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Understanding Transmitter Seals Webinar
- 1. Copyright © Yokogawa Corporation of America 1 What Do I Need to Know? Understanding Transmitter Seals Tonya Miller & Liz Majestic November 17, 2016
- 2. Copyright © Yokogawa Corporation of America 2 Host: Kristina Neahr Marketing Specialist kristina.neahr@us.yokogawa.com Presenter 1: Tonya Miller Technical Support Specialist support@us.yokogawa.com Presenter 2: Liz Majestic Application Engineer support@us.yokogawa.com Host & Presenters
- 3. Copyright © Yokogawa Corporation of America 3 Participant audio is muted. If your computer audio is not working, please join us using the teleconference number. Call-in toll-free number (US/Canada): 1-877- 668-4490 Call-in toll number (US/Canada): 1-408-792- 6300 Access code: 352 191 032 Event Logistics
- 4. Copyright © Yokogawa Corporation of America 4 Questions will be taken through the Q&A window. Click on ‘Chat’ in the upper right corner of your screen. Please send your questions to host. Questions will be answered at the end of the presentation or via e-mail shortly after. Event Logistics
- 5. Copyright © Yokogawa Corporation of America 5 Shortly after the event, you will receive an email containing a link to the recording, slide download, and access to all resources. As you exit the webinar, you will have the option to participate in a short survey. Your feedback is very important to us, so please take a minute to complete. Event Logistics
- 6. Copyright © Yokogawa Corporation of America 6 1. What is a diaphragm seal system? 2. How a diaphragm seal system works 3. Direct mount vs. capillary mount 4. When to use a diaphragm seal system 5. Performance considerations 6. Advantages & limitations
- 7. Copyright © Yokogawa Corporation of America 7 What is a Diaphragm Seal System?
- 8. Copyright © Yokogawa Corporation of America 8 Consists of a transmitter, a process connection, and a capillary connecting the two. Transmitter: Measures and converts the measured variable to a signal to be transmitted. Capillary: Connects the seal to the transmitter and contains the fill fluid. Process Connection: The part that is in contact with the process. and is available in a host of sizes, types, flange ratings, and wetted materials. What is a Diaphragm Seal System?
- 9. Copyright © Yokogawa Corporation of America 9 How a Diaphragm Seal System Works
- 10. Copyright © Yokogawa Corporation of America 10 How a Diaphragm Seal System Works
- 11. Copyright © Yokogawa Corporation of America 11 How a Diaphragm Seal System Works Instrument (such as a pressure transmitter) mounted- directly or by means of a capillary or cooling element. A diaphragm within the seal system separates the transmitter from the process medium. Any part of the diaphragm seal (i.e. diaphragm, lower housing, gaskets) which will be exposed to the process medium is selected from materials resistant to pressure, temperature and possible chemical attack by the process medium. The diaphragm seal is also filled with a transmitting or system fill fluid. Pressure applied by the process medium to the seal diaphragm is hydraulically transmitted to the pressure element of the transmitter, generating a pressure reading.
- 12. Copyright © Yokogawa Corporation of America 12 How a Diaphragm Seal System Works Principle of Hydraulics Mechanically transfers the force applied at the process diaphragm to the transmitter diaphragm. Fill fluid is a non-compressible liquid compatible with the process temperature and pressure. Basically- the process pressure is transmitted to the transmitter via the fill fluid.
- 13. Copyright © Yokogawa Corporation of America 13 Accuracy & Response Time System Accuracy & Response Time ≠ Transmitter Accuracy & Response Time Remember: System Accuracy = Transmitter Accuracy + Capillary/Diaphragm Seal Accuracy System Response Time = Transmitter Response + Capillary/Diaphragm Response
- 14. Copyright © Yokogawa Corporation of America 14 Direct vs. Capillary Mount
- 15. Copyright © Yokogawa Corporation of America 15 Direct Mount Seal is attached as an integral (close coupled) part of the transmitter body Capillary Mount Remote mounted diaphragm seal process connection with a capillary between the seal & transmitter Direct vs Capillary Mount
- 16. Copyright © Yokogawa Corporation of America 16 Connection system to mount various types of seals directly to a transmitter. Eliminates capillaries, improving the overall temperature effect. Reasons to use a Direct Mount System: Level measurements Flexibility in applications When close connection to tank is required Sanitary applications where capillaries are not recommended Direct Mount
- 17. Copyright © Yokogawa Corporation of America 17 A remote diaphragm seal system offers a cost effective means of preventing the process medium from coming in contact with a transmitter. Reasons to use a Remote Mount System: High temperatures Corrosive service Safety Prevent clogging of cell body or impulse lines Sanitary requirements Replacement of wet legs Avoid contamination Capillary (Remote) Mount
- 18. Copyright © Yokogawa Corporation of America 18 When to Use a Diaphragm Seal System
- 19. Copyright © Yokogawa Corporation of America 19 A transmitter alone is not always the solution Typical conditions: Process temperatures beyond the limits of the transmitter Special process connections (sanitary connections, PMC connections, quick disconnect) Presence of solids or viscous fluids Process is corrosive Hydrogen Permeation Replacement of inefficient wet legs When to Use a Diaphragm Seal System
- 20. Copyright © Yokogawa Corporation of America 20 Performance Considerations
- 21. Copyright © Yokogawa Corporation of America 21 Maximum process and ambient temperature changes How quickly will the measured variable change? Location of transmitter Expected highest temperature & lowest pressure Is the process under vacuum? Measurement span Maximum pressure limits on the system Is the process connection cleaned? Type of cleaning solution? Performance Considerations
- 22. Copyright © Yokogawa Corporation of America 22 Diaphragm Seal System Limitations
- 23. Copyright © Yokogawa Corporation of America 23 Limitations Small span measurements Increased response time Decreased total system accuracy Temperature-induced errors Tonya Tip: always use the smallest diameter diaphragm required *Recommended sizes for different measurement spans Limitations
- 24. Copyright © Yokogawa Corporation of America 24 Resources
- 25. Copyright © Yokogawa Corporation of America 25 Questions?
- 26. Copyright © Yokogawa Corporation of America 26 Thank you!
Editor's Notes
- Tonya – Today we will cover a Basic Introduction to Seal Systems and explain to you the top things you need to know. We will cover: What is a diaphragm seal system? How a diaphragm seal system works The difference between a direct mounted seal and a capillary mounted seal When to use a diaphragm seal system Performance considerations Diaphragm seal system limitations
- Process Connection: The part that includes the diaphragm seal. The process connection is what is in contact with the process and is available in a host of sizes, types, flange ratings, and wetted materials. (More on that later?)
- Tonya – To begin, I think perhaps we should cover the Operating principle of a diaphragm seal.
- Tonya – As illustrated in the previous drawing, a pressure measurement instrument such as a pressure transmitter is either mounted directly to the diaphragm seal or attached to the seal by means of a capillary or cooling element. A diaphragm within the Seal system separates the transmitter from the process medium. Any part of the diaphragm seal (i.e. diaphragm, lower housing, gaskets) which will be exposed to the process medium is selected from materials resistant to pressure, temperature and possible chemical attack by the process medium. The diaphragm seal is also filled with a transmitting or system fill fluid. Any pressure applied by the process medium to the seal diaphragm is hydraulically transmitted to the pressure element of the transmitter thus generating a pressure reading.
- Some engineers make the assumption that the Accuracy and Response Time for the entire system are the same as the transmitter used in the system. The accuracy of the entire seal system is equal to the transmitter accuracy plus any inaccuracies introduced by the capillary and diaphragm seal design. Therefore, the accuracy of the seal system is a combination of all components. Same for the Response Time. The system response time is equal to the transmitter response time plus the response time of the capillary, fill and seal design. System Accuracy = Transmitter Accuracy + Capillary/Diaphragm Seal Accuracy System Response Time = Transmitter Response + Capillary/Diaphragm Response
- There are two distinct types of seal systems: Direct Mount which is the seal attached as an integral (close coupled) part of the transmitter body And the second is a remote mounted diaphragm seal process connection that has a capillary between the seal and the transmitter. These devices are able to transfer or access additional data from field devices that previously only had one or two Process Variables accessible.
- A direct mount seal system is a connection system to mount various types of seals directly to a transmitter. The obvious advantage is the elimination of capillaries which helps with the overall temperature effect and reduction of care and maintenance of capillaries. Other reasons to use a DMS system: Level Measurements Flexibility in applications When close connection to tank is required Sanitary applications where capillaries are not recommended
- A remote diaphragm seal system offers a cost effective means of preventing the process medium from coming in contact with a transmitter. Advantages or reason to use: High temperature applications where the process fluid temperature is beyond the specs of the transmitter sensing element Corrosive service To isolate the process for safety reasons Prevention of suspended solids from entering the cell body or impulse lines which can become plugged. Requirements for sanitary connections Replacement of wet legs Ease of cleaning between batches to avoid contamination
- As discussed, seals are an extension of a pressure transmitter and there are always those applications that are not well suited for a transmitter alone. The answer for all of these conditions is adding a diaphragm seal system to the transmitter. Process temperatures beyond the limits of the transmitter. Special process connections. (Such as a sanitary connections, PMC connections, quick disconnect for easy cleaning between batches) Presence of solids or viscous fluids that could plug impulse lines or the transmitter. Process is corrosive. Process application subjects the measuring instrument to Hydrogen Permeation. Make sure to click on the ‘Hydrogen Permeation’ link when you receive these slides for more information on this subject. Link to: https://www.yokogawa.com/us/technical-library/resources/application-notes/hydrogen-permeation/ Or, in older facilities, replacement of inefficient wet legs.
- ***Use GS33G6E22-01E pages 5 and 6 to answer the questions to increase the length of the webex In order to select an appropriate seal and capillary combination, process conditions, installation requirements and overall system performance must be considered. Following are a list of questions to ask and points to consider: What are the maximum process and ambient temperature changes? How fast will the measured variable change? Where will the transmitter be installed? What is the highest temperature and lowest pressure expected? Is the process under vacuum? What is the measurement span? What are the maximum pressure limits on the system? Is the process connection cleaned? With what type solution?
- Everything comes at a cost, and diaphragm seals are no different. In some cases, these limitations can apply: small spans cannot be measured (spans less than 10 in water) increased response time The response time is the time it takes the pressure instrument to indicate 90% of the value of a sudden pressure variation. This is especially important for instrument/diaphragm seal assemblies which include a capillary. Response time increases significantly in systems with long capillaries. In applications requiring long capillaries, response times can be reduced by using larger diameter capillary tubing and reducing the viscosity of the system fill fluid. Be advised that increasing the inner diameter of the capillary increases the temperature influence of the measuring system. decreased accuracy temperature induced errors Temperature-induced errors from wide changes in ambient temperature - With all diaphragm seal applications, you always want to use the smallest diameter diaphragm that can measure the span required. The larger the surface area of the diaphragm, the more temperature-induced error will be contributed to the system. However, diaphragm seal technology does have a lower limit it can measure. So, you need to balance the two conditions. This chart illustrates the recommended sizes for different measurement spans. Keep in mind this is a guideline as there are design differences between seal types or even manufacturers that can change these limits.
- Since the topic of Pressure is so in depth, Yokogawa has created a full library of resources surrounding the subject. Just this week, we released a brand new eBook, which includes an entire section on diaphragm seal systems. (click through to banner, then 3 images) Click to video We also added a new video to our YouTube channel, answering 10 commonly asked questions about pressure & pressure transmitters. Links to both of these will be included in the slides you will receive after this webinar. Now I’m going to hand it back to Kristina, who will read some of the questions we received during the webinar. Kristina & Liz Q&A