Maintenance and troubleshooting:Commissioning procedures

Commissioning procedures

Incorrect commissioning of hydraulic components during initial start-up can result in damage due to inadequate lubrication, cavitation and aeration that may not manifest itself for hundreds or even thousands of service hours. To avoid damage to the system components during start-up, the manufacturer’s commissioning procedures should be followed wherever available.

The following are general procedures for commissioning hydraulic systems after components have been replaced from the system or if any other maintenance action has been carried out. The same procedures can be applied when commissioning new systems.


If the system is down as a result of a major component failure, such as a pump failure:

• Drain and clean the reservoir to ensure that it is free from metallic debris and other contamination.

• Change all filters.

• Change the fluid. In large systems where the cost of changing the fluid may be prohibitive, the fluid should be circulated through a 10 Jl filter (without bypass) before recharging it into the system.

• When fitting pumps and motors, check the drive coupling for its alignment with the pump shaft.

• On closed loop systems, closely inspect the high-pressure hoses or pipes and replace any suspect lines. A blown hose or a pipe can destroy a pump or a motor through cavitation.

• After fitting each cylinder, fill the cylinder with clean oil wherever possible, through its service port before connecting the service lines. This reduces the risk of air compression within the cylinder during start-up, which may result in damage to the seals, or the cylinder itself.

• After fitting motor and other connecting lines: In case of piston type motors, fill the motor casing with clean oil from the upper most port and connect the casing drain line.

• After fitting the pumps and connecting the service lines: Open the suction line valve at the reservoir and vent out all the air from the system at the pump suction line. This step is not necessary for a piston-type pump.


• Check that all the pipe and hose connections are tight.

• Confirm that the reservoir fluid level is above the minimum level.

• Confirm that all the controls are in neutral so that the system will start in an unloaded condition. Take safety precautions to prevent machine movement when the system is activated during initial start-up.

• Where the prime mover is an electrical equipment, confirm whether the direction of rotation of the motor is correct by inching the motor.

• Start the prime mover and run at the lowest possible speed (rpm).

• On closed loop systems, monitor the discharge pressure. If the manufacturer’s specified charge pressure is not established within 20-30 s, shut down the prime mover and investigate the problem. Do not operate the system without adequate charge pressure.

• On variable displacement pumps and motors with external, low-pressure pilot lines, vent out the air from the pilot line and ensure that the line is full of oil. Caution! Do not bleed the pilot lines carrying high-pressure fluid – personal injury may result. If in doubt do not bleed pilot lines.

• Allow the system to run in idle mode and unloaded for 5 min. Monitor the pump for any unusual noises or vibrations and inspect the system for leaks and observe the reservoir fluid level.

• Operate the system without a load. Stroke the cylinders slowly, taking care not to develop pressure at the end of the stroke to avoid compression of trapped air, which may result in damage to the seals. Continue to operate in this manner until all the air is expelled and the actuators operate smoothly.

• With the system at the correct operating temperature, check and, if necessary, adjust pressure settings according to the manufacturer’s specifications.

• Test the operation of the system with appropriate load.

• Inspect the system for leaks.

• Shut down the prime mover. Remove all gages fitted during commissioning and check the reservoir fluid level and top-up if necessary.

• Put the machine back into service.

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