The first commissioning run is critical to the trouble-free operation of a pump set. What is involved in this process?
The previous chapter of Pump Industry Australia’s (PIA) Pump Technical Handbook established how to prepare a centrifugal pump for commissioning. This instalment will discuss the commissioning run.
Assuming the pump has been started and is running under full load, the commissioning run takes place as follows:
1. When the pump discharge valve is fully open, record the following:
a. Suction and discharge pressures
b. Motor current and voltage
c. Flow rate (if practical).
2. Observe stuffing box for leakage. If a mechanical seal is fitted, there will be no observable leakage. If a packed gland is fitted, a small amount of leakage is necessary and the gland bolts must be tightened, slowly, until the leakage rate is one drop per minute. Note: over-tightening the gland bolts will result in no packing lubrication and will burn the packing and damage the shaft or sleeve. If steam is observed, back off the gland bolts immediately.
3. Observe the pump suction gauge to confirm the expected suction conditions are being met.
4. When the pump set has run up to speed and settled into smooth operation, monitor and record the following:
a. Pump suction and discharge pressures
b. Pump flow, if practical
c. Pump bearing temperatures
d. Pump vibration levels
e. Pump gland leakage.
Note: The above readings should be taken every 10 minutes for the first 30 minutes and at 30 minute intervals thereafter.
5. The following should be monitored and recorded for the electric motor:
a. Motor amps
b. Motor volts
c. Motor temperature
d. Motor bearing temperatures
e. Vibration levels as per the pump data above.
Note: These readings should be taken at the same time intervals as for the pump readings.
6. If the discharge outlet can be seen, check the flow. This can be done by following instructions in Section 2.13 of PIA’s Australian Pipe Friction Handbook.
7. After a two-hour run, shut the pump down and close the pump discharge valve immediately prior to stopping the pump.
Electric pump set
When a control panel is supplied with the system, check:
1. That both visual and audible alarms and indicators have been activated
2. After the pump has stopped, that the alarms and indicators, both audible and visual, revert to standby status.
Diesel pump set
For a diesel-driven pump, the following is necessary:
1. For radiator water-cooled engines, check the fan is rotating and fan belts are intact.
2. For heat exchange cooled engines, check the raw water flow and engine cooling water is topped up.
3. Monitor and record the following every 10 minutes for the first 30 minutes and at 30-minute intervals thereafter:
a. Engine temperature
b. Lubricating oil pressure and temperature
c. Cooling water temperature
d. Fuel supply
e. Heat exchanger engines, check raw-water cooling flow and outlet temperature.
Note: the engine temperature and oil temperature and pressure should be within the engine manufacturers recommended limits.
If the unit is a positive displacement pump, fitted with a pressure relief valve, close the pump discharge valve while the pump is running and ensure the relief valve lifts and bypasses liquid at the correct pressure setting.
Great care must be taken to ensure the pump valve is reopened quickly if the relief valve does not open at the set pressure, as extreme pressures can damage the pump and system pipework.
As the pump-set commissioning run proceeds, an evaluation of the results can be made. For this, a copy of the pump characteristic or performance test curve is required.
This evaluation is required to ensure that the pump is performing optimally and that it is running close to its specified duty.
Note the following:
- The commissioning run is not a pump performance test. The commercial instrumentation used on-site does not have the accuracy for exact testing.
- Standard pump industry units have been used for the readings taken during commissioning i.e. l/sec and kPa. For conversion units, refer to chapter 21 of the PIA Pump Technical Handbook.
The pump set has now been given a run with the necessary results recorded. This now allows us to evaluate pump-set performance, which will be covered in the next chapter.
