I am doing a water system automation to my whole house. Every morning, I have open a ball valve to the underground water tank in my backyard to fill the municipal drinking water.
Now, I want to control the Ball valve with an Arduino. I could use a solenoid valve, but I cannot control the solenoid valve manually when there is no electricity. It doesn't have a manual handle.
Therefore, I decided to attach a high torque dc motor to the existing ball valve, so that I can control it manually with my hand when required.
But cannot decide what motor to use. Servo, Stepper, Actuator or normal DC?
AND I want it to cost below $20.
Oh, so you are the one we all have to thank for our water.
In principle any of these could be made to work. Between a servo and a stepper, the former would make more sense in this application. An actuator or even solenoid can work given the correct transmission mechanism. A DC motor can also work, given a suitable gearbox and a limit switch to detect when it's 'done'.
What is cheapest ends up being a tradeoff between the motor, additional drive/detection electronics and the mechanical parts needed to make this work.
Frankly in your place I'd consider just using a solenoid-controlled valve instead and keep a battery at hand to "kick start" it in case of a power outage. Make a circuit that also has a push button or some other manual control to engage the device. Or maybe make a manual bypass loop around the electronic valve with the kind of manual valve you showed; this way you don't need a battery, but you'll have to remember to manually close the bypass loop at a later stage if you opened it during a power outage. Mechanically this will all be a lot simpler and more robust than what you're trying to do now.
I'd consider just using a solenoid-controlled valve instead and keep a battery at hand to "kick start" it in case of a power outage.
Unfortunately, charging the battery would be more of a hassle and would add more complexity to the project.
Or maybe make a manual bypass loop around the electronic valve with the kind of manual valve you showed; this way you don't need a battery, but you'll have to remember to manually close the bypass loop at a later stage if you opened it during a power outage.
This is good, but as you said I will need to remember to close the manual valve that I opened during the outage. So this also sucks.
Big problem with that type of valve is its tendency to seize up or get stiffer to operate.
A lot depends on the type of water, soft, hard, aggressive.
Cheap valves with brass balls can quickly corrode if the water is slightly alkaline and goes for the zinc.
You can get DZR (dezincification resistant) fittings, or look for stainless balls.
Cheap "O" ring internals soon leak especially if the ball gets pitted.
Watch out for unbranded Chinese stuff.
Most valves benefit from being exercised. Just an open and close once a day prolongs life.
If temperature isn't too high, I would go for decent PVC valves.
Never had one fail, but many brass ones have.
I have PVC ball valves fail quite often because they are the threaded type to connect to the threaded steel pipe. Pipe threads are tapered and the more you screw them together, the more pressure they put on the PVC housing. If you can get them for Metric threads, not tapered, they might last many years.
Hi there
I worked with valves and pipework in industry for decades.
Failure of plastic valves was rare, but badly made joints did.
A lot of people don't know the difference between NPT, BSP, RG etc.
A taper joint always uses a sealant, often PTFE tape. A parallel thread is not meant to seal on the thread, but people do and it leaks. Parallel is used with a gasket or O ring.
A lot of smaller plastic valves are demountable and one of the tails puts the pressure on the internal seals. If the tails get loose, the seal is poor and it leaks.
Quarter turn valves like the one shown fail in service usually down to seal breakdown.
It's hard to buy a decent one and even the good brands like Pegler are bad.
The point is that if you use a bad valve and it seizes, you need some motor protection.
First before choosing any motor you need to know how much torque is required. I would beg, borrow or steal a sial indicator type torque wrench and determine exactly the torque required. Once you know the required torque to operate the valve then choose a motor suited for the force needed, a geared DC motor with limit switches or stepper should work or any number of other motor types. Just make sure the motor can deliver needed torque with a nice overhead, like 50%. Your plan will require mating motor to valve, personally I would just buy an off the shelf, turn key solution.
Next personally I would just run with a off the shelf standard solenoid valve with battery backup. Relatively simple. However, your project and your call.
Agreed, but suggest using piloted solenoid valves. They take VERY LITTLE current to open and then the water pressure keeps them open until the solenoid closes and lets the valve close. I have had mine working on the irrigation system for over 15 years.
Think I would use a linear actuator with built in end limit switches to swing the valve handle 90 degrees. How much force is required at the end of the handle to turn the valve stem? Also, you would need a way to quick disconnect the actuator to manually turn the valve.
As @Paul_KD7HB and @Ron_Blain suggested, I estimated the torque required to turn the valve. It is about 8 Newtons. The mechanism to turn the valve, I will figure that out. So my only doubt is, is the motor that a considered earlier will be powerful enough to turn the valve or should I just increase the budget a get something better?
There's always the possibility of using a different type of valve. It depends if you need a full shut off to pressure.
Central heating systems use 2 way or 3 way valves that work for years at high temperatures and lowish pressures.
They use a ball but differently to to the one shown. Instead, a rubber ball moves to close the ports. They come with a motor driven actuator which is a dog's dinner of of gears, micro switches, resistors and diodes.
The motor is a mains synchronous motor which is stalled by introducing a diode to maintain the position.
It leads to overheating and burnout.
If the motor was maybe a stepper it would be more reliable. I guess the original Honeywell design was done for cost and didn't need complex electronics.
Google Sundial Y-Plan.
