little giant water pumps-opinions plz
 

http://www.jlaquatics.com/cgi-bin/sh...alogno=wp-lg2q
hello.has anyone used these pumps?.they look similar in performance to iwaki pumps.
it says the q series of the pumps are designed for high pressure applications
this model has 500gph at o head,and 400gph at 5 " head.
they come with 1\2 inch fittings
input appreciated.thnx

I have that pump (2-MDQ-SC), but haven't installed it yet.

It's really big (more than 10" long) and draws a lot of power (max: 180W). The flow specs are great though! It's a bit noisy, but nothing that a few rubber grommets can't fix.

I got mine at some flea market for ~$40 US...

180W is going to cause more damage than good. That was about what my HydroThruster runs at and it added more heat than the rad could remove. Add a monster rad or 2 smaller one's if your going to use it.

EDIT: Or use it with that chiller and test bed and don't bother putting it in a normal PC.

stats are here.... at 60hz about 2gpm at 4M head... so less than an iwaki md-20R would give while drawing only 50W...
http://www.littlegiant.com/littlegiant/specsheet.nsf/SpecSheets/580002/$File/995769_2-MD.pdf

Ben said 180w. Had no reason not to belive him. After a little searching.

http://www.wholesalepumps.com/Product.cfm?DID=16&PID=89

82 watts is a hell of a lot better than 180w! Still going to want a good rad though. And get a large case if you want it in the computer. :D

Odd though, volts (115) times amps (1.6) = 184W?

could be that the wattage listed is the amount of waste heat dumped into the liquid... which would mean the pump uses 102W of power to turn the impeller.

Or the amprage rating could be the max peak current drawn when starting the pump.

thnx for all the replies.it would be mounted externally.i use right now an 86 chevette heatercore,with 2x panaflo`s push pull arrangement.both fans are on shrouds

I have one of those pumps, it seems to do a fine job ( pushing salt water in my 125 gallon aquarium ) I dont know of any case that that monster would fit in.

Aardil

For AC : 115V*1.6A=184VA <- thats not the same as W.
The W is what does the usefull stuff (or not, depending on whether its pushing water or just heating it up ;) )

http://www.usmotors.com/Products/ProFacts/1-115.htm

The Little Giant wastes a lot of power, just because it's a true mag drive: the AC motor turns a spindle to which a set of magnets are attached, which in turn rotates the impeller.

The advantage is that none of this extra power ends up in the loop, because the motor is thermally isolated from the housing. The pump motor has a built-in fan, and under a certain load, it will start exhausting pretty warm air: warm enough to want to create a special vent just for it.

It would fit in my Chieftec Dragon DA-01 (see sig) but it would be a hard fit. I opted to go with the (leaky?) Johnson pump instead (see sig).

Pump info:
www.lgpc.com

I have a Little Giant 3-MD-SC myself. Its big, obnoxiously overpowered, and beefy. I like it. It was used in my extenal enclosure (and will be again, once I get it rebuilt).

somthing i remeber about in class...
since AC current is alternating.. there is a point where the current is at 0. sin wave. so @ 60Hz the curent is at 0 120 times a second. now i'm probly starting a flame war here but if I remeber corectly... you mutlipy the wattage (VxA) by 0.707
to get the true watt.
anybody want to verify or disprove this?

Yeah that works for a pure resitive load. Moters have capacitance and lots of inductance to mess up that neat formula. And don't forget the power factor problem caused by the current and voltage wave forms geting shifted in phase.

Grayson

Cant remember the numbers, but current lags slightly because it is out of phase with voltage, which is where the 0.707 comes in. I thought it only applys to three phase though....
However its not important really, the ampage given is start up current which can be upto 10x running current, and iirc that type of pump doesnt dump any heat into the water?

Oh well, dunno who this might interest, but anyway...
IIRC, 0.707 is the ratio between peak and RMS voltage.

The ratio between VA and W is the Cos(Phi) or Power factor. This varies between 0 and 1 depending on how inductive or resistive the load is.

purely resistive load (eg heater?), Cos(Phi)=1 so W=VA.
purely inductive load (ideal coil), Cos(Phi)=0, so W=0 (!)

Ok, here's another nice little link, with colourful sine curves etc.

Thanks for that excellent link lo, its been 12 years since I got out of tech school. This stuff is more fun to read when you dont have to take a test on it.