Application Notes

We know that you're always learning something new. In the application notes series we'll run through the basics elements of process control instrumentation. Use these docs to check on the functionality of a system or have a technical term explained.

Understanding and Controlling Foam In Industry

Introduction Exciting new technology developments in foam measurement and control are bringing important benefits to the waste water industry, as well as a wide range of other process industries. The accurate and reliable measurement of foam brings substantial savings to companies through the … [Read more...]

How To Prevent The Over Pressurization of Powder Silos

The latest silo protection technology provides much more than a safety system to prevent over filling and over-pressurisation. Introduction Level measurement specialists Hycontrol have been designing specialist silo protection systems for over  20 years and have extensive experience of the … [Read more...]

Oil/Water Interface Level

Introduction In oil production, measurement of oil/water interface level is a common requirement. Typically, displacers are used for this measurement (See figure 1). Other methods — such as point measurement based on capacitance — are also used. This application note describes a measurement method … [Read more...]

Introduction To Automatic Control

What is Automatic Control? Automatic control can be defined as the use of machines to measure and manipulate process variables. But, what are process variables? Process variables are varying properties of a process, such as temperature, pressure, flow, level, density, thickness, weight, colour, and … [Read more...]

Introduction To Process Dynamics

In order to do an optimal job of controlling a process, it is necessary to understand how the process responds to changes in its inputs. The more that is known about how a process functions, the easier it is to design a control system to match it. The most common reason for the failure of a control … [Read more...]

Second Order System

Second order systems are called quadratic lags or damped oscillators. Second order systems have mass, friction, and a restoring force. As such they have the ability to oscillate or overshoot in response to an input change. second order systems are described by the following second order linear … [Read more...]

Controller Tuning

General Controller tuning is the adjustment of the proportional band, reset time and derivative time to obtain the desired response of the control loop. Often, the desired response is the fastest response to a setpoint change or the fastest return to setpoint after a load change, but this is not … [Read more...]

Frequency Response

How fast is your transmitter? How fast is your recorder? How fast is the combination? These are not uncommon types of questions in the realm of process control, and the techniques of frequency response are a method of precisely answering them. Frequency response techniques are useful in at least … [Read more...]

The First Order System

In the study of control systems it is very difficult to make generalizations and formulate rules of thumb, because the dynamics, characteristics, and parameters of each system can vary so greatly. In an effort to help bring order to this subject, some types of simple systems have been modeled … [Read more...]

Control Stations And Switching

In the practical world of control systems it is often necessary for human operators to monitor and adjust the parameters of a control system. This is accomplished by control stations. Thus, control stations are the devices through which the control room operator communicates with the … [Read more...]