This video explains why slam shut devices are needed in a natural gas distribution system, the principle of operation and resetting of the Fisher Types OSE and OSX Slam-Shut products and their unique features and benefits.
The Type OSE gas safety shutoff valve is used to rapidly cut the gas flow during an overpressure or underpressure event. It is ideal for gas applications requiring positive shut off protection, tight accuracy, fast speed of response, and high shock and vibration resistance. The top entry design makes in-line maintenance easy, saving time and manpower requirements.
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Video Transcript:
In this video, we will talk about the benefits components and proper resetting method of the Fisher type OSE slam shut. Before performing any work, always be sure to read and follow all safety precautions as they are outlined in the instruction manual. Type OSE refers to the stand-alone slam shut while Type OSX refers to an integral configuration of the slam shut on regulators such as the EZH or EZR or 627 making them the EZH-OSX, EZR-OSX or 627-OSX. You will see both configurations in this video even though the narrative refers only to type OSE. The type OSE slam shut device is used to completely and rapidly cut off gas flow when the pipeline pressure either exceeds or drops below the set pressure. The features that are unique to the Type OSE are: It offers both overpressure and under pressure protection. Type OSE incorporates a two-stage tripping mechanism that significantly reduces nuisance tripping caused by vibrations or inlet pressure variations commonly experienced by other shut off valves. Maintains up to plus or minus one percent accuracy regardless of inlet pressure, flow rate, and the size of the slam shut Top entry design reduces maintenance time and manpower requirements. Parts can be inspected and replaced without removing the body from the line. Type OSE is water tight to 10 feet or three meters. The type OSE device offers remote alarm and remote shut off capability. After closing, the slam shut valve stays closed until the system is shut down and the valve is manually reset. An o-ring on the valve plug seal provides tight shut off. The Type OSE consists of a valve a mechanism box and either one or two manometric sensing devices. Pressure is registered through a control line into the manometric sensing device on one side of the diaphragm and is opposed by the set point control spring when the sensed pressure increases. The pressure on the diaphragm compresses the spring moving the manometric device stem toward the trigger pin D1. When the sensed pressure reaches the overpressure set point, the manometric device stem contacts pin D1 and triggers the release of the valve plug. The valve spring slams the valve plug into the orifice creating a tight seal. When the sensed pressure decreases, the pressure on the diaphragm allows the spring to relax, moving the manometric device tripping hook toward the trigger pin D2. When the sensed pressure reaches the under pressure set point, the manometric device stem contacts pin D2 and triggers the release of the valve plug. The valve spring slams the valve plug into the orifice creating a tight seal. After the Type OSE has tripped, it must be manually reset before it can be placed back in service. Resetting is performed in three steps. Step one is to push the reset pin away from the valve body. This action will lock in the first stage of the tripping mechanism. Step two is to equalize the pressure on both sides of the valve plug so that it can be lifted without damaging the device. Place the square end of the tool on the second stage releasing shaft at the center of the box and slowly rotate clockwise. When movement is started on the stem, the internal bypass will open and equalize the pressure on each side of the valve plug. Pause and allow pressure to equalize across the plug before continuing to rotate. Step three is to continue rotating the reset tool clockwise which will raise the valve plug and latch the second stage of the tripping mechanism. for more information please contact your local Emerson sales office or visit Emerson.com