DE LAS INDICACIONES GEOGRÁFICAS CAPITULO

Control Valve Validation and Calibration Test Results

Each control valves have been done Control Valve Validation and Calibration Test has been done to all control valves. All of them have passed the validation test, so calibration has not been required. The results show the linear lines in Figures 11, 12 and 13 which mean the control valves are linear valves.

In this section, all the undertakings involved for this project will be briefly explained. The undertaking task is Hardware Testing which includes control valve leak test testing and control valve validation and calibration.

Figure 14: Validation Graph Baumann 5100 Control Valve #01

Hysteresis Results

The hysteresis testing has been done to all the control valves in ICE laboratory. The results have been logged in LabVIEW and plotted by using EXCEL. For the water system, three hysteresis results of control valves and for the air system, the two hysteresis results will be discussed in this section.

Figures 16 and 17 show the minimum difference of up stroke and down stroke. The Baumann 24000S with an electric actuator control valve shows less difference in hysteresis because this control used electric motor to step up and step down. This travel position and the flow rate of the opening and closing is almost the same. The hysteresis graph for Baumann 24000S with positioner also shows that not much different hysteresis of valve opening and valve closing. This control valve with the positioner can eliminates the hysteresis of the valve. The positioner of the control valve will follow the setpoint and the air pressure will adjust the stem of the valve. The graph for Badger Meter Research control valve in Figure 18 shows that the gap of hysteresis was quite obvious. This is because of the friction happen to the valve due to “wear and tear”. For the air system, the hysteresis graph of Baumann 24000S with 3660 positioner in Figure 19 shows there is no difference in valve opening and valve closing. The response of valve to the step change follows exactly the same as the setpoint. The positioner works successfully without any error. Figure 20 shows the hysteresis of the Badger Meter Research control valve for the air system. The hysteresis of this control valve can obviously be observed. This happen because of the age of the valve. This valve requires service and maintenance.

Figure 16 : Baumann 24000S with Electric Actuator (Water System)

Figure 18 : Hysteresis for Badger Meter Control Valve (Water System)

Dead Band Results

Dead band can be overcome by the general procedure controller. This is not perfect as a huge blunder between the sought stream rate and the deliberate stream rate is required for the controller to bring about a change in the valve. The positioner does not require a distinction in the coveted stream and the deliberate stream to be influenced for remedial activity to happen. The positioner will modify if there is a blunder between the sought stem position and the deliberate stem position before the stream is influenced.

From Figures 19 and 20, the dead band of the valve can be observed. As it can be seen, there is no change in flowrate despite the steps change in valve position.

Figure 22 : Baumann 24000S with 3660 Positioner Dead Band Test ( Air System)

Figure 23 : Baumann 24000S with 3660 Positioner Dead Band Test (Water System) Baumann 24000S with 3660 Positioner Dead Band

Valve calibration in ICE lab

Concerning valve familiarization and calibration, the aim was to determine salient valve characteristics that can significantly affect the output, or at least, allow for the design of more efficient control methods that take into account these characteristics. Among others, two of the most important valve characteristics are: valve ‘Deadband’ and valve-flow behaviour.

‘Deadband’, as its name implies, refers to the non-operating range of a given element. Many, if not all, process elements have within them some deadband region. However, most of this ranges are too little to be of any significant influence to the overall system. For this particular element, it is pertinent that discover its operating ranges with respect to the input flow rate so that, where possible, the deadband region can be avoided.

As previously mentioned, another salient valve property is its relationship to flow rate and how ‘ideal’ this relationship seems. There are three main categorization of valve-flow relationship and each of these categories holds some form of advantage and disadvantage over the other.

Figure 22, the flow-valve characteristic test has been performed to analyse the flow specification of the control valve. The first step is to open the valve through five stages until it is fully opened. Meanwhile, the flowrate is recorded in Excel spreadsheet. By using excel inbuilt trendline feature, the linear equation of the valve has been developed as below.

Figure 24: System Valve-Flow Characteristics and Dead Band Region

The derived equation, with a correlation of 99.69%, is given below:

Equation 2: Linear equation for Badger Research Control Valve

Surmising form the image above, the conclusion that the chosen valve has a dead band region approximately around 0-15% valve opening and can safely categorize the valve-flow relationship under the quick-opening type. This implies that:

 The dead band region is redundant in terms of operating positions.

 As a quick opening valve, the dead band region is a more significant

detriment to the overall valve efficiency as this region could have been capable of more sensitive control action since its gradient would have been less.

 A little change in the valve positions would result in a relatively significant change in the flow rate.

Results summary

Summary of Calibration Results

Summary of Behaviour Testing Results

16 Table 6 : Summary of Behaviour Testing Results