Controlling the pressure levels is one of the challenges many instrumentation and automation engineers face. Pressure regulators are often used for this task, since they are self-regulating and don’t require a control loop connected to the plant distributed control system (DCS).
He shares links to some pressure regulator animations, a couple for the MR95 Pressure Reducing Regulator and one for a gas delivery over- and under-pressure configuration.
Let’s look at the second one with an EZH pressure regulator with a monitor in series. It is an interactive demonstration helping to show various scenarios of how pressure is maintained even in failure situations.
This demonstration features the EZH (Spring-to-Close) and EZHSO (Spring-to-Open) Series regulators in a wide-open monitor configuration. This configuration offers typical system overprotection and also provides underpressure protection. It accomplishes this by ensuring that minimal flow restriction occurs in the downstream working regulator. The EZHSO regulator will spring open in the event of a potential failure such as a ruptured diaphragm or loss of pilot supply pressure.
The EZHOSX (Spring-to-Close) upstream monitor regulator will take over regulating if the EZHSO springs open. This configuration will automatically restart in the event of a loss of inlet pressure. The OSE Slam Shut valve provides additional excess flow protection for the downstream system in the event that very low pressure conditions are detected.
The interactive demo description also notes that it is always recommended to install gas heaters in the system to prevent the possibility of pilot freezes.
The nice thing about this demonstration is seeing how this configuration adjusts to handle the various failure modes including regulator diaphragm failure, control line rupture, loss of pilot supply pressure, pilot diaphragm failure, and pilot freeze conditions. When you start the demonstration, a pause button appears. I found this very handy to follow the sequence of everything that occurs to maintain the pressure within the set limits.
If you ever have anyone asking you how pressure regulators work, this is a great demonstration to share with them.
You can connect and interact with Michael and other pressure regulator experts in the Regulators group in the Emerson Exchange 365 community. And, if you’re attending the World Gas Conference in Paris June 1-5, come see the EZH in action!