Testing & Commissioning Of Water Supply Piping System Network

Precommissioning Procedure for Water supply system

1. Ensure that the system installation is complete and mechanical completion is approved.
2. Ensure that no damage occurs between mechanical completion & precommissioning.
3. Check that the Water Booster piping network is complete with proper valves, water hammer arrester drains, vents, strainers, pressure switches & instruments in place as per final approved shop drawing.
4. Ensure the PRV stations are installed in all the floors & the by pass piping is completed & properly supported.
5. Ensure that the Water Booster network is hydraulically pressure tested and approved.
6. Ensure the water supply network is disinfected in line with the approved method statement.
7. Ensure that the entire system is cleaned internally & externally.
8. Ensure that the water supply pumps are precommissioned & commissioned in line with the approved procedure.
9. Ensure all the pressure switches are installed & wired properly.
10. Ensure the wiring to the DDC from the pump panel is complete.
11. Ensure all drain valves & vents are installed.
12. Ensure that the BMS connections are done.
13. Ensure that the identification of all the pipework are complete.
14. The wiring diagram of pump controls & schematic piping shall be displayed near or inside the control panel.

Commissioning Procedure for Water Supply System

1. Ensure that all the precommissioning checks are carried out successfully.
2. The Water supply system shall be completed tested for proper sequence of operation as approved.
3. System pressure will be maintained always at 16 bar. In the event of water consumption, pressure in the water supply system piping will fall down. Minor drop in pressure shall be compensated by the expansion vessels, but when the pressure reaches 15.0 bar, Pressure Switch PS1 will cut in and jockey pump will start. If pressure builds up to 16.00 bar, then jockey will stop.
4. While the jockey pump is in operation, if the pressure drops further to cut in pressure of PS2 (14.50 bar), then Main Booster pump will start and jockey will stop. Main pump will continue to run till the pressure reaches cut out pressure of PS2 (16.0 bar).
5. As the main pump starts only below 14.5 bar & stops at 16 bar, there is sufficient time for the pump to tranfer from star to delta thus avoiding the frequent running of pump only in star mode. Further the star to delta transition time shall be reduced.
6. While the Main Booster pump is in operation, if the pressure drops further to cut in pressure of PS3 (13.50 bar), then Second Main Booster pump will start and both the main pumps will run. Main Booster pumps will continue to run till the pressure reaches cut out pressure of PS2 and PS3 (16.0 bar)
7. While the Main Booster pumps are in operation, if the pressure drops further to cut in pressure of PS4 (12.50 bar), then Third Main Booster pump will start and all the three main pumps will run. All the Main Booster pumps will continue to run till the pressure reaches cut out pressure of PS2, PS3 and PS4 (16.0 bar).
8. While the 3 Nos. of Main Booster pumps are in operation and due to any reasons any one of the main pumps fails to work, then the Standby Booster pump (the next available pump) will start and both the Main Booster pump and Standby Booster pump will continue to run till the pressure reaches cut out pressure 16.0 bar.
9. The main pumps will stop in reverse sequence when the system demand reduces.
10. The above sequence of cut-in and cut-out of main pumps will change during each new demand cycle. Once the demand reduces all the pumps will stop in reverse sequence. The cyclic change over of duty of each pump will carry on during each cycle of operation. This cyclic change over of duty and standby pumps shall ensure to have uniform wear and tear of all the booster pumps.

SIGNALS TO BMS PANEL

1) Pump running status.
2) Pump trip status.
3) Water low-level status in the tank. / Dry run protection.
4) Pump Start/Stop command

PROTECTION OF PUMPS (shall be demonstrated)
1) Dry run protection for booster pumps by level switch inside the water tank.
2) Against overheating by adjustable temperature thermostat. Pumps will stop if the water temperature exceeds more than 90 oC.
3) Against motor overheating by thermister, which will be wired to the panel to trip the pump in case of temperature more than 90 oC.

Demonstration of sequence of operation: 

1. Pressure vessel & jockey pump: The water outlets in certain floors shall be opened & the pressure drop in the system shall be observed. The minor pressure difference shall be compensated by the pressure vessel, but as time passes the jockey pump will start.
2. Main pump 1: The jockey pump discharge valve will be closed, then the pressure drop in the system will increase & the main pump 1 will start.
   Main pump 2: The main pump 1 discharge valve will be closed, then the pressure drop in the system will increase & the main pump 2 will start.
3. Main pump 3: The main pump 2 discharge valve will be closed, then the pressure drop in the system will increase & the main pump 3 will start.
4. Stand by pump: The main pump 3 discharge valve will be closed, then the pressure drop in the system will increase & the standby pump will start.
5. Pressure Setting procedure for pressure switches: The pressure switches can be manually adjusted & set to the required pressure with the help of the pressure scale & the adjustment screw in the switches.
6. Open / Close condition of valves: All the valves in the system shall be open during pre-commissioning and commissioning except the test line valve & the PRV station by pass valves.
7. Commissioning of PRV stations: The pressure setting the PRV stations in all the floors including the by pass PRV shall be carried out by manually adjusting the pressure setting of PRV to 2 bar.

Attachments:

• Precommissioning check sheet for Water Supply System
• Commissioning check sheet for Water Supply System
• Precommissioning & Commissioning Plan for Plumbing System
• Risk Assesment