Dead Solenoids. Any suggestions?

[simnick]

I bought 3 of these cheap solenoids on eBay (http://www.ebay.com/itm/141191103554?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649).
I am using them to control cooling water and filtered water in, not wort (I have ball valves for that).
Already, 2 of them seem to have died. They don't turn on any more, and the resistance across them is effectively zero (just a few ohms, enough to piss off my power supply).
Any thoughts on what may have gone wrong, or is that just what I get with cheap chinese parts?
I know many would suggest spending more, but I a lot of folks seem to be selling this model, even here in the US, (such as http://www.adafruit.com/products/997) with an identical design, so I am not sure I would get more unless I spend $30 for brass ones.

 

[BrewerBrad82]

What is the electrical rating of the valves, and how much are you supplying them with? More than likely they are just cheapies. I have had great luck with a seller on Ebay called Valves4projects. They have a large selection, and the quality is there (for the ones I have anyhow)

 

[simnick]

Well, they don't say much on the valve (or on eBay), but I was feeding them about 11V according to my multimeter, and they say 12V on the valve. No mention of mA, but spark fun seemed to say they were about 300ma.

Looking at Valves4projects. They cost a little more than I want to pay at the moment (had to buy some other parts), but I might get them anyways.

 

[simnick]

So, they aren't dead. Instead, that appears to be their behavior when the pressure is too low. I cranked open the supply line, and it came alive again.

 

[ajdelange]

It says in the listing that they are servo valves which means that the solenoid operates a valve which pressurizes an actuator which operates the diaphragm. It also says on the label that they need a minimum of 0.02 MPa (2.9 psi) to operate.

 

[BrewerBrad82]

Well there we go!

 

[simnick]

Yeah, I realized they needed some pressure, but I did not have a good idea what 2.9 psi water supply was like. I had dialed down the flow to reduce cooling flow, and apparently dialed it too far. But as I dialed it while it was running, it did not immediately shut off.