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VALVE WITH PRESSURE CONTROLLER C1 W/O POSITIONER

Hi, I want to know if a control valve that receives signal 3-15 psig from a pressure controller C1P can still work without a positioner.

I understand that if the bench set of the actuador is 3-15 psig, so there is no problem, but what happens if my bench set is different?

In my case, originally a pressure regulator was required, due to size issues we migrate to a control valve. If I don´t include a positioner, will my control valve have a good control?

Best Regards

Angel Perez

• 22 Feb 2017 6:57 PM
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8 Replies

• R Freudinger

  

  • 22 Feb 2017 7:06 PM

  Angel, Typically what you described would be acceptable. There are some installations that may be more challenging. Does the example valve have graphite or other high friction packing?

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• Angel Perez

  

  • 22 Feb 2017 8:17 PM

  In reply to R Freudinger:

  This valve has Enviro-seal PTFE packing and will control pressure of natural gas. It´s to be used in a regulation & metering station.

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• MOH

  

  • 23 Feb 2017 2:02 AM

  In reply to Angel Perez:

  Hi Angel
  Positioners use feedback for valve position by mechanical for electronic link. and positioner is a local controller of valve position for accurate valve positioning.

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• R Freudinger

  

  • 24 Feb 2017 3:20 PM

  In reply to Angel Perez:

  I have personally observed a slight increase in set point deviation due to the increase in friction with PTFE ENVIROSEAL packing when compared to standard PTFE v-ring packing. In most applications it was well within the application requirements. If you cannot tolerate this you'll need to incorporate a positioner. If possible I would suggest you try it without the positioner first. Remember, if you do install a positioner you will need to re-tune your C1 controller to compensate for the increased gain of the positioner.

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• Riyaz Ali

  

  • 26 Feb 2017 5:57 AM

  In reply to R Freudinger:

  I agree with Ray that if you are replacing regulator with control valve, you may not have much performance issue without positioner. Generally positioner is used when following requirements are there;
  -- Overcome valve friction
  -- Increased seat load
  -- Double acting piston actuator
  -- split range application
  -- Proper control valve operation from available control signal
  -- Modification of control valve characteristics
  -- Reduced stroking time
  -- Reversal of control valve action
  
  Function of positioner is to track controller signal to reach target travel by reducing dead time, hysteresis.
  Hope this helps.

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• Angel Perez

  

  • 28 Feb 2017 12:16 AM

  In reply to Riyaz Ali:

  What happens if actuator bench set is different than controller output? is there no problem although I want to replace a pilot regulator?

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• Richard L Ritter III

  

  • 28 Feb 2017 2:33 AM

  In reply to Angel Perez:

  For a C1 controller see page 37 and 5 of this manual: www.documentation.emersonprocess.com/.../d103292x012.pdf It should be noted the upper bench set must be achieved by its output and if a positioner present the supply to the positioner should be 5 psig over the upper operating pressure range. If just a C1 straight to the actuator the output should be able to achieve the operating pressure ranges however a positioner is always highly recommended to overcome dead and and hysterysis as well as to allow the positioner to saturate the signal. Please call your local representative and they have the expertise to help at your site if needed: www2.emersonprocess.com/.../na.aspx If you need a refresher please take a look at our classroom and virtual learning, here is a classroom course that covers what you are doing: www2.emersonprocess.com/.../1710.aspx and here is a link to the virtual class: emersonprocess.csod.com/.../DetailsLo.aspx See you soon!!!

  Richard L Ritter III, PMP, MBA | Technology Specialist - Reliability Services | Final Control

  Emerson Automation Solutions | 

  Richard.Ritter@Emerson.com

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• Richard L Ritter III

  

  • 28 Feb 2017 2:39 AM

  In reply to Richard L Ritter III:

  P.S. Please ensure the bench set was done correctly with the actuator disconnected from all valve forces as well, see bench set procedure of the actuator you are working on.

  Richard L Ritter III, PMP, MBA | Technology Specialist - Reliability Services | Final Control

  Emerson Automation Solutions | 

  Richard.Ritter@Emerson.com

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