Problems with Feed Mixer Testing Mixing Evenness and Noise

Mixing uniformity and noise are two important indicators in the detection of feed mixers. There are many factors affecting the measurement results of these two indicators, and it is easy to neglect, resulting in inaccurate measurement results. This article gives a brief analysis of the factors affecting its determination. First, the mixing uniformity of the determination of the degree of uniformity There are two methods, namely, methyl violet method and precipitation method. The methyl violet method uses methyl violet as a tracer and adds it together with additives to the feed to be mixed. After the feed is mixed, the sample is taken from the middle portion of the mixture, and then the content of methyl violet in the sample is determined by a colorimetric method. As a basis to reflect the uniformity of feed mixing. Methyl violet method is the most commonly used method to determine the homogeneity of mixing, and it is also the most accurate and reliable method. This article only analyzes the influencing factors of determining the mixing uniformity with methyl violet method. 1. The material of the test material shall be corn flour processed according to the second-class corn specified in GB 1353. The geometric mean diameter of corn flour is not more than 1mm, geometric particle uniformity is not more than 2.5, and the moisture content is not more than 14%. In practice, these conditions are generally easy to ignore, and these conditions will affect the accuracy of the measurement of the mixing uniformity. Because the methyl violet method is used for the determination of each sample is 10g, of which the content of methyl violet is only one hundred thousandth of the sample, if the particles are not uniform, it will affect the distribution of the tiny part of the feed, This leads to inaccuracies in the measurement of the mixing uniformity. 2. Tracer methyl violet purple as tracer, the sensitivity is very high, the small amount of the difference has a great influence on the concentration of the filtrate, the change in concentration will affect the extinction value, thus affecting the measurement results of the mixing uniformity. Due to the different degree of methylation of different batches of methyl violet, the hue may be different. Therefore, in the test, the same batch must be used and fully mixed. When a feed mixer is used to produce compound feeds and concentrated feeds, methyl violet is ground and passed through a standard 0.1 mm (150 mesh/inch) round screen. When the feed mixer was used to produce the premix feed, the methyl violet was passed through a standard round sieve of 0.074 mm (200 mesh/inch) once after grinding. The tracer should be weighed with a balance of more than 0.01 mg and the tracer dose for each batch of mixed test is one hundred thousandth of the material. The tracer is preferably a paper with a relatively high density and a smooth surface, rather than being weighed and packaged with a rough paper so as not to cause tracer errors and affect the accuracy of the measurement of the mixing uniformity. 3. Mixing time In general, the longer the mixing time, the better the mixing uniformity, but this will reduce the productivity. Therefore, the test must be performed according to the mixing time specified in the instruction manual, and the mixing time cannot be arbitrarily shortened or extended, and each test The mixing time should be the same. 4. Sampling and Sample Separation After each batch of material is mixed and tested, samples shall be taken at equal intervals from the discharge port. The weight of each sample shall be maintained at 100-150 g. Each sample is sampled using the same method. The repeat time and number of times should be the same. 5. Sample handling precautions (1) Blank reagents must be taken from the same batch of corn flour. (2) When using the Bessel flask to process the analytical sample, the stopper must be properly capped to prevent the volatilization of ethanol, resulting in an increase in the concentration of the solution and affecting the extinction value of the sample. (3) When measuring the extinction value of each filtrate with a spectrophotometer, use the same blank agent to re-adjust before each measurement to ensure the accuracy of the measurement. Second, noise noise measurement of feed mixers is generally measured using a simple method, in the detection process, it is often easy to ignore the impact of the test environment. 1. Test environment requirements When measuring outdoors, the reflective surface should be a hard surface, concrete or asphalt ground; when measured indoors, the reflective surface is usually the ground level in the room, allowed to use wood or brick floor, and the reflective surface should be larger than the measuring surface. The projection on it. The sound absorption coefficient of the reflective surface should be less than 0.1. If the sound absorption coefficient is large, the distance should not exceed 1 m if it is grass or snow. Except for the sound source being measured, other reflectors should not be placed within the measurement surface. 2. Test environment identification In the on-site measurement, the outdoor or indoor measurement site should be identified first. The identification of the test environment is usually based on the determination of the sound absorption A at the test site and the measured surface area S, and the environmental correction value K2 is calculated by the following formula. (1) In the formula, S——measuring surface area, m2 A—the sound absorption in the test chamber, m2 A=αSv(2) where α—the average sound absorption coefficient Sv—the total surface area of ​​the test chamber, M2 Measurement can only be performed if K2 ≤ 7 or A/S ≥ 1 is satisfied. Otherwise, a small measurement surface should be used, and the measurement point should be located outside the near field, and then the K2 value or A/S value should be re-evaluated; if it still cannot meet the requirements, the noise power level of the machine cannot be measured by this method. 3. Background noise During the entire test process, the difference between the A sound level measured at each measuring point and the A sound level of the background noise at the measuring point of the machine under test shall not be less than 3 dB, otherwise the measurement is invalid. When the difference of the A level of the background noise is not more than 10 dB, the correction amount specified in the standard is corrected. 4. Meteorological conditions When measuring outdoors, the wind speed should be less than 6m/s. The sound level meter should use a wind shield. 5. Installation and operating conditions of the machine The machine under test shall be installed on the reflective surface of the measurement according to normal working conditions. The auxiliary device shall comply with the requirements of the test environment and background noise.