Impeller pumps gently transfer delicate product

16 May 2024

Five flexible impeller pumps have been employed to enable the smooth and hygienic transfer of fish roe suspended in water.

The pumps specified for use in this application needed to be capable of transferring the delicate roe at 36,000l/hr, while also operating slowly and gently to ensure that the fish eggs are not broken or damaged during the transfer process.

The company was looking for ways to boost the efficiency of its fish egg transfer process, by automating extraction of the fish roe, to benefit from better roe handling, hygiene and quality. This would also help maximise the economic value of the roe, as well as the return made on each fish.

It was intended that the pumps become a key component of an intricate roe extraction method which involves the automated separation of the fish eggs from each other as well as the skin or sack they are attached to.

The production process requires the roe to firstly be gently separated from the sack, in which eggs can separate in clumps or individually. The eggs are then gently stirred in a slowly rotating rotary separator to aid the separation of individual eggs and those which are broken. It is then washed several times to remove traces of the sack or broken roe and also to desalt the product.

North Ridge Pumps was asked to find a solution for this particular application. It suggested a flexible impeller pump which is a good option for pumping viscous liquids, creams, gels and solid-laden fluids. Impeller pumps are able to transfer delicate liquids at slow speeds and ensure that they retain their consistency without the ingredients separating.

The pump head consists of a simple rubber impeller rotating at slow speed. The vanes create small pockets which are able to transfer the roe suspended in water gently, with very little damage. The pump operates as a cross between a positive displacement pump and centrifugal enabling a high flow at medium pressures to be achieved.

The pump suggested by North Ridge Pumps for this application is able to self-prime up to 6m, up to 40m head and at 44,000l/hr, making it a good solution for applications requiring the transfer of sticky, gooey, oily, thick or creamy liquids.

The pump benefits include:

Versatility: Operating at different speeds to handle different fluid consistencies, either at full motor speed or reduced via an inverter or gearbox.

Flexible mounting: Works mounted in almost any position enabling mounting in almost any location on a machine

Gentle pumping action: This ensures that the fluid remains unchanged, affected through shear by its working motion or breakages.

Finally, the flow is non-pulsing which enables accurate flow measurement via a flowmeter.

With the specified pumps in place on the machine the fish processor now has an improved method and process for the sanitary and swift extraction of high value ingredients.