Main features of pipe bender
Type B uses the national standard GB7148-81 and the international ISO7150/1-1948 standard salicylic acid photometric method as the basic test means, supplemented by sample colorimetric reaction pretreatment, to achieve rapid and accurate colorimetric determination of samples, with stable,SensitiveReliable and mercury-free.
The pipe bender performs the bending of the pipe as well as the bending of the sheet. In the case of pure bending, when the pipe with outer diameter d and wall thickness t is bent under the action of external moment m, the pipe wall outside the neutral layer is subjected to tensile stress σ1 and the pipe wall becomes thinner. The inner pipe wall of the neutral layer is thickened by the compressive stress σ1. Moreover, the shape of the cross section changes from circular to approximately elliptical due to the combined forces F1 and F2. When the deformation is too large, the outer tube wall will crack and the inner tube wall will wrinkle.
The degree of deformation of the pipe depends on the relative bending radius R/D and the relative thickness t/D values. The smaller the R/D and t/D values, the greater the degree of deformation. In order to ensure the quality of pipe forming, the degree of deformation must be controlled within the permitted range. The bending forming limit of pipe not only depends on the mechanical properties of the material and the bending method, but also considers the use requirements of the pipe. The forming limit of pipe fittings shall include the following contents:
Key words: heat exchange equipment
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Type of ammonia nitrogen analyzer
Ammonia nitrogen analyzer according to the different test standards, there are A, B type. Type A is GB7479-87 by Nessler' s reagent colorimetric method. Type B adopts the national standard GB7148-81 and the salicylic acid photometric method specified in the international ISO7150/1-1948 as the basic testing method, supplemented by the sample colorimetric reaction pretreatment, to realize the rapid and accurate colorimetric determination of the sample, which has the advantages of stability, sensitivity, reliability and mercury-free.
Operation steps of ammonia nitrogen analyzer
Pour distilled water or ultra-pure water into a cuvette (about 2/3 height); wipe the water marks and fingerprints on the outer wall with a non-falling paper towel or soft cloth, then put it into the measuring seat of the instrument and cover the shading cover.
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