We recommend having your pallet scale checked on a regular basis. That is a service that we provide all the time. We have state certified scale technicians and our test weights are certified each year at the state lab.
But let’s say that you are a new company or perhaps you are one of those rare companies that chooses to not have your scales checked on a regular basis. How can you tell if your floor scale needs to be calibrated or not?
There are some obvious examples such as your scale displaying error codes or it’s just not working at all. But often times the scale will work and display weights, the question is… are those weights accurate?
It’s always a good idea to have some type of check weight available at your location to verify your scale weight. This usually is not a real certified weight. It could be a large container or some type of item that generally weighs the same all the time. Having an item like this handy can help you to see if your scales are accurate and within tolerance, need to be calibrated, or if something has gone wrong and need troubleshooting, repaired, and then calibrated.
What if Your Pallet Scale Needs to be Calibrated?
If your scale is inaccurate, then it’s time to call your scale company and have them check the scale with certified test weights. The scale tech can then adjust the scale and calibrate it if needed. If you have other scales at your facility, it might be wise to have all of them checked on the same trip for efficiency. You can call our service department at (919) 776-7737 or you can fill out the RFQ form on our website or email us as well.
From a scale company perspective, when we hear the question, why does the number on the scale fluctuate so much? There are several answers below that could be true.
When we define the word fluctuate, the definition is: rise and fall irregularly in number or amount. Sometimes the word fluctuation can be used interchangeably with bouncing or changing.
From a healthcare scale or bathroom scale perspective: It is normal to see your body weight vary daily. It could be various reasons such as food or water intake. Maybe a new diet.
In the scenarios that we see more often as an Industrial Scale Company, when we’re asked why does the number on the scale fluctuate so much? The answers below are usually true.
Often with industrial scales a customer places an object on the scale and it is a certain weight. There is usually little to no fluctuation. If the scale does fluctuate more than a couple graduations, then it likely means that some component in the scale is not working correctly (main board, load cell, etc…) or it could mean that the scale needs to be re-calibrated.
With commercial scales or industrial scales, if you place an object or weight on the scale, there should be little to no fluctuation. If the weight is bouncing around, then you likely have a problem of some type. Sometimes it can be something as simple as wind or water. If you’ve ever tried to weigh trucks on a 70 foot long truck scale on a windy day, you have likely seen truck weights fluctuating. Once the wind subsides, the weigh fluctuation should as well. As for water, if a junction box has water inside, that can cause fluctuations. Dry out the j-box and often the weight stabilizes.
On most scales or laboratory balances you will often see a “Zero” button and you will probably see a “Tare” button as well. What do these two buttons do? Are they the same?
If you’ve pressed these buttons before, they might seem like they do the same thing. Actually, they are similar, but they actually do different things.
ZERO BUTTON ON A SCALE OR LAB BALANCE
The “Zero” button should be pressed when the scale is a graduation or two away from zero and you would like it to be perfectly on 0.00 before you start weighing. For example, if you have a floor scale and it is flashing between 0 and 1 lb. If you press the “Zero” key, that will hopefully zero the scale off and it will be ready for weighing.
Technically, the zero point is actually set during the scale calibration along with span calibration. Why would you have to zero the scale? Perhaps there is some buildup on the scale platform that has accumulated since the scale was last calibrated or perhaps the scale needs to be re-calibrated…
Basically, the “Zero” button should only be pressed when no load is on the scale. On legal for trade scales, there is a limit to how much weight you can “zero off” the scale.
TARE BUTTON ON A SCALE OR LAB BALANCE
What does tare mean? The “Tare” button is pressed when you have placed something on the scale (like a box, container, or empty truck) and you need to disregard the weight of that item. After adding the truck or container to the scale, pressing the “Tare” key will set the display to display 0.00 and then whatever you’re looking to weigh can then be added to the scale in the “Net” mode.
For example, let’s say you are using a parts counting scale and you often use a plastic container when you are counting out bolts. You place the empty plastic container on the scale, press “Tare” and then count parts. The only weight you will see on the scale is the weight of the bolts (and the number of bolts, since you are counting them).
Then when you’re finished, you can remove the plastic container from the scale. When you do this, the weight of the plastic container will still be displayed since you “tared” that off earlier. You then press the “Tare” key to remove that container weight from the scale and the display will once again be showing 0.00 and ready to weigh.
It’s a good idea to have your scales calibrated on a regular basis with certified test weights by state certified scale technicians. This will make sure the zero of each scale or lab balance is set correctly and the span from zero to the max capacity is correct. Contact the service department by calling (919) 776-7737 to get your scales checked.
Our local scale calibration and repair customers throughout the central sections of North Carolina are very important to us. We typically stock 90%+ of the standard replacement scale parts that they may need.
However, if you have certain types of scales that aren’t as common or if you have a large number of scales or load cells at your facility… then it can be a smart strategy to keep some spare parts on hand to minimize any downtime. Call us today (919) 776-7737 to determine what replacement scale parts and hardware you need.
If your business relies heavily on your scale(s), then it’s imperative to stock some spare parts to minimize unplanned downtime. Downtime can be a real problem. Especially for certain businesses and at certain times.
Our suggestion is to contact our scale repair & service department and discuss your scales and down time and identify any spare parts that are really important or any spare parts that are difficult to obtain.
Unfortunately, customers often don’t think about downtime and potential failures until it’s too late. This year, we’ve seen some scales that were down for weeks while they wait for replacement parts to arrive from the manufacturer. This is why we encourage you to contact us to determine what items you need to stock.
Supply Chain Issues & Longer Lead Times!
You’ve likely experienced this in your business and we certainly have as well. Between rising prices and labor shortages and continued medical issues, it’s greatly affected the manufacturing and logistics industries. We have seen parts that used to be a 2 day lead time, turn into a 2 month lead time. This is why it’s important to contact us today and discuss what item(s) you need to stock so you can experience the least amount of down time as possible.
These are real concerns that in the past we haven’t had to think much about. However, with certain lead times at record levels… it just makes good sense to plan.
How much money could you potentially lose if your scale is shut down for a couple weeks? What about a couple of months? When you think about it in those terms, if can sometimes lessen the burden of spending a few thousand dollars to keep some spare scale parts on your shelf.
Which Spare Replacement Scale Parts should I Keep on my Shelf to Minimize Unplanned Downtime?
The truth is that spare parts can be expensive to keep on your shelf. We see this every year when we analyze our inventory and determine what items sold and what items collected dust.
And, as mentioned earlier, we stock A LOT of replacement scale parts like load cells, weight indicators, main boards, etc… But, the truth is that we can’t possibly stock every single spare part that every single customer of ours might need. That’s why it’s important to discuss this with our service department and determine what item(s) we feel you should stock.
This will cost you some money but we would argue it’s still not as expensive as a few weeks of unplanned downtime with a broken down truck scale. It goes without saying, but this suggestion regarding spare parts also needs to factor in how important a particular scale is to your business.
For example, if you are a metal recycler, one broken floor scale might be easier to manage since you likely have several other floor scales you could use. However, if you have a broken down truck scale and that’s the only truck scale you own, that item would be much harder to do with out. In our opinion, if you want to reduce potential down time… you might want to stock the following items:
Replacement Weight Indicator
Digital Weight Indicators are items that often break or get damaged on job sites. Sometimes the damage is through lightning, while other times it’s from being knocked off a desk and dropped to the floor or perhaps being run over or hit. Other times “nobody knows what happened“….. In any of these scenarios, the weight indicator is a very important component to a scale system. Without a functioning scale controller, your employees can’t see the actual weight on the scale platform.
To take it one step further… some companies use very sophisticated weight controllers that are programmed for various tasks like truck in/out or truck storage, batching, etc… Those scale indicators need to function and if they fail, there needs to be a replacement available ASAP. For applications like this, it can be a good idea to stock a spare indicator with the custom software installed.
Replacement Scale Boards
Boards are one of the most essential components to a scale. These boards connect all of the components required to power the scale. It’s smart to have the main board, display board, analog output board, summing board(s), remote display main board, etc…. This will vary depending on the customer and which scale(s) you have.
Replacement / Spare Load Cells
We have to include load cells on this list since they are so prevalent in most weighing systems. However, in a lot of cases, we do have stock for most standard strain gauge load cells. This is a great example where we recommend contacting us and discussing what we have in stock and what we recommend that you stock. For example, of the past several years there have been multiple new digital truck scales available which take a digital load cell, cables, and digital weight indicator. Similar challenges exist with hydraulic truck scale replacement parts as well.
if you have a scale or multiple scales that are very important to your business process, then you need to contact us and discuss recommended spare parts and what we stock versus what we suggest that you stock.
A little forward thinking can minimize the unplanned downtime and it could mean the difference between a few hours of downtime or multiple weeks without a scale.
And these spare parts discussions (they can be phone calls or emails) probably need to happen every year since things change. Items become obsolete, new products get purchased, etc…
Since 1980, Central Carolina Scale has been providing outstanding weighing equipment and scale repair service for our customers. Our truck scale calibration and inspection service is what our customers depend on to keep their scales accurate and dependable year round.
Most customers choose to have their truck scales checked and calibrated at several predetermined points during the year. We can customize your service based on your needs and requirements. And, by choosing this method of periodic scheduled service; the customer benefits by receiving priority scheduling, reduced labor rates, and discounted parts.
Before our factory trained, state certified scale technicians hit the road, they perform all mandated DOT vehicle inspections. Safety has always been a top priority.
Once our scale technician reaches the job site, the technician will notify the customer. Then the technician blocks off the scale to keep trucks from entering during the inspection and adjustment period. Keep in mind, Central Carolina Scale works with our customers truck traffic to be as accommodating as possible.
BUILDUP UNDER THE TRUCK SCALE
The next step in a truck scale inspection is to inspect all critical components. Depending on the scale, the technician checks for buildup of dirt, sand, mud and debris underneath the scale. Dirt buildup under the scale platform is often one of the top reasons for scale inaccuracy.
If the truck scale has bumper bolts, the technician will examine these and adjust if necessary. It’s also a good time to look at any other areas that may need to be addressed periodically such as junction boxes, grounding, rubber t-grip molding, load cell caps, pit cleanliness and more depending on the type of scale. The technician also checks cabling, structural steel, and concrete approach pads.
Next, the scale technician will drive the fully loaded test truck across the scale and check the sections for consistency and accuracy. Weights are recorded and used to assist with adjusting.
Next, the technician unloads all the certified test weights into a specialized weight cart. This cart is also certified by the state weights and measures department and is traceable to NIST. Then, the technician checks each section of the motor truck scale.
The technician can once again drive across the sections with the fully loaded test truck which includes the certified weights and certified weight cart. The section weights and the overall weights should be consistent and accurate. The calibration and inspection is now complete.
The technician loads his vehicle and reopens the scale for traffic. Once the technician has moved off the scale and the scale has reopened, the technician completes all the necessary paperwork. The inspection detail report shows both the condition of the scale and components, as well as the as found and as left test results.
Central Carolina Scale has the factory trained technicians, certified test weights, and certified test carts to accurately and thoroughly check your vehicle scales. Give us a call today (919) 776-7737 and we can work with you to customize a service plan that will improve your accuracy and limit downtime.
In a concrete batching plant typically all of the ingredients that go into the concrete are measured by weight with certified digital scales. As you can imagine, those scales that are batching and mixing of concrete, need to be calibrated on a regular basis in order to maintain accurate weighing.
At Central Carolina Scale, we have checked and tested ready mixed concrete hopper scales for many years. Over all these years, concrete batching plant calibration procedures have evolved and we have also made changes to adapt to new guidelines and requirements. Whether it’s asphalt plant calibration or concrete batching, we have many years of experience repairing and calibrating these digital scale systems throughout central and eastern North Carolina.
While we don’t sell Command Alkon or Mettler Toledo indicators, we have worked on many systems that include those units. Popular instruments that we offer for sale include the Cardinal 205.
For concrete producers looking to achieve National Ready Mixed Concrete Association (NRMCA) Plant Certification, they need to adhere to the Guidance to Concrete Producers maintaining plant certification. This includes a list of Primary Requirements, Plant Inspector Guide and most importantly to us, the Scale Accuracy Verification guide.
Scale Accuracy Verification
There are some differences in what the scale companies are accustomed to doing in accordance with NIST Handbook 44 and what is required by the NRMCA plant certification and ASTM C94. Some of these differences are described in the Plant Inspector’s Guide.
Minimum quantity of test weights should be at 10% of scale capacity. Aggregate scale capacities will generally govern the minimum amount of test weights required – about 4000 lbs is typically needed. (There may be situations where the plant configuration does not permit the minimum test weights to be used and that has to be verified by the plant inspector).
Test weights should be certified to be accurate to 0.01% of their indicated load within the last two years. This is typically not a problem with commercial scale companies.
Scale checks should be done through range of use of the scales. Scale companies may only verify it through 50% of the scale capacity.
Up through 50% of the scale capacity, scale checks should be done using a build-up test load using a combination of product and test weights in a process called a substitution loading. Scale increments should not be skipped. In substitution loading, product in the scale should only be to the load previously verified – as close as possible.
Over 50% of the scale capacity, strain test loading is permitted. An unknown quantity of product is charged and the incremental weight indication with the test weights is verified. At least two points should be tested in this portion of the scale – through typical range of use.
Scale accuracy requirements (ASTM C94) is the greater of
● ±0.15% of scale capacity (governs at the lower end)
● ±0.4% of applied test load
● If it’s not accurate the scale has to be adjusted.
Maintenance tolerances in accordance with Handbook 44 are stated on the basis of scale divisions (min grad) but are generally more restrictive than those in C94 that state tolerances based on applied load or scale capacity.
A copy of the scale verification data sheets should be obtained to indicate details of the test loads used, test load increments, load indications and load error. A certificate just indicating a scale is OK is not acceptable.
Definitions of load testing, concrete batching plant calibration format, discussions and numerical examples of the scale accuracy verification are available in the NRMCA Plant Inspector Guide.
Batching Plant Calibration Frequency
Accuracy checks of measuring devices (scales, water meters, admixture dispensers and moisture probes) should be performed at least once every 6 months.
State DOTs may have a requirement for these to be performed more frequently. The requirement with the greater frequency governs. Documentation of these verifications should be maintained and made available to the inspector during the plant inspection.
Also, scale accuracy should be verified anytime the plant is moved (portable plants), maintenance activities on the plant impact the weighing systems, or when there is a concern on scale accuracy determined from the batch man operating the batching process or the quality of concrete.
For customers throughout the central part of North Carolina, adhering to the NRMCA requirements can be accomplished with the help of the experienced service technicians of Central Carolina Scale located in Sanford, NC.
We have the trucks to handle these requirements and we have the large certified test weights (and small weights too) needed to accurately test your digital scales.
And we also stock a huge amount of replacement load cells, digital weight indicators, load cell cable, and other scale accessories to keep your batching plant up and going year round.
Contact our service department today (919) 776-7737 or fill out the RFQ button on our website for additional information.
At Central Carolina Scale in addition to selling and installing truck scales; we also check, test, adjust, and calibrate truck scales just about every working day of the year. We have factory trained technicians who can troubleshoot even the smallest problem areas like a load cell that might be creeping. We also have certified test weights and a weight cart which allows us to provide the highest level of truck scale service available in North Carolina. When we’re finished doing our scale check, we supply the customer with documentation that shows before and after readings and how much weight we tested the scale with, etc…
The Standards Division checks any scales where “money changes hands.” This would include scales at grocery stores, livestock scales, buffets, agricultural-supply centers, highway patrol weigh stations and scrap metal facilities. Scales are checked on an annual basis or by complaint. The only exception is stockyards, which are checked twice a year.
When consumers bring unwanted appliances, metal debris or even old vehicles to a scrap metal facility the items are generally weighed on a truck scale. At some facilities, this scale can record up to 100,000 pounds of weight. The entire weight of the vehicle, trailer and scrap metal is recorded on the scale. After unloading inside the facility, the consumer then drives the emptied vehicle and trailer back over a scale at the exit and this weight is recorded. The consumer is paid for the difference of the two weights. Depending on the amount of scrap brought in, the amount could be a couple of hundred dollars.
To check a heavy truck scale, Inspector Glenn Farmer uses a six-wheeled, gas-powered, steel test cart. A hydraulic arm is used to fill the cart with certified 1,000-pound and 500-pound weights. For the test, he uses a known weight (the cart plus added weight) and test different quadrants of the scale. A five-section scale would have 18 different test points. There are two different types of truck scales, mechanical and load. To test a mechanical scale, Farmer must move his cart side to side to record weight. To check the accuracy of a load scale, he moves the cart down the center of the scale.
The Standards Division uses National Institute of Standards and Technology guidelines to determine tolerance levels on the scales. A tolerance level is the amount of weight a scale is allowed to vary. For a scale that can measure more than 25,000 pounds of weight, the tolerance level would be 60 pounds. A scale that does not pass inspection must be pulled out of service until the facility fixes the problem. “Many times the issue is debris buildup in the crevices of the scale,” Farmer said. “Pine straw, cans and other debris can cause the scale not to weigh correctly.
Our advice to the company is to power wash or use an air hose to clean the area around the scale.” If the scale is still recording incorrect weights after cleaning, the facility may call a scale calibration company to fix the problem. Some facilities will have a representative from their scale company go along with the standards inspector on the day of their inspection. This means that most problems can be fixed immediately, and the facility doesn’t have to endure a prolonged shutdown of a scale if problems are found.
This was a nice write up about testing scales and how important it is to keep your scales weighing accurately. It’s always a good idea to keep your scales clean and weighing as accurate as possible, year round. One easy way to do that is to contact us at (919) 776-7737 and set up a maintenance schedule for your scales. You’ll save money and you will have accurate scales with the regular scale checks.
Over time, truck scale accuracy can change due to a variety of issues, mostly usage and wear and tear. When you’re looking at a truck scale, accuracy is very important to your business because the value of the product you are transporting affects your bottom line and correlates to the weight you see displayed on the scale indicator. It can also be a safety concern as well, since truck weights must be in compliance with federal safety regulations.
WEIGHMENTS PER DAY: 100
SCALE ERROR: 10 LB
PRICE PER POUND OF YOUR PRODUCT: $0.50
DAILY LOSS: $500
YEARLY LOSS: $150,000
As you can see from the example above, small errors can add up very quickly.
So, you might be thinking, but my scale was calibrated when it was installed, I should be good, right?
Well, the initial installation, does not guarantee continued accuracy. When a truck scale is first installed, it is tested by the scale company and the state weights and measures, both using certified test weights. This is done to ensure the scale’s accuracy as well protect the scale buyer, seller, and the scale installation company. At this point, the scale is certified and ready for everyday use.
However, the scale will need to be checked and adjusted at least a couple of times a year at a minimum. As you can see from the example above, just a few pounds of errors can cost your company a lot of money.
It’s important to remember, scale calibration does not lock in forever. It is dependent on several factors such as frequency of use, weather, gravity, electrical currents etc…. can throw off the accuracy of a measurement device.
We’ve been checking, testing and adjusting scales for a long time. And over the years of calibrating scales you learn a few things and pick up on a few nuggets of wisdom regarding scales and how to keep them working year round. Scales are precision instruments that need to be maintained on a fairly regular basis in order to ensure accuracy and reliability. Your scale accuracy can influence your profitability greatly. There are lots of examples, everything from ingredients used in a recipe for batching to recycling metal or aluminum. Every ounce counts and a scale that isn’t accurate can cost you, or your customer. Of course, if your scale breaks down, you’re going to be down for potentially several hours depending on the service and replacement parts needed. The bottom line is, Scales are important and need to be maintained.
Regular service and calibration from a factory trained service technician is important. We have seen examples in the past where companies realized that they need regular maintenance on their scales, but to save money they would choose a different company who didn’t have factory training on the actual scales the company owned. As fate would have it, the scale broke and their technician spent large amounts of time trying to troubleshoot the problem, which was difficult since he didn’t have factory training on this particular brand. CCS was contacted and the scale was repaired and working within a couple of hours.
Another example is a company who buys/sells based on the weight of items loaded on their trucks. With most truck scales we recommend at least a semi-annual check and calibration but the customer felt the costs were not worthwhile for their business and they wanted to go with a call as needed model. Over the course of the year they noticed that their truck weights seemed to be off, so they called CCS to check and calibrate their truck scales. Their scales were off by several graduations and the customer had been losing what turned out to be hundreds of dollars in profits per truck over the past several weeks. At that point, the customer was very interested in discussing a quarterly scale check and calibration. Continue reading →
Recently, I was informed of a situation that involved a digital infant scale and a “test weight” also known as a 5 pound consumer barbell weight. Apparently, the barbell weight was used to check the digital scale and it was thought that the scale had not been calibrated correctly due to a scale readout of 5.2 lbs.
Actually, consumer barbell weights like those used in the above scenario are manufactured to tolerances between +/-1% and +/-7%, a significant range of tolerance as compared to NIST certified test weights. Using a consumer barbell weight with a wider manufacturing accepted tolerance than the scale may result in a scale display reading that seems inaccurate. A +/-5% tolerance on a 5 pound consumer barbell weight means the weight can weigh from 4.75 lb to 5.25 lb and still be sold as a 5 pound weight. Compare that to a 5 pound NIST Class F weight which is manufactured and adjusted to within +/-230 mg tolerance. In the example above, the user contesting the calibration accuracy of the digital scale checked their consumer barbell weight again, this time on a certified Legal for Trade scale and found that it weighed 5.2 pounds, meaning the digital scale was correct.