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September 3rd, 2010
Temperature sensors are a part of a gauge, temperature or thermometer control device. These sensors detect changes in temperature after which the device reads, determines the change, translates it into degrees and then displays it. Devices such as thermostats react to the change by turning other devices on or off to adjust the temperature that is being monitored.
Types of temperature sensors:
Thermistors
With a change in temperature, the resistance of semiconductor material inside thermistors also changes. As the temperature rises, the resistance begins to fall. Thermistors are widely used in appliances and household items to measure and respond to changes in temperature.
The upper range of thermistors is 500 degrees F. Thermistors are extremely sensitive compared to other types of sensors such as resistive temperature detectors (RTDs) and thermocouples. While sensing the changes in temperature, thermistors have an average to fast response time.
Resistive temperature detectors (RTD)
RTDs or resistive temperature detectors are another type of resistance sensor where its resistance rises with a rise in temperature. The increase in resistance of RTDs can be correlated to degrees. An RTD can measure temperatures from -400 degrees F to 1200 degrees F. These temperature sensors are extensively used in industry for measuring fluid and surface temperatures.
Thermocouples
Thermocouples have an extensive range of operating temperatures. While a usual household oven utilises a thermistor temperature sensor, a kiln on the other had uses a thermocouple due to its higher operating temperature. The device to which thermocouples are connected reads the voltage and transforms it into a temperature reading.
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September 2nd, 2010
Pressure sensors are devices which are manufactured to gauge the pressure imposed on different liquids and gases. In technical terms, pressure is known as an expression of the force which is required to stop fluid expanding. Pressure which is measured by these sensors is stated in force per unit area.
An electric signal is generated by pressure sensors which is related to the pressure imposed on the applications. If you run a utility plant where high pressure is imposed for production purposes then you must install pressure sensors in the units. They will provide you with pressure-related information.
Due to different requirements, different types of pressure sensors are introduced in the market. This includes absolute pressure sensors, gauge pressure sensors, vacuum pressure sensors, sealed and differential pressure sensors.
What are differential pressure sensors?
Out of the different options, differential pressure sensors are most commonly seen in a lot of the industrial applications. This is because they are designed to gauge pressure changes between two or more applications. With the help of differential pressure sensors, you can measure pressure which is introduced in different units. In some cases, these pressure sensors are used to monitor pressure level or flow in pressurised vessels.
Differential pressure sensors can gauge pressure from 0-0.25mbar up to 0-200bar. They are available at output signals such as 4-20mA and 0-1-Vdc.
If you have decided to buy differential pressure sensors for your industrial applications then you have to consider the pressure range, operating temperature range, cost, etc.
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September 2nd, 2010
Are you planning to employ pressure sensors in your manufacturing plant? It is a good decision if you want to avoid any untoward incidents. With pressure sensors, you can keep a constant tab on the applied pressure. It is important that you understand different aspects associated with pressure sensors. Given below are some of the important aspects related to pressure sensors:
1. Functions performed
Pressure sensors are used to gauge or measure the applied pressure. They are basically used to calculate the force of gases as well as liquids. Pressure sensors help the users in their endeavour of preventing gas and liquid pressure from increasing or decreasing too much. They can be designed to sound off an alarm whenever the applied pressure exceeds the permissible limits. Similarly, these sensors initiate an alarm when the applied pressure is less than implied.
2. Uses of pressure sensors
Pressure sensors are used in several industries. Manufacturers use them for measuring the given variables:
- Altitude
- Level
- Flow
- Speed of liquids and gases
Keep in mind that the design and technology used in pressure sensors varies depending on the industry. Moreover, greater cost means that the sensor will perform faster and better.
3. Different types of Pressure Sensors
Pressure sensors are available in many different types. They are classified on the basis of the pressure measured. Sealed, gauge, differential, absolute and vacuum are the five different types of pressure sensors. You can thus purchase a pressure sensor depending upon the type of pressure to be measured.
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September 1st, 2010
Pressure transducers are commonly used for detecting and measuring process variables like temperature, level, composition and flow, and transmit a constant analogue output signal. These output signals can be current, voltage or proportional pneumatic. They are used for recording, indication, control and data acquisition systems.
Different types of pressure transducers are available for measuring the vacuum pressure, differential pressure, static pressure and the derived variables like partial pressures of gases and vapours.
How pressure transducers work
Pressure transducers determine a pressure, and convert it into a proportional output signal. This output signal can then be transmitted to a remote location. For instance, if the calculated pressure range is 0-100 psi (pounds per square inch) with an output range of 0-5 volts DC proportional to that range, the output signal of 50 percent full range, or 2.5 volts would indicate a 50 psi pressure value.
The calibrated voltmeter display would read 50 psi, and not 2.5 volts. In the past, transducers used diaphragms, bellows and bourdon tubes in motion balance systems like slide wires, capacitance and variable resistors. Most transducers available today use high-accuracy, solid-state capacitance, piezoelectric or strain gage sensing principles.
Types of pressure measured
Pressure transducers come with a pounds per square inch gauge (psig). This is a positive pressure compared to the absolute, atmospheric pressure like the differential pressure and pounds per square inch absolute (psia). Pressure transducers compare two different pressures and transmit a proportional output, vacuum pressure – a negative pressure compared to the atmospheric pressure.
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August 31st, 2010
A transducer is a device that transforms one form of energy into another. Most transducers convert electrical waves into the mechanical vibrations, or vice versa. Phonograph pickup cartridges, microphones and loudspeakers are some types of transducers.
Types of transducers include –
• Thermocouple
• Strain gauge
• Pressure transducers
• Sonar transducers
Thermocouple
The thermocouple is a type of transducer that comprises of a pair of wires of different semi-conductors or conductors, soldered or welded at one end. They are used for temperature measurement. Thermocouple temperature sensors are convenient and have a low heat capacity.
Strain Gauge
These transducers are devices that are used for measuring the distortion or strain on the surface. Some strain gauges work by the alterations in electrical resistance of a wire that is connected to the surface. Other strain gauges work on the magnetic induction in two coils, one of which is attached to the surface. Changes in capacitance can also be used in a similar way.
Pressure Transducers
The pressure measurement is usually achieved by determining the deflection of an elastic tube or diaphragm (for instance, a Bourdon tube). Material properties required for such type of pressure transducers include tubes or diaphragms that are similar to the restoring springs used in high-mechanical-impedance displacement transducers. These pressure transducers can also be applied with semiconductor fabrication techniques.
Sonar Transducers
These transducers transmit and receive the sound waves in water. Sonar transducers are also known as ultrasonic transducers that detect and generate vibrations above the normal frequency range of human hearing. They are used to clean delicate instruments, to cut hard materials, to measure liquid levels in fuel tanks of space vehicles and to drill oil wells.
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August 31st, 2010
Pressure sensors are one of the most useful industrial applications these days. They can in fact be described as a boon for the industry professionals. Pressure sensors not only perform the function of measuring pressure but also help to avert any untoward incidents. This is why they are used on a large scale in manufacturing plants.
The following are some of the different aspects of pressure sensors:
What are pressure sensors?
Pressure sensors are basically devices which are used to measure pressure. This is why they are also known as pressure transducers or indicators. They are mostly used to gauge the force of gases or liquids. Pressure is supplied to liquids as well gases to prevent them from increasing. Thus, pressure sensors function as an alarm or warning signal whenever the applied pressure exceeds the permissible limits.
What are they used for?
They are mainly used in industries in which manufacturers are required to measure different aspects like the level, flow and speed of liquids and gases. However, keep in mind that the designs of these devices vary on the basis of the application or industry in which they are used. The cost of the pressure sensors is decided upon the production cost and functions performed.
Different types of pressure sensors
Pressure sensors are available in many different types. To be precise, there are five different types of pressure sensors. Pressure sensors are classified on the basis of the functions performed by them. For example, they are classified on the basis of the range of measurements and type of element being used.
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August 30th, 2010
Pressure sensors are industrial products which are designed to monitor the pressure imposed on different fluids. These devices work as transducers which convert the energy into another readable form. Different variables such as gas flow, fluid, water level and altitude are measured with pressure sensors. In some industries, pressure sensors are also known as pressure transmitters or indicators.
Various types of pressure sensors
Due to the different measurement requirements, various pressure sensors are manufactured these days. Absolute pressure sensors are most commonly used, as they sense pressure according to the vacuum. Even gauge pressure sensors are installed in various applications because they can easily check pressure in different locations.
Vacuum pressure sensors can monitor the pressure which is less than the atmospheric pressure. Differential pressure sensors are designed to monitor the pressure of two or more pressure switches. These sensors are preferred by many operators because they monitor more than one system. Lastly, sealed sensors are used to calculate sea level pressure.
What technologies are used in pressure sensors?
To manufacture different pressure sensors, various new technologies have been introduced by manufacturers. Fiber optic technology uses small sized fiber optic interferometers to monitor pressure changes. Mechanical deflection is a technology which uses the mechanical properties of the liquid to measure the pressure.
Various other technologies such as semiconductor piezoresistive, vibrating elements, microelectromechanical systems and vibrating capacitance are also used. The pressure sensors manufactured by using these technologies are used in different applications.
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August 29th, 2010
Pressure sensors are used to calculate the pressure of different gases and liquids. Pressure can be defined as the force needed to prevent fluid from expanding. A pressure sensor is effective to generate an alert due to the pressure imposed.
There are different types of pressure sensors used to measure the variables. They are broadly classified into the pressure ranges they measure and the temperature ranges they operate on. Some common types of pressure sensor are listed below.
Absolute pressure sensor
Absolute pressure sensors are used to calculate pressure in relation to absolute vacuum pressure. Atmospheric pressure at sea level in relation to vacuum is 101.325 kPa.
Vacuum pressure sensor
Vacuum pressure sensor is used to measure pressure less than atmospheric pressure at a certain location. This may sometimes cause confusion in the industry as some people may consider a vacuum sensor as one which is related to either absolute vacuum or atmospheric pressure.
Gauge pressure sensor
A gauge pressure sensor is versatile in use as it can be easily standardised to calculate pressure with reference to a known atmospheric pressure at a specific location. An example of a gauge pressure sensor is a tire pressure gauge.
Sealed pressure sensor
A sealed pressure sensor is similar to a gauge pressure sensor, except that it is calibrated beforehand by the manufacturers. This is done to measure pressure in relation to sea level pressure.
Differential pressure sensor
Differential pressure sensors are used to measure the level or flow in pressurised vessels. They also calculate the difference in two or more pressures set as inputs in the sensing unit, e.g., a measuring drop in pressure in an oil filter.
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August 28th, 2010
Pressure switches are warning devices that are used for a variety of applications in a number of different industries. These switches help to detect hazardous changes in pressure and initiate a safety warning as well. Pressure switches can also alter elements within the system or sound an alarm to bring the situation under control.
Most switches are designed to adjust, close or open an internal contact that is based on a previously programmed level or point of functioning. There are two main kinds of pressure switch available today that are being used in different industries.
Solid state pressure switches- These pressure switches have digital and analog features and can be fully programmed. Solid state pressure switches can also have more than one switch point and digital displays. They offer a number of advantages, with the main one being their long operational life which is about 100 million cycles. Apart from this, other advantages include a high resistance to vibration and external shock, durability, high rates of accuracy, adaptability to several ranging system pressures, vast range of frequency response and enduring stability.
Electromechanical pressure switches- The pressure switch usually has an electronic snap-action attached to the sensory elements. Regardless of the type of element, these pressure switches never fail to react to the pressure of the system. Snap-action switches close or open contacts based on the lows or highs identified by these electromechanical pressure switches.
For decades, electromechanical pressure switches were the only kind used in different industries. However, the introduction and advantages of solid state pressure switches have made them more popular today.
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August 27th, 2010
The offshore oil industry uses pressure transducers for a number of different applications. They are used for drilling controls, measurement and the control of process variables and drilling down-hole tools.
The uses of pressure transducers are elaborated in the following points:
Down-hole tools
Different kinds of pressure transducers are used in down-hole tools to keep a check on hydraulic pressure and also pipeline oil pressure. A pressure transducer with a high functional temperature is due to the extreme environment. Some models provide ranges up to 1,000 bar and operating temperatures up to 150 degrees Celsius.
Wellheads
Wellhead assemblies make use of different technologies to measure wellhead pressure. Pressure transducers are used in perilous environments. Due to this, the device should be internally safe and should have an explosion–free design. Pressure transducers used in hazardous environments should also be robust and weather-proof.
Hydraulic manifolds
Offshore oil production makes use of sub sea hydraulic packs for various control functions. Pressure transducers used for such purposes should be of a small design and capable of working with extreme case pressure. 10 pressure transducers may be required by sub sea hydraulic packs. The pressure transducer can have the outside housing removed with only the PCB exposed to the outside environment to decrease the profile.
Core analysis
Process of core analysis involves an oil sample to be gushed at high pressure via a segment of rock core. The pressure sensor should provide precise measurements in such applications.
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