Pump geniuses lay your wisdom on me

[citizensnips]

Trying to decide between the two Keg King pumps for a new system. The biggest requirement on the pump will be pushing up to 45L of wort into a conical fermenter from the bottom port up. So I'm looking at 45L of hydrostatic pressure towards the end of transfer.

For any of those who know pump maths (I'm weak here) please enlighten me on which pump I should buy,

The MKII With specs of

Voltage: 220-240 at 50-60hz
Max Head: 3.4m
Max Flow: 19L/min
Fittings: 1/2 BS

and 65W with

Voltage: 220-240 at 50-60hz
Power rating: 65w
Max Head: 6.5m
Max Flow: 52L/min
Wiring: AU Standard 10amp plug
Fittings: 3/4" BSP

For the record I'll be running 1/2" fittings and hoses of everything as well as my kettle will sit virtually at the same height as the inlet on the conical it is running to (with the pump sitting below the level of wort of course).

Any advice would be much appreciated for a man finally buying a pump after 11 years of home brewing.

Cheers

 

[MHB]

Far from a pump genius, but have had a bit of experience.
Short answer is that I think both will do the job, if the extra $100 doesn't make you pucker I think it will be well worth the extra expense.
You will notice the extra power in unexpected places, like if you are using the pump to create the whirlpool it will make a big difference.
Another consideration is that a big pump doing it easy will last a lot longer than a little pump busting a nut!
Mark

 

[citizensnips]

Far from a pump genius, but have had a bit of experience.
Short answer is that I think both will do the job, if the extra $100 doesn't make you pucker I think it will be well worth the extra expense.
You will notice the extra power in unexpected places, like if you are using the pump to create the whirlpool it will make a big difference.
Another consideration is that a big pump doing it easy will last a lot longer than a little pump busting a nut!
Mark

Cheers Mark I recon you're probably on the money.

Very true with longevity. I'll be using it with CIP as well so can't hurt for some extra force.

I'd rather invest in something and know it would do the job rather than save the coin and hope it will achieve its purpose.

 

[millsii]

The biggest requirement on the pump will be pushing up to 45L of wort into a conical fermenter from the bottom port up. So I'm looking at 45L of hydrostatic pressure towards the end of transfer.

For any of those who know pump maths (I'm weak here) please enlighten me on which pump I should buy,

In regards to head pressure, it is the height of the liquid above the pump, not the volume of the liquid. So the pressure the pump will see will be the level of your wort in the fermenter.

As mentioned before, either of those pumps will do the job and given the pump will be roughly the same level as the inlet to your fermenter, the smaller pump won't be working overly hard.

For magnetic drive pumps you use the outlet/delivery side valve to control the flow rate. Effectively increases the pressure the pump is pumping against. For the larger pump you will need to throttle the valve more depending on your intended transfer rate into your fermenter.

 

[citizensnips]

In regards to head pressure, it is the height of the liquid above the pump, not the volume of the liquid. So the pressure the pump will see will be the level of your wort in the fermenter.

As mentioned before, either of those pumps will do the job and given the pump will be roughly the same level as the inlet to your fermenter, the smaller pump won't be working overly hard.

For magnetic drive pumps you use the outlet/delivery side valve to control the flow rate. Effectively increases the pressure the pump is pumping against. For the larger pump you will need to throttle the valve more depending on your intended transfer rate into your fermenter.

Yeah fair call.

I'm a little confused Millsii, are you suggesting the 45L of wort is irrelevant even though it will be physically pushing against the weight of the volume? I get max head is the height it can pump 'up to' so to speak but I assumed this was based on no resistance.

I'm just not convinced the MKII will push in against 40L of wort but I'm only going of a size/vibe thing.....not off any pump equations etc..

I'll also be using it to CIP as well as pasteurise my conical so the extra power could be of bonus there but I do realise the larger pump would have to be quite heavily backed off during transfer. That said those pumps don't mind it at all.

If I can be sure the smaller will do the job I'll get it

 

[millsii]

Yeah fair call.

I'm a little confused Millsii, are you suggesting the 45L of wort is irrelevant even though it will be physically pushing against the weight of the volume? I get max head is the height it can pump 'up to' so to speak but I assumed this was based on no resistance.

The height of the liquid is what matters. ie you can be pushing into a volume of 1000L, but if the height of the liquid is 1m above the pump, the pump will only see 1m of static head pressure, not 1000kg.

Alternately you may only have 20L of liquid, but the liquid top level is 10m above the pump. The pump sees the 10m static head and not the 20kg of weight.

This is why the pumps quote the delivery head pressure and not weight of liquid.

 

[MHB]

Those saying its about head (height of liquid) not about volume are quite right.
This is a super simple example of a pump curve, its a shame the supplier doesn't provide one for their pumps

It shows that at high head (for the two pumps mentioned 3.5 and 6.4 meters of water) the flow will be zero, at low head the flow will be at its highest. Remember that the curve is for water. If you were pumping wort at say 1.050 you wont get quite the same lift or flow from Pressure = Ro*g*h (Ro being the density of the liquid water is 1.000, g is acceleration due to gravity 9.81m/s and h is the head in meters), if you increase the density the head will fall.

Another important consideration is that for CIP pressure is important but so is volume of flow, you need enough to wet the entire inside surface of what you are cleaning, there are even equations that lay out how many litres/minute /meter of circumference you need to get proper cleaning (I would have to go digging if you need them).
Frankly I doubt either of these pumps will have a high enough pressure/flow at a meter or more of head to do an ideal job, you can get there but it will be slower.
Seriously go for the bigger pump and have a look for a rotating CIP sprayer, they will clean at lower flows.
Mark

 

[citizensnips]

Appreciate the explanations lads, that's a big help.

The height definitely makes sense although the fact that the back-pressure from the volume of the fermenter does not affect the performance of the pump is beyond me.

A lot of processes I use them for (at work) suggests otherwise,

You're right with CIP and I did like the idea of knowing I could go flat out with the larger pump and it be only of benefit.

Looks like my doubts will forever haunt me if I buy the small one and it's inadequate. Maybe you're on the money Mark, time to lash out and go big.

 

[millsii]

Appreciate the explanations lads, that's a big help.

The height definitely makes sense although the fact that the back-pressure from the volume of the fermenter does not affect the performance of the pump is beyond me.

A lot of processes I use them for (at work) suggests otherwise,

Good info from Mark!

You are right about it not purely being about the static head/lift. There are also dynamic losses when the fluid is moving. ie through any fittings, friction losses in the pipework and exit losses at the discharge point. However for most home brewing with the short pumping distances, discharge height and throttling discharge valve would be main things to consider.

Enjoy the benefits a pump brings to your brew day!

 

[citizensnips]

Yep was great advice.

Taking the dive and buying the big boy!

 

[Meddo]

My experience having had both with 1/2" ID tubing and BSP fittings on the smaller pump and 3/4" on the larger:

• The larger pump gives significantly more flow and generates a much better whirlpool, although this will be reduced somewhat if you're only running 1/2" lines.
• The large one is much noisier with a built-in cooling fan.
• The smaller version has a slightly better designed SS head with regards to draining / avoiding pooled fluids if oriented correctly.
• Neither will effectively drive a 1/2" rotating CIP spray ball, even the larger pump will only splash rather than spray the walls of a 460 mm diameter kettle.
• Can't see either having a problem filling the conical as you've described.
• The larger unit is significantly larger and heavier physically, and has much more robust hex head bolts rather than the fairly easily damaged philips head ones on the smaller unit.
• It's REALLY easy to snap off the outlet port on the stock plastic heads for both units when attaching fittings - I'd recommend budgeting for the stainless head upgrade for whichever you pick.
• The larger unit is a much better (although not perfect) match for sanitary tri-clamp fittings if you want to go down that path - although as far as I know neither have a sanitary tri-clamp head available, you'll need to adapt off the BSP ports.
• Personal opinion is that if the extra cost doesn't bother you (too much) the larger pump is a better unit and a better match for double-batches or above, especially for whirlpooling, although it does need significant throttling on the outlet side if you want to avoid splashing when filling cube / FV / whatever.

 

[koshari]

Appreciate the explanations lads, that's a big help.


A lot of processes I use them for (at work) suggests otherwise,

You may have some exposure with posative displacement type pumps which behave a little different.

But the comments above pretty much are all in reference to centrifical pumps where the fluid can slip round the impeller. the fundamental difference being that gagging the output of centrifical pretty much reduces the flow as per the diagram posted earlier.
A posative displacement on the other hand providing the motor doesnt stall results in the velocity through the valve increasing keeping the volumetric flow rate similar.

 

[citizensnips]

My experience having had both with 1/2" ID tubing and BSP fittings on the smaller pump and 3/4" on the larger:

• The larger pump gives significantly more flow and generates a much better whirlpool, although this will be reduced somewhat if you're only running 1/2" lines.
• The large one is much noisier with a built-in cooling fan.
• The smaller version has a slightly better designed SS head with regards to draining / avoiding pooled fluids if oriented correctly.
• Neither will effectively drive a 1/2" rotating CIP spray ball, even the larger pump will only splash rather than spray the walls of a 460 mm diameter kettle.
• Can't see either having a problem filling the conical as you've described.
• The larger unit is significantly larger and heavier physically, and has much more robust hex head bolts rather than the fairly easily damaged philips head ones on the smaller unit.
• It's REALLY easy to snap off the outlet port on the stock plastic heads for both units when attaching fittings - I'd recommend budgeting for the stainless head upgrade for whichever you pick.
• The larger unit is a much better (although not perfect) match for sanitary tri-clamp fittings if you want to go down that path - although as far as I know neither have a sanitary tri-clamp head available, you'll need to adapt off the BSP ports.
• Personal opinion is that if the extra cost doesn't bother you (too much) the larger pump is a better unit and a better match for double-batches or above, especially for whirlpooling, although it does need significant throttling on the outlet side if you want to avoid splashing when filling cube / FV / whatever.

Cheers for all the info Meddo. I've decided to go down to the bigger pump route although unfortunately I already have my system set with 1/2" Tri Clamp fittings so I will be reducing it's output down from 3/4" to 1/2". That said I will still be purchasing 3/4" BSP female tri clamp attachments for the inlet and outlet of the pump.

I'm assuming even with the downsize in inlet/outlet diameter it will still generate greater output through 1/2" lines than the 25W pump would be able to? Otherwise it could be a PITA upgrade of TC fittings.

Interesting that pump cannot sufficiently push through a CIP ball, I'm interested to see how it travels when I get it. Although I won't be using the CIP to clean (for the most part) I still do want it to have a decent enough flow to effectively disperse liquids.

Agree with the stainless head, I'd already settled on purchasing it with the pump.

During transfer I will have to heavily restrict the output of the pump to make sure it's entering the fermenter at the right temperature. From what I've heard and read, the magnetically driven pumps seem to thrive with a bit of back pressure. Thoughts on this?

 

[MHB]

Centripetal pumps as a class don't mind having the outlet throttled, mag or direct drive not really important.
I would be tempted to put the a 3/4 valve directly to the outlet, then the tri-clover, use the most open bore fittings you can (some cheap SS fittings have very nominal bores, use bigger rather than smaller) silicone tube has a low friction but still keep your runs as short as possible to minimise pressure loss and maximise flow.

Using CIP (cleaning in place) to not clean sounds like a bit of a contradiction in terms... For cleaning in place with a spray ball you need have enough flow to wet all the surfaces, enough force (pressure) to knock off soil and enough volume of flow to wash away the soil, it takes a fair bit of water/cleaner moving pretty fast. Directed sprayers let you get away with less, using more in one place than you can supply to the whole tank.
I went and looked up the numbers, Kunze says 20hL/meter/hour of tank circumference, say your CCV was 500mm in diameter the circumference would be ~1.6m, times the 2000l/h gives about 3,140L/h, or 52L/minute (coincidently that's the maximum flow for the bigger pump at zero head (you will get less, lift and flow loss)).
When you are looking at a spray ball, there are different types, go for one that sprays up and out (cleans lid and walls) the liquid running down will clean the lower sides and bottom of the CCV.

The top pattern will work better for you.
Mark

 

[citizensnips]

Thanks Mark, that's awesome info.

It's definitely a contradiction in the name sense yes. However it's main purpose will be in pasteurising the fermenter, just like a lot of commerical breweries use them for (as well as cleaning/running chem sanitiser through. I'm hesitant to mention this as I can imagine a lot of folk are going on to elaborate the dangers with pressure/vacuums as well as questioning how this will be achieved etc.....either way I'm keen to try and replicate it on a small scale system.

Regardless, that's a great recommendation on spray ball pattern, I hadn't thought of that.

Yeah looking at your figures and granted you were running 3/4" tube on the 65W pump, even with standard losses you would still achieve a reasonable spray pattern.

Appreciate your efforts,

Cheers