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At first glance the duties of a winery pump would appear very simple - to move liquid from A to B. But with such a vast array of pump types and options, it is easy to get bogged down.
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Positive displacement
In general, winery pumps should be of a positive displacement type. Which means they can ‘suck’, that their rotor or stator speed is generally low, and they can work to high pressure (as much as 12 bar). The most common pump types used in wineries are eccentric screw, peristaltic, rubber impeller and lobe.
Variable speed
For gentle handling of wine and minimising dissolved oxygen pickup, a variable speed drive on the pump is essential. This can be achieved by a phase inverter or by a mechanical drive. Mechanical drives have more torque at low speeds, but the motor must be running to change the speed. If using a positive displacement pump for filtration, variable speed is essential to keep the filter below the maximum pressure.
Robust
In a busy winery it is inevitable that pumps will get some abuse. The most common errors are letting pumps run dry and pumping against a closed valve. This misuse will damage a positive displacement pump and if the stator is rubber on metal (for example an eccentric screw or rubber impeller pump) can result in burning the rubber – with the risk of tainting the entire tank. However, this can be avoided by opting for a product sensor on the inlet and a pressure switch on the outlet.
Remote
With a remote control (either wireless or wired) topping up a tank becomes a one-person operation. Racking can also be done precisely, especially if the remote can control the speed as well. It is now also possible to get remotes that connect to an app on your smart phone which provides pump control and flow rate info.
Photos: Danbury Ridge Wine Estate
the contents will flow under gravity though the by-pass, without power and unsupervised. I am not a fan of using a by-pass to control flow rate to a filter. The wine will be forced to go round and round the pump unnecessarily and a variable speed pump is much better.
Big and slow
For gentle handling, it is far better to have a large pump running at slow speeds. A small pump thrashing away at 2500rpm may do the same work and move the same volume, but is likely to cause a higher dissolved oxygen pickup.
Minimising dissolved oxygen (DO) pickup
Pumps are often falsely accused of causing DO pickup. However, if there is no oxygen getting into the juice or wine, then there can be no effect of the pump. To avoid DO pickup it is
particularly important to ensure: ◆ All hoses are fully flood filled with inert gas, and that plenty of inert gas is used in both the to and from tanks. ◆ O-rings on fittings are regularly replaced and fittings are tightened with a spanner or key. Hand tightening is not enough. ◆ Hoses are in good condition with no pin-prick holes, and with hose clamps which are tight. Preferably double hose clamps or even better hygienically swaged ends. ◆ Start slowly and finish slowly. These are the times when there will be maximum turbulence in the tank and the highest risk of DO pick up. If all the above is adhered to, a humble centrifugal pump will do the job and they have the advantage of being cheap and robust. If you need any more help selecting a pump, just give us a call.
By-pass
Positive displacement pumps will not allow the product to run though the pump head. A by-pass is useful for primming; especially with a long hose run to the pump. In addition, a by-pass can be used to allow gravity to gently do half the work. This means that when racking or transferring wine to and from tanks of the same size, half
www.bevtech.co.uk David Cowderoy 01444 411141 / 07400 208205 paper-plane david@bevtech.co.uk M AY 2 0 2 1 | V I N E YA R D
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