A sheet metal company made thin stainless steel sheets in their process. Before the sheets were rolled up, it went through a washing system. Two blower-type air knives were mounted after the wash cycle to remove the residual water from the surface. They purchased the blower-style air knives under the belief that they would save money by not using compressed air. They found out quickly that it was not a true statement especially when it comes to the total cost of ownership.
With the dirty environment at their facility, the inlet filter on the blower was getting plugged. The blower motor would heat up from the filter being restricted. After eight months of service, the blower motor failed due to excessive heat. The replacement was very costly, and it created a production stoppage for an entire day. The manufacturer of the blower-type air knife recommended that the filter should be changed every month instead of quarterly. This recommendation increased the monthly budget for the blower system, but they did not want to replace the blower motor again. Instead of a quarterly stop in production for maintenance, the washing system had to be stopped every month for filter change-out. They decided to contact EXAIR to see if their concept of “saving money” with the blower-type air knife was valid.
To better explain the concept, I divided the comparisons into different categories explaining the details between the Super Air Knife and the blower system.
- Initial Cost:
- Blower System – They are an expensive set up when you have to include a blower, ducting, and a knife. To have any flexibility, a control panel with a VFD will be needed.
- Super Air Knife – It is a fraction of the cost. With their system above, we were roughly 1/4 the cost. A capital expense would not be required for ordering two Super Air Knives to remove the water from the stainless steel sheets.
- Blower System – The intake filter had to be changed every month, and the customer estimated a cost of $150.00 each. The motor and belt also had to be checked quarterly as a preventive maintenance. Being that the blower motor is a mechanical device, the bearings and belts will wear and have to be replaced. Without proper maintenance, things can break prematurely. This customer had to already replace the motor in their system.
- Super Air Knife – They do not have any moving parts to wear out, and they are not affected by the dirty environment. Only compressed air is needed to operate. The maintenance requirement is to change the compressed air filter once a year. The annual price for the replacement filter is less than $35.00.
- Compressed air usage:
- Blower System – This device does not require any compressed air to operate, but it does use an electric motor. For this customer, they had a 7.5KW blower motor. With the inherent designs of blower-type air knives, they have reduced blowing forces and turbulent air flows. This combination required maximum power output on the 7.5KW blower motor.
- Super Air Knife –With their unique design, it has one of the highest efficiencies in the market place. It can entrain 40 parts of ambient “free” air with every 1 part of compressed air. With laminar flow and the power of compressed air, the Super Air Knives can be used at a much lower air pressure. To compare with the electric blower motor above, the Super Air Knives only required 11KW of compressor power to operate.
- Blower System – With the turbulent air flow, the blower units are very loud. It can have a sound level near 93 dBA. If operators are working near the system, they would require PPE for hearing. The cost for proper hearing equipment and the training for the operators will add more cost with using blower systems.
- Super Air Knife – These units are very quiet. Even at an elevated pressure, the sound level is only 72 dBA at 100 PSIG. This level is below the maximum noise exposure for hearing safety as marked in OSHA 29CFR 1910.95(a).
I tabulated the annual cost comparison and shared it with the customer to better explain the total cost of ownership. After reviewing the information, they decided to try two pieces of the model 110230 Super Air Knife Kits. When they replaced the blower-type air knives, the customer did share some additional information. First, they were amazed at the ease of installation. The blower-type air knives had to be electrically wired; floor space was sacrificed for the blower; the connection hoses were large and bulky; and the mounting was cumbersome. The customer also noticed the amount of power that was created by the Super Air Knives. They were able to increase the feed rates of the stainless steel sheets if they wanted and still keep the surface dry. This gave them flexibility in their production system. And of course, the maintenance time and cost were practically eliminated. Compressed air is expensive, but if you use EXAIR products, you can use the compressed air very efficiently. As noticed in the tabulation above, the total cost of ownership is very expensive for the blower-type air knives as compared to the Super Air Knives. You can contact an Application Engineer at EXAIR if you want to discuss further the benefits of using the Super Air Knives.