Tag: instrumentation
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Designing a System to Measure & Display a Shaft Rotation Speed
We would like to design a system to measure and display the rotational speed of a shaft. To accomplish this, we shall use a number of integrated circuits (ICs) to create the desired functionality of this system. A simple technique to measure the speed is to count the number of shaft rotations during a given…
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What is a Microsyn Transducer?
This is a variable-reluctance transducer used to detect small motions, giving output signals as low as 0.01° of changes in angles. The figure below shows an example of Microsyn: In the Microsyn transducer above, the coils are connected in such a way that at the null position of the rotary element, the voltages in coils…
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Steam-heated Reboiler Control System
When steam-heated reboilers are used in distillation columns and the heating medium is steam, a flow control loop for the steam will typically be incorporated. The control valve can then be placed either in the steam or condensate line. Steam pressure compensation is always recommended in these cases, and the controls are illustrated in the…
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Installation Considerations of an Orifice Plate Flow Sensor
If a constriction is placed in a pipe as shown in figure 1 below, the flow must be higher through the restriction to maintain mass flow at all points. Since the mass flow must be equal at all points, the flow velocity must increase in the region of A2. As there is no net gain…
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Furnace Control System for a Rapidly Changing Demand
Let’s consider the figure below: In the system above, the output of temperature controller TC represents the process demand, and this signal is applied as one of the inputs, each to a high (>) and a low (<) signal selector block (module). The second input to the high (>) selector is obtained from the measurement…
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Industrial Process Temperature Control System
Let’s consider the industrial process control system shown below: The requirement is to control the temperature ϴ in the tank. The voltage r, obtained from a potentiometer, is calibrated in terms of the desired temperature ϴc. This voltage represents the input quantity to the feedback control system. The actual temperature ϴ, the output quantity, is…
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How to Perform Mass flow Measurements with DP sensors
Let’s assume we are measuring flow by differential-creating primary device for example an orifice plate and a DP cell as illustrated in Figure 1 below: The differential head across the primary device is corrected for temperature variation in the first calculation block, but there is no need for pressure correction because a liquid is virtually…
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Key factors to consider when selecting flowmeters
Selecting the right flow measuring instrument for a given flow application can be a challenging task given the numerous measurement techniques available. In this article, we look at some of the key pointers that can help you in the decision making process. What is discussed here isn’t exhaustive in itself but should act as some…
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Instrumentation and Controls for a Steam Desuperheater
A steam generator is an item of plant equipment that is found in almost every manufacturing site, and its output of steam has many critical uses in a variety of production processes. Steam has been assigned a measurement quality and a scale based on what is known as its dryness, which indicates how much “free”…
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The Instrumentation for Furnace Control
The figure below shows a typical basic furnace used to raise the temperature of a heat-transfer medium that is used on other equipment in a plant process. From the figure above, the temperature of the heat-transfer medium is the parameter that sets the demand on the heating system. The amount of heat required is manually…