Page 30

NORA Oilheat Technicians Manual

one of two categories: spin-on filters and cartridge type filters. The spin on filter is similar to the oil filter on your car. The filter container, or can, and filter element (resin-coated filter paper with large surface area folded into a filter housing) are all one piece. The cartridge type has a replaceable filter element cartridge that you place into a filter can that attaches to the filter head. See Figure 2-2. Filter elements are made from a variety of materials, including: wool felt, wound yarn, sintered plastic in a continuous microspun fiber, resin-coated paper, and stainless steel mesh. Filters are sized by flow rate gallons per hour (GPH) and pressure drop (inches mercury Hg). Each filter also has a micron, or mesh rating. These ratings represent the amount of pressure drop or filtration capability. The rating means the filter will remove 95% of the particles of that size or larger. A lower micron/mesh rating indicates a tighter filter construction, able to remove finer particles. Filter elements made from sintered plastics with pore sizes in the range 30-75 microns and large surface area or spin on filters with resin-coated paper in the 10 micron range seem to work best. Most fuel units contain a 100 micron mesh strainer. Nozzles also have a mesh or sintered bronze filter nominally rated for filtration to 40 microns. The tangential metering slots— the things that get plugged up in the nozzle—are typically 60 to 90 microns. Grease or dirt on your fingers can plug the nozzle, so they must be carefully handled. Felt and wound yarn filters may shed fine fibers that may clog low firing rate nozzles. See Figure 2-3. To be fully effective, a modern filter must stop particles from reaching the Chapter 2 Heating Oil Figure 2-2: Filters: Cartridge type and spin-on to the magnet, then it is probably bacterial contamination. Other indicators of these microorganisms are a matty, lumpy, or stringy consistency and a rank moldy odor. Water detection paste Water detection pastes determine the depth of water at the bottom of the storage tank. Apply the paste in a thin coating on a gauge stick from zero up to a couple inches above the suspected oil water interface. Carefully lower the stick into the tank until it lightly touches bottom. Hold it in this position for 30 seconds to a minute. Remove the stick— the water level will be clearly indicated by a definite color change where water contacts the paste. Water paste will not detect an oil-water emulsion. You should check customers’ tanks for water once a year, and then drain off the water if detected. Oil filtration The installation of filters in burner fuel suction lines is strongly recommended. Filters protect the pump and nozzle by trapping contaminants before they reach these components. There are passages in the oilburner nozzle that are smaller than the diameter of a human hair. It takes very little contamination to plug up these passages in the nozzle. This is why it is critical to do everything to be sure clean oil is delivered to the burner. There are a wide variety of filters available, but they all fall into Replaceable Element Spin-on Cartridge 2-10 Heating Oil and Its Properties


NORA Oilheat Technicians Manual
To see the actual publication please follow the link above