Mash beaten up from mash tun to lauter tun

[Woolsocks]

Our malt is getting beaten up as we transfer it from mash tun to lauter tun, causing major runoff issues. Here are pictures of the damage taking place:



It's moved by a centrifugal pump on a VFD. Is this the wrong kind of pump? Am I running it too fast? Do I need a different impeller?

[gitchegumee]

More information...

How fast are you running this pump? Is it on a VFD? What is the size of the pump? Are you transferring BACK to the kettle (as in decoction)? There is a whole discussion on mash pumps elsewhere here; suffice to say that I prefer a flexible impeller pump for this purpose, but centrifugal pump on a VFD should get the job done well without lots of hull destruction.

[dick murton]

A centrifugal pump 0f the type used for moving beer is not the best type of pump for moving solids such as yeast slurry or mash. Because they rotate at high speed to be able to transfer a liquid of low viscosity, they need to rotate at high speed, resulting in damage to the particles, in this case the grist, and although you may not notice it immediately, the impeller itself. Eventually, the impeller will be worn away to the point where is becomes useless. In larger breweries they generally use open vane low speed impeller pumps for moving mash, but I have heard of people successfully using diaphragm pumps, peristaltic pumps and Mohno (one of a number of spellings) pumps for mash. These types are certainly used for moving yeast slurries.




Afraid I don't have a picture of an open vane impeller pump, but typically they only have two impeller vanes.

[dick murton]

I didn't expect the drawings to take up that much space!!

[jboekamp]

What you need is a slurry pump of the kind mentioned by Dick. I would stay away from mono pumps (worm pump). Have worked in a micro brewery where we had problems with one damaging the husks during transfer. I have heard of centrifugal pumps with special impellers to make them suitable for mash transfer but have never seen any in action.

Cheers,
Jurriaan

[CPESystems]

Flexible impeller pump

A flexible impeller pump is a good option and reasonably priced when compared to a peristaltic or progressive cavity pump. These are very popular in distilleries for mash in wort transfer.

http://www.cpesystems.com/collection...-impeller-pump