Temperature sensor probe. Sensors are basic devices that detect or measure temperature or other physical properties. A temperature probe is a metal sensing rod that can be inserted into a refrigerator or freezer. Sensor probes inside the cool storage unit detect or measure temperature or other physical properties. They are connected via wires or wirelessly to the monitoring device, which continually displays and records the temperature readings.
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Explore This IssueOctober/November 2018
An important distinction between a sensor and a probe is that a probe is much more resistant to harsh conditions. A temperature probe is able to withstand temperatures that are too cold for most sensors or contact-type switches. Because they are so hardy, temperature probes can be placed in cold and wet environments that could ruin electronics or be inappropriate for a thermometer.
Most commercial-grade refrigerators have access ports to allow for third-party temperature probes, which is best practice. However, users can drill a hole in the side, insert the probe and then seal the hole, or simply place the probe in the refrigerator and run the wire through the door opening. The gasket around the door should make a strong enough seal around the wire to keep the outside air from seeping in.
Temperature buffer. A sensor probe can be used with or without a temperature buffer, which acts as a cushion against temperature fluctuations in a freezer or refrigerator. A typical buffer is a bottle filled with glycol solution or glass beads. A probe is then inserted into the bottle. Buffers help to mimic the temperature of the food in your refrigerator or freezer. Without a buffer, the probe or sensor measures the atmosphere inside the storage unit, which can change rapidly with defrost cycles, door openings, or fans circulating the air. The air temperature of the storage unit changes much more quickly than the temperature of food products, so a buffered probe reading more accurately represents the temperature of the stored goods.
Buffers also reduce false alarms caused by slight changes in the air temperature inside the unit. False alarms are not only a nuisance, they can cause the data logs to record misleading information, which can make it seem like a facility is not maintaining compliance.
Wireless probes. A hardwired monitoring system connects sensors to the base device with wires. A wireless system uses built-in radio transmitters to communicate data readings to the monitoring system. A wireless temperature probe allows for greater flexibility in the placement of the probe, sensor, and remote monitoring system.
Automatic Data Logging
Because it is important to keep an ongoing record of temperatures to document that food is stored properly, select a monitoring system that logs and stores data. This data history is also valuable in identifying trends in temperature fluctuations. Recognizing unusual patterns could provide insight regarding potential equipment complications.
Monitoring systems record tens of thousands of data points, dates, and times. Cloud-based logging provides an unlimited number of records for users to view, graph, print, and export data trends. More advanced systems allow users to log both the highest and lowest temperatures over a set period of time. This provides a snapshot showing whether the temperatures were within range that day, which is especially convenient when the person responsible for temperatures is not the same as the person designated to receive alarm notifications.
A simple measure to help maintain safe food temperatures is to monitor the power at each refrigerator or freezer’s outlet with a power-out sensor. If a breaker trips and power is lost at the cooling unit, monitoring the power will provide ample time to take corrective action, rather than waiting until the food temperature limits are at a dangerous point.