When discussing projects with engineers at shows and exhibitions, the same questions and conversations about commissioning a new progressive cavity (PC) pump seem to arise time and time again. PC pumps are commonly designed with features to make maintenance and installation user friendly. When commissioning a new pump, users may wonder what they should expect when using a PC pump for the first time. Before initially using the pump, remember the 10 things in this article to avoid many first-time mistakes.
- Align belts and sheaves. Belt-driven units can be both versatile and reliable, but improper setup and maintenance practices can lead to premature belt failure. Inaccurate or negligent configuration can also have a severe impact on the operating life of motors and driven components. Confirm the belt drive setup prior to startup, because these components may shift during the process of transportation or installation. When verifying setup, check that the sheaves are aligned within the pump’s tolerance.
- Confirm wiring and belt drive tension. Confirm that electric power leads are wired per the wiring diagram. This should also be verified by either the plant’s electrician or the contractor’s electrician. Lastly, confirm the pump’s rotation via a short “bump test.” Check the belt tension and confirm it is as described in the operating manual. If needed, adjust belt tension.
- Protect from short circuit issues.General electrical checkpoints should be verified for proper commissioning. If the fusers or trip points are set too low it can cause operational risks and problems, while electrical system components could be damaged if they are set too high. It is highly encouraged that the plant electrician be present along with the controls supplier during this verification.
- Ensure required voltage. Work with the plant or contract electrician to make sure that the required voltage is available. The motor leads for the operating amp and line voltage should be checked at the motor conduit box. Additionally, verify electric circuits are properly protected with sufficient fuse, breakers and the appropriate time delay settings. The starting torque for a PC pump is high compared to other types of pumps and then becomes linear with speed after the initial startup phase. PC pumps are often driven by variable frequency drives (VFDs). Be sure to consult a VFD expert to properly adjust parameters.
- Check seals. For packing seals: Tighten packing or seal gland nuts. Be sure to install packing gland nuts finger-tight and check for leaks. When tightening, tighten in very minor increments and allow time to adjust. Keep in mind that packing seals are designed to leak at a small rate. This minimal leaking helps to cool and lubricate the shaft and wearing components. Install packing or seal lubrication. Confirm or reconfirm that the packing materials are compatible with the process fluid. Verify the packing type and that packing or seal lubrication are installed correctly per the drawings given by the manufacturer. If required, lubricate the packing per manufacturer’s recommendations. For mechanically sealed units: Check alignment. Double-check alignment of the mechanical seals and ensure all fasteners are fully torqued to proper specifications. Installation aids such as alignment clips, strips or spacers should be placed in the “operating” position. If you are using a lubricated mechanical seal, confirm the fluid type and level. Mechanical seal lubrication or pressurization systems vary widely in configuration. Consult the manufacturer’s installation, startup and operating instructions if available.
- Position coupling and belt guards. Because safety guards are often removed during the installation process, ensure that all safety guards are secured in their proper position. These guards provide protection in the risk of anything being caught in the fast-moving rotating shaft. If there are any concerns about the guarding, consult local safety codes or the equipment manufacturer.
- Install drain plugs. During transport and storage, drain plugs may be shipped loosely to prohibit any moisture intrusion. Confirm these drain plugs or inspection covers have been installed completely, then ensure that there is fluid in the pump on startup to help prime the system.
- Check lubricating fluid. Verify that proper lubricating fluid is in the pump, whether it is water or another proper fluid. Depending on the manufacturer and configuration, PC pumps and components may or may not be shipped and supplied with first-fill lubricants. Grease-lubricated items will need to be filled, and the suction housing should be filled with process fluid or water if water testing is occurring. After verifying the lubricating fluid is present, check the oil level in the drive gearbox since some gearboxes may be shipped from the manufacturer with oil and some may not.
- Open inlet and discharge valves. Pipe protection is essential, since malfunction due to unopened valves is typical with any positive displacement pump. Closed valves or other line obstructions in the pump’s upstream or downstream piping may potentially lead to catastrophic failure of the pump or the piping system. To ensure a smooth process, make sure that all valves are open in the inlet and discharge lines that are connected to the pump.
- Monitor startup. On the first day of startup, it is encouraged to reference and use the provided manufacturer’s startup procedure and checklist to document the pump’s performance.
Provide Pump Protection
If automated, be sure to run a test sequence to ensure interlocks are working correctly. Verify suction piping and head pressure are sufficient to meet the net positive suction head (NPSH) requirements of the installed pump. After starting up the pumping equipment, consider the direction of pump rotation and the material that is being pumped at the inlet and outlet. Check the pressure gauges and flow meters. This is a great time to record a baseline vibration spectrum to check noise or vibration from the pump, the gear motor or motor.
Lastly, measure and record the bearing housing temperature. This should not exceed 160 F, though bearings may run warm during their initial break-in period.
PC pumps generally use a metal rotor with an elastomeric stator material. This arrangement requires the presence of liquid to provide some lubrication and cooling. Protection against dry-run conditions are available from most major PC pump manufacturers. If there is not a provision for protecting pumps from run dry over pressure, there are solutions such as grinders to help the investment.
Correctly commissioning a PC pump is essential to many projects, since PC pumps are vital to many operations. Following these 10 steps, from opening valves to verifying electrical checkpoints, will help ensure necessary measures are not missed and the process runs smoothly from the start.