AC or DC Solenoid?

[Kengar]

I am going to set up a CO2 scrubber on my skimmer input line, with control to limit air being pulled through the scrubber only when pH drops below certain level (e.g., 8). Air will otherwise be regular room air. BRS has a nice video showing such an arrangement, using solenoid valve to regulate the flow of air.

Question: there are 24 V DC solenoid valves and 120 Volt AC solenoid valves available, e.g., from McMaster Carr, Grainger, etc. Either would work with Apex control. Any pros or cons to using one versus the other?

Thanks

 

[BrettDS]

AC or DC Solenoid?

I have had my apex controlling a number of solenoids to manage my RODI system for close to four years now. Except for one they are all AC solenoids because at the time I installed them the Apex didn't have 24V accessory ports and I figured that it was easier just to plug the solenoids directly into the EB8 rather than connecting them to a DC adapter and then plugging them into the EB8.

I do have one 12VDC 3 way valve, but that's only because I couldn't find a 120VAC 3 way valve in the size I needed.

All of the solenoids I have are working great and have been extremely reliable for years.

The things I would suggest that you consider are the following...

The AC solenoids I have buzz a little. And it seems to get worse as they get older. None of them are super loud or anything, but they are audible. My RODI station is in the garage, so the buzzing doesn't annoy me, but if your solenoid will be in living space then you might want to consider DC.

Also, 120VAC can be more dangerous than 24VDC, especially around salt water. Again, in my case the solenoids are in my garage and away from the water, but if this was something that you were going to be installing in your tank, especially near the water line I might be inclined to go with DC for the safety factor.

Finally, if you have a newer apex with an open 24VDC accessory port then it's pretty quick and easy to just plug the solenoid into that without even worrying about getting an AC to DC adapter or even taking up a plug on your energy bar.

 

[Kengar]

Finally, if you have a newer apex with an open 24VDC accessory port then it's pretty quick and easy to just plug the solenoid into that without even worrying about getting an AC to DC adapter or even taking up a plug on your energy bar.

I do have newer Apex. I would need to get one of those connectors that are configured for the 24V outlet, but no different than needing to put on a 3-prong plug for the other AC outlets.

I'm wondering, though, whether AC or DC is more reliable over the long haul. More heat output? Other considerations????

The scrubber and solenoid would be hard-mounted to a board that the Apex gear is all mounted to, which board is, itself, hard-mounted above sump. Nothing is falling into salt water; hard-mounts are construction screws.

 

[reefgeezer]

I'd choose DC just for the safety factor. AC or DC, the thing to watch unless you are using a relay is to make sure the appex port will handle the load. Solenoids are generally rated in amps drawn. Some can draw quite a bit.

 

[BrettDS]

I think Neptune sells a 24V solenoid that plugs right into the 24VDC accessory port, so that might be the quickest and easiest option.

 

[mcgyvr]

While AC may have a slight efficiency advantage everything else favors dc solenoids..
Go DC...

 

[Kengar]

While AC may have a slight efficiency advantage everything else favors dc solenoids..
Go DC...

Go DC? That was last year (Yay, CAPS!). As a St. Louis native, this year was Go St. Louis! YAAAAAAAAAYYYYYY BLUES!!!!! Woooo!

 

[otimer]

In case of air/gas solenoid valve for that purpose, ac or dc has not a big difference as long as they are maintained dry. In the safety view point, dc is bertter.
But one thing to be considered is the cv of the valve you applied. Generally sol v/v have low cv, that means the flow resistance of the valve seat is very high which makes flow rate decrease significantly. This might degrade the performance of the skimmer.

If you look at the inside of a pvc ball valve, the opening of valve ball is almost same as the id of the connecting pipe. We call this a full-port valve.
But sol v/v are quite different and they have very small opening.

One more point to be checked is the minimum working pressure of the v/v you select, the solenoid do not open the v/v seat, but releases the closing force to the seat, and the fluid pressure will open the sheat in some sol v/v of 1/2" or bigger.
The suction pressure(vacuum) is much lower than that can open the v/v seat of this kind of v/v.