Home of the BrewNosers

GuingesRock wrote:I've seen less ramshackle ones than that in the OR. They use peristaltic pumps like that for cardiopulmonary bypass.

GuingesRock wrote:It's been a long long time since I worked in an OR. But they would be brilliant pumps. Might be worth doing a search for used medical equipment ...peristaltic pumps.

GuingesRock wrote: They change the disposable sterile tubing every time

http://byo.com/american-pale-ale/item/1280-pump-it-up

Peristaltic Pumps

Another pump useful in homebrewing is a peristaltic pump, perfect for establishing sparge rate in an infusion mash.

Homebrewers typically rely on gravity to transfer liquids. In a common infusion mash setup grains are sparged by gravity draining hot water from the “hot liquor tank” through the lauter tun, and wort is collected below. Five-gallon batches are usually sparged within 30 minutes, requiring a flow rate of at least 600 milliliters per minute.

One objective during the sparge is to equalize the flow rate of water on top of the grain bed with the wort runoff flow from the bottom of the grain bed. If the runoff is too slow relative to the sparge, the lauter tun may overflow. If the runoff is too fast, the risk increases of a stuck runoff in which the siphoning action of the runoff flow sucks the grain bed in on itself, and the grain bed becomes compacted and impermeable to flow.

Equalizing sparge and runoff flows can be can be difficult with gravity drainage. The flow rate from a given vessel depends on the level of liquid in the vessel, and while the level in the lauter tun is usually constant during the sparge, the level in the hot liquor tank vessel may not be.

And since the flow rate from the hot liquor tank depends on the liquid level inside, the homebrewer must make continual adjustments of the
outlet valves in order to equalize the flows.

A peristaltic pump can achieve constant flow rates with a single setting and few or no adjustments. This pump is a type of positive displacement pump. Unlike the centrifugal type, the flow rate is insensitive to inlet and outlet pressures over the working
pressure range of the pump. The range is specified by the manufacturer and within it, each rotation of the roller assembly pumps a specific amount of fluid.

The advantages of the peristaltic pump are easy cleaning (only the tubing contacts the fluid), simple flow adjustment, and no priming requirements. However, peristaltic pumps are expensive. New pumps with sizes and features useful to homebrewers range from $150 to $400.

A good peristaltic pump choice is the Masterflex 7553-50 pump drive with a model 7021-24 pump head. This is available from Cole-Parmer, a scientific equipment company. Food-grade Norprene or Tygon tubing should be used.