Synchronized Water Fountains

[CyrexCore2k]

Hey all

I was just curious if anyone has done any work with electronic valves and can give me some tips. I'm not sure if I should be looking for a soft switch that controls voltage to an electric pump or if there are pumps that can be controlled by signal wires.

Also is there a specific term for a soft switch that controls a higher voltage?

 

[Resqueline]

The motor driver "modules" could be called Variable Frequency Drives, but what kind of power levels and pump types are you into here?

 

[CyrexCore2k]

I'm not really sure at this point. I suppose to start I'm just looking for low psi equipment that I can plug straight into a wall socket to build a prototype of sorts.

The way I envision it working is I'll have a main reservoir with a built in pump that keeps the tank at a certain psi. The output hose would be split to the various jets which would all be controlled by fast acting electronic valves. Each of the valves would be powered but the switch would be an electronic soft switch that is hooked to a digital controller. I've already created the controller though, right now all it does is make lights blink. :]

Alternatively, if there aren't any readily available electronic valves I could probably build the soft switch assembly myself if I knew the proper terms for what I'm looking for. Basically the signal wire would control the flow of a higher wattage circuit.

For an early prototype or simple proof of concept I was thinking of a valve I could just hook to a regular garden hose and go from there.

 

[Resqueline]

Old washing- & dishwashing machines are a source of pumps & valves. The inlet valve is activated directly by mains voltage, and likewise the expeller & circulatory pumps which presumably delivers a relatively constant pressure by nature of their centrifugal impellers.
These valves a not soft controllabe and not high flow afaik but could be good enough for a test.

 

[55pilot]

For your final project, you should consider a domestic pressure boot pump in series with a constant pressure tank. Depending upon the desired pressure and flow rate, you are looking at a couple of hundred dollars to a couple of thousand dollars. You will not save much money trying to build a system out of parts.

As has already been pointed out, for smaller scale, a pump out of a washing machine may be the way to go. You may be able to get away with connecting the pump output to a small constant pressure tank and letting it run continuously.

As for valves, once again I would follow the earlier suggestion for using valves from washing machines. You can buy relays (reed or solid state) to drive those values. These valves are not very fast, so you are not going to be getting 10 cycles per second from them. If you need that kind of a frequency response, you are looking a specialized (read; expensive) vales and controllers.

One source for valves is sprinkler systems. They usually run off 24V AC, so you will still need a relay to connect them to your controller. Home improvement stores carry them, or you can get better prices from online places.

Keep us posted...

---55p

 

[CyrexCore2k]

Alright I managed to get some research done today and found that some common digitally controlled valves are called electrically proportional valves. Unfortunately they're pretty expensive. I expect this is due to the fact that they aren't simple on/off valves and have to accurately control flow in steps. Perhaps something I'm looking for in the future but for right now I just need an on off valve.

So I managed to find this:

http://www.omega.com/ppt/pptsc.asp?ref=SV120_Series&Nav=prel04

It's a normally closed valve that opens when 120V power is supplied.

I had to do a bit of digging but I finally managed to figure out that digital switches are actually called relays (I kept searching for "soft switches" on Google) so from there I was able to actually find some products that would allow me to hook my controller up to something which would turn the valve on or off for me:

http://www.omega.com/ppt/pptsc.asp?ref=SSR330_660&Nav=autm01

I am a little concerned because I haven't seen any relays that operate with 3V signals. This one works with 4V.

 

[CyrexCore2k]

For your final project, you should consider a domestic pressure boot pump in series with a constant pressure tank. Depending upon the desired pressure and flow rate, you are looking at a couple of hundred dollars to a couple of thousand dollars. You will not save much money trying to build a system out of parts.

I definitely agree with you here. I wasn't planning on attempting to build such an apparatus myself. I'll look into this more after I just get a single valve working with a garden hose. :] baby steps.

 

[55pilot]

You are looking in the wrong places for your parts.

Unless you are looking at extremely high pressures or high flow, plastic control valves for sprinkler systems will do the trick for you. They will be a lot cheaper than $85 each. They can be had from your local hardware store or a number of online places.

To drive the valve from a microprocessor, you will need a relay. Look for them at DigiKey.com or Mouser.com or Jameco.com The first two are major distributors and carry parts from thousands of manufacturers and have links to the parts' datasheet next to the part. They do sell to the hobbyist, but their small quantity prices are really high. Jameco is basically a retailer and a surplus store. They have a much smaller selection, usually don't have data sheets on their site, but you usually get much better prices.

I suspect that you are using a 3.3V microprocessor. While there are mechanical relays that will operate at 3.3V, they likely require more drive current than your microprocessor can provide. Also, don't forget a flyback diode if you go the mechanical relay route.

You may be better off using solid state relays, as you can get ones that will operate down to 5mA. You will need to size the current limiting resistor so that the 3.3V microprocessor output causes the specified current (typically between 5mA and 20mA) to flow through the control side of the relay. You will need to be careful specifying the relay as not all solid state relays can handle AC.

Good luck.

---55p

 

[CyrexCore2k]

Alright I took your advice and went with the solid state relay and hooked everything up. Basically my laptop hooks up to my controller using a USB cable, the controller bread board has two wires coming off it that go to the input side of the SSR. I have a 26VAC transformer plugged in with one lead directly attached to the valve solenoid and the other lead attached to one lead on the output side of the SSR and the other lead attached to the valve. I removed the solenoid assembly from the valve to see if everything is working and it all does as expected.

The problem I'm running into is that the valve takes several seconds to shut off. I've confirmed this is an issue with the valve and not the SSR by playing with the leads directly attached to the transformer. I wasn't really surprised when this happened since this is something I've already observed with lawn sprinkler systems. Also I noticed the spring for the solenoid is really weak. I can get it to depress all the way just by tapping it. So at this point I'm wondering if I should be looking at higher voltage solenoid valves?

Also I thought it was odd that the solenoid uses AC power. Why would sprinkler manufacturers choose to do that?

 

[(*steve*)]

Welcome back!

The problem I'm running into is that the valve takes several seconds to shut off. I've confirmed this is an issue with the valve and not the SSR by playing with the leads directly attached to the transformer. I wasn't really surprised when this happened since this is something I've already observed with lawn sprinkler systems. Also I noticed the spring for the solenoid is really weak. I can get it to depress all the way just by tapping it. So at this point I'm wondering if I should be looking at higher voltage solenoid valves?

It's a feature. If you turn off the valve too quickly you can create pressure waves that will rupture pipes. In general it's also not a problem in reticulation for the water to be turned off slowly. These valves typically use water pressure to turn the valve off, the solenoid only allows the water to perform this task, it does not directly open and close the valve.

Also I thought it was odd that the solenoid uses AC power. Why would sprinkler manufacturers choose to do that?

The do this because it's simpler, cheaper, and mostly because it prevents problems that you get with DC. That problem is that DC will cause one conductor to be eroded if there is any moisture and leakage current (as there is likely to be if you bury wires)

 

[(*steve*)]

OK, just going over your thread again.

If you need to turn the water on and off very quickly then you'll probably need some more specialised equipment, possibly with protection against water-hammer.

edit: or turn on an d off individual pumps which would probably start up and stop faster than valves would open and close.

 

[CyrexCore2k]

Welcome back!

Thank you!

It's a feature. If you turn off the valve too quickly you can create pressure waves that will rupture pipes. In general it's also not a problem in reticulation for the water to be turned off slowly. These valves typically use water pressure to turn the valve off, the solenoid only allows the water to perform this task, it does not directly open and close the valve.

Ah the infamous fluid hammer I was reading about. So what type of valves are used in cases where I don't mind fluid hammer or better yet, plan to deal with it through some other method so I can have more precise control over the fountains?

*EDIT* Just read your second post.

I was thinking of perhaps getting 3 way valves and hooking an electric valve with no fluid hammer protection to the inlet, the fountain to output 1 and another valve with fluid hammer protection to output 2. This still leaves me with the question of what kind of electric valve is capable of acting that quickly and probably won't have the fluid hammer prevention feature.

 

[(*steve*)]

I think you'll start posting in http://www.hydraulicspoint.com

Seriously, you need to seek out people with domain knowledge in this area -- it's no longer even peripheral to electronics.

 

[CyrexCore2k]

Just wanted to thank everyone for their help. I managed to get the first valve working as expected.

 

[cancom]

Controllers

Just wanted to thank everyone for their help. I managed to get the first valve working as expected.

My heating/ac, lake pump system, doorbell, irrigation pumps and zone controllers have been controlled from an old Win98 pc for years. You may want to look at an inexpensive ($24) 8 relay LP controller from a guy on ebay. There are USB boards out there as well that convert to serial data interface if you require more than 8 outputs and 4 inputs.....more $ of course for a Vellman K8055 .

I can supply VBasic code, which I wrote for COM ports, if you need it.

As a few guys have mentioned, I'd research high pressure pumps, actuators and accumulators...maybe look into pressure washer mechanics???

Good luck with the project.

cancom