Selecting truck scales

by Melissa Alexander
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Truck scales represent a major capital investment for most grain facilities. Three elements make up the total cost of the system: the scale itself, the foundation/installation and maintenance/upkeep.

A properly sized and installed truck scale can provide more than 20 years of service, and spending more up front actually may save money over the useful life of the scale. Thus, price should not be the only consideration when selecting a system.

Grain facilities should analyze their specific needs to make a solid decision on which truck scale to purchase.

Following are some of the key elements to consider when purchasing a truck scale:

Weighbridge size and capacity. Be certain of the truck types that will be weighed, including capacity and size. This is the single most critical factor in selecting scale capacity and type. A truck scale should not be undersized or oversized. Too many 100-tonne scales are purchased for a task easily handled by a 60-tonne scale.

Consider the number of weighments per day, and factor in for future needs, such as the possibility of heavier or longer trucks.

Site location. This includes traffic patterns, soil conditions, water table, environmental issues, grain dust hazards and any governmental weights and measures requirements.

Configuration and type. Should the scale be installed in a full pit, shallow pit or above grade? Should the weighbridge be concrete or steel? The scale typically will be subject to governmental inspection, and approval requires proper scale calibration, installation and adequate ingress and egress ramps.

Weather. Is the scale area subject to heavy moisture or even flooding? Does history show that rains from seasonal hurricanes or tornadoes inundate the proposed truck scale area? Do lightning storms occur?

Load cells. Load cells are the most critical component of the scale. A vital link to good weighing, load cells are the most vulnerable to damage and replacement. The most common choices of load cell technology are electronic (analog or digital) and hydrostatic (non-electronic). Both types are certified by the U.S. National Type Evaluation Program for legal-for-trade use. Determine the advantages and disadvantages of each type for your specific application.

If corrosion is a possibility from salt or other elements, stainless steel load cells should be supplied.

Interference. Protection is a necessity for measured RFI/EMI noise levels that can cause malfunctions in reading. Radio transmitters, citizen band radios, walkie-talkies, police radios, air conditioners, diesels and electrical machinery all can cause problems.

Downtime. Long-term reliability should be emphasized over initial cost to minimize downtime. Maintenance on truck scales can be huge — some customers have seen maintenance expense in one year equal to the price of the scale, usually from water, lightning and rodent damage.

Installation. It is not uncommon for truck scale pits and foundations to be built by contractors inexperienced with the system. The contractor must be supervised to assure rigid adherence to the specifications. A faulty pit or an improperly installed scale creates a lifetime of problems for the scale.

References and warranties. Insist on references and, if possible, an on-site inspection of the type of scale you are planning to purchase. Examine the warranties and guarantees, particularly of the load cells. Remember, a warranty won’t prevent a failure or downtime; it only helps compensate after a failure.

Finally, evaluate each proposal carefully. Consider the product detail provided, the manufacturer’s history, the method of shipment, and terms of sale.