Bar Codes are an excellent solution in many environments. In a grocery store bar codes are used successfully to speed up the check out process. Many welding supply distributors have adopted bar codes on their stock items to speed up the processing of invoices at their sales counters.
Bar codes are ideally suited to controlled environments. These environments are typically dry and not abusive to the bar code. Warehouse receiving and shipping areas are two other examples of ideal environments.
Cylinders on the other hand are not in a controlled environment and take a lot of abuse. Cylinders are knocked against each other during shipment and are also painted and shot blasted on a regular basis. Cylinders are often found being used in welding shops, manufacturing plants and on heavy construction sites. Bar codes do not hold up well to this type of abuse.
Bar codes are also ideal short-term methods of tracking a product. But cylinders last a very long time. So the type of identification tag used to track the cylinder should have an equally long life expectancy. While two or three years is considered a long time for bar codes in harsh environments, Trovan transponders have been successfully used on cylinders for more than 15 years without having to be replaced.
Why does the transponder work so much better?
The Trovan transponder
excels in those areas where a bar code often fails. Here are a few examples:
Scanning or reading a bar code works by measuring the contrast between the dark bars and the light areas between the bars. In direct sunlight, there is often too much light reflected from the bar code and it becomes very difficult to read. When working in direct sunlight you will often see a driver using his hand to shield the bar code from the direct sunlight so the bar code can be read. If the driver is using a laser scanner, he will also get as close to the bar code as possible with the reader, in effect touching the bar code. This provides a shadow effect making the bar code readable.
Both of these techniques force the driver to take extra steps in order to read the bar code. These extra steps make the job more difficult, slowing the driver down and negatively affecting productivity.
The Trovan transponder by contrast works on a radio frequency.Too much light or too little light does not affect the transponder. In fact the transponder can be completely covered and still be read easily.
Cement dust, dirt, ice, snow, grease, oil, paint and mud are all commonly found on compressed gas cylinders. In most cases, a bar code even partially covered with mud or cement dust cannot be read. If the laser scanner cannot see the bar
code clearly, it cannot read it. The Trovan transponder can be completely
covered with dirt, mud, ice, snow and even paint and still be easily read.
If you try to use a bar code in these adverse conditions, the driver may end up spending a significant amount of time cleaning the bar code which negatively impacts his productivity. If the bar code is severely scratched, it will not read even when cleaned. Many distributors have a significant number of cylinders that come out of mines, processing plants or cement plants coated with dirt, dust or mud. In these environments virtually every bar code has to be cleaned before it can be read. In colder climates the bar code may be covered with ice. The ice would have to be scraped or chipped off before the bar code could be read. With the Trovan transponder, these conditions pose no problem.
Line of Sight
The bar code reader has to see the bar code in order to read it. When cylinders are stacked together on a pallet, the bar codes will be facing different directions. If the driver is on one side of the cylinder and the bar code is on the opposite side of the cylinder; it will be very difficult to read the bar code. A common practice in bar code installations is to place two or three bar codes on the cylinder facing different directions to make them easier to read. This may make it easier to read but it doubles or triples the cost of the bar codes. It also doubles or triples the installation time.
The Trovan transponder reader does not have to see the transponder. It just has to be near the transponder. In most cases the driver can position his transponder reader in the general area of the transponder and be able to read it.
Bright sunlight not only makes the bar code difficult to read, unless precautions are taken, the ultraviolet rays will cause the label to fade making it virtually impossible to read. A simple scratch in the wrong place makes the label useless. Shot blasting and periodic refurbishing such as painting will ruin the bar code unless precautions are taken. These precautions (such as covering or protecting the bar code) take more time and reduce productivity.
The Trovan transponder has been exposed to the following types of abuses and still functioned properly:
1. Painted multiple times with aluminum-based paint
2. Bead blasted repeatedly
3. Placed in a steam cabinet at 400 degrees Fahrenheit for five minutes
4. Heated to 300 degrees Fahrenheit for thirty minutes
5. Exposed to high doses of radiation
6. Subjected to 100,000 volts of electricity
7. Placed in liquid nitrogen
Studies by large corporations in the compressed gas industry have shown the expected life of a bar code to be less than three years. Depending upon the environment, a life cycle of less than one year may be more typical. In some specialized applications, the cylinder is bead blasted and repainted every time the cylinder is filled. In these environments the bar code would last only one trip to a customer and back while the transponder would last indefinitely.
The Trovan transponder has also been subjected to a process called accelerated life testing. This process determines what would happen to the product as it ages for periods of ten, twenty or thirty years. This scientific process aged the Trovan transponder to thirty years and it still performed properly.
How does the life span of the bar code affect productivity?
To answer this question we will use a life expectancy of two years for the bar code. Each time a bar code is replaced, the following must be done: old bar code removed, new bar code retrieved (we are assuming preprinted bar codes in this example), new bar code attached to cylinder, a handheld computer is used to associate the new bar code number to the cylinder, the handheld computer is transferred to the host computer system, captured label information is downloaded to the computer system and the computer system updates master records with a new label number. If we use a conservative figure of four minutes per cylinder, a distributor with 100,000 cylinders would need a full time person on a permanent basis just to replace the bar code labels that were falling off or were unreadable.
To this equation you must also factor in the negative effect on productivity encountered by the driver. When a driver picks up a cylinder on his route and the bar code will not read, he must manually enter the serial number and then remember to set the cylinder aside when he returns so a new label can be attached to the cylinder.
To summarize, the following areas should be factored in when considering the short life cycle of the bar code:
- Cost of a person to constantly replace the bar codes that are being replaced because of damage.
- Cost of bar codes used for replacement, typically two per cylinder.
- Negative impact on driver productivity - including frustration factor.
- Human errors introduced into the system due to constant re-labeling.
- Lack of confidence in the system due to the large number of labels replaced
Bar codes are often looked upon favorably because of their low initial cost. In order to determine the true value of a product you must look at all of the variables. To obtain a true comparison you would need to include the cost of replacing the bar codes every two or three years (depending your environment). You would factor in the labor costs, label costs and any downtime for the cylinder. On the other hand, the Trovan transponder has proven to last significantly longer reducing associated label and labor costs.
In fact, our experience has shown that when properly applied, The Trovan transponders have a loss rate of less than one tenth ofone percent. So while bar codes have a price advantage on the initial installation, in the long run they can prove to be much more expensive.
So the answer to the question, whether a bar code or a transponder is better depends upon your environment. If your cylinders are in a protected, dry environment, bar codes may be the solution of choice. If your environment is wet and harsh, transponders would be an excellent alternative.