How do you control your pump speed? PWM help

[BeirKaiser]

Hello everyone,

I received bought a pump for my homebrew setup. How does everyone control the speed of the pump? I’ve found so few mini chips with knobs but no idea what to pick.
Stats:

• Name: Solar Water pump
• Brushless motor
• Material: Plastic
• Color: Black
• Input/Output: 1/2 "male thead
• Voltage: 12 V DC
• Nominal Maximum Current: 1000MA
• Power: 22 W
• Max Flow: 800 L/H
• Max Water Seat: 5 m
• Max circulation water temperature: 100 ° C

It only has a motor +/- and power +/-, no third wire. Or a brake. No idea what I’m doing View attachment 715452View attachment 715453View attachment 715454View attachment 715455

 

[Nagorg]

With a ball valve on the outflow side. So, not controlling the pump speed; it runs full throttle. The valve controls the flow though which it reall what you are after...

 

[BeirKaiser]

With a ball valve on the outflow side. So, not controlling the pump speed; it runs full throttle. The valve controls the flow though which it reall what you are after...

Yeah but on a ball valve you’re increasing the pressure in order to reduce slow. I’d rather just makes the motor go slower than have pressure washer

 

[Nagorg]

Whats the concern? Its pretty much the normal way to regulate flow with a water pump.

 

[Vale71]

Whats the concern? Its pretty much the normal way to regulate flow with a water pump.

It's actually the least recommended way to regulate flow with a water pump.

 

[Vale71]

This is the one I'm using:

https://www.amazon.com/Universal-St...p+speed+pwm+controller&qid=1611418150&sr=8-39

 

[Nagorg]

It's actually the least recommended way to regulate flow with a water pump.

Why do you say that? I suppose it could depend on the pump but this is a home-brew thread and using a ball valve is quite common.

 

[Vale71]

Why do you say that? I suppose it could depend on the pump but this is a home-brew thread and using a ball valve is quite common.

Cavitation will happen and it will ruin your pump even when home brewing. Common does not always equal best. As a matter of fact I find the opposite is (alarmingly) often the case.

Plus ball valves have non-linear response and this can make getting exactly the flow rate you need very hit and miss. Plus they need to be disassembled and cleaned every time. And the list goes on...

 

[Nagorg]

Cavitation typically only happens when starving the pump from the intake side. I've been using a ball valve on the outflow side of my chugger for years and never had any problems.

Besides, what kind of flow control do you need? I struggle to understand the need for the type of precise control that you are referencing.

 

[day_trippr]

My 17 year old pair of valve-throttled 815pl mag pumps say someone is worrying too much...

Cheers!

 

[Vale71]

For example in a recirculating infusion system? Increasing the flow by even a small amount past the optimal point can easily result in a stuck mash and that's really the worst that can happen in a recirculating system. I'm assuming the OP has something like that in mind.

 

[Vale71]

My 17 year old pair of valve-throttled 815pl mag pumps say someone is worrying too much...

Cheers!

Probably. Either that or you're not using them often enough...

 

[day_trippr]

Lol you know better than that

Cheers!

 

[BeirKaiser]

I struggle to understand the need for the type of precise control that you are referencing.

I’m not worried about precision, the is defaulted at 800L/h on my pump and I don’t need to restrict the flow and increase pressure. I don’t need to power pressure wash my grains when sparging.

This is the one I'm using:

https://www.amazon.com/Universal-St...p+speed+pwm+controller&qid=1611418150&sr=8-39

Thank you, good to know someone else had the same idea. Now I just need to find a brushless version

 

[Nagorg]

I don’t need to power pressure wash my grains when sparging.

LOL Okay, whatever and to each his own. I really dont think there would be a problem there but glad you got the answer you were looking for.

 

[Misplaced_Canuck]

If it makes you feel better, I have a Little Giant pump that I've used for almost 30 years, using a ball valve on the output side, at anywhere between 10 and 40 batches per year. Still going strong.

MC

 

[Birrofilo]

With a ball valve on the outflow side. So, not controlling the pump speed; it runs full throttle. The valve controls the flow though which it reall what you are after...

If the pump is of the kind with a "magnetic transmission" (trascinamento magnetico), the pump does actually run at the reduced speed which is dictated by the ball valve, and there is no risk of damage.

This is a common solution which is also in-built inside many "all-in-one" kettles.

A pump with some kind of solid transmission would instead be stressed by the ball valve and it's the pump speed which must be controlled.

 

[Vale71]

If the pump is of the kind with a "magnetic transmission" (trascinamento magnetico), the pump does actually run at the reduced speed which is dictated by the ball valve, and there is no risk of damage.

That's not what happens at all. Look up how a magnetic drive pump actually works, for example here:

https://www.michael-smith-engineers.co.uk/resources/useful-info/magnetic-drive-pumps
The small pumps we use are of the "canned motor" type.

 

[Birrofilo]

That's not what happens at all. Look up how a magnetic drive pump actually works, for example here:

https://www.michael-smith-engineers.co.uk/resources/useful-info/magnetic-drive-pumps

I don't see the connection between what you say and the document you link.

 

[BeirKaiser]

Thank you for everyone that helped! I contacted several companies, most of which in broken English, but I finally found a solution! Two birds with one stone in fact! This will control my pump and convert it to AC!

https://www.amazon.com/UTUO-dimmable-Adjustable-transformer-brightness/dp/B08MZZPB53/

 

[day_trippr]

"Transmission" may be a bit strong of an analog for how a "mag-pump" works, I prefer "variable slip clutch"
But, indeed, that is a side benefit of the design - the primary benefit being not having to deal with shaft seals in a fairly hostile application (pumping near boiling acidic sugar water).

btw, the linked article doesn't even discuss the clutch effect...

Cheers!

 

[Vale71]

btw, the linked article doesn't even discuss the clutch effect...

That's because it doesn't exist.

 

[Birrofilo]

"Transmission" may be a bit strong of an analog for how a "mag-pump" works, I prefer "variable slip clutch"
But, indeed, that is a side benefit of the design - the primary benefit being not having to deal with shaft seals in a fairly hostile application (pumping near boiling acidic sugar water).

btw, the linked article doesn't even discuss the clutch effect...

Cheers!

I know, the word is "drive", but as a foreign writer I don't always have the correct term at hand.

But the point is that the magnets will try to spin the pump at a certain speed, but the pump will turn only at the speed which is allowed by the ball valve, and without any damage.

 

[day_trippr]

.

 

[TheMadKing]

Magnetic couplings can indeed decouple and save your motor from an overload condition, but the impeller does not very its speed depending on the pressure demands on the system. When decoupling occurs, the impeller just stops, then you have to turn your pump off to allow the magnets to recouple and then it will work again unless there is too much resistance on the impeller.

A PWM pump DOES allow for very precise control of flow, as well as greater energy efficiency, and longer pump life. Throttle valves are far more common, and far more widely used in industry and there is absolutely nothing wrong with them.

The non-linearity of ball valves can be mitigated by using a linear control valve (gate valve) and it will get you more than enough precision for brewing. The Blichmann Riptide pumps come standard with these valves and I love mine.

Turns out everyone is right here.. ish

Here are some helpful links

https://www.michael-smith-engineers.co.uk/resources/useful-info/magnetic-couplings
https://www.isa.org/intech-plus/2017/march/control-valve-versus-variable-speed-drive-for-flow
https://www.mpofcinci.com/blog/flow-control-valve-types/

 

[chipmunk]

Magnetic couplings can indeed decouple and save your motor from an overload condition, but the impeller does not very its speed depending on the pressure demands on the system. When decoupling occurs, the impeller just stops, then you have to turn your pump off to allow the magnets to recouple and then it will work again unless there is too much resistance on the impeller.

I’ll add that contrary to what is commonly thought, the maximum load on pump motors is usually at full flow conditions and not when throttled down.

 

[jddevinn]

Cavitation will happen and it will ruin your pump even when home brewing. Common does not always equal best. As a matter of fact I find the opposite is (alarmingly) often the case.

That's not what happens at all. Look up how a magnetic drive pump actually works, for example here:

https://www.michael-smith-engineers.co.uk/resources/useful-info/magnetic-drive-pumps
The small pumps we use are of the "canned motor" type.

Blitchmann, March, Chugger all disagree with you and state to use the valve on the outlet to control flow. This style pump will not cavitate unless they are starved (valve on inlet) or not bled.

https://www.marchpump.com/blog/wher...en trying to control the,is trying to put out.

https://www.blichmannengineering.com/pub/media/wysiwyg/RipTide_Pump_V8.pdf

 

[Stand]

Six of one half dozen the other. Do what makes you happy.

 

[BarryBrews]

I'm sure the engineers at Blichmann knew what they were doing when they added the outlet control valve. With my flow meter (see attached photo) and the outlet valve control, I get total flow control and reproducibility. Plus the Blichmann pump is soooo quiet! Literally, except for the first 75 minutes of the 90 minute boil, the pump runs continuously throughout the brew day. I really feel this is a top drawer set up and if amortized over 200 brews would only cost $1.50 per brew day. So, after you are sure you love brewing, you should think long term when it comes to your equipment as most of it could last generations.

 

[Toto's]

Well me i did a DIY variable outlet, i added a dimmer to the outlet for the simple reason that i find is loud but i have a valve at the output as well.
I think that there is no problem to control the output with a valve but at the end
Do what makes you happy

 

[50calshooter]

Pumps made for brewing are designed to have the out put flow regulated. You never regulate the speed of a pump by regulating the motor. It is an A.C. motor and is not designed to have the voltage or speed altered. D.C. motors are a different breed-you alter the output by altering the Direct Current voltage.

 

[greglarious]

Pumps made for brewing are designed to have the out put flow regulated. You never regulate the speed of a pump by regulating the motor. It is an A.C. motor and is not designed to have the voltage or speed altered. D.C. motors are a different breed-you alter the output by altering the Direct Current voltage.

This statement is coming from a place that is unfamiliar with either motors or circuits. Speed is almost never controlled via voltage. Pulse width modulation (PWM) is how both AC and DC motor speed is controlled. PWM speed controllers are affordable and available for every application you might need. Attempting to adjust speed by altering voltage as you suggested is an extremely poor choice applicable only to DC motors. Nobody would ever do that as reducing voltage will also reduce torque along with speed. There are certain very specific motors that do not support PWM speed controllers.