January 2008 | Commentary | Viewpoint

Who Ruined the Inventory?

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If you got a call from a customer complaining that the temperature-sensitive goods you shipped were ruined, would you be able to track down where and how it happened? If the problem was on their end, could you prove it? What if a supplier sent your company decayed goods?

Nobody needs disputes like this wreaking havoc throughout the supply chain. These kinds of disputes are predictable, however, if any link in the supply chain is deficient in temperature- or humidity-monitoring techniques.

The following five best practices ensure both appropriate storage and handling techniques and your ability to document them.

1. Put warehouse mapping on a regular schedule. Don't make the mistake of thinking that warehouse temperature and humidity mapping is a one-time proposition. Even gradual changes in supply inventories can combine to create different temperature or humidity dynamics in a warehouse, such as hot spots where airflow has become restricted.

Closely regulated companies, such as those in the pharmaceutical industry, may require ongoing monitoring of warehouse conditions. But for many other companies, monitoring is more a matter of customer-driven compliance issues. Showing a customer that warehouse conditions were monitored one year ago or even two months ago might not cut it in the event of a dispute.

2. Determine critical mapping points. Many companies go through the motions of warehouse mapping without proper knowledge of what is truly required.

One example: a 50,000-square-foot warehouse with 30-foot-tall ceilings that uses only a few data loggers and places them all at the six-foot level, ignoring the dynamics of hot air rising.

Such practices ignore typical problem areas near ceilings, doors, heaters, and exterior walls or where racking, shelving, or pallets constrict airflow. Exits to unconditioned spaces or outside should always be monitored; so should areas near any HVAC outlets.

3. Select appropriate data loggers. In recent years, a proliferation of data logger models has been introduced. Warehouse and supply chain personnel who understand current options will have a much easier time finding the technology that best matches their application.

Putting a thermometer here or there in a facility is not meaningful. Chart recorders or data loggers that keep track of temperature and/or humidity over time are required. Choosing the best instrument begins with zeroing in on your requirements for data capacity, sampling rate, monitoring range, size, battery life, calibration schedules, software, and networking capabilities.

Push-to-start data loggers are an important tool for shippers. These loggers allow the monitoring process to begin as soon as inventory is loaded on trucks or sealed in packages. For packages being shipped by air, smaller, coin-sized data loggers may be of particular interest.

The types of data loggers that include minimum/maximum displays can be useful in managing potential supply chain issues. When shipments arrive, these loggers provide a quick reference to ensure that their temperature and/or humidity conditions remained within required specifications.

4. Data handling and retention. Documentation is key. If you do get that customer call complaining about ruined inventory—or need to make a call to your supplier—it should only be a matter of minutes before all the temperature and humidity monitoring data is immediately accessible. That's the beauty of data loggers.

All monitoring data can be exported to Excel spreadsheets and when required, calculations of mean kinetic temperatures (fixed temperatures that simulate the effects of temperature variations over time) can be performed. For those who prefer to use chart recorders, the physical charts can be filed appropriately so they can be retrieved when needed.

5. Keep an eye on productivity. While monitoring temperature and humidity conditions is important in many supply chains, it does not need to eat up personnel time to any great extent.

Three common errors can make temperature and humidity monitoring an onerous and time-consuming task.

First, some warehouses do not have a sufficient number of data loggers or chart recorders to complete a mapping exercise in one step, so they spend a good deal of time rotating loggers from place to place.

Data loggers and chart recorders are relatively inexpensive items compared to the total capital expenses that many warehouses incur. The labor costs for mapping a facility's environmental conditions piecemeal usually cannot be justified.

Second, excessive sampling causes a problem. Temperature and humidity changes occur relatively slowly. In a typical open warehouse of moderate size, sampling every 10 to 15 minutes should adequately evaluate temperature trends.

Excess sampling is both unwieldy and an unnecessary drain on productivity that ties up both computers and managers in processing too much data.

Third, using out-of-date technology can threaten the success of an environmental monitoring program. Purchasers sometimes buy monitoring instruments from sources with limited model options instead of from suppliers offering a wide range of instruments with varying features.

For example, chart recorders and data loggers that use both audio and visual alarms to alert of unacceptable conditions are important to source. USB-enabled downloading is another big time-saver, as are the min/max display instruments that can tell at a glance whether temperature or humidity has veered into the unacceptable range.

By following proper inventory monitoring strategies and avoiding common errors, you can reduce the likelihood of receiving a call from a customer asking, "Who ruined my inventory?"

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