calculation method, developed MIOTom
In addition to fashion Promstroyproject, now sometimes use the method of calculation, developed MIOTom. This method is based on a formula derived M. Baranov, equally suitable for conventional and inverted suction.
The toxicity of harmful emissions into account the so-called height of the spectrum to the hazards (high range flow). More toxic than the selection from the bath, the smaller should be the height of the spectrum of hazards. For the calculation made three heights of the spectrum hazards:
for very bad bathrooms (etching in nitric and hydrofluoric acids, matting in acids, Lead plating, removal of metallic coatings in nitric acid, chromium, lighting, cyanide coating at r = 30-f-40 В° C, anodized in potassium bichromate, oxidation)
k = 40 mm;
for harmful bath (pickling in hydrochloric and sulfuric acids, potassium cyanide in a pickling and potassium bichromate, zheleznenie, removal of metallic coatings in sulfuric and hydrochloric acids, amalgamation, elektroobezzhirivanie)
k = 80 mm;
for all other bathrooms
k = 160 mm.
The correction factor x, which depends on the depth of the liquid level I in the bath (on the level of slit suction to the level of the solution) is 1.
Coefficient s, which takes into account the mobility of the air, varies from 1 to 1.65 for a quiet air y = 0,2 m / sec. Coefficient s is smaller, the greater the difference in D =-tn.
Some of the values of s are given in Table. 24. For air, having a mobility (v = () A-0, 5 m / sec). coefficient of s slightly larger by about 20-30%. Need to stipulate that the values of s, greater than 1.3. inspire doubt.
Although the authors of the formula (66) does not stipulate the limits of its application, one should pay attention to the fact that for a cold bath with a temperature equal to room temperature, the formula is flawed. Indeed, if tB = tn, then the expression under the radical vanishes;
consequently, the whole right side of zero. The minimum value of At, for which values are given in formula factors, is 20 В° C, ie, the minimum temperature of the solution in a bath of 35 В° C.
Unsuitability MIOTa method for calculating the suction side of cold baths, tables and devices operating at low temperatures greatly reduces its value. In most practical cases be preferable to use the method Promstroyproject.
For a tentative calculation of the volume of air, removed exhaust us, and to verify the calculation formulas are sometimes used by the norms of the specific volume of air to 1 in the mirror.
Table. 26 shows some data on specific volume of air removed from baths onboard suction. Data taken from domestic and foreign practices. Figures table relate to bilateral suction; for unilateral suction should be increased na 20-30%.
In addition to plating and pickling baths, the table lists some other vehicles, supplied with onboard suction devices.