Chemical Processing - September 2007 - (Page 52)

overlooked: the filter vessel should properly fit the existing pipe. Generally, the filter should be sized to match the pipe to which it will be installed. Unless there’s some limiting factor — such as available installation space, low flow rate or an operating pressure exceeding 3,000 psig — the filter shouldn’t be installed with connections that are smaller than the existing pipe. If the pipe is 2 in., install a filter with connections that are at least 2 in.. This simple practice will eliminate excessive pressure drop. 7. Fluid physical characteristics. A Material Safety Data Sheet (MSDS) provides important precautions for the handling and use of the fluid, but a Fluid Product Data Sheet (FPDS) offers the most useful information for specifying filtration systems. So, be sure to have this information available when contacting a filtration supplier. The FPDS gives greater detail about the fluid’s physical characteristics, including viscosity, specific gravity, materials compatibility and recommended applications. The fluid manufacturer may be able to supplement the FPDS with specific recommendations about filtration. 8. Temperature. Provide the filter supplier with a realistic estimate of the fluid’s operating temperature. Consider the operating temperature range that you expect 99% of the time, adding ±10°F for safety. Unrealistically broad ranges will undoubtedly drive up system costs and may compromise performance. Temperature can affect many design decisions, including the specifications for seal material, adhesives and filtration media. Outdoor applications can present additional challenges. In cold climates insulation, heat tracing and circulation heaters can help to mitigate the effects of lower temperatures. Tropical and high humidity environments can take a toll on system components such as motors and instrumentation. Ensure that the motors are rated for high temperature conditions. Controls can be cooled and protected with a simple fan inside the control panel. >> Turbine oil filtration system Figure 2. This unit provides particulate removal to 3 micron and water removal to less than 100 ppm while handling flows from 1 to 135 gal/min. Unrealistically broad temperature ranges will drive up system costs and may compromise performance. 9. Space for installation. This is one of the most commonly overlooked aspects of a specification. Give the filtration supplier dimensional data detailing space limitations at the installation location. Consider the headspace above the filter necessary to allow easy removal. In some cases, it may make sense to opt for a horizontal filter instead of a vertical one or to put the filter at another location in the process line that provides 52 • September 2007 more space. In addition, consider filter inspection and changing responsibilities. The operators must have an adequate work staging area as well as a place, such as a 55-gal. drum, for used filter disposal. An adequately sized work area will encourage good work practices, including frequent and safely performed filter changes. 10. Filter-element filtration rating. Such ratings can be confusing because the system for rating a process filter differs from that for an oil filter. An “absolute” rating from a process filter supplier may differ from an efficiency rating supplied by a hydraulic or lube oil supplier. It’s common to confuse a micron rating with an efficiency rating when they are two distinct specifications. For example, a filter may have the capability to block particulates of 10 microns or larger but may effectively block only 50% of those particulates. Therefore, the filter should be specified to match the desired purity of the stream. In critical applications, use a filter that can provide at least a 95% efficiency rating, preferably 99%. In general applications, a 50% rating suffices. The minimum efficiency target for turbine oil or hydraulic oil filtration should be 99.5%. In oil applications, choose an element that has been tested per ISO 16889 (Multi-Pass Filter Element Test). This test evaluates filter element efficiency and dirtholding capacity and determines the micron size rating of the element at a given efficiency. To have a practical meaning, efficiency should always be combined with the micron rating. Any reputable filter manufacturer can easily give this information, so ask if the filter element is rated and tested per ISO 16889. If it isn’t, then the micron rating of the element may be questionable. www.chemicalprocessing.com http://www.chemicalprocessing.com

Table of Contents Feed for the Digital Edition of Chemical Processing - September 2007

Contents From the Editor Field Notes In Process Energy Saver Compliance Advisor Succeed at Simulation Rethink Your Approach to Process Safety Avoid Blending Blunders Get the Right Cartridge or Bag Filter Wireless Proponents Take HART Membrane Boasts Material Benefits Process Puzzler Plant InSites Chem Show Product Preview ISA Product Preview Equipment & Services Product Spotlight/Classifieds Ad Index End Point

Chemical Processing - September 2007

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