Probes
PRTs, Thermistors, Thermocouples and Liquid in Glass Thermometers
 Secondary Standards PRTs |
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Hart’s high-temp secondary standards fill the gap between affordable, but temperature-limited secondary PRTs and more expensive, highly accurate SPRTs.
If you’re using block calibrators, furnaces, or temperature points above normal PRT temperatures (420 °C), then these two PRTs are for you. The 5626 is nominally 100W and the 5628 is nominally 25.5W. Both instruments have a temperature range of –200 °C to 661 °C. They make great working or check standards for calibration work up to the aluminum point.
Using a regular PRT at temperatures above 500 °C exposes the platinum to contamination. If the PRT is used as a reference or calibration standard, contamination is a major problem. SPRTs, which are more expensive and delicate, can handle the higher temperatures, but with greater risk to the instrument due to shock, contamination, or mishandling. The 5626 and 5628 are designed to reduce the contamination risk through the use of internal protection while not impairing performance.
In addition to the right measurement performance and durability, a PRT for secondary applications should be priced affordably. Hart’s new PRTs are inexpensive and come with an accredited calibration. The calibration comes complete with ITS-90 constants and a resistance-versus-temperature table.
Check the temperature range, check the stability, check the price! Who else gives you this much quality, performance, and value for your money? No one!
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Secondary Reference Temperature Standards |
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For years, you’ve relied on our 5612, 5613, and 5614 Secondary Reference probes. These field-durable, lab-accurate PRTs have been replaced by the 5615, which comes with a NVLAP accredited calibration.
The 5615-12 is a Platinum Resistance Thermometer (PRT) with an Inconel™ 600 sheath that’s 305 mm (12 in) long and 6.35 mm (0.250 in) in diameter. It is a secondary reference temperature standard designed to bridge the gap between the highest laboratory standards and industrial or second-tier lab locations. It has short-term accuracy of ± 0.013 °C at 0.01 °C.
The element is constructed of reference-grade platinum wire (99.999 % pure) for excellent stability. The wire is wound in a coil and placed in a mandrel where it’s uniformly supported in a manner to virtually eliminate hysteresis. The electrical configuration is a four-wire current-potential hookup to eliminate effects of lead-wire resistance.
These Inconel™-sheathed probes have a fully supported sensing element, making them more durable than SPRTs. The element is protected in an ultrahigh-purity ceramic case with a hermetic glass seal to improve output stability by locking out moisture and contaminants
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Precision Industrial PRTs |
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When buying a PRT, performance isn’t the only criterion you need to look at. The real issues are price-to-accuracy and price-to-durability ratios.
The 5627A probes have a temperature range up to 420 °C and an accuracy as good as ±0.05 °C. They come in three different lengths. (The six-inch and nine-inch model covers –200 °C to 300 °C.) Each instrument is shipped with its ITS-90 coefficients and a calibration table in 1 °C increments.
One of the best features of this sensor is that it conforms to the standard 385 curve, letting you use your DIN/IEC RTD meters fully. Why use a probe that’s less accurate than your meter?
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Fast Response PRTs |
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For special temperature measurement applications requiring fast response or short immersion over a wide temperature range, Hart’s new 5622 series PRTs are the perfect solution.
Made by Netsushin, one of the world’s leading PRT manufacturers, this series includes four models with stainless steel sheaths ranging from 0.5 to 3.2 mm (0.02 to 0.125 in) in diameter. Because these high-quality wire-wound sensors come in small packages, heat transfer to the sensors occurs quickly. Time constants from 0 °C to 100 °C are as fast as 0.4 seconds.
Immersion requirements for these probes is also a plus, ranging from just 10 mm to 64 mm (0.4 to 2.5 inch), depending on the model. Getting into shallow or tight places is not a problem. And because these probes can handle temperatures from –200 °C to 350 °C, they’re more versatile than most thermistors
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| Small Diameter Industrial PRTs |
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For secondary level performance with full ITS-90 calibration, Hart’s 5618B series PRTs are an excellent choice for critical temperature measurements. Featuring a 3.2 mm diameter (1/8 in) sheath, these industrial standards probes have reduced response time without compromising precision. This small diameter 5618A probe works well in many applications where immersion depth is limited. Larger diameter probes give more measurement error in short immersion depth applications because they conduct more heat between ambient and the sensor.
With each probe you will receive a full NVLAP-accredited calibration report. On the report you’ll get the test data and the ITS-90 calibration coefficients that you can easily input into your Hart thermometer. If you are using a 1521 Handheld Thermometer readout, we’ll program the coefficients directly into your INFO-CON connector.
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| Special Application PRTs |
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| 5623B Precision RTD Freezer Probe |
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If you need a precision measurement at low temperatures, do not look any further than Hart Scientific.
The 5623B, precision “freezer probe,” is specially sealed from the sensing element to the end of the probe cable, preventing ingress of moisture when exposed to temperatures as low as –200 °C. The entire assembly withstands temperatures over its full range (–200 °C to 156 °C), which is ideal for verification of freezers or autoclaves where a thermo-well isn’t available. The 5623B assembly can be fully immersed in fluids when the application may require use in a liquid bath. The 5623B is available in a 6.35 mm (0.25 in) dia. × 125 mm (6 in) long Inconel™ sheath. With accuracy (that includes calibration uncertainty and short-term drift) of ± 0.05 °C over its full range, the 5623B is just right as a secondary standard for calibration of other process sensors.
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| 5624 Platinum Resistance Thermometer to 1000°C |
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We’re pleased to introduce the world’s finest high-temperature secondary PRT, our Model 5624.
Ideal for use as a reference thermometer in high-temperature furnaces, the 5624 can reach a temperature of 1000°C with long-term drift at 0°C of 10 mK and accuracy (including short-term stability and calibration uncertainty over the full range) of 55 mK! Due to Hart Scientific’s proprietary sensor design, this PRT has short-term stability of 5 mK, and an immersion requirement of less than 153 mm (6") at 700°C.
The 5624 is assembled in an alumina sheath that is 508 mm (20") long and 6.35 mm (0.25") in diameter. Several termination configurations can be selected to match different thermometer readouts. Each 5624 comes with a NIST-traceable, NVLAP-accredited fixed-point calibration from 0°C to 962°C. That’s a fixed-point calibration! The 5624 also comes in a protective carrying case.
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| Thermistors |
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| Thermistor Standards 5640 to 5644 |
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If you want a high-accuracy probe with excellent stability at a great price, the Model 5640-series Thermistor Standards Probes give you all three in a great package. Why pay for an SPRT when you can get ±0.001 °C accuracy from 0 °C to 60 °C in a calibrated thermistor probe for about one-third the cost of an uncalibrated SPRT alone?
Each probe uses an ultra-stable glass thermistor enclosed in a thin-wall stainless steel tube. The basic semiconductor element is a bead of manganese, nickel, and cobalt oxides mounted on 0.1 mm platinum wires. For long-term stability, the thermistor is aged at various temperatures for 16 weeks. During the aging process, verification of the probe’s stability is done to ensure performance to published specs.
The 5640, 5641, and 5642 thermistor probes are designed for the temperature range of 0 °C to 60 °C. The 5643 and 5644 probes span the 0 °C to 100 °C temperature range. They offer stability of either ±0.002 °C or ±0.005 °C. These stability levels are guaranteed for one full year.
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| Seconday Thermistor Probes |
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Hundreds of thousands of thermistors are sold every year, but only a few have the stability necessary for use as high-accuracy thermometry standards. If you're looking for economical lab-grade thermistor probes for accurate work across a narrow temperature range, Hart's Secondary Reference Series thermistor probes are the best you can buy.
These thermistors are available in a variety of sheath materials appropriate for your specific application. In addition to our metal-sheathed probes, we offer flexible Teflon encapsulated and silicone coated thermistors that have smaller tips and can measure those places where even a metal-sheathed thermistor can't reach.
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| Type R and S Thermocouple Standards |
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Made from the finest platinum and platinum-rhodium alloy, the Type R and Type S Thermocouples cover a temperature range of 0 °C to 1450 °C with uncertainties as good as 0.15 °C over most of that range. With four different models for each type, we have the thermocouple to fit your application.
The measuring junction of both the 5649 and the 5650 is encased in a 0.25-inch (6.35 mm) alumina sheath that can be ordered in lengths of 20 or 25 inches (50.8 or 63.5 cm) to fit the specific requirements of your application. A reference, or “cold,” junction may also be ordered. The reference junction uses a stainless steel sheath and is 8.25 inches long (21 cm) by 0.188 inches in diameter (4.8 mm). The thin diameter minimizes the immersion depth needed, but the extra length ensures you can get all the immersion you like.
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| Liquid in Glass Thermometers |
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Need LIG thermometers? These Ertco models are manufactured in strict accordance with ASTM precision specifications and provide accurate and reproducible measurements. These total-immersion thermometers are perfect for critical temperature measurements or as calibration standards.
When used properly, these thermometers typically have errors of less than ±.01% of scale. Each one is accurate to ±1 scale division, and stem diameters vary from 7 to 8 mm. Individual serial numbers are given to each unit.
Every LIG thermometer is factory calibrated against NIST standards. The NIST-traceable certificate gives the ice point reading, five calibration points, tabulated corrections (to one-tenth of the smallest scale division) for each calibration point, the serial and test number of the NIST standard and test notes.
Choose from a variety of total-immersion thermometers from Ertco and put them on the same order as your other Hart instruments. Like always, we’ll take care of your customer service needs.
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Products > Calibration > Temperature > Probes 
