STRAINER DEVICE

The strainer as element of water installations, used for removing of impurities in water and non-corrosive liquids industrial systems is the subject matter of the invention.

Net strainers for removing impurities, consisting of a conduit having flanges at the first and at the second end, which can be mounted as part of pipeline or installations, having covers attached from below by the use of bolts, are already known. The strainer is a pipe, equipped inside with a serial cylindrical sieve, positioned at an angle of 50 degrees downward with respect to the flow direction. The overflow chamber, where the strainer is mounted, has usually a smaller diameter than the supplying pipeline, and the diameter of the sieve itself is smaller or approximately equal to the diameter of the overflow chamber. The symmetry axis of the filter coincides with the axis of overflow chamber. As result of such solution the cover of overflow chamber is situated also along the axis of this filter. The inlet gaskets of overflow chamber at the inlet side as well as the cover gasket are situated along one axis line and are pressed simultaneously together when the cover is mounted by the use of bolts, which are parallel to the axis of the chamber. The filter is assembled by putting the filter down to the overflow chamber, the opening of which can be seen under the strainer and is directed downward at an angle of 50 degrees. The assembly of gaskets, of the filter itself and of covers requires a certain protection of the space below strainer and does not guarantee a visual contact with mounted elements, causing defects during exchange

procedures. Usually some leaks of the liquid can appear; the device must be repaired of course.

The substance of the invention is that the flow chamber has a rectangular side opening, covered with cover which is fastened from outside by the use of stud-bolts and nuts. There are projections inside the chamber, situated on two opposite walls. There are gaskets with cylindrical filter on flat surfaces between projections. The slope angle of the cut off wedge of the gasket takes values between 0.5 and 1.5 degrees. On the contrary, the flat surfaces inside chamber diverge in the direction from the rear wall of chamber towards side opening, with respect to the transversal symmetry axis of chamber, at angles between 1 and 3 degrees. The ring gasket has inside a circular hollow for the cylindrical filter and outside its surfaces are slantwise cut off. The cross section of the ring gasket looks thus like a wedge, which is cut off from one side, where its thickness is minimal, and has a resisting element from the other side where its thickness is maximal.

There are two possible variants of the device. According to the first one the ring gasket has a side hollow on the external side, where an elastic ring is placed. Another variant means that the ring gasket, which is situated on the external side, has circular elastic projections on its side.

The shape of the flow chamber and of the ring gaskets results in a very compact form of the strainer. Its length was minimised and thus it needs less place as part of the pipeline. Furthermore, the inlet and outlet ends are situated along one axis and the cylindrical filter diameter is larger than the

nominal internal pipe diameter. The filter diameter equals approximately its height. The active surface of the sieve was thus increased, the whirling of liquid reduced and consequently such parameters as flow resistance coefficient and flow coefficient were improved. Thanks to the invention some advantages during exploitation of the device were achieved. An exchange of filter requires only free access to the side cover. The flow chamber is then directly accessible and can be visually checked. The interior of overflow chamber, cylindrical filter, ring gaskets, elastic rings, circular projections and cover gaskets can be easily seen.

An example of the device, according to the invention, is shown in:

Figure 1 where a side view of the strainer is presented;

Figure 2 a longitudinal section of the strainer can be seen;

Figure 3 a transverse section of the flow chamber with partial view of the outlet;

Figure 4 a longitudinal section of flow chamber with partial view of the inlet;

Figure 5 a section of the filter together with ring gaskets having projections; Figure 6 a section of the filter together with ring gaskets and an elastic ring;

Figure 7 a side view of the filter, with ring gaskets having projections.

The strainer can be made as founded conduit having a first end 1 with flange 2, connected from the other side, through flow chamber 3, with the

second end 4, having flange 5. The flow chamber 3 has a rectangular side opening 6, covered by cover 7, attached to the conduit by the use of stud-bolts 8 and nuts 9. Inside overflow chamber 3 the following elements are mounted: cylindrical filter 10 fitted by ring gaskets 11, which have been put to inside through rectangular side opening 6 and pressed together on the convergent flat surfaces of walls 12 and 15 and on surfaces of projections 13 or of elastic rings 14 from the outside of ring gaskets 11, through cover 7, after having screwed on the nuts 9 on stud-bolts 8.

The inside of chamber 3 has projections 16 at wall 12 with opening, close to the first end 1, as well as on the opposite wall 15, which fix the position of ring gaskets 11, together with cylindrical filter 10. On the contrary, walls 12 and 15, between projections 16, have flat surfaces which diverge from the rear wall 17 up to edge 18 of side opening 6, each deviating at angle between 1 and 3 degrees with respect to transversal symmetry axis 19 of flow chamber 3.

The cylindrical filter 10 is fixed on both ends by ring gasket 11, from inside in circular hollows 20; from outside it has slant-wise shaped surfaces, which are cut off in such way that the ring gasket 11 is in the form of a cut off wedge, from one side it has the minimal thickness, from the other side is ended by a resistant element 21, and is the thickest. The slope angle of the wedge formed ring gasket 11 takes values between 0.5 and 1.5 degrees. According to one possible solution the ring gasket 11 on the outer side has an additional side-channel where an elastic ring 14 is fitted. According to another solution the ring gasket 11 has elastic circular projections 13 on its outer surface.

The strainer body 10 is the element which eliminates impurities. It is made of metal net 22 having meshes depending on requirements concerning separation of impurities and sediments. There is a drain plug 23 at the lowest point of flow chamber 3, for removing impurities. Nets having very small meshes which are made of a very thin wire are usually placed inside a metallic basket being in the form of cylinder with rectangular holes enabling flow of liquid.

There can be several blinded openings 24 in the upper part of flow chamber 3, in order to enable transducers, which are used for liquid parameter measurements, to be mounted.

The invention eliminates many inconveniences during assembly and exchange procedures, because of the fact, that cover 7 as well as the ring gasket are positioned by grooves and bolts, what means a simple assembly and a safe and tight connection of the cover. Thanks to ring gasket 11 , the cross-section of which is of a cut off wedge form, and thanks to pressing down the filter 10 by cover 7 a tight connection of gaskets 14 and 16 and of projections 13 with surfaces inside chamber 3 is achieved.

Thanks to making the most of flow through ability the flow resistance was reduced, the coefficient K _v increased, and thanks to the slope angle of 45 degrees the active sieve surface was also increased.

The use of gaskets having circular cross-section, integrated with cover, reduces the possibility of gaskets being damaged and makes easier the cover assembly (the gasket is fitted and does not slip out). Thanks to the circular shape of gasket a safe adhesion of the whole surface was achieved. The shape of the strainer simplifies all supervision procedures because the filter is

mounted and removed from one side of the chamber, perpendicularly to the liquid flow axis. The conduit diameter is fully occupied by the stream of liquid. The cover 7, covering the chamber, has a gasket 25 which is placed in a circular groove, ensuring the installation to be tight even at high pressures.