 to convert the readings to ppm of product. This test is easier to run and this product completely breaks down to hydrazine at 260° C.

Safety, Storage & Handling

For full details concerning safety precautions, storage and handling procedures for Accepta 2565 please refer to the latest Safety Data Sheet. To download the latest safety data for this product use the following link:

Safety Data for Accepta 2565

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