Maintenance Program for the Atomizer Wheel

To reduce risk of Atomizer Wheel disintegration caused by the following:

• High temperature
• Stress corrosion cracking
• Wear or abrasion
• Material fatigue
• Other wheel damage

Experience over many years shows that spray drying plants equipped with rotary atomizers do not constitute any health and safety risk when carefully operated and maintained in accordance with operating and maintenance instructions and safe industrial practices.

However, in cases where insufficient attention has been paid to the maintenance of atomizer wheels and/or where non-original parts have been incorporated in Niro atomizer wheels, dangerous incidents have occurred involving wheel fragmentation during spray dryer operation. Niro wishes to bring the possibility of such incident to the attention of its customers, and at the same time emphasize the serious risks involved.

Careful monitoring of the condition of atomizer wheels and regular maintenance is essential to prevent such dangerous incidents.

The atomizer wheel is a key component in a spray drying plant. It is rotated at high speed and is consequently exposed to very high centrifugal forces and high levels of tensile stress. The Niro atomizer wheel is designed to withstand the high level of tensile stress by:

• Careful mechanical design emphasizing avoidance of stress corrosion and securing an adequate cross section of high strength material in all parts of the wheel
• Careful material selection to withstand the influence of temperature, corrosion and wear during atomizer operation

However, as the wheel is operating in an industrial environment, it is subject to degrading effects such as wear and corrosion, and therefore should be carefully monitored and maintained by its operator.

Examples of abrasive wear and stress corrosion cracking.
Abrasive wear in the Atomizer Wheel with wear resistant inserts.
	Atomizer wheel
Surface corrosion on the outside of the Atomizer

	Curved Channel Atomizer Wheel
Stress corrosion cracking in an Curved Channel Atomizer Wheel.

Operating and Maintenance Instructions

The safe operation of all Niro equipment, including the atomizer wheel, depends upon the operation and maintenance of the equipment in strict compliance with the operating and maintenance instructions provided in the manuals and any other training program for the customer. It is imperative that operators are aware of the following:

• Never run the atomizer wheel at speeds higher than those specified or recommended by Niro
• Never run the atomizer wheel when it might be only partially assembled, i.e. without upper plate or with loose bolts
• Never attempt an atomizer wheel repair
• Only use approved cleaning liquids for atomizer wheel cleaning, i.e. water, dilute organic acids, and CIP liquids recommended for stainless steel surfaces. When in doubt, consult Niro. Under no circumstances use chlorine containing liquids
• Only use original Niro replacement parts Service Intervals

The Niro Atomizer Wheel Service Program is a voluntary program that supplements the wheel inspections carried out by plant operators on site. The program requires that the entire atomizer wheel is returned to a Niro office for inspection, repair and spin test.

The service procedure begins with a careful inspection for possible degrading effects. Unless the wheel is considered to be unsafe or damaged beyond repair, the service also includes repair or replacement of damaged parts. The service procedure is concluded by balancing of the wheel parts as well as the assembled wheel.

Niro recommends that every atomizer wheel is submitted to Niro at certain times in its operational life.

The recommended points in time are:

• For stainless steel wheels containing wear resistant parts:
• 1st service after 2 years of operational duty
• 2nd service after 4 years of operational duty
• 3rd service after 5 years of operational duty
• For stainless steel wheels containing no wear resistant parts:
• 1st service after 5 years of operational duty
• 2nd service after 8 years of operational duty
• 3rd service after 10 years of operational duty
• Thereafter, service is recommended each year.

These recommendations are guidelines only and are not considered an extension of warranty. Any signs of damage or suspicion thereof should be taken seriously.

In case of doubt about the condition of the wheel, the entire wheel should be returned to Niro for an Atomizer Wheel service inspection, repair, and spin test.

Concluding Remarks

Since the control of the operational conditions is solely in the hands of the operator, Niro cannot guarantee wheel performance beyond what is provided in its contract terms. However, Niro and every plant operator have a common interest to avoid the potential risk of personal injury and damage to equipment.

Therefore, operators are urged to be aware of the need to give proper attention to the condition, operation and maintenance of atomizer wheels as outlined in Niro's operating and maintenance instructions, and to only use original Niro replacement parts.

Furthermore, it is advisable to make use of Niro's Atomizer Wheel Service Program as part of a preventive maintenance program.

For a full description of the Wheel Maintenance Program please see the Atomizer Instruction Manual.