Metalock Engineering Group repaired this 12” Allen Gwynne mixed flow bowl pump to get it back in service as quickly as possible. Part of the repair included building up an impeller blade, machining back to original dimensions. The impeller shroud was lightly machined to remove the worn area and the pump was reassembled to set the correct clearances.
Metalock Engineering Group has recently overhauled a 25 year old 12-inch Allen Gwynne mixed flow bowl pump that Anglian Water Supplies used for surface water drainage and which had become noisy, inefficient and tended to run backwards when it was shut down.
The pump had to be dismantled on site as it was too long to remove in one piece from its location due to height restrictions in the pump house at Cotton Valley STW, Milton Keynes. On strip down it was found that water lubrication holes had silted up and blocked causing the bearings to wear away. As a result the impeller had rubbed on the shroud and worn a deep groove.
Metalock Engineering Group completely refurbished the unit by fitting new bearings and shaft sleeves throughout and building up the worn impeller with weld followed by machining. A new wear ring was fitted to the back of the impeller. The pump body was then machined to suit. The impeller shroud was lightly machined to remove the worn area and the pump reassembled to set the correct clearances.
While this work was being undertaken in Metalock’s workshops, the non-return valve was completely stripped on site, overhauled and cleaned to prevent water flowing back through the pump. New rubber seals were fitted and new studs made to replace the old badly corroded ones.
The alternative to refurbishment would have been a replacement pump, the production lead time for which would have meant being without a pump for several weeks. Instead, the overhaul enabled the pump to be back in operation in 30 days without a need for electrical and location modifications. The success of this project indicates that one should not always go for pump replacement in the first instance but contact Metalock Engineering Group who can provide a quicker and less costly solution.