Patent Application
20130340857
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1. Field of the Invention
The present disclosure relates to protection devices for a valve element, in particular an enclosure or housing for protecting a valve positioner or position indicator in a demanding operating environment.
2. Description of Related Art
Valve positioners and position indicators are often used in control valve applications to control the open/closed position of a valve in response to an input signal. The valve positioner automatically adjusts its output to the actuator to maintain the desired position in proportion to the input signal. Valve positioners are usually mechanically connected to the valve stem or actuator and typically are available in three configurations: pneumatic positioners, analog I/P and digital controller.
Positioners allow for precise positioning accuracy and faster response to process upsets. With the increasing emphasis in the industry on economic performance of process control, positioners are usually considered for every valve application where process optimization is important. Thus, a properly functioning valve positioner is a vital element for ensuring cost-effective process operation and stability.
A common problem faced in the industry is corrosion of the positioner, gauges and the fasteners as a result of operating in very demanding environments, e.g. outdoors in weather, extreme temperature and/or corrosive environments. In these environments, especially in atmospheres containing corrosive substances such as salts and chemicals (e.g. caustic), positioners often become damaged, which can lead to diminished positioner performance, maintenance/repair and complete failure. This is often time consuming and expensive.
One solution that has been proposed is constructing positioners from corrosion resistant materials such as stainless steel. However, although the corrosion resistant materials provide an added measure of protection in demanding operating environments, the valve positioner and its ports can still become damaged over time requiring the positioner to be completely removed from service for repair or replacement.
Accordingly, in light of the foregoing, a need exists for an improved and more robust protection device capable of protecting a valve positioner in demanding environmental and operating conditions while also allowing for maintenance and inspection of the positioner without removing it from service.
An object of this invention is to provide an improved and more robust protection device capable of protecting a valve positioner in demanding environmental and operating conditions. Another object of this invention is to provide a protection device that allows for maintenance and inspection of a valve positioner without removing the positioner from service. Additional objects and advantages of this invention shall become apparent in the ensuing descriptions of the invention.
Accordingly, an improved and more robust protection device and method of using a protection device with a valve positioner are provided that are capable of protecting a valve positioner in demanding environmental and operating conditions while also allowing for maintenance and inspection of the positioner without removing it from service. The protection device includes a housing configured to protect the valve positioner from external corrosion. The housing includes a top base, a bottom base and a central body extending between the top base and the bottom base. The central body may be joined to an edge of the top base and an edge of the bottom base thereby forming a perimeter circumscribing the top base and the bottom base. The housing is preferably configured is configured to allow the atmosphere inside the housing to be purged and replaced. In an embodiment, the housing may also be at least partially constructed from a substantially transparent thermoplastic material to allow for inspection of the valve positioner without removing the housing.
The foregoing brief summary of the invention presents a simplified summary of the claimed subject matter in order to provide a basic understanding of some aspects of the claimed subject matter. This summary is not an extensive overview of the claimed subject matter. It is intended to neither identify key or critical elements of the claimed subject matter nor delineate the scope of the claimed subject matter. Its sole purpose is to present some concepts of the claimed subject matter in a simplified form as a prelude to the more detailed description that is presented below.
Additionally, the foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be understood. Additional features and advantages of the invention will be described hereinafter, which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features, which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.
The accompanying drawings illustrate various embodiments of this invention. However, it is to be understood that these embodiments are not intended to be exhaustive, nor limiting of the invention. These embodiments are but examples of some of the forms in which the invention may be practiced.
The claimed subject matter is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. An embodiment of a protection device for a valve positioner in accordance with this invention is shown generally in
With reference initially to
The housing is also configured to provide enough clearance to allow one or more component connections (160) to be made to the valve positioner (120). As one of ordinary skill in the art appreciates, the configuration of the housing and the number of sides of the central body (150) will depend on the configuration and clearance requirements of the valve positioner (120) as well as other considerations such as valve accessibility. The housing also includes one or more apertures or ports (141) configured to allow the components (160) to be connected to the valve positioner (120). The interface between the port (141) and component connection (160) is preferably sealed to prevent external corrosion. Examples of components include, but are not limited to, gauges, tubing, pneumatic connections, electrical connections, data cables, and so forth.
The housing is constructed from a material configured to protect the valve positioner (120) from the effects of external corrosion. The housing can be manufactured from any corrosion resistant plastic or metal sheet. An example of a suitable plastic material includes, but is not limited to, a thermoplastic material such as rigid polyvinyl chloride material. The housing may also be at least partially constructed from a substantially transparent thermoplastic material to allow for inspection of the valve positioner without removing the housing. Examples of substantially transparent thermoplastic materials include polycarbonate resin thermoplastic materials such as poly(methyl methacrylate) (PMMA), polycarbonate resin, and so forth. The housing may be formed by any conventional molding method such as injection molding, compression molding, and so forth. Alternatively, the housing may be machined.
The protection device (100) is not only configured to protect the valve positioner (120) from the effects of external corrosion, but it is also configured to allow the atmosphere inside the housing (170) to be purged and replaced as desired. In a preferred embodiment, the atmosphere inside the housing (170) is replaced and purged using the plant air that is emitted from the valve positioner (120) as a result of the actuation of the valve. The plant air pushes the atmosphere inside the housing (170) through one or more apertures or vents provided to the housing thereby replacing it with fresh plant air, which prevents the buildup of any corrosion causing elements within the atmosphere inside the protection device (100). The one or more apertures or vents are sized to prevent the housing from over-pressurizing. In a preferred embodiment, bottom base (140) has one or more apertures or vents drilled in it.
In one preferred embodiment as shown in
Alternatively, the central body (150) may be secured to the bottom base (140) and/or top base (150) by a bonding agent such as glue configured to secure thermoplastic materials to one another. The bottom base (140) and central body (150) are preferably constructed from rigid polyvinyl chloride material, and the top base (130) is constructed from a substantially transparent thermoplastic material. However, as one of ordinary skill in the art appreciates, depending on the accessibility of the valve positioner (120) for inspection, other portions of the housing (e.g. the bottom base and/or central body) may be partially or entirely constructed from a substantially transparent thermoplastic material such as poly(methyl methacrylate) (PMMA), polycarbonate resin, and so forth.
In another preferred embodiment as shown in
As discussed above, the housing may be constructed from a material configured to protect the valve positioner (120) from the effects of external corrosion. The support members (155) may be also constructed from a similar material, e.g. a thermoplastic such as rigid polyvinyl chloride. The housing may also be at least partially constructed from a substantially transparent thermoplastic material to allow for inspection of the valve positioner (120) without removing the housing. Examples of substantially transparent thermoplastic materials include polycarbonate resin thermoplastic materials such as poly(methyl methacrylate) (PMMA), polycarbonate resin, and so forth.
In operation, the protection device (100) as described above is secured in position around a valve (110) with a valve positioner (120). The protection device (100) may be secured to the valve (110), preferably secured to the valve actuator (111) or yoke. In a preferred embodiment, the bottom base (140) is secured to the valve positioner (120). Any components (e.g. pneumatic air connection, data cable, etc.) that need to be connected to the valve positioner are routed through one or more apertures or ports (141) that are configured to allow the components (160) to be connected to the valve positioner (120). The central body (150) is then releasably secured to the bottom base (140). The top base (150) is also secured to the central body (150). The top base (150), bottom base (140) and central body (150) define a hollow enclosure when secured to each other.
The atmosphere inside the housing (170) is replaced and purged using the plant air that is emitted from the valve positioner (120) as a result of the actuation of the valve. The plant air pushes the atmosphere inside the housing (170) through one or more vents provided to the housing thereby replacing it with fresh plant air. This prevents the buildup of any corrosion causing elements within the atmosphere inside the protection device (100). As discussed above, the housing may also be at least partially constructed from a substantially transparent thermoplastic material to allow for inspection of the valve positioner (120) without removing the protection device (100) surrounding the valve positioner (120). In addition, in the event the valve positioner (120) or valve (110) requires maintenance, the central body (150) and top base (130), i.e. the top portion of the protection device, may be removed from the bottom base (140) by removing any connection means that secure these elements together. Since the central body (150) is removably connected to the bottom base (140), the central body and top base (130) may be removed without removing the bottom base (140), which allows for faster and easier access to the valve positioner (120) by maintenance personnel.
Any reference to patents, documents and other writings contained herein shall not be construed as an admission as to their status with respect to being or not being prior art. Although the present invention and its advantages have been described in detail, it is understood that the array of features and embodiments taught herein may be combined and rearranged in a large number of additional combinations not directly disclosed, as will be apparent to one having ordinary skill in the art.
Moreover, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the following claims. There are, of course, other alternate embodiments, which are obvious from the foregoing descriptions of the invention, which are intended to be included within the scope of the invention, as defined by the following claims.
