VersaTrak Temperature Probes
Precision matters, and we make it simple.
Not All Probes are Equal
The team at VersaTrak takes temperature probes very seriously. The temperature probe is the starting point in delivering the most accurate reading possible. When it comes to “emulating” products for which VersaTrak is monitoring, it is an absolute must that the probe/simulator we manufacture be as close as possible to the actual item.
Every testing agency (NSF, NIST, ETL) recommends, when simulating liquid products, the use of a 50/50 mix of glycol and distilled water. This mixture allows for product simulation at a variety of temperature ranges while maintaining the behavior of the product being simulated. Any other material will distort the temperature readings and the performance of the probe and delay the response time.
In addition to the simulator liquid formula, the vessel in which it is contained is of utmost importance. The best way to deliver the most accurate “product” temperature is to use the actual container with same amount of simulator liquid as the actual product. Whether in the lab or pharmacy, an identical match to the actual product being monitored should be used for simulation. Keep in mind that even if the shape of the simulator might be the same, there is no surety that this will effectively emulate your products. Only the actual container, filled with the precise liquid mixture, will provide the most accurate simulation for the critical products being monitored.
The Big Difference Between Probes
There are a wide variety of temperature probes and “product simulators” on the market to choose from, each with its own purpose and application including solid plastic blocks and glycol solution filled vials or bottles. However, these solid plastic simulators do not accurately “simulate” the
vaccine vials they are supposed to mimic.
Every element on earth has a Thermal Conductivity value (i.e. “the property of a material to conduct or give off heat”). A refrigerator does not actually cool anything; it removes heat from the environment and the products stored inside it. Consequently, if you are trying to use a “product simulator” to monitor specific items, you will achieve the most accurate results by using a simulator that is closest to the physical makeup and thermal conductivity characteristics of your target item(s) as possible.
Below are the findings of NIST on the validity of solid plastic simulators:
“We recently tested high density polyethylene plastic for this exact purpose. The thermal conductivity of HDPE plastic is close to that of glass, air, and water (the key components of a vaccine vial), so we thought it might closely track stored vaccine temperatures as a result. However, we found that the plastic provided a poor approximation of the temperature response of the vaccine. During normal, closed-door refrigerator cycling, a probe in a plastic cylinder of a diameter and height similar to that of a vaccine vial consistently recorded temperature extremes as much as 1°C higher than a neighboring vaccine vial. During routine door opening, this temperature difference increased to 2°C or more. Given this, I would say that HDPE plastic is *not* a good choice for vaccine temperature monitoring, because it may lead to significant “false positive” temperature excursions and/or missed temperature excursions. We also tested a glycerol/water mixture (20%/80%) in this testing (0.5 mL fill in a vial with same nominal dimensions as a vaccine vial) and found the performance much better, with typical temperature offsets from vaccine temperatures on the order of 0.1 °C or less.”
Buyer beware should you deviate from the industry standard of using Glycol/Glycerin based simulators. DO NOT sacrifice accuracy and best practices because someone is trying to create something “unique” to sell. These companies are putting you and your patients at risk.
Don't be Fooled
Simply put, you can’t transfer a “NIST” calibration/certification by simply comparing a temperature from a different thermometer.