Back Pull-Out Design

Back pull-out is not a brand feature. It is a construction principle written into ANSI/ASME B73.1, ISO 2858 and BS EN733, and it exists for one reason: so the pump can be serviced without disturbing the pipework.

Four of the five Flowsteer series state back pull-out construction explicitly, and the fifth is built to a standard that requires it.

The Problem It Solves

On a pump without back pull-out, servicing the wet end means taking the pump off the pipework. Two flanges are broken, gaskets are replaced, the pipe run is supported, and on reassembly the whole alignment has to be re-established.

Most of the labour in that job is pipework, not pump. The seal itself takes minutes.

How the Construction Works

The casing is a separate component, bolted between the suction and discharge flanges and never removed. Behind it sits a stuffing box cover, then the bearing frame carrying the shaft.

The bearing frame, shaft, seal and impeller are bolted to the casing as one assembly. Undo those bolts and the assembly withdraws rearwards, leaving the casing in place.

A spacer coupling improves it further: with the spacer removed there is room to withdraw the assembly without moving the motor.

What It Changes In Practice

The pipework stays bolted, gasketed and aligned throughout.

The seal, impeller, shaft sleeve and bearings are serviced on a bench rather than over a pit.

Pump-to-pipe alignment cannot drift because nothing moved. Only the coupling alignment needs re-checking.

Plant rooms need clearance behind the pump equal to roughly the shaft and bearing housing length — worth designing in from the start.

Which Flowsteer Series Use It

ISO CI — back pull-out end-suction to ISO 2858.

KCP — back pull-out construction with polymer wetted parts.

FA — back pull-out within the EN733 layout.

VNP — back pull-out according to ISO 2858, in a vertical arrangement.

ANSI CN — built to ANSI/ASME B73.1, which is itself a back pull-out standard.