Thermocouple & Calibration Info

Thermocouple reference equipment provides high accuracy monitoring by eliminating the need for cold junction compensation in thermocouples, a major cause of measurement errors. Thermocouples are a temperature-measuring devices formed by the junction of two dissimilar metals. A thermocouple produces a voltage proportional to the difference in temperature between the hot junction and the lead wire (cold) junction. Since the measurement is of the temperature difference between the two junctions, it is a relative reading. To make a more useful absolute reading, a reference sensor is set to and placed next to the cold junction. This is referred to as cold junction compensation.

Though cold junction compensation makes thermocouple readings more useful, they can distort readings by 1°C, or more. In thermocouple reference equipment, a controlled reference temperature, usually 0°C, replaces the cold junction compensation. The accuracy when using reference equipment can be as high as ±0.05°C, much better than standard thermocouple set-ups and there is no long-term drift.

Thermocouple reference equipment is integrated into existing monitoring systems and, depending upon the model, can monitor dozens (or more) of thermocouples.

Temperature Calibration

Temperature is the most commonly measured parameter in commercial and industrial settings. Industries as diverse as food processing, pharmaceuticals, cold storage, paper manufacturing, and others absolutely rely on process temperatures being within a certain range. To maintain accuracy, calibrating temperature monitoring equipment is necessary.

Measuring temperature involves a wide range of specialty sensors such as thermocouples, thermistors, resistive temperature detectors (RTDs), infrared (IR) sensors, bimetal thermometers, and others. These sensors produces an electrical output such as resistance, millivolts or milliamps which correspond to the temperature. These output signals are sent to a readout or controller where they are displayed or used to control a process function.

When discussing temperature calibration it’s important to note that output of the temperature sensors, themselves, cannot be adjusted. Instead, the controller or readout is adjusted to account for the inaccuracy of the sensor.

Calibration is a comparison between two devices. The first device is the unit to be calibrated, often called the unit under test. The second device is the standard, which has a known accuracy. Using the standard as a guide, the unit under test is adjusted until both units display the same results while exposed to the same temperature. Typically, calibration of an instrument is checked at several points throughout the calibration range of the instrument.

Not all standards are created equally. While all standards have a known accuracy, there are some—known as primary standards— that are the highest level of accuracy for a specific parameter. Primary standards achieve their high accuracy by relying upon measurement technologies using fundamental physical constants that do not drift such as the triple point of water. These fixed values minimize uncertainty, making primary standards the most accurate calibration tools.

ITS-90

Temperature calibrations are done in accordance with The International Temperature Scale of 1990. ITS-90 is the legal temperature scale that establishes a number of fixed point temperatures that can be used as reference values. The purpose of which is to define procedures for calibrating temperature equipment in such a way that the values of obtained are precise and reproducible, while at the same time approximating the corresponding thermodynamic values as closely as possible.

Traceability

To improve the quality of a calibration to levels acceptable to outside organizations, it is generally desirable for the calibration and subsequent measurements to be traceable to internationally recognized standards. Establishing traceability is accomplished by a formal comparison to a standard which is directly or indirectly related to national standards ( such as NIST in the USA), international standards, or certified reference materials.

Temperature Calibrator Specifications

There are three specifications that are of extreme importance when selecting a temperature calibrator. Understanding these specifications and their implications will go a long ways towards helping you select the best calibrator for your needs.

Accuracy: An expression of how closely a measured value agrees with the true or expected value of the quantity of interest (NCSL glossary). For temperature calibrators, accuracy is the relationship between the instrument’s display temperature and the actual temperature of calibration well. Accuracy is improved by regular calibrations to a traceable standard.

Stability: The tendency of an attribute to remain within tolerance (NCSL glossary). When a calibrator reaches its set-point, there is some fluctuation in temperature as the unit tries to maintain that temperature. That fluctuation can influence calibrations. Stability adds to accuracy in determining overall system uncertainty.

Uniformity: Temperature homogeneity of the heat source throughout the test zone. All calibrators have slight temperature differences from the bottom of the of the test well to the top as well as from the middle of the test well outward. A few simple strategies allow users to place probes in such a way as to minimize uniformity errors.

Things to consider when selecting a temperature calibrator:

  • What type of electrical signal does it output?
  • Do I need to calibrate sensors or just temperature displays?
  • Which is more important? Speed to change temperatures or doing multiple probes at a time?
  • How deep does the dry block or liquid bath need to be?
  • What are the physical characteristics (size, shape) of the sensor?
  • Over what temperature range is it used?
  • And what accuracies are relied on over those temperatures?
  • Must the calibrations occur in a laboratory or can they be done in the field or even in-situ?

dpstar is the leading supplier and manufacturer in Malaysia. We are one of the largest distributor throughout South East Asia. For more inquiry and info about us, don’t hesitate to visit our website.Alternatively if you have a bespoke requirement please don’t hesitate to call we have experienced engineers and staffs to help you according to your needs.

RTD Sensor Info

RTDs (resistance temperature detectors) are one of the most common temperature sensor types used in industrial applications. Thermocouples and thermistors are popular temperature sensors as well, but RTD sensors are more accurate over a wide temperature range and more stable over time, making them an excellent choice for many applications.

An RTD sensor is essentially a resistor whose resistance value increases with temperature. Due to the predictable change in resistance of certain materials as temperature changes, it is possible to acquire highly accurate and consistent temperature measurements. Most RTD sensors have a response time between 0.5 to 5 seconds or more. RTD sensors can be constructed with pure platinum, nickel or copper. RTDs made with platinum are also known as PRTs (platinum resistance thermometer) and are the most frequently used given their higher temperature capabilities, stability and repeatability.

Specifications for RTD sensors include a base resistance value and a temperature coefficient of resistance (TCR) value. Typical base resistance values can range from 10 to several thousands of Ohms (Ω) depending on material and type. The base resistance value indicates the nominal resistance of the sensor at 0°C (nickel and platinum) or 25°C (copper), with 100Ω being the most common.

The temperature coefficient of resistance does not affect a sensor’s accuracy, but is important to the measuring device that calculates changes in temperature based on the base resistance. PRTs have two standards of TCRs; the European standard (IEC 751) requires a TCR of 0.00385Ω/Ω/°C; and the American standard requires a TCR of 0.00392Ω/Ω/°C. Assuming a TCR of 0.00385Ω/Ω/°C — meaning that for every degree change in temperature, the resistance increases by 0.385Ω — a 100Ω PRT’s resistance will be 138.5Ω at 100°C. Thus, the measuring device used needs to be attuned to the TCR of an RTD sensor in order to accurately report changes in temperature, but the difference in TCR value has no impact on the sensor itself.

Between RTDs, thermocouples and thermistors, RTD sensors are the most accurate and stable over time, and are resistant to contamination under 660°C. They also boast high repeatability, which means that RTDs can accurately measure identical temperatures even when exposed to repeated heating and cooling cycles with minimal discrepancies. An RTD sensor will consistently measure 100°C after being put into an oven and subsequently a freezer multiple times. In contrast, a thermocouple is more likely to measure 100°C, then 98°C, then 103°C and so on when placed in the same situation. Since most applications do not require immediate responses (less than 0.5 to 5 seconds) to temperature changes, RTDs are an ideal solution for many industrial applications, which dpstar includes in its product line of dpstar Manufacturing Sdn Bhd (Maltec-T) .

dpstar is the leading supplier and manufacturer in Malaysia. We are one of the largest distributor throughout South East Asia. For more inquiry and info about us, don’t hesitate to visit our website.Alternatively if you have a bespoke requirement please don’t hesitate to call we have experienced engineers and staffs to help you according to your needs.

Extra Info About Temperature Controller

Temperature control in manufacturing is a quintessential part of proper product formation. If the temperature slips above or below the ideal range needed for a particular stage in a manufacturing process, the results can be harmful—improperly adhered coatings, a weakened base material, or an overall compromised component—so it becomes increasingly important that the manufacturer not only determine the proper temperature for each stage, but also monitor the temperature inside the machine and receive appropriate feedback.

Temperature controllers in manufacturing operations serve exactly this function: they ensure that a machine is running properly by gauging the temperature at different stages in the process and comparing the data to the programmed temperature specifications. As a result, manufacturers can quickly and easily discover temperature related machine malfunctions, and treat them as necessary.

There are three general kinds of temperature controllers that are used to monitor temperature during manufacturing processes: on-off, proportional, and PID controls.

dpstar is the leading supplier and manufacturer in Malaysia. We are one of the largest distributor throughout South East Asia. For more inquiry and info about us, don’t hesitate to visit our website.Alternatively if you have a bespoke requirement please don’t hesitate to call we have experienced engineers and staffs to help you according to your needs.

Temperature Controller: On/Off Temperature Controls

An on/off temperature control is the least expensive of the control types, and also the most simple in terms of how it works. The control is either on or off—if the temperature drops below a certain point, the control signals to the machine to turn raise the temperature. Likewise, if a temperature goes above a certain point, the control is triggered to tell the machine to lower the temperature. A common example of on/off systems is a household thermostat. When the temperature drops below a certain point, the controller triggers the heater to raise the temperature back to the programmed value. With air-conditioning it works the other way: if the temperature rises past a certain point, the controller triggers the air-conditioner, dropping the temperature back to the programmed norm.

On/off controls are often used in processes where the temperature change is very slow, and precise control of temperature isn’t necessary.

dpstar is the leading supplier and manufacturer in Malaysia. We are one of the largest distributor throughout South East Asia. For more inquiry and info about us, don’t hesitate to visit our website.Alternatively if you have a bespoke requirement please don’t hesitate to call we have experienced engineers and staffs to help you according to your needs.

Temperature Controller : Proportional Control Info

Unlike on/off controls, which only respond when a set limit is reached, proportional controls are designed to respond to temperature change before it slips out of the desired range. Essentially, proportional controls increase or decrease the power supply as the temperature reaches its upper or lower limit, or setpoint, which slows or speeds the heater and helps stabilize the temperature.

The temperature range in which proportional controls either lessen or increase the power supply to slow or speed heating is known as the “proportional band.” If a temperature reaches the lower or upper setpoints, the control then functions as a full on/off control—the temperature is either turned fully on to increase the temperature, or fully off to drop the temperature. When the temperature is within the proportional band, and the power supply is decreased or increased, the heat is raised or lowered in relation to how far the temperature is from the setpoint.

dpstar is the leading supplier and manufacturer in Malaysia. We are one of the largest distributor throughout South East Asia. For more inquiry and info about us, don’t hesitate to visit our website.Alternatively if you have a bespoke requirement please don’t hesitate to call we have experienced engineers and staffs to help you according to your needs.

Thermocouples

thermocouplethermocouple

A thermocouple is a coupling of two dissimilar alloy wires, which can be welded into the tip of a probe shaft, or set in a thermally conductive potting. A thermocouple meter/instrument purchased along with several different types of thermocouple probes may be used to measure all kinds of temperature from internal food to equipment surfaces. They are very accurate, offer a wide temperature range, and are extremely durable. The response time is a function of the placement of the junction in the tip of the shaft, the thermal conductivity of the potting used and the diameter of the probe shaft.

dpstar is the leading supplier and manufacturer in Malaysia. We are one of the largest distributor throughout South East Asia. For more inquiry and info about us, don’t hesitate to visit our website.Alternatively if you have a bespoke requirement please don’t hesitate to call we have experienced engineers and staffs to help you according to your needs.

Cartridge Heater Info

Cartridge Heater

Cartridge heaters are high-density heating cells that have their nickel chrome heating cores positioned internally as close as possible to the outside shell. The specially formulated MgO electrical insulating medium utilized inside a cartridge heater is transformed into a rock-hard, highly efficient heat transferring medium through a special cold forming process.

Cartridge heaters can withstand tough industrial usage; they can transmit up to 200 watts/in² heating capacity and are able to attain up to 1500°F sheath temperature. In order to facilitate installation and heat transmission,dpstar cartridge heaters are supplied with electrical leads that are connected internally within a 3/8 inch cold section. In excessively hot applications, the length of this cold section could be increased.

Cartridge heaters can be dual-voltage, three-phase, and/or supplied with a ground terminal. With ten different termination styles, mounting attachments and various optional features, Maltec-H is a top manufacturing company in Malaysia that manufactures high-density cartridge heaters are widely used in numerous high temperature industrial applications. Here are some examples:

dpstar is the leading supplier and manufacturer in Malaysia. We are one of the largest distributor throughout South East Asia. For more inquiry and info about us, don’t hesitate to visit our website.Alternatively if you have a bespoke requirement please don’t hesitate to call we have experienced engineers and staffs to help you according to your needs.