LIGHT LIQUID TRAP

Abstract: In a light liquid trap with an upwardly open container (10) in which a first riser pipe (between 19 and 30) extends upwardly above the upper edge of an overflow pipe (19) communicating downwardly with an outlet (15, 16) through a second riser pipe (14), an air bell (21) is placed at the top of the container with its lower end disposed at a lower level than the overflow edge (20) of the outlet and with its upper part in pressure transfer connection (34, 35) with the upper end of the overflow pipe and the first riser pipe. The air bell accommodates at least one air channel (28) extending a distance down into the bell from the bell top wall (22) where it communicates with the atmosphere. In operation, separated light liquid gathers in the bell, and when the bell collection capacity has been fully utilized, additional supply of light liquid bring its level up to or above the floor height; but the light liquid trap will still have a certain hydraulic capacity, though greatly reduced.

Description: Light liquid trap The invention concerns a light liquid trap of the type stated in the introductory portion of claim 1. In a known light liquid trap of this type, which is shown and de- scribed in the DK Patent Specification 42 587, the air bell is positioned in a special vessel within the con¬ tainer, and the upper edge of this vessel is disposed somewhat higher than the outlet of the container, said vessel collecting separated light liquid, such as e.g. oil and fat. When the light liquid in the vessel reaches above the lower edge of the air bell, it blocks the air in the bell and produces a positive pressure in it which is transferred to the liquid above the upper end of the overflow pipe and the first riser pipe, and when the positive pressure has attained a certain size, it presses the liquid down into these pipes, thus interrupting the connection between these and thereby the entire flow. The special vessel must then be emptied of light liquid before liquid can again flow through the apparatus. The hydraulic capacity of such a light liquid trap, i.e. the amount of liquid that can flow through it per unit of time, depends partly upon the available pressure head at the inlet side, partly upon the pressure loss through the system. In the mentioned known trap, the upper edge of the special vessel in combination with the risk of underflow of light liquid puts narrow limits on the ob tainable pressure head, and this in connection with a relatively great pressure loss means that the apparatus cannot in practice satisfy the requirements normally made of the hydraulic capacity of light liquid traps used in connection with floor outlets. It is also known to use blocking mechanisms with a block¬ ing body whose specific gravity is between the specific gravities of the light and the heavy liquids so that the heavy liquid can lift the blocking body and run out. Nor can these known light liquid traps satisfy the practical requirements of hydraulic capacity, and some of them do not protect the separated light liquid from being flushed out. It is common to these known types of light liquid traps that it cannot be seen whether the collection capacity has been utilized and blocking has taken place, without first having to remove a cover or a grate. If a large amount of water is to be discharged, e.g. from a heating plant or a hot water tank with a view to cleaning or re¬ pair, it must first be ascertained whether blocking has occurred and then it must be ensured that the hydraulic capacity of the outlet installation is not exceeded so that discharge will cause blocking. The object of the invention is to provide a. light liquid trap of the present type which has a sufficiently large hydraulic capacity to satisfy the requirements in prac¬ tice, and which still has so limited dimensions that it lends itself for use in connection with an ordinary floor outle . The light liquid rap of the invention is characterized by being constructed as stated in the characterizing por¬ tion of claim 1. Then, the pressure head of the light liquid trap and thus its hydraulic capacity will be far greater than known in the past, because the light liquid which is collected in the bell is first allowed freely to rise to the lower openings in the channels of the bell - i.e. without any blocking effect taking place - and then to continue the rise past the openings, thus interrupting the bell communication with the atmosphere and gradually producing a blocking effect which, in the shown embodiments, effectively blocks light liquid flow, while heavy liquid can still pass the light liquid trap, but to a reduced degree. Claim 2 defines a feature which makes it easy to lift '■ the air bell with a view to removing separated light liquid or cleaning, and claims 3 and 4 define an expedient structure enabling large flow cross-sections and corre¬ spondingly small pressure losses. The guide baffle defined in claim 5 contributes to pro- ducing a favourable flow course in the container, and this applies in particular when the guide baffle is con¬ structed as stated in claim 6. The conical body defined in claim 7 ensures that liquid flow from the upper end of the first riser pipe to the upper end of the overflow pipe does not entrain air out of the air channel from the air bell by ejector effect. The embodiment defined in claim 8 provides for a con¬ siderably improved separation of light liquid from the discharge liquid. The invention will be explained more fully below with reference to the drawing, in which fig. 1 is a vertical section through an embodiment of the light liquid trap of the invention, fig. 2 is a horizontal section along the line II-II in fig. l, fig. 3 is a vertical section through another embodiment of the light liquid trap of the invention, fig. 4 shows the same, seen from above, and fig. 5 is a horizontal section along the line V-V in fig. 3. In the drawing, the numeral 10 designates an upwardly open container of a square cross-section and with side walls 11 and a bottom 12. One side wall 11 is formed at the bottom with a side outlet 13 terminating in a channel 14 which extends upwardly along the outer side of the container and terminates in an outlet box 15 with an outlet spout 16. A cleaning plug (not shown) may be fitted in the part of the container wall 11 which faces the outlet box 15. Just above the side outlet 13, the container has an inter¬ mediate bottom 17 with a circular central opening 18, above which there is placed an overflow pipe 19 which is secured to the intermediate bottom and whose upper edge is disposed somewhat below the overflow edge 20 of the outlet channel 14. The container 10 upwardly mounts a downwardly open air bell 21 whose top wall 22 is flush with the upper edge of the container. The air bell 21, like the container, has a square cross-section, and its side walls 23 to¬ gether with the container walls form relatively narrow inlet channels 24 for the liquid to the treated. Out- wardly directed, plate-shaped ears 25 forming a grate in the inlet are placed at the upper edge of the bell walls on the outer side thereof. The lower edge of the air bell is disposed at a somewhat lower level than the upper edge of the overflow pipe 19 and is thus immersed in the liquid, and it rests on corner brackets 26 in the con¬ tainer. An annular guide baffle 27 is placed on the con¬ tainer walls 11 immediately below the lower end of the inlet channels 24, the cross-section of said baffle being in the form of an isosceles triangle with an in¬ wardly directed apex. The air bell 21. is formed with two or more vent channels 28 which extend from the top wall 22 down to a level : somewhat above the lowest liquid level, and which commu¬ nicate with the atmosphere just below the top wall through openings 29 in the bell side walls 23. An outer pipe 30 is place d around and co-axially with the overflow pipe 19 and has its lower edge disposed a distance above the intermediate bottom 17, said outer pipe being formed with an outwardly extending flange 31. The outer pipe 30 has at the top a top wall 32 which is disposed a distance above the upper edge of the overflow pipe 19 and has a central opening 33, above which a thinner, top-wall-secured pipe 34 is ' placed, said pipe 34 extending vertically upwards and being secured to the air bell top wall 22 at its upper edge. The pipe 34 is formed with air vents 35 just below this top wall, and the pipe thus forms an air passage connecting the upper part of the bell with the area between the top wall 32 of the outer pipe 30 and the upper end of the overflow pipe 19. A conical body 36 shown in broken lines may be placed in opposite and covering relationship with the opening 33 in the top wall 32 and at a slight dis¬ tance from it, the downwardly facing tip of said body extending somewhat down into the overflow pipe 19. The light liquid trap is shown mounted on an outlet in a floor 37. When pure water is conveyed to the light liquid trap, it passes freely through it until the amount of influx exceeds its hydraulic capacity, and then the liquid rises on the floor until the amount of influx again declines below the hydraulic capacity, and the liquid on the floor disappears. If the discharge water contains light liquid, the part of it that separates most quickly will rise in the bell 21 in which it may stand unaffected by additional supplies without being flushed out. When the influx has ceased, all the light liquid in the last part of the influx which remains out¬ side the outer pipe, will move upwards and be guided into the bell by the guide baffle 27. If the influx is caused by a bucket of light-liquid-containing water being emptied, most of the contents will remain in the light liquid trap because the trap has the required vo¬ lume for this, and the light liquid will be separated almost completely, unless further influx occurs within a short period of the order of one minute. When the light liquid level reaches the lower end of the vent passages 24, these will be closed, and in case of further rise the trapped air will be pressurized, and this pressure propagates through the air vents 35 and the pipe 34 to the liquid level in the overflow pipe 19 and the outer pipe 30. When the dividing face 38 between the light liquid and heavier liquid approaches the lower edge of the air bell, and the hydraulic capa¬ city begins declining, the light liquid collection capa¬ city is fully utilized, and light liquid is then to be emptied. If this is not done and accumulation of light liquid continues, the hydraulic capacity will decline significantly, and the light liquid will gradully rise to a floor height level. However, there will still be a limited hydraulic capacity even if light liquid stands above the floor, e.g. at a height of up to about 20 cm. Thus, fully utilized capacity will be clearly indicated, without removal of covers or grates, and without the trap being blocked beyond the point where water from dripping taps and the like cannot pass. As will be seen the light liquid trap is entirely with¬ out movable parts, and it cannot be put out of operation by instantaneous loads. The liquid level between the outer pipe and the overflow pipe will never get below the upper edge of the overflow pipe so that the heavy liquid will always be discharged. The slot-shaped peri¬ pheral downflow in combination with the guide baffle 27 below the bell results in a uniform distribution with favourable flow conditions below the bell. The same reference numerals are used in figs. 3-5 as in figs. 1 and 2 for similar parts. The structure shown in the first-mentioned figures differs from the one des¬ cribed above essentially only in that a lamella separa¬ tor is inserted in the space between the container walls 11 and the outer pipe 30, said lamella separator being generally designated by 40 and consisting of two co-axial cylindrical pipes 41 and 42, between which a plurality of helicoid-shaped thin plates 43 is placed; these plates 43 extend in spiral shape from a point below and in the vi- cinity of the outlets from the inlet channels 25 to an area somewhat above the lower end of the outer pipe 30. The inner cylindrical pipe 41 limits together with the outer pipe 30 a ring-spaced space 45, through which the light liquid separated in the lamella separator may rise up into the air bell 21. The lamella separator involves a significant improvement in the separation effect. Such a lamella separator is described in the Patent Application No. filed simultaneously with this application. Both the relative dimensions of the various components in the shown and described structures and the technical details may be varied in many ways and for many purposes within the scope of the invention. For example, the outer pipe 30 may optionally extend right up to the top wall 22 of the bell with air passage at the top. The actual container may moreover have a much greater extent than the bell and the riser pipes and e.g. in the form of large oil separators be formed with concrete walls. In that case, most of the separated light liquid is accom¬ modated outside the bell, so the light liquid storage capacity of the light weight trap will be very great.

Claims: P a t C l a i m s 1. A light liquid trap having an overflow pipe (19) placed in an upwardly open container (10), said over¬ flow pipe having its upper end in communication with an area in the vicinity of the bottom of the container (10) through a first riser pipe (between 19 and 30) and its lower end in communication with a second riser pipe (14) leading to an outlet (16), said container accommodating at its top an air bell (21) whose upper part is in pressure connection with the upper end of the overflow pipe (19) and the first riser pipe (between 10 and 30), c h a r a c t e r i z e d in that the lower edge of the air bell is disposed at a lower level than the outlet overflow edge (20), and that the air bell (21) has one or more air channels (28) which are adapted to connect the interior of the bell (21) with the atmosphere through channel openings disposed at a higher level than the out¬ let overflow edge (20). 2. A light liquid trap according to claim 1, c h a - r a c t e r i z e d in that the lower edge of the air bell (21) rests on support bosses (26) on the inner side of the container wall or walls (11). 3. A light liquid trap according to claim 1 or 2, c h a r a c t e r i z e d in that the overflow pipe (19) is placed in the centre of the container (10) and is surrounded by an outer pipe (30), whose lower end is disposed a distance above the inlet to the overflow pipe (19) and forms together with said pipe the first riser pipe (between 19 and 30). 4. A light liquid trap according to claim 1, 2 or 3, c h a r a c t e r i z e d in that the upper end of the outer pipe (30) which is d sposed a distance above the upper edge of the overflow pipe (19), is connected with and secured to the lower end of a thinner, substantially vertical pipe (34) through a top wall, the upper end of said pipe (34) being secured to the air bell. 5. A light liquid trap according to any of the preced¬ ing claims, c h a r a c t e r i z e d in that an annular guide baffle (27) is placed on the inner side of the container wall or walls (11) below the space be- tween the said wall or walls and the air bell (21). 6. A light liquid trap according to claim 5,.c h a - r a c t e r i z e d in that the guide baffle (27) in cross-section has the shape of an isosceles triangle with the apex facing inwardly. 7. A light liquid trap according to claim 4, 5 or 6, c h a r a c t e r i z e d in that a conical body (36) with a downwardly facing tip is placed on the underside of and at a small distance from the top wall of the outer pipe and opposite the vertical pipe secured thereto. 8. A light liquid trap according to any of claims 3-7, c h a r a c t e r i z e d in that a lamella separator (10) having spiral-shaped fluid channels is placed be¬ low the air bell (21) in the space between the container wall or walls (11) and the outer pipe (30).

Inventors: JOHANNESSEN JOERGEN MOSBAEK, JOHANNESSEN, JOERGEN, MOSBAEK
Applicants: JOHANNESSEN JOERGEN MOSBAEK, JOERGEN MOSBAEK JOHANNESSEN APS
Application year: 1986
Main classification: E03F5
IPC codes: B01D17, E03F5