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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Is there a fluid by-pass in a submersible fountain pump.
I was just curious if one of these pumps has a hi pressure by pass. I
was going to use one to make a low pressure coolant pump with limited flow, but don't want to burn the motor up if there is not a by pass. Thanks, Steve |
#2
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Is there a fluid by-pass in a submersible fountain pump.
On 15 Apr 2006 20:43:58 -0700, "
wrote: I was just curious if one of these pumps has a hi pressure by pass. I was going to use one to make a low pressure coolant pump with limited flow, but don't want to burn the motor up if there is not a by pass. Thanks, Steve My guess is that they are centrifugal or "impeller" type pumps. That type of pump is intrinsically pressure-limited, doesn't need need a bypass. A restriction in the line (or gravity head) reduces flow rate and downstream pressure while max pump outlet pressure remains fairly constant at given RPM. |
#3
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Is there a fluid by-pass in a submersible fountain pump.
The power curve for centrigugal pumps peaks at maximum flow & pressure.
At zero flow [blocked outlet] very little power is used because the only work being done is slightly heating the fluid. At maximum flow and zero head there is also very little work being done because there is no lift [pressure increase]. Only positive displacement [cylinder or gear] pumps have a problem with low flow. Bugs |
#4
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Is there a fluid by-pass in a submersible fountain pump.
Bugs wrote: The power curve for centrigugal pumps peaks at maximum flow & pressure. At zero flow [blocked outlet] very little power is used because the only work being done is slightly heating the fluid. At maximum flow and zero head there is also very little work being done because there is no lift [pressure increase]. Only positive displacement [cylinder or gear] pumps have a problem with low flow. Not universally true. Some centrifugal pumps do require a minimum flow for cooling parts of the pumphead - like bearings. In one actual centrifugal pump rated for 45 l/min, that I just had for repair, the minimum flow is 3 l/min and this pump has plastic sleeve bearings inside pumphead. It all depends on the pump design. Kristian Ukkonen. |
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