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Up to a few years ago, accuracy was not a very critical aspect and tolerances of a few degrees did not jeopardize a process. From the time that hazard analysis and critical control points (HACCP) programs became a necessity in the food industry, measurement accuracy has become a discriminating factor. Due to health risk factors, now an error of a few tenths of a degree can decide whether food can still be kept or must be discarded. In 1990, Hanna began to produce thermometers for our customers’ HACCP programs to comply with new governmental regulations. Soon after, Hanna became the market leader in Europe as a result of the technological solutions offered to our users.
As previously described, the electronic components of an instrument shift with time. Hanna has made it possible for users, with the simple touch of a button, to verify whether the response of the instrument is within the tolerance limit of ±0.02oC.
The CAL Check system acts by substituting the sensor with an internal resistor which corresponds to 0oC; thus simulates the response that the temperature probe would have at 0oC.
Hanna thermometers can be divided into four main technologies: thermistor, thermocouple, Pt100, and infrared.
A variety of thermistor based testers are available. They include versions with a folding probe, reinforced handle for insertion into semi-solids, and ones that can mount on a refrigerator.
Multiple temperature data loggers are available. These include versions with built-in and external thermistor probes.
Availability on Request
The thermistor is a semi-conductor device whose resistivity (r) varies as a function of temperature (T):
Temperature resistance coefficient is the parameter that determines if the resistivity variation is positive (as with the Positive Temperature Coefficient, or PTC sensors) or negative (as with the Negative Temperature Coefficient, or NTC thermistors). It is possible to determine the temperature by applying a potential difference and measuring the resistance.
Thermistor sensors are suitable for a temperature range of -50 to 150oC (-58 to 302oF). Higher temperatures may damage the semi-conductor sensor. Accurate temperature measurements are possible (tenths of degree) due to the high sensitivity of the sensor.
The thermocouple consists of the junction of two wires of different metals. At a given temperature, a potential difference results at the opposite extremes of the two wires (Seebeck effect), with the respective variations linearly related within small intervals. It is therefore possible to determine the temperature given the potential difference and characteristics of the two metals. The measurement end of the thermocouple probe is called the hot junction, while the connection of the thermocouple to the meter is the cold junction. An error is introduced as the cold junction is exposed to the ambient temperature. This error can be eliminated by physically putting the cold junction into an ice bath and forcing a reference temperature of 0oC, or by electronically compensating for the cold junction temperature effect. There are various types of thermocouples, identified by an ANSI code using a letter of the alphabet. The K type is the most commonly used thermocouple.
Accessories include the calibration keys used with thermistor thermometers and shockproof rubber boots to add additional protection to the meters. Also include are the handles and extension cables used with probes that do not have a handle.
To empower customers to achieve quality
by supplying intuitive, accurate, and reliable analytical instruments with exceptional customer service and value.
We take pride in every product we build. From an original idea, to a completed product ready for testing. We oversee every aspect of the manufacturing process. It is this level of attention to detail that sets us apart.
To empower customers to achieve quality by supplying intuitive, accurate, and reliable analytical instruments with exceptional customer service and value.
We take pride in every product we build. From an original idea, to a completed product ready for testing. We oversee every aspect of the manufacturing process. It is this level of attention to detail that sets us apart.
To empower customers to achieve quality by supplying intuitive, accurate, and reliable analytical instruments with exceptional customer service and value.
We take pride in every product we build. From an original idea, to a completed product ready for testing. We oversee every aspect of the manufacturing process. It is this level of attention to detail that sets us apart.
