If a valve doesn’t function, your course of doesn’t run, and that is cash down the drain. Or worse, a spurious trip shuts the method down. Or worst of all, a valve malfunction results in a harmful failure. Solenoid valves in oil and fuel purposes management the actuators that transfer large process valves, including in emergency shutdown (ESD) systems. The solenoid needs to exhaust air to allow the ESD valve to return to fail-safe mode each time sensors detect a dangerous process situation. These valves must be quick-acting, sturdy and, above all, dependable to forestall downtime and the related losses that happen when a course of isn’t operating.
And that is much more important for oil and gasoline operations where there’s restricted power obtainable, corresponding to remote wellheads or satellite offshore platforms. Here, solenoids face a double reliability challenge. First, a failure to operate correctly can not solely cause costly downtime, however a maintenance call to a remote location additionally takes longer and prices more than an area restore. Second, to scale back the demand for energy, many valve producers resort to compromises that truly reduce reliability. This is dangerous sufficient for process valves, but for emergency shutoff valves and different security instrumented methods (SIS), it’s unacceptable.
Poppet valves are usually higher suited than spool valves for distant places as a outcome of they’re much less complex. For low-power purposes, look for a solenoid valve with an FFR of 10 and a design that isolates the media from the coil. (Courtesy of Norgren Inc.)
Choosing a reliable low-power solenoid
Many factors can hinder the reliability and performance of a solenoid valve. Friction, media flow, sticking of the spool, magnetic forces, remanence of electrical current and material characteristics are all forces solenoid valve manufacturers have to overcome to build the most dependable valve.
High spring pressure is essential to offsetting these forces and the friction they trigger. However, in low-power functions, most manufacturers have to compromise spring drive to permit the valve to shift with minimal power. The reduction in spring force ends in a force-to-friction ratio (FFR) as little as 6, although the widely accepted safety degree is an FFR of 10.
Several components of valve design play into the quantity of friction generated. Optimizing each of these allows a valve to have higher spring pressure while still sustaining a excessive FFR.
For instance, the valve operates by electromagnetism — a current stimulates the valve to open, permitting the media to flow to the actuator and transfer the method valve. This media could also be air, but it may also be natural gasoline, instrument gasoline or even liquid. Withheld is especially true in remote operations that must use whatever media is out there. This means there’s a trade-off between magnetism and corrosion. Valves by which the media is obtainable in contact with the coil have to be made from anticorrosive materials, which have poor magnetic properties. A valve design that isolates the media from the coil — a dry armature — permits using extremely magnetized material. As a result, there isn’t a residual magnetism after the coil is de-energized, which in turn permits quicker response occasions. This design additionally protects reliability by stopping contaminants within the media from reaching the inner workings of the valve.
Another factor is the valve housing design. Usually a heavy (high-force) spring requires a high-power coil to beat the spring strength. Integrating the valve and coil into a single housing improves effectivity by preventing vitality loss, allowing for using a low-power coil, leading to much less power consumption with out diminishing FFR. This built-in coil and housing design additionally reduces heat, stopping spurious journeys or coil burnouts. A dense, thermally environment friendly (low-heat generating) coil in a housing that acts as a heat sink, designed with no air hole to entice warmth across the coil, virtually eliminates coil burnout concerns and protects course of availability and safety.
Poppet valves are typically better suited than spool valves for distant operations. The reduced complexity of poppet valves will increase reliability by decreasing sticking or friction points, and decreases the variety of elements that can fail. Spool valves typically have massive dynamic seals and plenty of require lubricating grease. Over time, particularly if the valves are not cycled, the seals stick and the grease hardens, resulting in greater friction that have to be overcome. There have been stories of valve failure as a result of moisture in the instrument media, which thickens the grease.
A direct-acting valve is your finest option wherever possible in low-power environments. Not only is the design less advanced than an indirect-acting piloted valve, but also pilot mechanisms usually have vent ports that can admit moisture and contamination, leading to corrosion and permitting the valve to stay in the open place even when de-energized. Also, direct-acting solenoids are particularly designed to shift the valves with zero minimum strain requirements.
Note that some bigger actuators require high move charges and so a pilot operation is important. In this case, you will want to ascertain that all elements are rated to the identical reliability ranking because the solenoid.
Finally, since most remote areas are by definition harsh environments, a solenoid put in there will need to have robust building and have the ability to withstand and function at excessive temperatures whereas nonetheless sustaining the same reliability and security capabilities required in much less harsh environments.
When choosing a solenoid management valve for a remote operation, it is potential to find a valve that doesn’t compromise efficiency and reliability to reduce power demands. Look for a high FFR, simple dry armature design, nice magnetic and warmth conductivity properties and strong development.
Andrew Barko is the gross sales engineer for the Energy Sector of IMI Precision Engineering, makers of IMI Norgren, IMI Maxseal and IMI Herion model parts for power operations. He provides cross-functional experience in utility engineering and enterprise development to the oil, gas, petrochemical and energy industries and is certified as a pneumatic Specialist by the International Fluid Power Society (IFPS).
Collin Skufca is the key account supervisor for the Energy Sector for IMI Precision Engineering. He provides expertise in new enterprise development and customer relationship administration to the oil, gas, petrochemical and energy industries and is licensed as a pneumatic specialist by the International Fluid Power Society (IFPS).
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