Balancing rotary pumps

On balance, centrifugal pumps always should be considered first in comparison with reciprocating or rotary positive displacement types, but those do have their places. Range of applications of various kinds of pumps are identified by Figure 7.14. 

Figure 3.24. Mettler TA 2000 C ihermoanalyzer schematic diagram. I. furnace for regular gas atmosphere 2. furnace for corrosive gas atmospheres 3. inlet valve 4. needle valve 5, gas flow meter 6. pressure gauges 7. exhaust valve 8. shut-off valve 9, bypass valve 10. plate valve 11. fore-vacuum valve 12. diffusion pump 13. rotary pump 14, balance 15. sample cup holder.

All the mechanical part of the balance, with the beam, set of weights, beam position sensor and compensation electromagnet, is enclosed in a thick-walled metallic chamber, which allows evacuation of the balance and beam cavity (of total volume of about 40 L) to a pressure of 4 x 10 bar with a mechanical rotary pump and to 4 x 10 bar with an additional diffusion pump. The evacuation can be performed either before starting the heating or during the course of the measurements. The gas distribution system allows the furnace space to be filled with various gases. Both static and dynamic atmospheres can be provided in the furnace, and two gases can be introduced in a preset ratio. 

The problem could be maintenance, operation, or design, or a combination of any or all these factors. In all honesty, you should never. see this set of evidence marks because it indicates a lack of control. Now because the mechanic cannot control operational problems or design problems, the first phase to correct this situation is to control the mechanical maintenance factors, like alignment, proper bolting and torque. sequences, be sure shafts are straight and round, and dynamically balance all rotary components. Reinstall the pump and wait for the next failure. Once the maintenance factors are under control, there should appear a clear vision and path to resolve any operational and/or design weaknesses. 

Figure 13-17 shows a balanced, single, rotary dement seal mounted onto the pump shaft, pressed against the stationary face and gland, mounted in the seal chamber. Note the individual component parts of the rotary element. 

The sequence of rotor assembly and balance correction shall follow ISO 5406. For balancing, the rotor does not include the pump half coupling hub or the rotary units of the mechanical seals. 

After all of the elutants have been collected in the round-bottom flask, attach the flask to the rotary evaporator and remove the solvent, under vacuum. (Be careful that the solvent doesn t bump up into the trap ) After removing the hexanes and CH2CI2, attach the flask to a vacuum pump for about 3 minutes to ensure that all of the solvent and dimer have been removed from the product. Remove the flask and weigh it on the 4-place balance to determine the amount of product obtained. Calculate the percentage yield. 

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