Little giant pump 3-MD-HC

[klyph]

I bought a used pump for 80 bucks. Hope I don't die from all the chemicals and/or sewage it was used for.

 

[diatonic]

I bought a used pump for 80 bucks. Hope I don't die from all the chemicals and/or sewage it was used for.

An overnight soak in Oxi Clean should remove any residual chemicals & sewage.

 

[dozer4412]

I tried this post yesterday, but was in a little too much of a hurry and think it’s a little confusing.

I just recently got a Little Giant 3-MD-HC pump and am planning to connect it to tubing using Tri Clover clamps. I see Austin Homebrew Supply sells a polypropylene coupling because “threading metal fittings onto the pump head can damage the pump’s threads”. Replacement heads for the 3-MD-HC seem to be in the $100 range and I’d rather not mess up my threads and have to worry about getting a new head. I’m thinking for getting a 3/4" to 1/2" reducer for the inlet, link below, and then threading a 1/2" female Tri Clover onto the reducer.

I’d like to get peoples thoughts about this. Will a reducer make it harder to prime? Should I just go with a 3/4" polypropylene nipple and then thread a 3/4" Tri Clover onto that? If I do go with a 3/4" nipple and 3/4" Tri Clover will I have any issues connecting a 3/4" Tri Clover to a the 1/2" Tri Clover on the end of my tubing?

http://www.amazon.com/dp/B00270ZS5I/?tag=skimlinks_replacement-20

 

[BrewBeemer]

Keep the inlet full size at 3/4", any inlet restriction or fitting reduction size has a big reduction in the pumps performance. Reducing the outlet isn't a problem as with a valve on the outlet to throttle the flow down.

 

[diatonic]

Temperature ranges are to be taken with a grain of salt. I wouldn't think twice about using it for boiling wort. Often times temperature ratings (or any other rating) are simply made at whatever the highest temperature that the equipment would be expected to be used in the typical application for the piece of equipment.

The housing is made from Ryton, which is a proprietary plastic made by Chevron Phillips. Here is a quote directly from the Chevron Phillips website:

PPS (Ryton) has not been found to dissolve in any solvent at temperatures below about 200°C (392°F).


It's up to you...

I think this is worth discussing, and I have one of these pumps on the way.

There is more at play in the temperature ratings than just the materials used in the pump. I think that if it was a good idea to use these pumps at boiling temperatures, the manufacturer would certify them to that temperature. It would help them sell more pumps.

Since it is a self-priming pump, it must draw a suction at the inlet of the pump. If it didn't, it couldn't self prime. When you have liquid at close to its boiling point, and drop the pressure, you can drop below saturation pressure and have cavitation. Essentially boiling at the inlet, and those bubbles collapsing at the outlet. I don't know if that is why they are only rated to 200F, but it might be.

From http://en.wikipedia.org/wiki/Cavitation:
Suction cavitation

Suction cavitation occurs when the pump suction is under a low-pressure/high-vacuum condition where the liquid turns into a vapor at the eye of the pump impeller. This vapor is carried over to the discharge side of the pump, where it no longer sees vacuum and is compressed back into a liquid by the discharge pressure. This imploding action occurs violently and attacks the face of the impeller. An impeller that has been operating under a suction cavitation condition can have large chunks of material removed from its face or very small bits of material removed, causing the impeller to look spongelike. Both cases will cause premature failure of the pump, often due to bearing failure. Suction cavitation is often identified by a sound like gravel or marbles in the pump casing.

In automotive applications, a clogged filter in a hydraulic system (power steering, power brakes) can cause suction cavitation making a noise that rises and falls in synch with engine RPM. It is fairly often a high pitched whine, like set of nylon gears not quite meshing correctly.

I think that if Little Giant could ensure that they would operate well at 212F, they would say so. They could sell more pumps. They would be able to be used in more applications.

It's just something I thought was worth discussing.

 

[jwright]

I've been watching the last several auctions for these on eb@Y.

Today's pump went for $180. looks like he is selling them one at a time now - a much better way to make the most $$.

Unfortunately this is what ebay is great at - putting a small number of bidders up against each other to really drive the price up. Look at the increase in the last month, <90 to now 180! That alone makes it hard to stomach. Add to that a healthy dose of skepticism about some of the 'bidders' and it really makes me HATE using the fleabay.

Arrrgh

Just venting because I don't have one.
jason

 

[MrH]

Since it is a self-priming pump, it must draw a suction at the inlet of the pump. If it didn't, it couldn't self prime. When you have liquid at close to its boiling point, and drop the pressure, you can drop below saturation pressure and have cavitation. Essentially boiling at the inlet, and those bubbles collapsing at the outlet. I don't know if that is why they are only rated to 200F, but it might be.

Where did you get the idea that these are self-priming? I've been using one for 15 years, and while it may be a lot of great things, self-priming it certainly aint. I may be wrong, but I don't think I've ever seen a mag coupled pump that was self-priming. In fact I think that would be incredibly difficult to pull off considering the relative weakness of the magnetic coupling. We rarely pump at true boiling temps. Unless you're pumping while actively boiling, the temp drops pretty quickly at flameout, especially if you whirlpool before cooling. I know that for my setup, by the time I start pumping the temp is usually down to around 204F, which is really barely over the rated temp. Like I said, 15 years and I'm still using the same head and haven't seen any crazing at all.

MrH

 

[diatonic]

Thanks MrH! Not sure why I thought they were self priming, but good to hear from someone who has so much experience with one. I'll chalk it up to trying to consume too much information while enjoying homebrew lately

 

[MrH]

Thanks MrH! Not sure why I thought they were self priming, but good to hear from someone who has so much experience with one. I'll chalk it up to trying to consume too much information while enjoying homebrew lately

Geeze, you're really confused diatonic! I think you meant consuming too much homebrew while enjoying information hehe .

Anyway, on the priming front, I always had trouble priming mine, but the version I have has a 1/2" inlet. I think you all will have a much easier time achieving and keeping prime with a 3/4" inlet. While upgrading my rig this time around, I have mounted mine vertically and higher up (closer to my kettles) so hopefully I'll have an easier time with it. I've also installed a drain at the lowest point in my plumbing for ease of cleaning and just in case I need to encourage the prime.


MrH

 

[BrewBeemer]

I was thinking add a radiator drain petcock near the top of the pump inlet to let the trapped air escape, the most mess will be just a couple of drops when filled with liquid. PNW, like in Washington state?

 

[evandy]

Keep the inlet full size at 3/4", any inlet resstriction or fitting reduction size has a big reduction in the pumps performance. Reducing the outlet isn't a problem as with a valve on the outlet to throttle the flow down.

Isn't there a limit to this? If the tubing to feed the pump is 1/2", then puting a 3/4 to 1/2 reducer won't change anything.

 

[MrH]

PNW, like in Washington state?

Yes, on the peninsula...

 

[BrewBeemer]

Isn't there a limit to this? If the tubing to feed the pump is 1/2", then puting a 3/4 to 1/2 reducer won't change anything.

I would never use it that way, I would use a 3/4" inlet pump with 3/4" feeding it.
As far as using 3/4" tubing then reducing it down to 1/2" at the pumps 1/2" inlet this will have less tubing flow resistance vs using straight 1/2" but not that much of a difference. The biggest problem's at the pump with the 1/2" inlet vs 3/4".
When I dumped my March 809 pump for a LG that has 3/4" inlet I used a reducer to step the 1/2" PVC to 3/4" on the LG vs the March pumps 1/2" inlet just to get the Koi ponds waterfall flowing again for their O2. Ok it flowed until I repiped with all 3/4" on the inlet side a couple days later. With 3/4" at 7' long for the inlet vs the 1/2" before the LG pump woke up big time. They hate any inlet flow resistance vs the size that came with the pump.

 

[GreenMonti]

I can't think of any pump that like's a smaller intake then what it comes with. The venturie is designed around the flow input. I also think pump placement has a lot to do with the different experiences with said pumps. Some have little, and some have heavy head pressure by comparison. That's right, head pressure goes both ways. A 1/2" drain at 1 foot has much less drainage then a 1/2" drain at 4 feet. This also applies to a single tier vs a double tier stand.

 

[BrewBeemer]

I can't think of any pump that like's a smaller intake then what it comes with. The venturie is designed around the flow input. I also think pump placement has a lot to do with the different experiences with said pumps. Some have little, and some have heavy head pressure by comparison. That's right, head pressure goes both ways. A 1/2" drain at 1 foot has much less drainage then a 1/2" drain at 4 feet. This also applies to a single tier vs a double tier stand.

That about says it all about a manufactures pump with all the engineering designed into it then a pump owner trying to use it for what it was not designed or used as with a do it yourself improved design or use added.
Frictional tubing fluid flow losses alone without any head pressure not counting the diameter, length, number of bends plus the fluids viscosity all add to the pumps performance output or lack of. Thru digging wells in the 70's plus being around a family friend that was in the pump bunsiness for over 60 years I was always told to use the manufactures pumps high output specs and cut them in half to meet real life or world performace flows after it's installed. Pressures at different flow volumes will change also. If this matches your demand of a selected pump you've picked the right pump. This with centrifugal pumps. Ranch high pressure piston pumps pushing uphill 350' to a tank is a totally different topic on specs as well muti stage submersible well pumps. This has worked for me keeping me out of trouble with selecting the proper pumps the past 41 years. With the offer of two brand new March 908 pumps for $75 I jumped on them and only later found out I wasn't happy with their outputs. Good thing I unloaded them right away and went to LG pumps 4 years ago and never looked back. My $0.02 on this topic.

 

[benbradford]

I previously owned an aquarium business, and had fairly good luck with the little giant pumps, however, I did see some old models fail at times. My favorite pump when installing and personally, was the mag 7 or mag 9 or mag 12 pumps. I have not been able yet to find any info on the temperature rating of these, but for the price and the performance, they were always my favorite. I found a phone number and am thinking of calling during business hours to see if they can give some info on the temps...

 

[FenoMeno]

I am a bit confused on the 3/4 inlet to 1/2 out.
I just bought @ of these for my build, and looking for correct disconnects. I bought all 1/2" silicone as all my other ball valves were 1/2.
I understand the restriction of a reducer, but how do you get around it if everything else is 1/2"? (this is my first build)

Now I am not sure what size connects to buy either...

 

[TomRep]

I e-mailed Supreme (Mag pump company) and they do not make any Mag pumps to the standards we need.
tom

 

[diatonic]

I am a bit confused on the 3/4 inlet to 1/2 out.
I just bought @ of these for my build, and looking for correct disconnects. I bought all 1/2" silicone as all my other ball valves were 1/2.
I understand the restriction of a reducer, but how do you get around it if everything else is 1/2"? (this is my first build)

Now I am not sure what size connects to buy either...

On the inlet I used a 3/4" NPT close nipple, 3/4" NPT 90 elbow, 3/4" to 1/2" reducer bushing, to a 1/2" NPT male QD. Outlet has a 1/2" NPT ball valve to a 1/2" NPT male QD. Works great. I also use 1/2" silicone.

 

[FenoMeno]

Diatonic,
Just watched your video: March vs. LG --Thanks for the demo!
I am anxious to try my 2 new pumps.
I guess watching your whirlpool with the 3/4 to 1/2, doesn't worry me anymore. It looks like it did fine. Perhaps 3/4" all the way would really make this pump sing, but for our purposes...well your video shows it all. Thanks again.

btw, how do you have that mounted?

 

[FenoMeno]

Actually, my thoughts for the inlet were to order 3/4" barb, and try to squeeze my 1/2 silicone over it, and skip the reducer. Anyone try that stretch?