How to Remove the Impeller of a Trash Pump
The trash pump is normally used to remove the waste water. They function on the simple principle that the water will flow in the path of least resistance. These pumps are powered with impellers, to generate additional force due to rotation, with the help of impeller blades to push out the debris containing water. The impeller is installed in the central housing of the trash pump, and works to create centrifugal force, to pressurize the water flow through the trash pump.
The trash pumps have different types of mechanism for the impellers. The open type impeller has a series of blades mounted on the hub in the center. It has no side walls or any covering. There is maximum amount of vane wear in this type of impellers. The semi closed impellers differ in design. They possess a side wall at the back end. This type of impellers are adjustable, they have minimum wear, and work with maximum efficiency.
Closed impellers have side walls on both ends. This type of impeller also have wear rings. The rings and the impellers wear away after long use. The clearance between the ring and impeller increases and the pump loses its efficiency. The enlarged clearance could cause longer priming, and reduced capacity of the pump. If efficiency is tolerable for your use, it is suggested that no remedial action be taken, irrespective of amount of clearance your unit has. This is due to the fact that excess clearance is not usually dangerous for the pump. Generally, new pump clearances may be refurbished by merely shimming the back of impeller. In case they are excessively worn out, the rings and the impellers may require replacement. You can easily remove the impeller for replacement by following these easy steps:
Step 1: Read the Manufacturer’s Instructions
Read the instructions in the user’s manual for undertaking the removal for impeller. Go through the procedure explained by the sketches and part numbers to understand it. Always refer it when you are in doubt.
Step 2: Disconnecting the Spark Plug
Unplug the connection to spark plug, to avoid any accidental starting of the engine.
Step 3: Opening the Casing
Open the pump’s cap, by removing the cap screws. Pull out the impeller casing. After that, take out the casing seal from the adapter.
Step 4: Removing Volute
Unscrew the screws securing the volute with a wrench. Remove the volute from its adapter. The volute is a funnel that is wrapped around the impeller, whose cross-section area increases towards the discharge port. It slows down the flowing liquid and helps to increase its pressure.
Step 5: Removing the Impeller
Unscrew the impeller from the engine shaft of the pump. Turn it counterclockwise and remove. You can slightly hit the impeller with a rubber mallet, to loosen it on the shaft. Remove the nut, which holds the spring and seal assembly on the engine shaft. Take out the spring and slide the seal assembly to take it out. Also remove the shims.
Replace the worn out or damaged parts and reassemble the pump, according to the instructions given in user’s manual.