Author Topic: Motorized Valves for Potential Mote Liquid Flow Control  (Read 336 times)

galah

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Motorized Valves for Potential Mote Liquid Flow Control
« on: November 28, 2018, 10:48:40 PM »
Another possibility here is to use a motorized ball valve instead of a solenoid.
hint, search for 'DN20 motorized ball valve' on ebay

The one I have takes about 4s to turn on (or off). It draws ~30mA at 12V to switch.   Its a 3 wire thing, 2 wires turn it on, 2 wires turn it off.  Its got cams and switches to go idle (ie not draw current and stop in the correct spot) once its on (or off).         
3 LiPos, one for the moteino, 2 more stacked for the solenoid.        4 fets and 2 resistors for the drive.

They don't need any water pressure to actually operate, so good for those of us that are not on mains water. Solenoids I have checked seem to need pressure - not that I've checked a latching solenoid however.

And they have big bores so flow lots of water.   

Uncle Buzz

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Re: Motorized Valves for Potential Mote Liquid Flow Control
« Reply #1 on: November 29, 2018, 04:06:09 AM »
the problem with such motorized valve is the double action which needs power to open, and to close. So if you loose power before closing your valve, it will stay open... A simple action valve normally closed needs power to stay open, but if there's something wrong with power, it will automatically close itself and with water, it's often better to keep valves closed than opened...
« Last Edit: November 29, 2018, 04:11:04 AM by Uncle Buzz »

TomWS

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Re: Motorized Valves for Potential Mote Liquid Flow Control
« Reply #2 on: November 29, 2018, 07:46:42 AM »
Another possibility here is to use a motorized ball valve instead of a solenoid.
hint, search for 'DN20 motorized ball valve' on ebay
This looks interesting for another project I have (remote shutoff valve for the house supply), but requires way too much power for sprinkler zones. I didn't see any that activated with 30mA, most were 60mA, but, assuming you can find one that does, it's still 1.44WattSeconds vs <0.1WattSeconds for the 2xAA with boost to fire the Latching Solenoid. 

The other thing that concerns me about this valve is whether it is truly NPT threads.  Some claim this, but I've seen this before where the actual thread was BSP - which is expensive to find matching fittings in the US.  Have you bought any of these to check the fittings?
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They don't need any water pressure to actually operate, so good for those of us that are not on mains water. Solenoids I have checked seem to need pressure - not that I've checked a latching solenoid however.
This isn't an issue for an irrigation valve.  If there's no water, no point in operating.
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And they have big bores so flow lots of water.
Yes, very important for House supply shutoff!  Not so important for a landscape sprinkler.

Thanks for the lead.
« Last Edit: November 29, 2018, 07:49:53 AM by TomWS »

galah

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Re: Motorized Valves for Potential Mote Liquid Flow Control
« Reply #3 on: December 03, 2018, 05:45:26 PM »
{quote} The other thing that concerns me about this valve is whether it is truly NPT threads.  Some claim this, but I've seen this before where the actual thread was BSP - which is expensive to find matching fittings in the US.  Have you bought any of these to check the fittings?{quote}

I'm in Australia. I've got a 20mm one filling from a dam water tank I pump up to, to a drinking trough header tank. maybe 20m head.
Australia went metric recently. Well bank in 1974, just 44 years back.  However lots of plumbing fittings never converted. I can confirm the 20mm one is a standard 3/4 inch tap thread. Which is BSP.     British Standard Pipe.   
So you may be out of luck unless you can find a cheap and friendly chinese BSP to NPT adaptor.

My spreadsheet figured that the battery usage of the ball valve (sorry if that isn't the US term, but I still struggle with faucet to tap name mapping) suggested that at a couple of 4 second actuations a day was significantly smaller than the moteino current sleeping 8 minutes then doing a radio poll.   The 30ma / 12V was measured, the 4s was estimated by watching it open.    Although that power supply has an 11ma offset so maybe 20mA is closer the mark.        Its as easy to swap and charge 3 LiPo batteries as 1 every year or so.

I'm sure your charge pump and double AA wins on elegance and size and efficiency, but you also have a higher component count. My solution got thrown together quickly on a very small piece of veroboard and components already in the workroom.    (I'd bought the ball valve some months prior when I tripped over the add.

I've got a 1 inch motorized ball valve on order , interesting to see what that is like to actuate. That part of the home paddock irrigation leaks, I should turn it off too.

Do you know whether the latching solenoid requires significant water pressure to either actuate or hold?    All  the power-to-enable 24VAC kind I've played with need a few 10's of PSI to turn on.    I only get that sort of pressure when pumps are running, which is infrequent.

TomWS

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Re: Motorized Valves for Potential Mote Liquid Flow Control
« Reply #4 on: December 03, 2018, 06:42:37 PM »
I can confirm the 20mm one is a standard 3/4 inch tap thread. Which is BSP.     British Standard Pipe. 
Yeah, I realized that's what the DN20 stands for.
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So you may be out of luck unless you can find a cheap and friendly chinese BSP to NPT adaptor.
This is clearly a case of you get what you pay for.  For something like this probably the best I could do is around $8USD per adapter (need two per valve).  Still, where I would use this for a House Water Supply cutoff, the price of the fittings are insignificant - having a remote shut off is ideal.
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Do you know whether the latching solenoid requires significant water pressure to either actuate or hold?    All  the power-to-enable 24VAC kind I've played with need a few 10's of PSI to turn on.    I only get that sort of pressure when pumps are running, which is infrequent.
The solenoid self latches so, as soon as there is enough pressure to activate, the water will flow through the valve.  To shut off, the solenoid, again, releases and, in that case, the requirement is that the downstream pressure needs to bleed before the valve shuts off completely.  For irrigation, this works well in both cases.  It would not be good for a house shut off valve.


galah

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Re: Motorized Valves for Potential Mote Liquid Flow Control
« Reply #5 on: December 10, 2018, 10:36:59 PM »
The 1 inch DN25 motorised ball valve arrived.
I got a 5 wire job this time, thinking being able to indicate state would be good.
This seems to break out the control contacts a bit, compared to the 3 wire DN20.
Apply 12 v one way to a pair of wires, it opens.   Draws 20mA while the motor runs,  then hits a stop and draws ~300mA.
reverse the polarity to close.     Which is somewhat different to the description.

There are also a pair of contacts that close to indicate fully-open or fully-closed.  You would want to use those to disable the motor drive via an H bridge or whatever was used.   

There is a nice big 20mm hole up the centre when its on, should give decent flow.
Appears to have metal gears in the drive train, the DN20 looked to be plastic.   I don't see this as high duty cycle, but time will tell.
   

TomWS

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Re: Motorized Valves for Potential Mote Liquid Flow Control
« Reply #6 on: December 10, 2018, 11:28:50 PM »
The 1 inch DN25 motorised ball valve arrived.
I got a 5 wire job this time, thinking being able to indicate state would be good.
This seems to break out the control contacts a bit, compared to the 3 wire DN20.
Apply 12 v one way to a pair of wires, it opens.   Draws 20mA while the motor runs,  then hits a stop and draws ~300mA.
reverse the polarity to close.     Which is somewhat different to the description.
Curious.  Any idea why the power spike (other than maybe the motor stalls)?
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There are also a pair of contacts that close to indicate fully-open or fully-closed.  You would want to use those to disable the motor drive via an H bridge or whatever was used.   
Yeah, that's useful for verification purposes too.

I've been looking at motorizing a valve to provide proportional control.  Ball valves aren't great at this, but can still be used if the flow rate/angle ratio is learned.
There are a couple of 2 axis magnetometers that are reasonably inexpensive.  I use one on my Antenna Rotator and it works well. 

If you want to pursue this more I'll split this off into a new thread.
Tom

galah

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Re: Motorized Valves for Potential Mote Liquid Flow Control
« Reply #7 on: December 11, 2018, 04:20:50 AM »
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Curious.  Any idea why the power spike (other than maybe the motor stalls)?
I suspect there is a mechanical stop on this valve at each end, and it gets hit.   And the motor is wound with 12V/300ma = 40 ohms of wire.
The DN20 seems capable of continuous rotation. The DN25 seems to do 90 degrees, then backwards and forwards.  I'd have to disassemble more than just the cover to know more. 

Quote
I've been looking at motorizing a valve to provide proportional control.  Ball valves aren't great at this, but can still be used if the flow rate/angle ratio is learned.
There are a couple of 2 axis magnetometers that are reasonably inexpensive.  I use one on my Antenna Rotator and it works well. 
I didn't see much in the way good ways to attach an angle sensor to the ball.
Can I attach a photo of the valve with the lid off.. ok, I see an insert image button.

I can well imagine a mag field sensor would work on a beam antenna.  If I can figure out how to attach one to a depth gauge on a water tank I'm interested. I suspect the ultrasonic ones won;t like th humidity for long.
 
Valve open on the right
« Last Edit: December 11, 2018, 09:57:52 AM by Felix »

galah

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Re: Motorized Valves for Potential Mote Liquid Flow Control
« Reply #8 on: December 11, 2018, 04:25:53 AM »
not at all sure how well just timing how long you leave it open from the closed reference point would work.
I don't have any immediate need to modulate the flow of my taps.  On or off is good enough for me today.

TomWS

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Re: Motorized Valves for Potential Mote Liquid Flow Control
« Reply #9 on: December 11, 2018, 09:21:45 AM »
In my case, I have a set of valves redirecting the flow from my hot water recirculator into a radiant heat loop under my Master Bathroom floor.   Right now, at the beginning of the cold season, I manually set the valves so that a portion of the recirculated hot water flows into the loop.  The portion is set up to produce a 10 degree drop across the loop.  I'd use the proportional control valve to control this flow.

I have a prototype I started last year (it may be two years now  :-[ ) in which a 12V gear motor is coupled to the shaft of a ball valve using a 3D printed coupler.  The center of the coupler has a hole that holds a 1" long magnet orthogonal to the valve/motor shaft axis.  My thinking is that two analog Hall Sensors can be positioned at 90 degrees to each other to read the angle of the magnet as it rotates.  Another incarnation has a separate gear that has the magnet mounted on it and a 2axis magnetometer positioned above it would be able to read the angle, similar to my Antenna Rotator setup (https://lowpowerlab.com/forum/general-topics/low-volume-custom-pcb-enclosure/msg17695/#msg17695)

For a simple open/close valve I wouldn't use the valve stops and would simply drive the motor in one direction.  For the proportional valve, I'd want to reverse the motor to make sure the valve never has to fully open (or close as the case may be) to set a flow rate but I wouldn't use the stops in this case either.

I'll have to dig out that project to post photos of what I have thus far.

Tom