tailieunhanh - Industrial Machinery Repair Part Episode 2 Part 7

Tham khảo tài liệu 'industrial machinery repair part episode 2 part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 384 Packing and Seals Table Common failure modes of packing and mechanical seals THE CAUSES THE PROBLEM Excessive leakage Continuous stream of liquid No leakage 1 Shaft hard to turn 1 Shaft damage under packing Frequent replacement required Bellows spring failure Seal face failure Packed box Nonrotating 1 Cut ends of packing not staggered Line pressure too high Not packed properly Packed box too loose Packing gland too loose Packing gland too tight Rotating Cut end of packing not staggered Line pressure too high Mechanical damage seals seat Noncompatible packing Packing gland too loose Packing gland too tight Mechanical seal Internal flush 1 Flush flow pressure too low Flush pressure too high Improperly installed Induced Misalignment Internal flush line plugged Line pressure too high Physical shaft misalignment Seal not compatible with application External flush Contamination in flush liquid External flush line plugged Flush flow pressure too low flush pressure too high Improperly installed Induced misalignment Line pressure too high Physical shaft misalignment Seal not compatible with application Source Integrated Systems Inc. Packing and Seals 385 Seal Flushing When installed in corrosive chemical applications mechanical seals must have a clear water flush system to prevent chemical attack. The flushing system must provide a positive flow of clean liquid to the seal and also provide an enclosed drain line that removes the flushing liquid. The flow rate and pressure of the flushing liquid will vary depending on the specific type of seal but must be enough to assure complete continuous flushing. Packed Boxes Packing is used to seal shafts in a variety of applications. In equipment where the shaft is not continuously rotating . valves packed boxes can be used successfully without any leakage around the shaft. In rotating applications such as pump shafts the application must be able to tolerate some leakage around the shaft. Nonrotating Applications In .