Shortys HVAC Supplies can supply a complete Armstrong model 4280 if needed. This style pump is a custom built pump and is ordered by model number, size, serial number, motor horsepower and motor RPM. This information will be stamped on a plate located on the pump volute or baseplate.
The size is a combination of suction pipe size, discharge pipe size and impeller size before trim. As an example a model 4280 3x2.5x8 would sized for a 3" suction pipe, 2.5" discharge pipe and the impeller will be an 8" impeller. The impeller will be trimmed to match the pump curve and the motor will be selected for the amount of horsepower required.
Armstrong also made an old style version of this pump that uses a size such as 1-1.5D instead of the pipe and impeller sizes. This pump will have a tangental discharge line which means it is off to one side. The new version will have a centered discharge line.
If you need parts to repair an Armstrong 4280 pump please give us a call or send an email with the nomenclature from the pump nameplate and we will be happy to send you a quote. We typically stock all normal repair pats for this new style pump. Many parts for the old style have been discontinued.