Re: Small Pumps 101

It looks like a fun question is a brewing about pump options and requirements. I received a great lesson from Dave Berg and it is worth repeating and expanding. "A pump has one working end." The other end just sucks. A centrifugal pump is an interesting device especially if you are planning on pumping hot liquids. The closer the liquid temperature gets to boiling, the more inlet head pressure is required. Trying to lift boiling or near boiling liquids above the vessel reduces the atmospheric pressure on the liquid and also lowers the boiling point. The result is cavitation due to steam. About the only style (other than positive displacement) of pump used with hot liquids would be a centrifugal pump with an impeller. Most folks use the magnetic drive version because the pump is completely sealed. The internal magnet is cast onto a impeller and the external magnet is connected to the motor shaft. The other option is a wet seal but the cost explodes at this point. If you look at a pump book, it typically gives GPM ratings at various head pressures and also list the maximum head available. What you typically want to do is to determine how much flow you require, ensure the pump is close to the appropriate temperature range, and then calculate the drag of the circuit to ensure you have adequate pressure to perform the required task. Bottom line is simple. If you are making a rims system, choose a pump with low hp, flow, and head pressure. If you are planning on a counterflow cooling system and speed is important, move toward the higher pressure or larger HP version. One last note: If you are planning on moving sparge water from a holding location to a mashtun or lautertun and if your water contains temporary hardness, the pump will cavitate as it disassociates the carbon dioxide and calcium from the warm water. Before you move the water, recirculate and watch the CO2 bubble. When the bubbles are done, the water works fine! OK, I needed a break from work and now need to get back. Next last note: Design plumbing and hoses for easy disassembly after each usage. A hose clamp connection is not a sanitary fitting and needs to be disassembled to ensure sanitation. Rick O What do I want in a pump? More specifically does it matter if the pump is Impeller driven vs Magnetic driven? Kris To unsubscribe from this group, send an email to: mnbrewers-unsubscribe(a)yahoogroups.com Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/