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Making Sure You Have the Right Control Valves

Control Valves | KB Delta

Control valves are slowly becoming a victim of their own success. While many processing plants will utilize hundreds of valves to control various fluctuating factors within their systems, their effectiveness at performing these roles is resulting in them being taken for granted and underappreciated.


More Than Just a Simple Control

There are many important factors to consider within a manufacturing plant, but valves are invariably at the center of every stage in the process. While it can be logically argued that control valves are solely responsible for a set task of regulating either temperature, pressure, flowrate or another such element, their value is far greater than the sum of their parts.

Beyond being a simple cog in the machine, control valves have a greater influence over the holistic operation than any other single component. While other contributing factors to a system’s output can have a sizeable effect on the result you achieve, valves are responsible for the consistency with which these results are achieved. This consistency is an underlying principle which defines the overall product quality of any manufacturer.

Furthermore, valves can be fine-tuned to produce less wastage in materials and energy within the process. By manipulating their controls, you can tilt the balance of how your operation performs, but to achieve this with a degree of reasonable accuracy requires the valve itself to be in full working order.


The Right Tool for the Job

While maintenance plays a critical role in the upkeep of your control valves, there’s one factor which is more important towards the overall performance levels you can achieve: choosing the correct type of valve.

There are many basic types of valves available to choose between, however, there are also many variations within these basic types which can further complicate your choice.

While this is a question for a trained engineer to answer, it’s equally important that everyone in contact with the equipment knows at least the basics behind this choice. The first step to comprehension is in understanding exactly what and how your system operates. Crucially, this also needs to include what can occur within the system at any given time, so that any emergency situations which can potentially arise will be accounted for and sufficient controls will be in place to safeguard against them. Contingency planning for worst-case scenarios, no matter how small the risk, will ensure that you make the correct choice in selecting the right valve and the correct parts to accommodate any problems.

One Size Does Not Fit All

Once you have identified the type of system you will use in your operation and also the specific types of control valves that will monitor and manage the performance of the system, there are still further choices to be made. For example, the size of the valve.

The size of valve is another key consideration that can greatly affect performance issues of the system. While there is the age-old joke amongst engineers regarding a confusion between metric and imperial measurements that can result in an engineering problem, there’s another fundamental issue which needs to be addressed. How big will your operation be?

This involves not only the immediate specifications required but ideally any future plans. This potentially affects both the valve and the parts surrounding it in the system that may need to be capable of handling a differently sized load.

As for the choice with regards to size, once you’ve established the parameters of the flowrate, your control valve should:

  • never be less than 20% active for the minimum flow rate while maximum capacity
  • fall roughly within the range of 60-80% open


Establish Your Operational Environment

The environment which your valve will be required to function within also plays a decisive factor in selecting appropriate equipment for the task at hand. This should include but not be limited to:

  • Back pressure
  • Temperature extremes
  • Corrosive and toxic materials
  • Flow patterns and requisite networking
  • Viscosity of fluid
  • Internal and external pressures
  • Accessibility for maintenance and repairs

The characteristics of the valve and the connecting parts must be fully capable of not only performing within the conditions they will be deployed into, they must also be able to perform at the peak of their abilities in these surroundings.

Durability is an important consideration, especially in demanding and extreme environments. By selecting equipment that can best handle the operational situation, your system will become more robust which in turn provides a reliable business capable of producing results of greater consistency.


Response Time

A final major factor to be scrutinized is the amount of control that you will need to exert over the system being designed. The valves response time is critical to achieving the necessary levels demanded by your operation, with the amount of precision available with your controls intrinsically linked to the levels of efficiency you can successfully function at and the overall quality of your products. As such, this can heavily favor some control valves over others as each different type of valve works on a slightly different principle.

The response time itself is measured between the amount of time passing between the first command signal being issued, to the point where the valves aperture has changed to within 63% of the movements completion. This can be divided into two distinct time frames.

  1. Dead time – the amount of time it takes from the command being given for the valve to begin moving
  2. Process time – which is the time it takes the valve to move through 63% of its total required distance to fulfill the command

Not only is this response time responsible for the ensuring that the chosen control valve is suitable for the task at hand, each of the above criteria plays an essential role in ensuring that the valve is suitable for providing control over the system, to the correct degree and with adequate levels of reliability.


In Conclusion

By ensuring that you have the right valve connected to the right parts of your system, you are a large part of the way to realizing an efficient operational arm within your business.

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