The right control valve will extend the life of the entire system, whereas the wrong one will result in substantial damage to the system. How can the correct valve be chosen?
FREMONT, CA: The control valve plays the most crucial role in establishing and controlling a process efficiently. The selection of the correct valve needs to match the requirements in terms of application’s fluid characteristics, including versatility, ability to handle a range of flow rates, connectivity, and also control over the flow.
Basics of Process control valve:
Control valves can alter the flow of the fluid by varying the size of the flow passage depending on the signal obtained from the controller. The process helps in the direct control of flow rate and the consequential factors like pressure, temperature, and liquid level. Many types of control valves are available depending on the situation for which it is applied. Finding the apt valve for the scenario is a challenge since many factors are related to the selection of the perfect control valves. Some of the crucial factors that are included are the maintenance and longevity of the valve, economic restrictions, plant outage schedules, and life of the valve.
Various supporting factors affecting the selection of control valve:
Industry and country standards affect the suitability and apt matching of the specific valve during selections. Besides, the choice of the control valve for a particular application depends on the varying opinions of the related people. The customer expectations—end users, engineering-procurement-construction (EPC) contractors, and installation contractors also weigh in the decisions relating to varying priorities in selection criteria.
The characteristics to look for before choosing the control valve:
1. Versatility and toughness: If the valve can handle all the intensities of the conditions from minimum to maximum; if it is robust enough to withstand harsh circumstances, then the versatility and toughness of the valve are represented.
2. Flexible to all conditions like clean, dirty, corrosive, viscous, abrasive, high pressure, and gases: Standardization across the install base assists with maintenance requirements and spare parts inventory.
3. Stability over flow control: Consistent control is critical in all conditions. Inconsistency in control will result in the production of downtime and loss of product.
4. Compliance with appropriate linear, equal percentage and other features of control: As many different scenarios demand different features from the valve, a single valve should have the ability to meet all of them.
5. Connectivity to a building’s process management system: Remote monitoring and control are quite necessary for processing applications. Ensure the compatibility of the valve with the building/process management system.
Factors to monitor for proper control valve maintenance:
The criteria that need to be met for the selection of the valves are listed. By possessing these features, valves verify proper maintenance:
• A seat ring with self-aligning for an airtight shutoff, without need for shimming.
• Easy inspection and adjustment with access to packing.
• The splined or coupled shafts connections are built to allow ease of connecting/disconnect from actuation.
• Shaft protection for blowout proofing
• Self-purging and enclosed actuator linkage
• Ease of working on the valve without having to dismantle the unit from pipeline.
• The integrity of the valve should be high to maintain tight shutoff for minimizing the loss of working fluid. It has to be noted that control valves are not isolation valves; it is advised against the use in lieu of proper isolation valves for plant safety.