There are two magnetic-driven pumps in our hypochlorine unit. When we installed and started the pump for the first time, flow and pressure were good, but then the bush and sleeve broke, along with the thrust bearing, which are sic material. After repairing the pumps with new parts, they did not produce sufficient flow, but the discharge pressure was good and we checked the all parameters that can affect pump performance, including piping strain, piping restriction and alignment and vibration. There is no check valve on the discharge side and when we want to start the pumps and stop them, we close the valve on discharge side first and then open it to reach to operation condition. What is the reason for the low flow for this type of pump? What is the rule to use a check valve in centrifugal pumps if we did not install it? What is the rule for the internal clearance on the impeller side and also between bush and sleeve bearing on pump performance?
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Ross Mackay Forum Moderator 93 Posts
Re: Low-flow pump after repair27 August 2007 at 1:29pmThis is the kind of situation that is best handled by the local pump supplier and/or manufacturer. There are too many unexplained factors that could exist. If you are getting the same pressure after the repair, but a low flow, then the repair parts may not have been the same as the original ones. The purpose of a check valve is to prevent pressure from a system operating backwards into the pump when the pump is shutting down or starting up. There is no rule of internal clearance. This is subject to the manufacturers design criteria.