DD295417A5 - DEVICE FOR CALIBRATING RADIOMETRIC, GAMMA RADIATION, OR BZW. NEUTRONOUS MODULATION OF DENSITY. MOISTURE CONTENT PROBES - Google Patents

Abstract

The invention relates to a device for the calibration of radiometric, on the gamma-ray scattering or Neutronenmoderierung based density and Moisture Propartion probes, with the help of which it is possible, the calibration effort for new or completed under other conditions (same type) probes of the same principle of action and construction essential to decrease. The device consists of a watertight container with a probe receptacle, around which gleichzeszig filling stages of a given volume of liquid are arranged and are filled in a certain mode with a suitable liquid, usually drinking water, each filling level in each case a certain density or a certain moisture content corresponds and thus gives a specific calibration point according to an assignment rule. Fig. 1 {calibration; Gammastrahlenbestreuung; waterproof container; radiometric density and moisture content probe; neutron moderation; Probe recording; filling stages; calibration; Assignment rule}

Description

are arranged around the uniform filling levels of a given liquid volume. The filling stages, usually filled with water (from room temperature to 2O ⁰ C), each correspond to a specific density or a certain proportion of Teucht. Each further filled filling stage provides a different reading so that probes of known assignment prescriptions are used to determine the otherwise valid assignment rules of the same or other probes, using real-calibrated probes and their assignment rules to be recalibrated, on the same principle and Setup working probes are assigned in certain settings of the calibration device, the density or moisture content values that correspond to the actual values.

embodiment

The invention will be explained in more detail below with reference to two embodiments. The accompanying drawings show

Fig. 1: calibration container for (usually rod-shaped) depth probes

Fig. 2: calibration container for (usually cuboid) surface probes.

FIG. 1 shows the overall view of a calibration container for rod-shaped radiometric depth probes for determination of density and moisture content in extended media, eg agricultural heaps. The container 5 is made of plastic. To a central probe receptacle 1 (plastic, iron), in which the probes are inserted in registration, there are fan-shaped arranged Füllstufen 2, which are waterproof together to the total container assembled (glued). The thickness of the wall 3 should be chosen as small as possible in order to keep the background value of the impulse rates low without water filling. The thickness of the wall 4 is determined by the required stability of the container. In the probe holder 1 is a stopper 4, which is mounted at a height such that the sources of the probes are located during the calibration process approximately in the center of the container. The stop is interchangeable, so that it can be adapted to different types of probes.

FIG. 2 shows the overall view of a calibration container for (usually) cuboid radiometric surface probes for determination of density and moisture content on extended media, eg agricultural heaps. The container may consist of a total of plastic, for example. This is a bucket-like container 5, on the thin-walled lid or other suitable receptacle 7, the most cuboid surface probe 6 reproducible and lockable 10 can be placed. Various overflow openings 11 determined experimentally in their distance guarantee a reproducible filling of the container in such a sequence that the overall calibration curve of the probe is swept over in approximately equal (here for example eight) distances. After reaching the respective filling level, the associated overflow opening 11 is closed by a screw provided with a sealing ring. After the pulse rate has been determined, continue to fill up until the next overflow opening and then proceed as above. The designation 8 of the individual filling stages in both containers (eg with numbers) serves for the clear assignment of the calibration container values to the real density or moisture content of the goods to be measured. To avoid disturbing effects of scattering by different documents on which the containers would normally have to aich at their bottom a stand 9, which ensures a sufficient distance of the probes located in the containers of the pad, so that stray radiation components from the pad r jm probe signal negligible are low. The reference to the actual values is made in a primary calibration of a probe of the type concerned with real goods of known density or moisture content. When using water as a scattering substance, the density range is limited to 0 to about 1000KgrrT ³ , while in the determination of moisture content the total range to be swept (0 to 1000 kg water m " ³ ) is detected.

Claims (2)

Device for calibrating radiometric density and moisture proportioning probes based on gamma-random scattering or neutrononeration, consisting of a watertight container with a probe receptacle, characterized in that filling stages (2) for receiving a probe are mounted in the receptacle (5) around the probe receptacle (1; predetermined liquid volume, each corresponding to a specific density or a moisture content, are arranged. For this 2 pages drawings Field of application of the invention The invention relates to a device for calibrating both radiometric density and moisture proportioning probes, which are based on the scattering of gamma radiation or the deceleration (moderating) of fast neutrons and the determination of density and moisture content in stored media (preferred density range: 0 ... 1 000kgm " ³ , Moisture Content Range: 0 ... 1 000kg water rrT ³ ) They are used to calibrate similar probes, both for new probes and those for which a little expensive calibration check may be appropriate, eg after repairs, module replacement, radiation source change. Characteristics of the known prior art The radiometric density or moisture content determination in naturally or artificially stored media is an indirect method, the use of which requires a calibration in the measuring medium. The result of this calibration is an assignment rule (equation, table of values, calibration curve) between the pulse rate as the radiometric signal and the density determined by other methods or the moisture content of the medium. The assignment rule must always be checked or recreated if the work parameters to be kept constant due to repairs, module replacement, radiation source change u.a. may have changed (e.g., replacement of a calibrated probe with an uncalibrated probe). For calibration, mainly experimental devices have been used, using either real or standard containers. These devices provide accurate results, but require a great deal of time and material, especially because when calibrated with organic materials their shelf life is sometimes very limited in time. This is therefore economically justifiable only for the initial calibration of a probe or for site or media-drawn calibrations. Solutions which are obvious to the invention are represented in the patents SU 409119, DD 253301, the Offenlogungsschrift 2747440, in a publication in the journal Isotopenpraxis 18 (1S82) H. 11, pp. 373-378. The SU document includes a neutron moisture meter control calibration assembly that is only for moisture content probes and is unsuitable for the practice of consuming heavy gases. DD PS describes a carrier framework in which shaped bodies of measuring material are held relative to one another with respect to their position relative to the probe in a defined arrangement which influences the pulse rate of the sonds. The disadvantage of this device is that so only Dichtesondei. can be calibrated. DE Patent 2747440 contains a calibration standard for nuclear radiation Moisture, which is characterized by plane-parallel arranged hydrophobic layers of materials with less or stronger moderator effect and recordings for the probes. Disadvantage of this solution is that only Feuchtigkeitsmeßgeräte can be calibrated and the construction of the device is complicated and expensive. The same applies to the solution presented in the magazine. Furthermore, there is a proposal presented at the conference "Humidity 88" of the Chamber of Technology Suhl 1988 which, although suitable for both probes, has the disadvantage that a very large water reservoir is required and the necessary settling time of the floating on the water probe carrier leads to relatively long Kalibrieizeiten. Object of the invention The aim of the invention is to reduce to Ak ^f \ ialisierung and verification of Zuordnungsvorsuhriften radiometric density and moisture content probes after Rückstrei / principle required effort significantly and also allow the transformation of calibration curves to other same type probes. This is also because, as experience has shown, the calibrated density and moisture content values of a storable calibration substance are subject to a change over time and therefore complicated new provisions are required. Explanation of the essence of the invention The object of the invention is to develop a device which is suitable for the calibration of radiometric depth probes for density and moisture proportion probes as well as radiometric surface probes for density and moisture content, requires relatively low Herstollungsaufwand, easily transportable and under practical! - can be used. According to the invention, the object is achieved by attaching a probe receptacle to a watertight container,