When a valve fails, the maintenance technician is usually pressured to quickly find a replacement. Looking at this schematic, it looks like an easy valve to replace. The most important factor in selecting a replacement is often based on what the supplier has in stock rather than what is most suitable.
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Despite being short on time, cutting corners when troubleshooting and not understanding each component&#;s technical tasks in an application can cost much more time as technicians try to discover why the shiny new valve does not operate when it&#;s energized.
In the above schematic, the valve used is likely a zero-differential pressure type (it requires no back pressure to operate). Buying a two-port valve without thoroughly reading the specs could result in getting a process valve with a maximum and/or minimum operating differential.
Pressure differentials are a potential minefield for technicians and engineers unfamiliar with the terminology. In short, the pressure differential across the main valve is the inlet pressure minus the outlet pressure. So, if a valve&#;s max operating differential is 3 bar, and supply pressure is 5 bar, then the valve needs to at least 2 bar at the outlet port to operate.
Taking the example of the nozzle. There is about 0 bar on the outlet So the differential will be 5 bar, which exceeds the maximum. Therefore, the valve will not open when the solenoid is energized.
If the valve has a minimum operating pressure differential, it needs at least that amount at the outlet port to stay open. For example, if the minimum operating differential is 0.5 bar, the valve might open. But if inlet pressure drops to 3 bar, and the outlet is around 2.7, the valve will not stay open. The rapid opening and closing could become a head-scratcher.
If the nozzle&#;s flow rate is much lower after changing the valve, even though the port sizes are the same, the low rate could be due to the replacement&#;s orifice size. If the new valve&#;s orifice is smaller, flow can be restricted. Understanding flow rates is important; they are found in product catalogs. But standards and manufacturers in different parts of the world use different methods of measuring a valve&#;s flow rates.
Here&#;s another snag that crops when ordering replacement valves: being unaware of the compromises made when selecting metal-seal valves instead of rubber-seal types. Again, just because your supplier has metal-seal valves in stock, do not rush into buying one unless you know there is no risk of it failing in your application.
Metal-seal valves do tend to operate quicker than rubber-sealed valves, but their valve spools will not hold position and could cause mid porting if the valve is subject to vibration or is mounted vertically. These valves usually have a mechanism for keeping them stable, such as spring force or a detent. Be sure you are familiar with the symbology so you can check these details in the valve&#;s schematic in the catalog. If you do not know the specifics of the seals, determining why there are problems with a replacement valve might needlessly eat up lots of time and stall production.
Technicians replacing pilot-operated solenoid valves should ensure the replacements are not external pilot types. They will not operate if external pilot pressure is not applied. If the replacement has a small port next to the solenoid marked 10, 12, 14, a, b or X, chances are it is an external-pilot valve and technicians need to add a supply line to that port. As with the metal-seal valves, knowing what to look for in the schematic symbol is more important than a shorter lead time.
The potential stress from the above examples can be alleviated if spare parts are kept in stock and ready for when a breakdown occurs. Just as important is good technical documentation and schematics readily available for technicians to research when they troubleshoot a fault.
Probably the most common cause for frequent valve (or products in general) failure I have seen is contamination. This is usually due to lack of understanding of air treatment and filtration in a facility. Many shift technicians have very broad knowledge of mechanical and electrical systems, so specific expertise in subjects such as pneumatics is not as strong. The picture below shows how dirt can build up inside pneumatic components and clog up the internal parts if facility air is not correctly treated.
Several problems, including the sale of remanufactured and poor-quality valves, plague the industrial valve industry. These issues put engineering safety at serious risk and may result in excessive downtime and accidents.
Therefore, industrial valve purchases must be well thought out to guarantee dependable and secure operations. This article lists six crucial variables to consider when buying valves for industrial applications.
The Use of the Valve Place and Purpose
Verifying a valve&#;s precise usage and environment before purchasing is essential. Valves can be used to regulate pressure, control flow, or isolate equipment, among other things.
Understanding the valve's intended application aids in choosing the right type, size, and design to satisfy operational requirements successfully.
Source: Unsplash
Valve General Requirements
It is crucial to consider the general criteria particular to the application while buying valves. This involves evaluating the valve's operating circumstances, including pressure and temperature ranges, the type of media being handled (liquids, gases, or slurries), and any unique environmental concerns.
Understanding these elements ensures the selected valve can endure the circumstances and work at its best. The following are some general guidelines for valves that you should remember:
Valve Type
Choose the type of valve best for your application. Ball, gate, globe, butterfly, and check valves are common valve types. Each variety has unique qualities and is suitable for various uses.
Valve Size
Specify the suitable valve size based on your system&#;s flow rate and pipe dimensions. Valves come in various sizes, usually in inches or millimeters.
Pressure Rating
Consider the operating pressure in your system when choosing a valve, and select one with a pressure rating that is higher than or equal to the needed pressure. In most cases, pressure ratings are given in pounds per square inch (psi) or bars.
Temperature Range
Consider the range of temperatures across which the valve will function and select a valve that can withstand those conditions. Different substances and building techniques are appropriate for various temperature ranges.
Valve Material Compatibility
Check the valve's material to ensure it is compatible with the liquid or gas passing through it. Different substances, such as PVC, brass, bronze, or stainless steel, offer differing corrosion resistance and compatibility with various media.
Flow Characteristics
Consider your system's flow requirements when choosing a valve, such as whether you need one that can turn on and off or throttle and regulate flow. Specific flow control applications suit some valves better than others.
End Connections
Choose the appropriate end connections for your piping system. Fittings that are threaded, flanged, welded, or compressed are examples of common types. Verify that the valve's end connections meet the needs of your system.
Operation and Actuation
For more information, please visit Nozzle Check Valves.
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Consider if you need a manually operated valve or one that can be automated using actuators or control systems for operation and actuators. Applications requiring frequent operation, precision, or remote control are good candidates for actuated valves.
Compliance & Standards
Depending on your application's demands, ensure the valve complies with pertinent industry standards like ANSI, API, ISO, or particular certifications like NSF, UL, or ATEX.
Maintenance & Service
Consider the ease of maintenance, the accessibility of replacement parts, and the reputation of the supplier or manufacturer for technical assistance and post-purchase support.
Source: Unsplash
6 Factors That Should Be Considered When Purchasing Valves
1. Valve Material Requirements
In industrial settings, various corrosive, erosive, and abrasive chemicals are exposed to valves. The material requirements for the valve shell and its internal components must be examined.
The material selection should be appropriate for handling the media to avoid early wear, leakage, or failure. When choosing the valve, chemical compatibility, thermal resistance, and mechanical strength should be carefully considered.
2. Compliance with Safety Standards and Pipeline Regulations
In terms of industrial applications, safety comes first and foremost. Confirming that the valves being purchased adhere to the necessary safety requirements and pipeline laws is crucial.
Following these guidelines ensures a safe and legal working environment by reducing the possibility of leaks, equipment breakdowns, and potential hazards.
3. Valve Performance and Packaging/Transportation Requirements
Based on the application&#;s needs, it is crucial to determine the performance criteria for valves, including sealing performance and leakage rates.
To safeguard the valves during shipping and handling, consideration should also be paid to the packing and transportation requirements. Protective coatings can be required to prevent corrosion if the valves are exposed to hostile environments.
4. Quality Testing of the Valve
It is crucial to confirm the quality of the valves through meticulous testing to guarantee their dependability and longevity. It also entails determining if the valves adhere to the necessary design specifications.
Ball valves, for instance, must follow API6D, while butterfly valves must follow API609. Quality testing should cover various topics, including material integrity, dimensional accuracy, and functional performance, to ensure the valves satisfy the necessary criteria.
5. Valve performance requirements and packaging and transportation requirements
It's essential to consider the performance specifications of valves before buying them and to ensure they adhere to established industry standards. Sealing performance requirements and protective coating needs are two important things to consider.
Performance Requirements for Sealing: Valves must adhere to strict sealing regulations to ensure operating effectiveness and prevent leaks. To suit the unique requirements of your application, factors including sealing grade and sealing leakage should be carefully examined.
6. Quality testing of the valve
It is essential to conduct quality testing on valves to guarantee their dependability and efficiency. Valve makers frequently conduct extensive testing processes to ascertain whether the valves adhere to the design criteria.
API6D for ball valves and API609 for butterfly valves are a few examples of design standards that are frequently utilized.
Final Words
Several things must be considered when buying valves for industrial applications to guarantee dependable and secure operations. Engineers and procurement experts can make well-informed selections and choose valves that best meet their unique application needs by carefully assessing the use, general requirements, material compatibility, safety regulations, performance criteria, and quality testing.
Dombor: Your Trusted Valve Solution Supplier
Dombor is a reputable supplier that offers a one-stop purchasing solution for industrial valves. We ensure that customers can discover the ideal valves for their particular applications by offering various valves created to fulfill the needs of various industries. Dombor offers pre-sale consulting services to help customers choose the best valves for their needs while providing invaluable technical advice.
For more gate valve manufacturers in usainformation, please contact us. We will provide professional answers.
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