Poor March Pump 809 HS Flowrate

[JVD_X]

Hello,

I was hoping you guys could check my math. I have been having problems achieving a decent flow rate from my march pump. The outlet to the pump is facing up and the inlet is supplied by silicone tubing from about 1.5 feet above. The pump primes just fine.

The issue is that by the time I go through the RIMS and back into the mash, my maximum flow rate is very low. The top of my mash tun is about 3.5 feet above the outlet of the pump.

I use the 1/2" coolant quick disconnects from McMaster-Carr but realized that the internal is only 3/8" ID.

I did some fuzzy math and found that by moving from a true 1/2" port to a 3/8" port I am dropping my total potential flow from 7 gallons a minute to 3.3 gallons a minute and that is assuming zero head.

Does this sound right?

 

[lamarguy]

I use the 1/2" coolant quick disconnects from McMaster-Carr but realized that the internal is only 3/8" ID.

I've noticed that magnetic drive pumps don't create much head pressure, which is complicated by any line restrictions. That's why I went with 1/2" ID cam lock fittings from McMaster. Plus, the seals are replaceable.

 

[The Pol]

So what is your actual flow rate? 3.3? Id say that is excellent.

The more plumbing you have, the slower it will go, resistance, just like inbeer lines.

 

[Baron ken]

I'm getting slightly < 1 gpm pumping through a 20' long 3/8" OD CFC. I have 1/2" silicone lines but also use the QD's (with 3/8" ID). I was wondering if I might have kinked my CFC line when I wound it up. Hoping more people chime in with their flowrates.

 

[The Pol]

I'm getting slightly < 1 gpm pumping through a 20' long 3/8" OD CFC. I have 1/2" silicone lines but also use the QD's (with 3/8" ID). I was wondering if I might have kinked my CFC line when I wound it up. Hoping more people chime in with their flowrates.

With 20' of 3/8" OD tubing, your flow rate is about the max you will see.

 

[Baron ken]

With 20' of 3/8" OD tubing, your flow rate is about the max you will see.

That's fine I guess. I just got my pump and built my CFC so I had no idea what to expect. Just trying to get some reassurance that my flowrate was about right, thanks.

 

[Brewers Hardware]

If you're not seeing bubbles in the effluent line, then you're not cavitating and therefore getting all the flow you'll get. That's my experience anyway. It just takes a tiny bit of air in that pump housing and the flow rate plummets. That was my main reason for going with Tri Clover fittings, to eliminate air leaks.

I also agree with the other posters regarding the 3/8" HEX. If you can make a 1/2" or even try 1/2" you should see better flow rates. Try bypassing the HEX with the same elevations just to see what happens.

 

[JVD_X]

So what is your actual flow rate? 3.3? Id say that is excellent.

The more plumbing you have, the slower it will go, resistance, just like inbeer lines.

No, that is the maximum I calculated, I get more like 1/2 a gallon per minute.

In most situations this is just fine, for example going through my RIMS you don't want to compact the grain bed. However, for every other situation it's not good. I would have expected twice or three times that flow.

I was looking at centrifugal pumps but I have no idea which one would meet our needs. It also appears that they have the same head pressure issues as magnetic drive pumps... so I am at a loss.

If you're not seeing bubbles in the effluent line, then you're not cavitating and therefore getting all the flow you'll get. That's my experience anyway. It just takes a tiny bit of air in that pump housing and the flow rate plummets. That was my main reason for going with Tri Clover fittings, to eliminate air leaks.

I also agree with the other posters regarding the 3/8" HEX. If you can make a 1/2" or even try 1/2" you should see better flow rates. Try bypassing the HEX with the same elevations just to see what happens.

This isn't the HEX it is the coolant quick disconnects from McMaster-Carr. I ordered some full 1/2" ones today.

 

[Brewers Hardware]

This isn't the HEX it is the coolant quick disconnects from McMaster-Carr. I ordered some full 1/2" ones today.

Oops, i got your OP crossed up with Baron's post about the 20' X 3/8" HEX.

 

[JVD_X]

FYI - after I opened my lines up to the full 1/2" quick disconnects... everything is smooth sailing. I saw the largest difference in the amount of grain that was NOT getting stuck in the larger diameter quick-disconnect, which was a major contributor to my pain. The second was simply the increased flow.

The quick-disconnects I was using will work in a lot of systems - just not mine.

 

[OMJ]

I've noticed that magnetic drive pumps don't create much head pressure, which is complicated by any line restrictions. That's why I went with 1/2" ID cam lock fittings from McMaster. Plus, the seals are replaceable.

Do you have the item numbers for the cam locks you went with?

 

[lamarguy]

Do you have the item numbers for the cam locks you went with?

1/2" barb socket

I used several different plug styles to connect all of my equipment, with the most common being a 1/2" straight threaded plug.

 

[wizardofza]

FYI - after I opened my lines up to the full 1/2" quick disconnects... everything is smooth sailing. I saw the largest difference in the amount of grain that was NOT getting stuck in the larger diameter quick-disconnect, which was a major contributor to my pain. The second was simply the increased flow.

The quick-disconnects I was using will work in a lot of systems - just not mine.

I'm using the 1/2" coolant QDs w/ 3/8" ID and experienced the exact same issue with my March setup.

Do you have part numbers for the 1/2" onces you're talking about?

 

[JVD_X]

They are a lot more expensive but I ended up switching to: McMaster-Carr part numbers 6537K93 and 6537K65.

 

[wizardofza]

I might have to change. I'm currently using 6739K64 and 6739K59. I'm assuming these are the culprits.

Thanks.