MilliK High Precision Thermometer | Temperature Measurement System
The new milliK is a high precision thermometer capable of performance to 0.003C with SPRTs and PRTs and also enables high accuracy measurement from thermistors, thermocouples and even 4-20 mA process inputs.It can be expanded with the millisKanner.
In addition to low uncertainty measurements from Reference Standards and Industrial sensor measurement, the milliK temperature measurement system can control Isotech temperature sources, sequencing through a programmable list of temperature set points and log data to internal memory or a USB drive.
- High Accuracy 0.003C
- SPRTs, PRTs, Thermistors, Thermocouples and 4 20mA Process Inputs
- Expandable to 33 Channels
- Can store a lifetime of logged data
The milliK High Precision Thermometer from Isotech sets a new standard for the high accuracy measurement and calibration of Platinum Resistance Thermometers, Thermistors, Thermocouple and Process Instrumentation (4-20mA) over the range -270C to 1820C.
The milliK has two input channels for sensors and a third channel for
current. It can be expanded to become a high-precision temperature measurement system with up to 33 channels reading SPRTs, RTDs, Thermistors, or Thermocouples with the option to control calibration baths and log readings accurately.
In addition to low uncertainty measurements from Reference Standards and
Industrial sensor measurement the milliK can control Isotech temperature
sources, sequencing through a programmable list of temperature set points and
log data to internal memory or a USB drive.
High Precision Thermometer with a Wide Range of Sensors
SPRTs, PRTs, Thermistors, Thermocouple and 4 — 20mA
High Accuracy
- < 5ppm for PRTs, 2V for Thermocouples and 1A Transmitters
- Logs Controls Isotech Temperature Sources
- Massive logging capacity controls Dry Blocks and Liquid Baths
Benefiting You
The milliK high precision thermometer sets a new standard for value, versatility and accuracy — <
5ppm over range for PRTs, 2V for Thermocouples and 1A for current
transmitters, see Data Sheet.
Supporting a wide range of sensors and functions it replaces individual devices
making a cost effective calibration solution.
A robust design and operation from AC or DC power allows the milliK to be used
in the laboratory, test room or out in the field.
The milliK high-precision temperature measurement system can display in C, F, K, Ohms, mV and mA with numeric and graphical display modes. The large back lit display makes configuring the instrument and
setting the scrolling strip charts intuitive. The USB port allows for the use of
a mouse, keyboard or USB Drive.
No Compromise Design
The design team have considered industrial users and applications in order to
avoid measurement errors and problems encountered in some instruments from other
manufacturers:
Eliminates Thermal EMF Errors in PRTS
Fast current reversal technology and solid state switching eliminate thermal EMF
effects avoiding the errors that occur with fixed DC instruments.
Lead Wire Correction
PRT lead wire errors are eliminated for up to 30m of four core screened
cable.
Galvanic Isolation
Not only are the two sensor channels galvanically isolated, the 4 — 20mA
input is also separately isolated. The benefits of the advance design are no
ground loops, improved safety and noise immunity.
High Resolution
The display resolution is 0.0001C (0.1mK) made possible by using a powerful
Sigma Delta Analogue to Digital converter to achieve a true measuring resolution
of just 28 equivalent to 0.00007C (0.07mK) for PRT inputs.
Convert Measurement Units / Unit-Converter
Value to be converted:
Classic measurement units calculator:
Measurement Categorie:Absorbed doseAccelerationAmount of substanceAngleAngular momentumAreaBytes / BitsCapacitanceCatalytic activityCO2 emissionComputer performance (FLOPS)Computer performance (IPS)Cooking / RecipesData rateDensityDistanceDose area productDose length productDynamic viscosityElectric chargeElectric conductanceElectric currentElectric dipole momentElectrical elastanceElectrical resistanceEnergyEquivalent doseFabric weight (Textiles)Font size (CSS)ForceFrequencyFuel consumptionIlluminanceImpulseInductanceIonizing radiation doseKinematic viscosityLeak rateLuminanceLuminous energyLuminous fluxLuminous intensityMagnetic fieldMagnetic field strengthMagnetic fluxMagnetomotive forceMass / WeightMass flow rateMolar concentrationMolar massMolar volumeMusical intervalNumeral systemsOil equivalentParts-Per .
..PowerPressureRadiation doseRadioactivityRotational speedSI-prefixesSolid angleSound levelSurface tensionTemperatureTextile measurementTimeTorqueVelocityVoltageVolumeVolumetric flow rate
Value to be converted:
Original unit:Ångström [Å]Astronomical unit [AU]Attometre [am]Cable lengthCentimeter [cm]Chain [ch]Cubit (british)Decameter [dam]Decimeter [dm]FathomFemtometre [fm]Foot [ft]FurlongGigameter [Gm]Hectometer [hm]Inch [in]Kilometer [km]Light daysLight hoursLight minutesLight secondsLight yearsLinkMegameter [Mm]Meter [m]Metric mileMicrometre [µm]Mil — ThouMile (international) [mi]Mile (US)Millimeter [mm]Nanometre [nm]Nautical mileParsec [pc]PerchePicometre [pm]Planck lengthPoleQuarterRodRoman mileStatute mileTwipX Unit — SiegbahnYards
Target unit:Ångström [Å]Astronomical unit [AU]Attometre [am]Cable lengthCentimeter [cm]Chain [ch]Cubit (british)Decameter [dam]Decimeter [dm]FathomFemtometre [fm]Foot [ft]FurlongGigameter [Gm]Hectometer [hm]Inch [in]Kilometer [km]Light daysLight hoursLight minutesLight secondsLight yearsLinkMegameter [Mm]Meter [m]Metric mileMicrometre [µm]Mil — ThouMile (international) [mi]Mile (US)Millimeter [mm]Nanometre [nm]Nautical mileParsec [pc]PerchePicometre [pm]Planck lengthPoleQuarterRodRoman mileStatute mileTwipX Unit — SiegbahnYards
Unit conversion is anything but trivial:
Millimeter, centimeter, decimeter, meter, kilometer, miles, nautical
miles, foot, yard, inch, cubit, parsecs and light years.
With all
these measurements distances can be calculated. And this is not even
close to all the possible measurements, rather only the most common
ones. In the case of areas (square meter, square kilometer, are, hectare,
Morgan, acre among others), Temperatures (degrees of Celsius, Kelvin,
Fahrenheit), Velocity (m/s, km/h, mph, knots, mach), weights (hundred
weight, kilogram, metric ton, US ton, imperial ton, pound among others)
and volumes (cubic meter, hectoliter, imperial gallon liquid, US gallon
liquid, US gallon dry, barrel among others) is not much better. To
complete the chaos the majority of these units also have subunits
and supra units (-> milli, centi, deci among others). In short: Chaos,
in which no one really seems to see clearly without the help of a
reference and varied forms of help.
A calculator to convert units of measurement like this one is perfect for unit conversion.
Conversion—calculator to convert measurement units. Supports a huge number of measurement units.
design, principle of operation, types — articles by NPO RIZUR
Bimetallic thermometer is used to measure the temperature of any type of medium (liquid, granular or gaseous) in the temperature range from -70° to +600°. The inner end of a spring made of a bimetallic tape is attached to the body of such a thermometer. Its second end is attached to the arrow showing the temperature.
As a rule, such thermometers are used in industry, but they are often used in everyday life: in rooms, pools, baths or saunas, on the street or greenhouses, and even in cars. nine0003
The bimetallic thermometer is designed to measure temperature both in stationary conditions and in technical installations.
Design of bimetallic thermometer
This thermometer has a round case, where the dial and kinematic mechanism with an arrow are located, as well as a bimetallic temperature sensitive element in a protective tube. So, the sensitive part of the thermometer (bulb) responds to temperature changes, and the indicating part (dial), respectively, shows an increase or decrease in temperature in the environment. nine0005
The principle of operation of industrial thermometer
The principle of operation of such a unit is quite simple. It is based on elastic deformation, which occurs under the influence of the temperature of two metal plates, firmly interconnected, which have different thermal coefficients of linear expansion. In this case, the bimetallic strip is bent towards the side of the material, the coefficient of linear expansion of which is less. As a result of such deformation, with the help of a kinematic unit, the bend is converted into a rotational movement of the pointer, which, in turn, shows the measured temperature value on the thermometer scale.
nine0005
Bimetal thermometer
is a great alternative to the fairly common liquid thermometers. There is only one drawback in his work: he needs a little more time in order to show the correct result. In addition, the cost of such thermometers is higher than usual.
Classification of industrial thermometers
Industrial bimetal thermometers are of two types:
1. Radial thermometers;
2. Axial thermometers.
The only difference between them is that the axis of the dial of a radial thermometer is at an angle of 90 degrees with respect to the axis of the bulb, while in an axial thermometer the axis of the dial completely coincides with the axis of the bulb.
Another classification divides bimetal thermometers into:
1. Pipe thermometers, which measure the temperature on the surface of pipes in heating systems;
2. Needle thermometers, which measure the temperature when a special probe needle is immersed in the measurement medium.
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At
the production of bimetallic thermometers takes into account the special conditions of their
further operation. For example, such thermometers can be combined with
hygrometer, which will allow for a rapid assessment of the atmosphere as
temperature as well as air humidity. In addition, industrial thermometers
are issued not only with universal those. characteristics, but also
highly specialized. So, such a device can work with any
temperatures in the range from -70°C to +600°C, as well as with any phase
conditions of the environment. Bimetallic thermometer
is a great alternative to the fairly common liquid thermometers. There is only one drawback in his work: he needs a little more time in order to show the correct result. In addition, the cost of such thermometers is higher than usual. nine0005
Classification of industrial thermometers
Industrial bimetal thermometers are of two types:
1. Radial thermometers;
2. Axial thermometers.
The only difference between them is that the dial axis of the radial thermometer is at an angle of 90 degrees with respect to the bulb axis, while in the axial thermometer the dial axis completely coincides with the bulb axis.
Another classification divides bimetal thermometers into:
1. Pipe thermometers, which measure the temperature on the surface of pipes in heating systems;
2. Needle thermometers, which measure the temperature when a special probe needle is immersed in the measurement medium.
At
the production of bimetallic thermometers takes into account the special conditions of their
further operation. For example, such thermometers can be combined with
hygrometer, which will allow for a rapid assessment of the atmosphere as
temperature as well as air humidity. In addition, industrial thermometers
are issued not only with universal those. characteristics, but also
highly specialized. So, such a device can work with any
temperatures in the range from -70°C to +600°C, as well as with any phase
environment states.
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Arduino, MK-90 and others: Temperature measurement
Due to the unexpected popularity, I decided to continue the «temperature» theme.
So what can modern temperature measurement technology offer us?
1. Thermocouple
The principle of operation is based on the Seebeck effect: a thermocouple usually consists of two different metals having two points of contact (junction). If the temperatures of the junction points are different, a so-called. thermoelectric power that can be successfully measured and eventually converted to a temperature value. nine0005
Thermocouples come in a variety of types (usually referred to as R, K, S, etc.) depending on the metal pair. The main plus is a wide temperature range: you can choose a thermocouple for measurements both for ultra-low — 200 °C, and for rather high temperatures of 2000 °C. In addition, they can be used in aggressive environments, if the metals included in the composition allow it.
However, they are of little use for amateur radio practice: there are a lot of errors that need to be dealt with. There is a non-linearity. Finally, the accuracy will be worse than ±1 °C. nine0005
2. Thermostat
The full name is «resistance thermometer». The principle of operation is based on the ability of materials to change their conductivity depending on temperature. Most often they are made of metal wire or film, and the greater the temperature coefficient of resistance (TCS) it has, the more accurate the result is. Under normal conditions, the accuracy is better than ±1 °C, ideally 0.001 °C is possible.
The thermostat’s greatest strength is the linearity of the conductivity to temperature ratio. nine0011 Platinum thermostat has the most ideal linearity, good TCR, high resistivity, wide temperature range. But … you yourself understand how this affects the cost of . The situation is slightly better with copper, but it has a low resistivity, which increases the dimensions of the sensor.
In amateur radio practice, it will probably be a little expensive to use. Although, in my memory, Russian engineers managed to use a copper relay winding.
Sometimes you can find references to bimetal thermostats of the KSD301 series — unfortunately, they have nothing to do with resistance thermometers. Their action is based on the properties of bimetallic wire — the ability to stretch when heated and shrink when cooled.
The KSD301 element is an executive , and not a measuring device — a thermal contact that is triggered when a certain temperature is reached, and returns to its original position when it cools down. nine0005
3. Thermistor
The principle of operation of the thermistor is similar to that of a thermostat, but they are made of semiconductor materials (compressed powder mixtures of oxides).
Thermistors have one magical property — high resistivity, so you can kill two or three birds with one stone: reduce the size and get rid of the wire error, obtaining high accuracy.
There is only one problem with them: unlike thermostats, the dependence has non-linear character , so it can be problematic to measure temperatures over a wide range with their help 🙁 The general temperature range for this class of devices is also lower than for thermostats and thermocouples: from -50 ° C to 300 ° C. thermistors with negative temperature coefficient (resistance decreases with increasing temperature) and with positive — they are often called PTC .
As a rule, they are used in analog circuits, performing preliminary calibration . For example, for a fan speed controller circuit on an op-amp, the finished circuit is connected to a thermistor preheated to a known temperature, after which «ordinary» elements (usually resistors) are selected or adjusted. In the diagram, thermistors are marked with the following symbol:
Typical examples of thermistors are MMT-1 , KMT-4 . They are inexpensive; depending on the type, they have an error of 10.
.20%.
4. Analog temperature sensor
It would be more accurate to call this class of devices «integrated temperature sensor» — IDT , which, like a thermostat, has a linear characteristic of output voltage versus temperature. It usually refers to a microcircuit with a low degree of integration.
The principle of operation of the IDT is based on the fact that the voltage drop across the p-n junction of the transistor is linearly dependent on temperature.
The influence of temperature on the transistor is a rather unpleasant problem, partly a thing of the past with the advent of microcircuits. By placing transistors on a single chip, chip manufacturers automatically achieve the same temperature conditions for all semiconductors, while in the past, designers had to introduce special «common» heatsinks for transistors or even look for other solutions. In this case, to obtain a linear dependence, it is required to compensate for the effects associated with the saturation current and the spread of the initial voltage drop across the p-n junction.
To do this, either emitter junctions are made of different areas, or, on the contrary, identical transistors are connected into a Bork cell. nine0005
This is not particularly important for us, the main thing is that we end up with precision sensor , which remains to be connected to an analog-to-digital converter (and as we know, Arduino from ATMEGA got a 1024-stage 6-channel ADC), which makes it possible very accurately measure the temperature, especially if you subject the circuit to a simple calibration.
Typical analog sensors in TO-92 package — LM335 from National Semiconductor, TMP36 from Analog Devices:
Of the minuses — you must take into account the voltage drop on the wires going to the sensor; separate power cable required. But it turns out relatively cheaply, it can be combined with each other in parallel (measurement of the minimum temperature) or in series (measurement of the average temperature).
Interestingly, there are ADC microcircuits with a built-in seven-segment display driver — and then MK is not needed at all to implement a digital thermometer;)
5.
Digital temperature sensor
Unlike the analog one, this sensor already contains built-in ADC and is capable of measuring on command and then reporting the temperature in a digital code.
A typical example is DS18B20 from MAXIM/DALLAS. So to say, a programmer’s dream — no calibration required, minimal wiring, the possibility of «parasitic power», many sensors can be located on the same bus (each has its own unique code programmed at the factory). nine0005
You will have to pay for this with the implementation of the bus OneWire , not the fact that it is supported by the MK at the hardware level (do not look for it in ATmega; and do not confuse it with TwoWire — these are different things). But this is all that programmers need 😉
The price of DS18B20 is, of course, higher than LMZx39 or TMP3x, but it transfers some of the problems to a purely software area, providing wider applications.
In the following articles on the topic of temperature, I will try to give practical examples of working with both analog and digital sensors.