The practical inspection question is whether the installed part still matches its intended hydraulic design. It is not whether every opening looks identical to an example from another pump. A hole near the hub may serve a different purpose, and an apparent depression may be a casting feature. Identify each feature from the correct drawing before putting a tool into it.<\/p>\n
For product context, the IS clean-water centrifugal pump range<\/a> provides a starting point for an equipment inquiry. Ask for the supplied assembly and impeller documents. The external product view does not certify that a particular order uses balancing holes.<\/p>\n Save the last stable operating condition and the condition associated with the complaint. Useful records include flow indication, suction and discharge pressure, speed, liquid temperature, bearing temperature and vibration trends. Note recent changes in liquid solids, chemical treatment, valve position or maintenance. A comparison at different speeds or duties can otherwise create a misleading connection between deposits and a bearing alarm.<\/p>\n Keep diagnosis separate from observation. Finding a plugged passage after an abnormal event is evidence worth investigating, but it does not prove that blockage caused the entire failure. An operating point outside the permitted range, rubbing, bearing installation or a separate lubrication problem may also need review. Link the inspection record to the wider centrifugal-pump maintenance inspection report<\/a> so related findings stay together.<\/p>\n Before opening the pump, isolate the driver, prevent automatic starting, isolate the process and safely release pressure and retained liquid under the site procedure. Deal with hazardous residues and lifting arrangements before removing the rotating assembly. Photographs should be taken from a safe, accessible position after the equipment has been made safe.<\/p>\n Give each passage an identifier and relate it to a repeatable reference on the impeller. Record which side was photographed, the direction of the view and the part number. Keep a photograph of the whole component alongside close views. This makes it possible to compare the same locations after cleaning and during a later overhaul.<\/p>\n Describe deposits without guessing their chemistry. Terms such as hard white deposit, dark soft material or fibrous blockage are more useful than an unsupported label such as corrosion product. Collect a sample when the maintenance investigation needs material identification. Record whether blockage appears at one mouth or continues through the passage.<\/p>\n Separate handling damage from service damage. A fresh mark produced during removal should not be entered as evidence of erosion. If the repair shop receives an already-cleaned component, state that the original deposit distribution was unavailable. The missing evidence matters when deciding whether to change water treatment, screening or the operating procedure.<\/p>\n The table below is a practical reporting framework, not a dimensional acceptance standard. The pressure-relief function is supported by CANTEACH, while Chalmers University’s balancing-hole design study<\/a> examines how geometry affects axial force and hydraulic performance. Neither source establishes limits for a BORRAPUMP model.<\/p>\n An incomplete row is a useful hold point. It identifies the missing evidence instead of encouraging a technician to invent an acceptable diameter from experience with another machine.<\/p>\n Choose cleaning methods that suit the impeller material, deposit and site contamination controls. Protect machined fits and sealing surfaces. Avoid driving a hard object through a passage simply because it fits the opening. An improvised drill can remove parent material, leave a burr or carry debris into another cavity.<\/p>\n After cleaning, establish that the passage is clear using the approved inspection method. Seeing light at one end may help, but it does not measure the condition of the entire bore. If access prevents a reliable assessment, record the limitation and arrange an appropriate inspection rather than marking the passage clear by assumption.<\/p>\n Document the final cleaned condition with the same location map used initially. Retain the cleaning method and any removed material samples. If a process is likely to leave residue, the work instruction should also define how cleanliness is confirmed before the component is returned to service. Cleaning is complete when evidence supports the required condition, not when the surface merely looks brighter.<\/p>\n Look for an opening that has become oval, locally thinned or irregular compared with the drawing. Inspect the transition into the shroud and accessible surrounding surfaces. A crack indication requires a suitable inspection and disposition; polishing the area until the indication is less visible is not a repair decision.<\/p>\n The balancing system may include a rear wear ring or another controlled leakage path. A clear passage cannot compensate for every change elsewhere in that system. Record ring condition and compare clearances with approved limits. The separate centrifugal-pump wear-ring clearance guide<\/a> explains why measurements need the correct equipment reference.<\/p>\nCollect the operating evidence before dismantling<\/h2>\n
![\"IS](\"https:\/\/borrapumps.com\/wp-content\/uploads\/2026\/10\/borra-realistic-20261016-img-025.webp\")
Map the passages before cleaning<\/h2>\n
Use an inspection table that leads to a decision<\/h2>\n
\n\n
\n \nInspection item<\/th>\n Evidence to retain<\/th>\n Decision before assembly<\/th>\n<\/tr>\n<\/thead>\n \n Passage identity<\/td>\n Drawing reference, part number and location map<\/td>\n Resolve any opening that does not match the supplied part<\/td>\n<\/tr>\n \n Obstruction<\/td>\n Before-cleaning photographs and deposit description<\/td>\n Remove deposits by an approved method and verify the full path<\/td>\n<\/tr>\n \n Opening condition<\/td>\n Views of both mouths and adjacent shroud<\/td>\n Refer cracks, missing metal or sharp erosion features for assessment<\/td>\n<\/tr>\n \n Size and shape<\/td>\n Approved measurement method, actual readings and drawing limit<\/td>\n Hold an enlarged, distorted or uncertain feature for engineering review<\/td>\n<\/tr>\n \n Surrounding components<\/td>\n Rear cavity, wear-ring and rubbing observations<\/td>\n Review interacting clearances rather than accepting holes alone<\/td>\n<\/tr>\n \n Previous repairs<\/td>\n Repair report and authorized drawing revision<\/td>\n Confirm the current configuration is approved<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n Clean without changing the hydraulic geometry<\/h2>\n
![\"CYZ-A](\"https:\/\/borrapumps.com\/wp-content\/uploads\/2026\/10\/borra-realistic-20261016-img-019.webp\")
Assess wear, cracking and neighboring clearances<\/h2>\n