Freezer applications of conveyor are very challenging but following these six items should help you avoid common mistakes.
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Food handling system completed for a distributor of Japanese cuisine.[/caption]
In the conveyor
world, there aren’t many more challenging applications than freezer installations. The deep cold introduces many obstacles for components. In general, the colder you go, the more things you must take into consideration. Here are 6 helpful tips for ensuring a successful freezer conveyor installation.
AC motors (both standard and XE) are only designed for temperatures down to -15 degrees F. If your application requires a motor rated for lower temperatures, you will need a non-standard motor. It’s also important to slightly oversize the horsepower of the motor to account for startup after long periods of idle time in a freezer.
24 Volt DC conveyor is becoming more and more common. Most 24VDC powered rollers and/or pancake motors are rated for temperatures down +32 degrees F. Special, low temperature grease can accommodate temperatures down to -40 degrees F. There is generally no additional charge for this, but it does add considerable lead time.
2. Reducer Lubricant
Standard conveyor gear reducer lubricant is rated for a minimum temperature of +10 degrees F. Low temperature lubricants are available and can operate effectively down to -30 degrees F. One common mistake we’ve seen in the field is customers who have supplied gear reducers with low temp lubricant but have not provided low temp grease in the reducer bearings.
3. Bearings and Rollers
Most bearings today are rated for low temperature applications, but you should confirm this. Our experience has been that gravity roller bearings should be provided with oil in lieu of grease for applications in which the temperature will dip below -22 degrees F. ABEC-1 bearings are rated for -40 degrees F.
Belt sheaves should also be oiled in lieu of greased for applications below 0 degrees F. Metal sheaves are recommended for applications down to -20 degrees F, while snub sheaves are good for applications down to -30 degrees F.
4. Belts and O-Rings
You should always use conveyor belts that are rated for the temperature of the application. V-belts and timing belts must be rated properly, or you could experience cracking and belt deterioration. Standard V-belts commonly used in curves and minimum pressure accumulation conveyor are rated for temperatures as low as -30 degrees F. However, if the conveyor commonly turns off, the belt will get stiff over time. We recommend upgrading to a Flex Life V-belt in these applications.
Another design consideration to keep in mind is that pulley diameters may increase in size for low temperatures. Increasing the size of the timing belt sprockets might prevent surface cracking of the belt which might affect the actual life of the belt
Standard O-rings are rated for a minimum temperature of 0 degrees F, but in applications down to -40 degrees F, special O-rings can be provided.
5. Photoelectric Eyes and Electrical Components
Believe it or not, one of the biggest issues in freezers is condensation. It causes havoc on electrical components and is especially prevalent near temperature transitions. In these areas, there are a few common solutions. Our experience has been that air curtains are very effective. These are basically two doors separating different temperature zones (think of entry points to office buildings).
Another common issue is ice buildup on photoelectric eyes (photo eyes). We’ve had good success utilizing limit switches or ultrasonic photo eyes in lieu of standard photo eyes. This helps avoid issues with false reads caused by ice or condensation on the lenses. Cable selection is also very important as you want to make sure you select cables that are flexible and rated for the deep cold.
If at all possible, electrical control cabinets should be located outside of the freezer environment. If the electrical control cabinet must be located in the freezer, then special accommodations must be made such as heating elements for the PLC and other sensitive electronic equipment.
6. Installation Labor
One thing you can definitely bank on is that if the freezer is operating during installation it’s going to take longer. Again, a lot depends upon the temperature as with deep cold applications workers will need more frequent safety breaks. When budgeting freezer installations, it’s not uncommon for the cost to be 1.5 times or double the cost of an ambient temperature installation. It’s also very important to torque all bolted connections down very tight and re-torque after a period of time as these have a tendency of contracting and loosening.
Applications of conveyor in freezers can be very tricky. The consequences of providing equipment not adequately designed for the rough and unforgiving deep cold can be severe. Bastian Solutions has years of experience specifying and supplying conveyors for all applications, and we’re happy to assist you. Contact us
today for assistance.
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