AN ULTRASONIC APPARATUS FOR MEASURING PRODUCT LEVEL IN TANKS OR SIMILAR STOREROOMS

Abstract: In an ultrasonic apparatus for measuring product level in tanks for liquid or powdered products, in particular on board vessels, an ultrasonic sensor (1) designed as a transmitter/receiver device to be positionable in an opening (3) in an end wall (4) of a tubular apparatus housing (5) facing the tank comprises a top flange (6) disposed against the external surface of the end wall (4) and secured against said end wall (4) by a superposed meter housing (8) which hermetically encapsulates an electronic unit (7) connected to the sensor (1). A bottom plate (9) of the meter housing (8) comprises, on the one hand, a flange portion (14) to secure the meter housing (8) to the end wall (4) with the top flange (6) of the sensor chamber (2) interlocked therebetween. To avoid disturbing secondary oscillations which would otherwise distort the measuring results oscillation damping gasket members (15 to 19) are inserted between the end wall (4) and the flange portion (14) of the meter housing (8) as well as between the top flange (6) of the sensor chamber (2), on the one hand, and the end wall (4) and the bottom plate (9) of the meter housing (8), respectively, on the other hand. To obtain an improved reflection by measuring under heeling a reflector (24) is secured to the internal surface of the end wall (4), said reflector having a conical reflecting surface (25) facing the sensor chamber (2).

Description: An ultrasonic Apparatus for Measuring Product Level in Tanks or Similar Storerooms. This invention relates to an ultrasonic appara¬ tus for measuring the level of liquid or powdered pro¬ ducts in tanks or similar closed storerooms, in parti¬ cular on board vessels, comprising an ultrasonic sensor in the form of a transmitter/receiver device mounted in a sensor chamber at or close to the ceiling of the tank or room and an electronic unit connected with the sensor and separated from the product in the tank, said unit comprising means for generating and supplying electric energy to the sensor and means for processing measuring signals derived from the sensor. With such an apparatus a contact-less measure¬ ment, possibly a remote measurement of the product level and, thereby, of the filling degree and the stored pro- duct quantity in a tank or a similar storeroom may be performed. From US-A- 3,834,233 an apparatus of the kind mentioned is known, wherein the ultrasonic transducer is mounted at the top of a downwardly open tube which on the one hand projects down into the product contained in the tank and on the other hand projects comparatively high above the tank, thus requiring a bulky super¬ structure. As a consequence, the apparatus is only suit¬ able for measuring on liquid products. Without being restricted thereto the invention particularly aims at providing an ultrasonic measuring apparatus which in addition to fulfilling the safety- requirements prescribed for measuring in tanks con¬ taining explosive products, e.g. oil products, by shielding the electrical equipment against any direct contact with the product also makes it possible to undertake reliable measurements of powdered as well as liquid products independently of the filling degree of the tank, i.e. even at a product level comparatively close to the ultrasonic sensor. Particularly, this requires that the ultrasonic radiation reflected against the sensor is distorted to a minimum by disturbing secondary oscillations. In order to accomplish this, an ultrasonic apparatus of the kind mentioned is characterized accord¬ ing to the invention in that in order to be positionable in an opening in a supporting wall facing the interior of the tank or room the sensor chamber is provided with a protruding top flange to be disposed against the external surface of said supporting wall around the opening, that the electronic unit is encapsulated in a separate, closed meter housing having a bottom plate with a passage for electrical connecting members to and from the ultrasonic sensor, said bottom plate having in its underside a recess adapted to receive said top flange and a flange portion outside the recess for securing the meter housing to said supporting surface with the top flange of the sensor chamber introduced between said bottom plate and said supporting wall, and that oscillation damping gasket members are inserted between the flange portion of the meter housing and the supporting wall as well as between the top flange of the sensor chamber on the one hand and the supporting wall and the bottom plate, respectively, on the other hand. With this design of the sensor chamber and the meter housing and positioning of these parts in close mutual connection with intermediate gasket members the risk of disturbing secondary oscillations is substan¬ tially removed, even with an explosion safe encap¬ sulation of the electronic unit in a meter housing hav¬ ing metallic walls. Thereby, reliable level measurements are made possible even at filling levels so close to the ultrasonic sensor that the reflected ultrasonic radiation would otherwise be strongly distorted by secondary oscillations produced by the metallic parts, Even though the apparatus according to the invention owing to the oscillation damping gasket mem¬ bers may actually be mounted in an opening directly in the ceiling of the tank or room, which will th^n by itself serve as a supporting wall, it is preferred that the supporting wall is constituted by one end wall in a substantially tubular apparatus housing which is open at its opposite end to be positionable opposite an opening in the ceiling of the tank or room. Thereby, a further improved possibility of a reliable measurement at a high filling degree up till complete filling is obtained on the one hand, and, on the other hand, when using the apparatus for measuring in tanks located directly below deck on board vessels such an apparatus housing extending above the tank makes it possible to read the tank contents directly at the apparatus, as the meter housing for that purpose may be provided with an indica¬ tor device visible from the outside, for instance a digital display. When used on board vessels a further improved possibility of measuring high filling degrees under all conditions may be obtained in that a reflector for reflecting ultrasonic radiation reflected from the interior of the tank or room against the. sensor chamber is secured to the surface of the supporting wall facing the interior of the tank or room. Such a reflector makes the apparatus largely independent of changes of the direction of the reflected ultrasonic radiation caused by a greater or smaller heeling of the vessel. In the following the invention will be more fully explained with reference to the schematical drawing showing a sectional view of an embodiment of an r> U _.\._ . O PI ' ..- ultrasonic measuring apparatus according to the invention. An ultrasonic sensor 1 formed as a transmit¬ ter/receiver device and comprising, for instance, one or more piezo-electrical crystals, is mounted in a sensor chamber 2, which for the purpose of damping disturbing oscillations may be filled with a filling material, e.g. silicone, in a manner known per se. The sensor chamber 2 is arranged in an opening 3 in a supporting wall which in the shown embodiment is constituted by an end wall 4 of a tubular apparatus housing 5. At the opposite end, the apparatus housing 5 is open and adapted to be positioned opposite an opening in the ceiling of a tank not shown which may for inst- ance be located on board a vessel. To be secured to the supporting wall 4 the sensor chamber 2 is provided with a protruding top flange 6 but is otherwise upwardly open. An electronic unit 7 electrically connected to the sensor 1 is hermetically encapsulated in a meter housing 8 having a bottom plate 9, wherein a passage 10 is provided for elektrical connecting members 12 to and from the sensor 1. At its underside the bottom plate 9 of the meter housing 8 is formed with a recess 13 to receive the top flange 6 of the sensor chamber 2, and outside the recess 13 it has a flange portion 14 to secure the meter housing 8 to the end wall 4 of the apparatus housing 5. Between the end wall 4 and the flange portion 14 of the meter housing 8 as well as between the top flange 6 of the sensor chamber 2 on the one hand and the end wall 4 and the bottom plate 9, respectively, on the other hand oscillation damping gasket members are pro- vided in order to avoid disturbing secondary oscilla- * • " tions of the metallic walls in the meter housing 8 and the apparatus housing 5. Thus, in the illustrated embodiment a flat annular gasket washer is mounted between the end wall 4 and the flange portion 9 of the meter housing 8. The gasket members between the top flange 6 of the sensor chamber 2 on the one hand and the end wall 4 and the recess 13 in the underside of the bottom plate 9, respectively, on the other hand are constituted in the illustrated embodiment by O-rings 16 to 19 inserted in circular recesses or grooves 20 to 23 in both sides of the top flange 6 and the surface thereof. To improve the reception by means of sensor 1 of ultrasonic radiation reflected from the interior of the tank or storeroom, not shown, through the tubular apparatus housing 5 an annular reflector 24 having a reflection surface 25 facing the sensor chamber 2 is secured to the underside of the end wall 4 around the sensor chamber 2, said reflection surface being consti- tuted in the illustrated embodiment by a conical surface co-axial to the sensor chamber 2 and having an inclina¬ tion of 45o in relation to the longitudinal axis of the apparatus. By means of said reflector reflected ultraso¬ nic radiation not directed directly towards the sensor chamber 2 will be reflected to a greater extent there- against so as to obtain a certain compensation for an inclined position of the axis of the apparatus in rela¬ tion to vertical. As a consequence, reliable measure¬ ments in tanks on board vessels can be made even under heeling of the vessel. OMPI. " rO

Claims: PATENT CLAIMS 1. An ultrasonic apparatus for measuring the level of liquid or powdered products in tanks or similar closed storerooms, in particular on board vessels, com- prising an ultrasonic sensor (1) in the form of a trans¬ mitter/receiver device mounted in a sensor chamber (2) at or close to the ceiling of the tank or room and an electronic unit (7) connected with the sensor (1) and separated from the product in the tank, said unit comprising means for generating and supplying electric energy to the sensor (1) and means for processing measuring signals derived from the sensor (1), charac¬ terized in that in order to be positionable in an opening (3) in a supporting wall (4) facing the interior of the tank or room the sensor chamber (2) is provided with a protruding top flange (6) to be disposed against the external surface of said supporting wall (4) around the opening (3), that the electronic unit" (7) is encap¬ sulated in a separate, closed meter housing (8) having a bottom plate (9) with a passage (10) for electrical con¬ necting members (12) to and from the ultrasonic sensor (1), said bottom plate (9) having in its underside a recess (13) adapted to receive said top flange (6) and a flange portion (14) outside the recess (13) for securing the meter housing (8) to said supporting surface (4) with the top flange (6) of the sensor chamber (2) intro¬ duced between said bottom plate (9) and said supporting wall (4), and that oscillation damping gasket members (15-19) are inserted between the flange portion (14) of the meter housing (8) and the supporting wall (4) as well as between the top flange (6) of the sensor chamber (2) on the one hand and the supporting wall (4) and the bottom plate (9), respectively, on the other hand. 2. An ultrasonic apparatus as claimed in claim 1, characterized in that the gasket members (16 to 19) between the top flange (6) of the sensor chamber (2) on the one hand and the supporting wall (4) and the bottom plate (9) of the meter housing (8), respectively, on the other hand are constituted by O-rings inserted in cir¬ cular recesses (20 to 23) in both sides of the top . flange (6) and on its edge surface. 3. An ultrasonic apparatus as claimed in claim 1 or 2, characterized in that the gasket member (15) between the flange portion (14) of the meter housing (8) and the supporting wall (4) is constituted by a flat gasket washer. 4. An ultrasonic apparatus as claimed in any of the preceding claims, characterized in that a reflector (24) for reflecting ultrasonic radiation reflected from the interior of the tank or room against the sensor chamber (2) is secured to the surface of the supporting wall (4) facing the interior of the tank or room. 5. An ultrasonic apparatus as claimed in claim 4, characterized in that the reflector (24) comprises a conical reflecting surface co-axial with the sensor chamber (2) .

Inventors: JENSEN NILS, LINDSTROEM ARNE, JENSEN, NILS, LINDSTROEM, ARNE
Applicants: JENSEN NILS, LINDSTROEM ARNE, JENSEN, NILS, LINDSTROEM, ARNE
Application year: 1983
Main classification: G01F23
IPC codes: G01F23