| Q1. How do your instruments compare with those from other companies? We believe we have the most accurate thermocouple and thermistor instruments available anywhere. We have not been able to find any thermocouple or thermistor instruments from other companies that meet or exceed our specifications. We obtain high measurement accuracies through a combination of techniques, including individual calibration of each instrument and probes against precision standards. Our pricing compares favorably with other high end instrumentation. We can usually provide better specifications at lower cost. And we can point to many instruments from other companies that have worse specifications and at the same time cost much more than ours do. Even if you do not need high accuracy in your measurements, you should consider our products because of the extremely versatile and powerful software that accompanies each instrument. We have compared our software with others, and we have found that our software is loaded with more important features and is easier to use. And comments from our customers have confirmed this over and over again. Q2. How should I choose between thermocouples or thermistors? Our type T thermocouple instruments have extremely high accuracies, in the order of 0.05 °C to 0.1°C. We can attain measurement accuracies of 0.02 °C (0.01 °C near ambient temperature) by special multipoint calibrations of thermocouples. And our type T thermocouple instruments have measurement resolutions of 0.01 °C or better. Our type T instruments can be used to measure temperatures over the range -200 to +400 °C ( -328 to 752 °F). Thermocouples have no self heating and can be very small in size. Small thermocouples respond to temperature changes much faster than thermistors or RTD's, which have more mass. And small thermocouples can be inserted in liquids or solids or attached to surfaces without disturbing the temperature field of the object that is being measured. Thermocouples are also available in hypodermic needles. And 40 gage bare wire thermocouples are only about 0.003" (0.08 mm) in diameter. If you need higher accuracies, then our thermistor instruments can provide measurement accuracies from 0.01 °C to 0.002 °C, with measurement resolutions from 0.0001 °C to 0.0004 °C depending on temperature. Measurement accuracies of 1 millikelvin (0.001 °C) are available over 0 °C to 30 °C by calibration in Triple Point of Water TPW and melting point of Gallium. Thermistors have a narrower measurement range than thermocouples. Our thermistor instruments cover the range of -10°C to 60 °C. If you are comparing costs, then our thermocouple instruments will always be lower in cost than our thermistor instruments for the same number of channels. Q3. How can you claim 0.01 °C or 0.1 °C measurement accuracy with thermocouples when the thermocouples themselves are not that accurate to begin with? The ASTM Standard for type T thermocouples specifies an accuracy of 1.0 °C for regular wire and 0.5 °C for SLE wire for temperature measurements up to 125 °C with a 0 °C reference junction temperature. This means that the millivolt output vs. temperature for those thermocouple wires that meet the standard must fit the NIST designated thermocouple tables for type T thermocouples over the range 0 °C to 125 °C to within 1.0 °C for regular wire and to within 0.5 °C for SLE wire. But with careful procedures and proper equipment, we can calibrate individual thermocouple wires to a much higher accuracy than the standard allows, by characterizing the deviation from the standard tables for that particular wire at several points along the mv. vs temperature curve. And accuracy of the thermocouple wire is not the only factor that determines final accuracy of the measurement. Other sources of error include reference junction error, voltage measurement error, and errors due to nonlinearity and drift. We have been able to minimize all of these errors by means of special proprietary techniques within our hardware and software. Our reference junction error is typically less than 0.003 °C, even with multiple channel instruments. Compare this with typical reference junction error (cold junction compensation) of 0.5 °C to 1 °C or more on most thermocouple instrumentation. If we provide the thermocouples, we first obtain very high grade thermocouple wire and then calibrate the thermocouple wire here against our precision temperature standards. Following a two point calibration, we have been able to attain total system measurement accuracies (including thermocouple wire error) of 0.05 °C or better with type T thermocouples at all temperatures over the range -5 °C to 60 °C. For more details and data, click here. More recently we have attained even higher accuracies approaching 0.01 °C or 0.02 °C over measurement ranges of -10 °C to 140 °C by means of multiple point calibrations of thermocouple wires. For more details and data, click here. The built in calibration wizard in our PinPoint Monitor software enables users to do their own thermocouple calibrations, provided they have a precision glass thermometer or other precision temperature measurement device for comparison. Accuracies better than ±0.1 °C should be attainable over a fairly wide range of temperatures when careful calibration procedures are followed. Q4. There are many different types of thermocouples. Which ones do you support? We build thermocouple instruments with type B, E, J, K, N, R, S or T thermocouple inputs. And we can
provide instruments with differential thermocouple input channels for very accurate measurements of small
temperature differences. Our type T thermocouple instruments provide the highest accuracy and type T thermoocuples have the best stability. If you are working in the range -200 to +400 °C ( -328 to 752 °F), then type T is the best choice.
Q5. How many channels are available in your instruments? Our standard 4 channel type T thermocouple instrument, Model S4TC, and our standard 16 channel type T thermocouple instrument, Model S16TC are normally in stock for immediate delivery. We build custom thermocouple instruments with 1 to 94 channels in the same enclosure. Our thermistor instruments are all made to order. These are available with 1 to 48 thermistor channels in the same enclosure. Q6. Will we need to send our instrument back for recalibration? All temperature instruments and temperature probes drift with time and with use. Our instruments and our probes are more stable than most. After you have used them for a period of time, you can get an idea of the drift in measurements by checking the temperature readings in a well made distilled water ice bath. A link to an NIST article about temperature measurements using distilled water ice as a reference is available here. Our software has a very easy to use one or two point calibration procedure. If you have a precision temperature standard, you can always recalibrate the instrument and probes at your location. And you can do a one point calibration at the ice point by putting the probes in an ice bath. If you wish to send your instrument back to us, we can do a multiple point recalibration against our precision temperature standards for a nominal charge. We keep the recalibration cost low because we wish to encourage our customers to send their GEC instruments here for recalibration. The data we obtain is valuable to us in our ongoing mission to characterize the long term drift of our instruments and our probes when used in the field. Q7. Do you sell thermocouples or thermistors by themselves? We only sell thermocouples or thermistors in combination with our precision temperature instruments. Q8. How much does your PinPoint Monitor software cost? The cost of the software is included in the price of each instrument. We do not price the software separately because it is required when operating the instrument. Q9. What is the value of your PinPoint Monitor software? Our software has more important features and is much easier to use than other temperature display and logging software packages that cost $750 to $1000 or more. But the value to a particular user depends on which features they use and how often they use the software. Those who use our temperature instrumentation frequently will find many of the software features invaluable in their work. Many of our users have told us that the stability and ease of use of our software is much better than any of the other programs they use in their daily activities. And many researchers using our instrumentation report that they are getting much more out of their research because of the detailed features and flexibility of the realtime display and realtime plotting functions in our PPM software. Q10. How can I learn more about your PinPoint Monitor software? Click over to the SOFTWARE page to see some details and some screen shots.
Q11. Is there a difference between the serial and USB versions of the instrument? The basic instrument uses an RS232 serial connection. USB is supported by means of an inexpensive USB to RS232 adapter. You should see no difference in the operation of the instrument or the software with either connection. |
