Temperature Sensing and Measurement Solutions THERMOMETRY PRODUCT GUIDE

Transcription

1 Temperature Sensing and Measurement Solutions THERMOMETRY PRODUCT GUIDE

2 INTRODUCING THE F100 PRECISION THERMOMETER NEXT-GENERATION TEMPERATURE MEASUREMENT FROM ASL NEW! Accuracy: ±0.02 C over full range. Resolution: C. Range: -200 C to +850 C. Stability: <0.005 C per year. Common inputs for SMART and normal PT100 and Thermistor probes. USB communications port as standard. Display in C, F, K (Kelvin) or ohms. Statistical functions: Average, Min/Max and Standard Deviation. New high performance handheld 2-channel thermometer for Pt100 and Thermistor probes. If you re looking for a step up in measurement accuracy with a battery powered, handheld thermometer, the F100 is for you. Our F100 can handle all your needs, with accuracies and resolutions normally associated with a bench top thermometer. Two inputs give you direct temperatures from Pt100 or Thermistor probes, or you can display the temperature difference between them. You can log measurements directly to memory or, if you prefer, use the USB port to control and data log with your PC. The F100 will display for you a statistical analysis of your measurements, with average value, min and max values and standard deviation. Because the F100 will display in ohms as well as temperature, you can even use it to calibrate one probe against another. Most instruments require you to enter calibrated probe data into memory to optimise measurement accuracy, which can mean a lot of data entering if you change probes regularly. With ASL s SMART connector on your probes, you only need to store the data once in the connector! The calibration data stays with the probe permanently. You can even use it on another F100 without any further action. The SMART connector saves you time and reduces error. If you have existing calibrated or uncalibrated probes, no problem, the F100 automatically registers if a probe is SMART or normal. The F100 offers laboratory performance with handheld convenience! Range Accuracy Resolution Stability Temperature co-efficient Data entry format Probe current Probe types Maximum cable length -200 C to +850 C, depending on thermometer probe. ±0.02 C (±20mK) C. Long term: typically <0.002 ohms per year (<0.005 C for Pt100). < C per C ambient change. ITS90 and CvD for calibrated probes; or EN60751 for un-calibrated probes. 1mA switched d.c. (Pt100); Auto-select 1mA, 25µA & 5µA for thermistors. Pt100 and Pt25 resistance thermometers plus NTC thermistors. 250 feet for Pt100; 75 feet for SMART Pt100. Thermometer input 2 x 5 pin industrial DIN socket with screw lock to connecting plug, accepting both normal and SMART probes. connectors Display Backlit LCD. Communications USB interface. Data storage capability 16,000 readings (combined total for both inputs) User functions Display hold, Display zero, one-shot measurement, measurement log. Statistical analysis: min/max, average, standard deviation. Operating conditions Full specification range: +15 C to +25 C. Full operating range: 0 C to +40 C <80%RH non-condensing. Power Nickel-Metal Hydride (Ni-MH) rechargeable battery. Charging socket built-in. Low battery indicator. Dimensions Weight 9.13"(L) x 3.82"(D) x 2.09"(W) nominal. 1.1 lbs

3 THERE IS A REASON WHY... National Laboratories and even our competitors choose ASL AC Resistance Technology as their best thermometry standard Why is AC better than DC? The ability to measure resistance accurately is key to precision thermometry, where the practical temperature scale is implemented using the resistance of a PRT (platinum resistance thermometer). Resistance is measured using a bridge circuit in which the unknown resistance is compared with a known reference resistor. The bridge can be excited using AC (sine-wave excitation) or DC and both have their advantages and disadvantages. The advantages of DC technology are simplicity and therefore cost. In terms of performance, AC technology is always better and it is therefore the technique of choice for all those involved with the most accurate measurements. The reasons why AC bridges offer better performance arise from fundamentals in the physics associated with measurement and the devices used in the implementation of a measurement bridge. These are as follows: The ratio transformer At the heart of an AC bridge is a ratio transformer. This is used to scale the voltage developed across the reference resistor in order to balance the bridge. Since the voltage ratio in a transformer depends only on the turns ratio and this is an integer and fixed ratio (turns cannot be lost or gained) this represents a fundamental measurement standard. This basic stability, which is inherent in the AC measurement technique, is unsurpassed. The stability of an ASL F18 bridge was monitored by a National Standards Laboratory over a 6 months period and shows no measurable trend. The spread of results was found to fall well within the quoted specification: Resistance error/ppm F18 stability: 100 resistor against a 100 reference May 95 June 95 July 95 Aug 95 Date By comparison, DC bridges depend on a larger number of components to achieve their performance, none of which offer equivalent inherent stability. Although modern analogue techniques and self-calibrating strategies using microprocessors improve the performance of the more recent DC bridges, these still cannot match the stability of an AC bridge. Elimination of thermal & electrochemical EMFs Any practical measurement system is subject to thermally generated EMFs which arise when the dissimilar metals in the PRT, reference resistor or measurement circuit are exposed to temperature gradients. A straight DC measurement of the voltage across the PRT would therefore lead to an incorrect value of resistance being determined. DC bridges periodically reverse the measurement current (actually using a low frequency AC excitation!) and average the voltages measured in an attempt to eliminate these effects. Whilst this eliminates truly static thermal and electrochemical EMFs, any changes that occur during Sept 95 Oct 95 Nov 95 the measurement time (which may be several minutes) lead to errors. Also, this current reversal strategy does not eliminate the effect of Peltier heating which leads to unavoidable errors in switched DC systems. The measurement current flowing in a circuit leads to the expected resistive heating effects in the PRT and conductors. However, it also leads to Peltier heating at any inter-metallic junctions. These junctions will either absorb or liberate heat, depending on the direction of the current flow. When a DC bridge reverses the measurement current, this also reverses the direction of the Peltier heating in the system (junctions which gave out heat and got hotter now absorb heat and are cooled) which changes junction temperatures and the corresponding thermal EMFs. This always leads to a positive error in indicated resistance. By contrast, AC bridges measure only the AC component of any voltage and do not allow time for significant heating or cooling to take place during the measurement cycle (typically 7ms). They are therefore completely immune to thermal and electrochemical EMFs. Line frequency rejection The measurement frequencies chosen for an AC bridge are harmonically linked to the local mains power frequency and allow for complete rejection of line/mains frequency interference and all its harmonics. An AC bridge is able to achieve this rejection on a cycle to cycle basis, whereas a DC bridge achieves similar rejection only by averaging over a long measurement period. The frequency used in ASL s high performance bridges is locked to the local mains supply to provide the very best immunity. Better noise performance All electronic systems are subject to internally generated noise that ultimately limits their measurement uncertainty. The inherent spectrum of noise in electronic systems shows a characteristic 1/f form in which the noise power increases in proportion to the reciprocal of frequency below a given corner frequency (this is basically the tendency of systems to move around the longer you leave them). AC bridges operate above the 1/f corner frequency and are therefore subject to a much lower noise floor than DC bridges which by definition operate at a near zero frequency. The lower noise level of an AC bridge offers lower uncertainty in the readings for measurements taken over the same time as an equivalent DC bridge. Noice voltage (nv/hz 0.5 ) Noise voltage vs Frequency Frequency (Hz) Speed of response This is a corollary of the above noise feature. Basically, noise and speed of response are performance parameters than can be traded. Given that AC offers a lower noise floor this means that an AC bridge can balance to the same precision much faster than its DC counterpart. Also, the elaborate and time wasting auto-zero and self calibrate cycles used in DC bridges are of course not required by an AC bridge which provides continuous temperature measurement. This means that the measurement time and consequently the throughput of any calibration system are much better with an AC bridge system. This is particularly important when a bridge is used with a scanner to multiplex around a number of probes. Ideal for temperature measurement DC bridges were primarily developed for the measurement of resistance in electrical metrology rather than temperature metrology applications. They make sequential measurements with forward and reverse current and also incur further delays caused by complex autozero and self calibrate cycles. This means that the measurement results are updated only every few seconds or even minutes (for more accurate measurements). When measuring the value of a fixed resistor where the resistance is relatively stable with temperature, a DC bridge is quite adequate for the task. On the other hand, the temperature and hence the resistance of a PRT are dynamic properties, subject to significant change over a relatively short time period. The fast and continuous measurement technique embodied in an AC bridge is therefore more appropriate than the slowly sampled output provided by DC bridge technology. AC bridges can in fact be used to provide measurement of dynamic effects which would completely defeat DC based systems. Noise matching of probe Noise matching transformers can be supplied with an AC bridge to match the noise of the probe to the bridge circuit, thereby reducing overall measurement noise. This is not possible with DC measurement techniques. No warm up time Because the heart of an AC bridge is the ratio transformer which provides inherent stability, it requires no warm-up time and can be used immediately after being switched on. By comparison, DC bridges usually require extended warm-up times for their internal circuits to stabilise. Are there any disadvantages of AC bridges? There is only one. the cost. AC bridge technology is by nature more complicated than its DC counterpart which makes it a more expensive solution. As with all things in life, you get what you pay for and AC bridges are simply the best devices for temperature measurement applications. Certainly, in primary standards laboratories, there is no question that the AC bridge has been and remains the device of choice for the temperature metrologist. Even, at the secondary calibration laboratory and at the industrial level, the inherent stability of AC with the corresponding measurement confidence and the high speed/throughput of the AC bridge offers the customer significant benefits. Application support If you have a temperature, or temperature related measurement or calibration problem, or are not sure what level of performance you need, our application engineers will be pleased to advise you.

4 PRIMARY MEASUREMENT STANDARDS F900 Precision Thermometry Bridge and F18 Precision Thermometry Bridge Typical Applications Primary Thermometry Calibration Research Oceanography The Model F900 and F18 are designed specifically for resistance thermometry to provide you with the best possible accuracy. The 25 Hz or 75 Hz operating frequency provides fast, continuous measurement with high immunity to thermal emfs and supply frequency noise sources. Practical measurements involve cables, connectors and imperfect operating environments, these AC bridges achieve their full specifications under a wide range of real operating conditions. Design features such as the unique input guard ensure that you really can obtain the specified accuracy over the range of 0.2 ohms to 390 ohms. F900 Specifications Accuracy of <±20ppb (±5 K) Resolution of 0.5ppb (0.125 K) Fast measurement time (2 seconds balance) Differential and absolute measurement No warm up time Traceable to International Standards F18 Specifications Accuracy of <±0.1ppm (±25 micro K) Resolution of 0.003ppm (0.75 micro K) Linearity of <±0.01ppm Stability of <0.02ppm/year Fast measurement time (2 seconds balance) Differential and absolute measurement Warm up time <30 seconds Traceable to International Standards SECONDARY MEASUREMENT STANDARDS F700 Precision Thermometry Bridge and F300 Precision Thermometry Bridge Typical Applications Secondary Thermometry Calibration Calorimetry Mass and density Flow and viscosity Pump and turbine efficiency The F700 and F300 are high accuracy resistance bridges designed specifically for use in secondary resistance thermometry. Their unique AC bridge circuitry eliminates thermal EMF effects to provide you with fast, reliable measurements under a wide range of real operating conditions. A special input guard circuit maintains accuracy by minimising the effect of probe or cable leakage to ground. The effect of cable and probe reactance is eliminated by an on-board quadrature servo allowing you typically to make measurements up to 300 metres from the PRT. With the F300 you have both a precision thermometer and a high accuracy calibration bridge. Make absolute or differential measurements with probes having R values between 0.25 and The comprehensive LED display shows your measurements in ratio, ohms, C or K, plus other information such as mode and status. Probe coefficients are easily entered using the Data entry buttons. F700 Specifications Accuracy of <±0.5ppm (±0.5mK over full range) Resolution of 0.25ppm (0.25mK over full range) Linearity of <±1 LSD (±0.25mK over full range) Differential & absolute measurement Warm up time <30 seconds Expandable up to 60 channels F300 Specifications Accuracy of <±0.001 C Resolution of C Direct readout in Ratio,Ohm, C or K ITS-90 conversion for C & K Differential & absolute measurement Supports 0.25 ohm to 1000 ohm probes Expandable to 60 channels

5 PORTABLE INSTRUMENTATION F200 True Temperature Indicator Using calibrated probes with our F200 you choose between storing calibration data into memory in the instrument or into the probe s SMART connector. Calibration data stays permanently with the probe in this connector, which the F200 instantly recognizes, ensuring fool proof measurement. Better yet, the SMART connectors use standard 5 pin DIN connectors, so you can mix SMART and passive connectors on the same input. How s that for versatility? Specifications Temperature range of -200 C to 962 C Accuracy of <±0.01 C Common inputs for both SMART and passive connectors. Single or differential measurement Galvanically isolated RS232 interface as standard ITS-90, EN60751 and CvD temperature conversion Clear vacuum fluorescent display in C, F, K or ohms, plus channel selected Self-calibrating against traceable external reference F250 MK II Precision Thermometer ASL s F250 provides you with high accuracy, dual channel temperature measurement for Platinum Resistance Thermometers (PRT) and exploits the inherent advantages of AC bridge technology to maintain repeatable measurements of the highest precision. Front panel data entry allows you to enter probe calibration data, so that the thermometer resistance can accurately be converted to temperature in C, F or K. A comprehensive range of features and multichannel capabilities make the F250 ideal for a wide range of simple or specialist applications. Specifications Temperature range of -200 C to 962 C Accuracy of <±0.01 C full range Selectable resolution of C or 0.01 C Dual channel inputs A, B or A-B Direct readout in ohms, C, F or K Front panel data entry with security key Up to 32 channels with SB250 switchbox SENSORS Isotech offers a full range of Sensors to mate with your new ASL thermometer. Whether you are looking at an F900 or F100 we have a sensing solution for you. Below are three tables outlining our more popular models fo. However, if you do not see what you are looking for please contact us with your requirements. PRIMARY STANDARDS Model Number 670 (Quartz) (Metal) Temp. Range -196 to 670 C -196 to 670 C Stability R0 typical drift <0.001 C R0 typical drift <0.002 C after 500 hours at 670 C after 500 hours at 670 C Repeatability R0 typical drift <0.002 C R0 typical drift <0.002 C -196 to 670 C -196 to 670 C Diameter 7.5mm 7.5mm Length 650mm 550mm Sensing Length 30mm 70mm Lead Wires 3' PTFE 4 wire 3' PTFE 4 wire SECONDARY STANDARDS Model Number S S Temp. Range -196 to 500 C -196 to 670 C Stability R0 typical drift <0.006 C R0 typical drift <0.006 C after 500 hours at 500 C after 500 hours at 670 C Repeatability R0 typical drift <0.001 C R0 typical drift <0.002 C -196 to 500 C -196 to 670 C Diameter 1/4" 1/4" Length 16" 16" Sensing Length 1-1/4" 1-1/4" Lead Wires 3' with 5-pin DIN 3' with 5-pin DIN WORKING STANDARDS Model Number T T T Temp. Range -50 to +250 C -196 to 250 C -196 to 450 C -196 to 670 C Stability R0 typical drift <0.002 R0 typical drift <0.001 R0 typical drift <0.01 R0 typical drift <0.002 C after 500 hours at 250 C 500 hours at 250 C 500 hours at 450 C 500 hours at 670 C Repeatability R0 typical drift <0.002 C after R0 typical drift <0.001 C after R0 typical drift <0.005 C after R0 typical drift <0.008 C after 100 times from 25 to 250 C 100 times from 25 to 250 C 100 times from 25 to 450 C 100 times from 25 to 670 C Diameter 4mm 1/4" 1/4" 1/4" Length 300mm 16" 16" 16" Sensing Length 6mm 1" 1" 1" Lead Wires 5' with 5-pin DIN 5' with 5-pin DIN 5' with 5-pin DIN 5' with 5-pin DIN

6 Want an ON-SITE Demonstration? Don t purchase a competitor s temperature calibrator without seeing what an ISOCAL-6 can do for you! CALL ISOTECH NOW! ISOCAL 6 CALIBRATION SYSTEM Having a hard time deciding on buying a Dry Block or Liquid Bath? Or spending too much money because you need both? Now you can have the benefits of both and more, with an Isocal-6 from Isotech! The Isocal-6 is a flexible range of calibration systems that can calibrate all types of temperature sensors. With the Isocal-6, different inserts are added to the bath to allow it to be used in 6 different modes, providing a solution for all temperature sensor calibration requirements. The Isocal-6 includes a removable metal insert as standard for use as a Dry Block Calibrator. With optional accessories the Isocal-6 can perform as: A dry block calibrator A stirred liquid bath A stirred ice bath 0 C reference (cooling models only) Metal Block Bath Stirred Liquid Bath Stirred Ice/Water Bath Black Body Source Surface Sensor Calibrator A blackbody source for IR thermometers A calibrator for surface sensors An ITS-90 fixed point apparatus ITS-90 Fixed-Point Apparatus The advantage of the Isocal-6 is that you need only purchase the main Block or Bath initially, and can add other accessories at any time to increase your accuracy, stability and overall capability. Each different calibrator type has unique advantages over another. For example, Stirred Liquid Baths generally provide better stability, uniformity and heat transfer than dry blocks. Angled probes will not readily fit into a metal block, but can be placed into the liquid. Although liquid baths are ideal for awkwardly shaped or short sensors and provide better axial and radial uniformity, they typically are much slower to heat and cool than dryblocks. Different Isocal-6 models cover the temperature range from -45 C to 250 C. Above this maximum temperature it is not practical to use a stirred liquid bath. For higher temperatures, see our other Dry Block Calibrators that go to 1200 C, many with accessories for Surface Sensor and Blackbody use. ISOTECH is a world leader in temperature metrology. With over 30 years of experience in the design, manufacture and practical use of precision temperature calibration standards, Isotech is an experienced supplier for national labs and field calibration technicians worldwide. Customers include the world s largest primary standards laboratories, accredited laboratories, defense organizations, large manufacturers and research organizations. On behalf of Isotech North America, Inc. and Isothermal Technology LTD, UK, thank you for requesting information on our products. We know you will find our products to be of superior design, conservatively specified and a great value. Isotech is the exclusive North American distributor for ASL products. Get full details on all of our products and request a complete catalog. Exclusive North American Distributor for ASL Products 158 Brentwood Drive Unit 4 Colchester, VT (802) (802) Fax