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Pall Manifold Assemblies | |
- Introduction to Filter Manifolds
- Benefits of Filter Manifolds
- Filter Manifolds - Commonly Integrated Subcomponents
A filter manifold incorporates many of the individual components that protect and operate a complex fluid system. A single manifold module typically contains complete filter assemblies, as well as many other components, such as flow control valves, check valves, system relief valves, bypass valves, differential pressure indicators, and temperature and pressure sensors. All of these items contribute to the flawless operation of an aircraft fluid system.
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The typical fluid system consists of a large number of components connected by tubing, along with the necessary pipe fittings and couplings. With all the components in a single module, many fluid connections and interconnections are contained within the housing. This reduces the number of connection points and the amount of tubing required by as much as 80%. This means there are fewer possible leak points, increasing the overall reliability of the fluid system.
Because it's a self-contained unit, the manifold is easier to maintain than each of the separate components it replaces. For example, all the differential pressure indicators can be inspected together and the filter elements can be quickly and easily changed at the same time, because they are located together. In addition, there are fewer connection points and fluid lines, reducing the number of maintenance tasks and the possibility for errors. The filter bowl can even be designed with a locking mechanism to eliminate the need for lock-wiring and its associated maintenance burden.
A filter manifold reduces the amount of time required for maintenance, engineering and inspection, so it provides lower costs of ownership. In addition, the fewer number of connectors and reduced tubing help to lower the actual hardware costs of the fluid system.
By incorporating numerous individual components within a single unit, manifolds eliminate the need for separate brackets and housings. Also, fewer fluid lines are needed, and those that remain are able to share tubing walls, instead of requiring individual, fully dedicated pipes. Together these reductions can amount to a weight savings of over 13kg for a typical large aircraft hydraulic installation.
Every Pall manifold is designed so that its components cannot be installed or replaced incorrectly, eliminating costly and time-consuming rework after maintenance. For an added layer of safety, manifolds can be designed so that during maintenance it is impossible to replace the filter bowl until after a replacement filter has been installed.
A filter manifold eliminates the need for several suppliers, since all the separate components are supplied by Pall and integrated into a single package. By using Pall as your single accountable source, controlling the entire manufacturing, assembly and verification test process, you're assured more consistent quality and a more reliable system.
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Filter Element
Filter elements are used to protect the pressure, return and case drain fluid system components from particulate contamination. All the latest aircraft applications utilize non-cleanable, disposable elements that are manufactured using Pall's proprietary "Ultipor®" media.
The filter bowl serves as a pressure vessel which provides easy access for filter element servicing without the need to remove system plumbing.
The DPI/DPS provides a warning that the filter element is becoming loaded and requires replacement. It does this by continually sensing the differential pressure across the filter element and providing a visual or electrical signal when the differential pressure exceeds a specified value.
If the element is not replaced upon DPI/DPS indication, the bypass valve will activate, re-routing the fluid directly through the filter head. This ensures system flow is maintained and all the contaminant collected by the filter element remains on the upstream side, instead of being washed downstream.
The check valve is located in the manifold head and controls the fluid flow direction, to ensure that there is no flow through the filter manifold in the reverse direction.
These devices are located in the manifold head bowl cavity, and prevent the loss of system fluid and air inclusion during replacement of the filter element.
This component controls the maximum system pressure. When pressure exceeds a specified limit, for example when a pump control mechanism fails, the relief valve actuates and reroutes excess fluids from the pressurized lines to the return line.
These sophisticated, fast-acting valves control the flow of the fluid system. In the most demanding systems, such as military fighter aircraft, these valves can respond within 15 milliseconds to regulate fluid flow. The action of these valves also provides system redundancy as well as valuable diagnostic and monitoring information to pilots and ground crews.
This allows fluid samples to be taken under conditions of full system pressure. Samples can then be analyzed to monitor the system's cleanliness.
The filter bowl can be attached to the manifold head using a ratchet mechanism. This eliminates the need for lock-wiring, enhancing safety of flight. The ratchet lever is spring-loaded, and engages the serration's machined into the collar of the filter bowl. The lever must be depressed to remove the filter bowl.
The addition of this element to the manifold puts all plumbing connections at the base module. Quick disconnects are used between the base and manifold to connect all flow paths. This configuration facilitates infield manifold replacement, eliminating the need to remove any system plumbing while also preventing system fluid loss and air inclusion.
Pall has supplied filter manifolds for over 20 years. Applications include:
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