A few tips for accurate temperature mapping in the pharmaceutical industry, and for specialty warehouse storage users in general
Proper temperature mapping is important, but shouldn’t really be too technically challenging. Here are a few tips on more getting 
accurate, useful data with the procedure.
Temperature mapping of specialty warehouse storage facilities must be accomplished in several different conditions
Of course, you should perform mapping when the warehouse is empty as well as when it is full so you understand how it performs at both extremes, and know its real tolerances. Both summer and winter mas should be developed, especially in those regions with high seasonal temperature variation.
The mapping should be done during a work day rather than w weekend, even though this is not generally very convenient. The cool room doors are opened and closed much more often during a regular working day, though, so weekend results cannot be as accurate as weekday ones. Some facilities also turn off the heating in sections which are unoccupied overnight or on weekends.
Temperature mapping really needs to be redone after making any substantial modifications to the facility, and also whenever the stock layout changes noticeably or the HVAC system is altered.
7 steps to achieving a reliable temperature map of a specialty warehouse storage facility
When making these maps, make sure to follow these 8 steps:
1) Choose a data logger with the features you need to monitor your facility effectively. Common useful features include:
- Storage capacity: A unit’s data storage capacity determines how many sample points each device can take before its memory is full, and the results must be uploaded. The more units you will need, the less frequently you want to be uploading the data from each.
- Sampling rate: Most data loggers allow you to select different sampling rates. Make sure your machinery allows the rate you need (see below for a brief discussion of sampling rates).
- Temperature range: This depends heavily on the type of space you are mapping. Most specialty warehouse storage facilities have particular ranges at which they are (supposed) to operate. Make sure your loggers could register temperatures both over and under the expected range by a larger margin than you can expect to use.
- Reading accuracy: +/-2 degrees and +/-2% relative humidity should be sufficient for most specialty warehouse storage maps, but refrigerated storage facilities require finer tolerances, and no more than +/- 0.5 degrees will really do.
- Physical size: Choose a logger that fits into each of your grid locations (see below for discussion).
- Battery life: Your chosen unit must have sufficient battery life for a full mapping sessions, with some margin (see below for a discussion of session length).
- Firmware and sample collection software: Choosing a logger with the right software ensures ease of use.
2) Spacing a three-dimensional sensor grid
Temperature sensing points need to be arranged along a 3-dimensional grid (length, width and height). In an open plan warehouse, experts suggest that sensors should be 30 to 100 metres apart (100 to 300 feet). A warehouse with significant numbers of walls or racks extensive enough to block airflow may require a finer grid, of course, as is detailed below.
3) Identify any critical mapping points.
Large and open spaces are more difficult to maintain at a consistent temperature and/or humidity. Make sure to measure temperatures at the places that could cause problems. Especially problematic spots in most specialty warehouse storage facilities can include:
- Areas next to external walls or the ceiling are more vulnerable to external temperature change and insolation.
- Heated air rises, so look for temperature stratification in larger spaces.
- Poor circulation or bad fan placement can cause higher temperatures near sources of heat like HVAC ducts or windows.
- Pallet storage, racks or shelves can cause hot spots to appear, because they limit airflow.
- Doors or exits to non-temperature controlled areas have a tendency to be left open, even against procedural command.
4) Determine the frequency at which to sample.
You need to track how conditions change in your specialty warehouse storage facility change over time as well as space, giving your map its important fourth dimension. For most kinds of specialty warehouse storage facilities, you will want to sample temperature (and humidity, but that is a different issue) every fifteen minutes for a period of at least one or two weeks. Again, try not to schedule this for particularly slow times.
Taking too many samples will make your analysis cumbersome without adding appreciably to accuracy, and too few will not allow you to track cyclical changes in the variables you are mapping.
5) Document the location of your sensors well.
Not only will this make the reading and recharging of the units easier, but if you record which unit was used in each position, you can determine if unexpected readings are due to faulty units, and remove them from the data.
- Name each logger according its location, or keep a list of serial numbers and locations assigned
- Label each logger with its location, perhaps with a sticker
- Create a map witch indicates the locations of all your data loggers.
6) Upload all recorded data.
Once the sampling period is over, collect all the loggers (which have already been labelled by location) and upload the logged data to your computer according to the mapping software you use. Many facilities export the data directly to MS Excel, and calculate the Mean Kinetic Temperature from there.
The Mean Kinetic Temperature of a specialty warehouse storage facility is a single temperature reading that approximates the effects of known variations in temperature over time. It allows one to estimate the thermal stress a product can be expected to accumulate during a period of storage and later in distribution. Minimum and maximum temperatures should be recorded in addition to the MKT.
7) Document (and repeat) your process.
Once you finish the first temperature map of the specialty warehouse storage facility, you should repeat the procedure exactly at least once. If at all possible, use the same data loggers in the exact same locations. Document every step again, even if it is the same procedure, in case of error.