Thermometer Probe and Digital Readout Combined into One Unit

The Fluke Calibration 1551A20DL Intrinsically Safe "Stik" Thermometer with Fixed RTD and Datalog, -50 °C to 160 °C, 6.35mm x 508mm (1/4 in. x 20 in.) is a stainless steel probe and digital readout, fixed together and calibrated as a single system. The accuracy specification is easy to understand, since it includes all uncertainty components, including drift, for up to one year. The large, backlit LCD display rotates 90°, making it easy to read from any angle. A user-configurable stability/trend indicator lets you know when your temperature is stable enough to record an accurate measurement. A user-settable auto-off function extends typical battery life to three hundred hours. A low-battery indicator and stop-measure function prevent erroneous measurements from being made due to low battery life. A simple, three-point calibration function allows you to easily and accurately calibrate the 1551A-20-DL. Data logging to internal memory of up to 10,000 time-stamped measurements is optionally available.

Why Calibrate Process Temperature Sensors?

Because temperature greatly effects the accuracy of volumetric measurements, process manufacturers of chemical, pharmaceutical, food or petroleum products require accurate temperature measurements, especially for processes where quality or custody transfer are regulated by government agencies. Since all temperature sensors are subject to drift with time, regular calibration or verification against a reliable reference thermometer is required. Finding a reference thermometer that is accurate, repeatable and robust, however, can be challenging.

What's Wrong with My Reference Thermometer?

Industrial reference thermometers available on the market today, such as mercury-in-glass thermometers (or "ASTM thermometers") and portable electronic thermometers are useful, but both come with inherent problems. Although accurate and repeatable, mercury thermometers are fragile. The risk of a mercury spill poses potential hazards to the environment and to the health of personnel. Many of the United States and European Union countries have already banned their use in industrial applications. Some organizations have replaced their mercury thermometers with more durable portable electronic thermometers, only to discover that the RTD probes lack the repeatability and dependability required of a legitimate reference thermometer.

The Best Alternative to Mercury Thermometers

The Fluke Calibration 1551A-20-DL is accurate, stable and durable, making it the best alternative to mercury thermometers and existing electronic thermometers. The thin-film RTD sensor incorporates the same characteristics of other premium reference thermometers designed by Hart Scientific, but it is more robust and less susceptible to drift. Accuracy and repeatability, however, are not sacrificed for improved durability.

Using a glass-stem mercury- or spirit-filled thermometer at different immersion depths, or at significantly different ambient temperatures from which it was calibrated, may require the application of emergent-stem corrections that can be tedious but necessary to calculate an accurate measurement. This is not required with the 1551A-20-DL; its sensor requires a minimum immersion depth of only 7 cm (2.8 in), with no appreciable effect on the measured temperature due to heat loss through stem conduction.

Some digital thermometers can become less accurate when used outside a narrow range of ambient temperatures. This is not the case for the 1551A-20-DL. Your measurement remains accurate in ambient temperatures from -10 °C to 50 °C (14 °F to 122 °F). With a superior probe design, combined with electronic functions that assist accurate measurement, the 1551A-20-DL "Stik" Thermometer surpasses the capabilities of other digital thermometers and is the perfect substitute for your mercury thermometers.