DELTA SENSOR LDA
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Frequently Asked Questions

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Expecially for international shippiings we provide tracking information through our carrier. Please contact us if you need that information or any kind of support.
We can arrange world wide dispatch to serve you. Alternatively you can use your own carrier and collect your goods at our warehouse.
Free charge for Portugal mainland for net orders above 1000,00 EUR, with next day delivery. Please call for shipping price for Portugal islands and international shippings. Cost will be weight and country dependent, as well shipping method and package shape.
Basically the required accuracy, process temperature, response time and dimensions of the probe. Thermocouples provide a response time better than the RTD's; RTD's have better accuracy and stability than thermocouples. In relation to the process temperature thermocouples allow measurement of temperature at temperatures higher than the RTD's.
Thermocouple N type is more stable and immune to junction medium contamination than the type K.
By using a thermowell, the thermometer will tend to have greater durability since it will not be in direct contact with the process. It is particularly useful in cases where the process has harsh conditions. The response time will be slightly longer but can be minimized with a minimum space between the walls of the protective sheath and the thermometer sheath.

For a better understanding is necessary to present the basic configuration of the sensing element. At the end of the sensor lead wires are welded and insulated, and the assembly is inserted in a metallic tube. Since the resistance value that allows the determination of temperature is only the sensor resistance and not the resistance of the connecting wires, there are three basic schemes for sensor connection that circumvent the inevitable fact of having to use lead wires to measure the sensor resistance.

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2-Wire Connection: (second left picture)

The Wheatstone bridge has a resistance thermometer with two wires connection. In the equilibrium condition of the bridge, which occurs when the galvanometer "G" indicates zero, one gets the following relationship between the resistance:

Rsensor + RL1 + RL2 = R1.R3 / R2

If R3 = R2 then Rsensor + RL1 + RL2 = R1. Since R1 is known, it is determined the value of Rsensor + RL1 + RL2.

Clearly, the value of sensor resistance values are increased resistance of the connecting wires, which decreases the quality of the measurement with the resulting error in temperature measurement.


3-Wire Connection: (third left picture)

In this case the bridge is connected to a three wires resistance thermometer. Considering again that R2 = R3, the balance of the bridge will result from the condition:

Rsensor + RL2 = R1 + RL1

How is it possible, with good approximation, consider approximately equal to RL1 RL2 RL3 approximately equal to, the effect of the wire is much attenuated.

This is the type of connection used in resistance thermometers for industrial applications.


4-Wire Connection: (on the right picture)

The four wire system connection completely eliminates the resistance of the connecting wires, being used in situations that require very precise measurements. PRT elements are manufactured with four wires connection.

This configuration is intended for use in laboratories, reading instruments of reference sensors allowing the circulation of a constant current (usually 1mA) through the sensor element and the potential difference measuring are made on the sensor terminals thus eliminating the effect of the resistance of the leads in the final result.

Because in fact the three configurations are used. The most common is the 3-wire, and 4-wire configuration that will achieve greater accuracy. The 2-wire configuration should be avoided if the sensor is for example Pt100. The 2-wire configuration is common for Pt1000, since the impedance of the cables is in most cases negligible compared with the resistance of the sensor.
You should use a thermocouple with a lower thermal mass as possible. If the medium and the acquisition unit allow, the hot junction must be exposed or grounded.

The easiest way of finding the right infrared thermometer for your application is during a commitment-free personal consultation with one of our team member, or using the optris Pyrometer Selector .

If you still prefer to keep looking for the right pyrometer yourself, you should start by determining the properties of the object surface on which your measurements are to be performed. A particularly important parameter in this respect is emissivity ε. The following wavelength ranges are available: 8-14 µm (non-metal surfaces), 5,0 µm (glass surfaces), 0,5 - 2,3 µm (metal) and 2,3 - 7,9 µm (special applications, as temperatures on films, combustion gases, temperatures through flames, laser applications)

The use of the right optics is indispensable in order to achieve precise measurement results. It depends on the size of the object to be measured and the distance between the object and the pyrometer. The easiest way of determining the right optics for your thermometer of choice is using the measurement spot calculator for pyrometers .

Data loggers are used in a wide variety of applications from simple monitoring of temperature in an office environment to monitoring the temperature of perishable products in transit or optimising the production process of food, pharmaceutical or engineering products. The same data logger can be used in a variety of applications, if you want to make a record of temperature, humidity, pressure or Voltage and current signals, we have a data logger to suit your needs.

Bellow is shown as an example, a typical graph that you would get from a Signatrol data logger. It was produced by the graphing software - TempIT, although some functions shown are only available in the PRO version:

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The tempmate data loggers have an integrated real-time clock (RTC), which is set at the factory with UTC time zone. This means that the date and time displayed in the PDF report is based on UTC and the 24-hour clock [MM / DD / YY HH: MM: SS]
Like any electronic document, a PDF file can be manipulated. However, even after analyzing the data, the original data remains stored in the tempmate recorder so that the data can always be downloaded again and compared with the PDF data in question. Therefore, it is important that the recorder is kept.
You need Adobe Acrobat Reader version 9.0 or above to open the PDF file correctly. If you have a previous version installed on your computer, please update at: https://acrobat.adobe.com/us/en/acrobat/pdf-reader.html
Yes, for each tempmate-S1 box or tempmate-M1 device, a certificate with 6 points will be sent at no additional cost. Also available in memory on the device in PDF version. You can download a website sample certificate from the link shown at product page.
Each recorder is shipped with a shelf life of at least 1 year and up to a maximum of 2 years, depending on storage conditions. The validity is printed on the recorder and it should never be considered to use it with the expiry date.

An atmosphere is defined as potentially explosive when its composition is not explosive, but due to unexpected circumstances, could evolve into explosive (the danger exists in a potential state). These circumstances could be:

  • Several stages of the productive process
  • Incidents or accidents (rupture of the canalization, leaks, fails in the supplying)
  • Weather conditions (high ambient temperature, air currents)
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  • Heating gas
  • Hydrocarbons
  • Glues solvents and adhesives
  • Varnishes and resins
  • Additives production for pharmaceutical products, artificial dyes, flavours and fragrances
  • Production agents for plastics, rubber, synthetic textiles and cleaning chemicals
  • Products used in the alcohol treatment and production and its derivatives

Metallic and organic products that create dust and powder on certain conditions can become active agents of an explosion. It presents an exclusive list of some of these products:

  • Magnesium
  • Aluminum
  • Sulphur
  • Cellulose
  • Corn to germinate and flour
  • Epoxy resins
  • Polystyrenes
  • Plastic dust
  • Coal
  • Wood
  • Sugar (low temperature)
Local authorities responsible for exploration concessions and corporations such as fire fighters and insurance company inspectors are usually aware of the risks of an explosion.

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Portuguese company of process instrumention and manufacturer of temperature, pressure and level sensors and transmitters.

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