Digital Flow Meters

[daw123]

I think I'm going to test it as per how M Cubed want it to be set up. I'll pinch one of the watercooling hoses as an experiment. If everything is set up correctly, then the M Cubed s/w should detect a fault since the flow in the loop will change (i.e. to nothing) and initiate shutdown.

It shoudln't do any damage to the CPU since the CPU will thermally throttle (provided I have thermal management enabled in BIOS) if the temps get too high and before too long the PC will be switched off.

If nothing happens, I'll release the hose.

 

[Gillbot]

Originally posted by: daw123

Originally posted by: Gillbot

Originally posted by: Rubycon

Originally posted by: daw123

Rubycon, does a PC shutdown immediately when you press the case power button, or does it go through the Windows shutdown process. I'm not sure because I've never tried. If the latter is the case, is there a way of stopping the Windows shutdown process, so that the PC shutdowns immediately.

With regard to your idea, how would I go about doing this (specifics please for a layman).

I figure that I can use the signal (essentially a switch which is usually on) from the TBalancer Extension Set, since this signal is what would be controlling the shutdown function via the case power switch if there were a problem and if it was connected as M Cubed intended.

When you ground ATXPWR on the mainboard Windows will initiate a shutdown. A hung program can stop it and if the system is hard locked it won't respond. HOWEVER if you hold that ground the system will shut down regardless of what Windows does OR if it's hard locked. At the very least you'd want it that way.

Disengaging mains power (breaking both legs hot/neutral if you're in the 'States running on 120VAC or both hots in the case of 240VAC) provides the most fail safe method to completely remove power. Electrically it's the same as you yanking the power cord from the machine but leaving the ground line intact. (A triple pole relay can be used if you desire to break the ground also but that is completely optional and MAY violate regulations depending on your local codes, etc.)

Solid state relays can be normally open or normally closed. In this case you want normally open - that is if the turn on voltage ceases to exist at the terminals the connection is broken. This is also known as fail open condition. Your monitoring circuit supplies the necessary turn on power - usually 3 to 20+ Volts either AC or DC depending on the relay type. When this power is removed the relay terminals will open. This is a solid state relay so it has no coil/armature/contacts, for example.

Finally I'd recommend a time delay with this circuit. Basically it warns you that flow has dropped/ceased and will give you time perhaps a minute (but not too long as parts heat up and if you restart the pump with hot parts the shock is not good, etc.) to correct the deficiency. This way the system is not plunged into darkness instantly without warning!

I believe that depends on the bios settings. Many boards have a section for ATX PWR where it states:
Instant Off
Delay
etc...

If you set it to instant off it will power down, otherwise it will initiate the power down sequence or whatever else you have it set to.

I think I understand. So if I change the ATX PWR settings in BIOS to Instant Off, when the BigNG extension set switches the case power switch to off, the PC will shutdown immediately.

Have I interpreted this correctly?

My goal is that if there is a problem with the water cooling loop, I want the PC to shutdown asap to save components from being sprayed with water.

Honestly, I don't think there is much that can help you from a leak. Especially one in the wrong place, ie: a tube or component above the mobo.

The main thing you will be targeting is a loss of flow. A small leak will still spray the system but maintain flow.

IMHO, you are over thinking this.

 

[Rubycon]

Pinching a hose to test is fine - if you overheat in the short time for the test you're running way too close to capacity!

Also if your goal is to shutdown for possible coolant loss than the ONLY way to go is by disconnecting mains from your system. ATX shutdown is not sufficient because +5V is still present and your hardware will not like getting hosed down while still powered on! I agree with Gill, possibly over thinking but you can never be too safe either.

 

[Gillbot]

Originally posted by: Rubycon
Pinching a hose to test is fine - if you overheat in the short time for the test you're running way too close to capacity!

Also if your goal is to shutdown for possible coolant loss than the ONLY way to go is by disconnecting mains from your system. ATX shutdown is not sufficient because +5V is still present and your hardware will not like getting hosed down while still powered on! I agree with Gill, possibly over thinking but you can never be too safe either.

sure you can, if you have $200 in "safety" parts on a $50 PC, IMHO it's too safe. Just keep $50 in spares on hand instead.