Liquid Level Switch for Reservoir - Turn off computer when get low

[Yoshi Moshi]

Is there a liquid level switch I can put into my system, that gets actuated when the liquid level in my system gets low? Like a switch or some other sensor that I put into my reservoir, the switch gets actuated when the level is depleted in my reservoir, turning of my computer. Can you point me to such a sensor?  I would like to leave my computer on when I'm not home, but I'm scared to do so with liquid flowing through it, but if there's some sort of switch I can put into my system that turns off the system if fluid gets low, it would be great.

[porina]

Water level switches exist and can be inexpensive. In essence they're usually some kind of float combined with a regular electrical switch. You need to find one that makes/breaks connection in the right way, then find some way to integrate that into your PC. I'm not sure what's the best way to go about that. For my uses when I looked them up in the past, they ran off low voltage DC so I could simply cut power directly. This wouldn't be suitable for a PC, where you have to manipulate it to send a power down signal in some way, gracefully or not.

[emosun]

it would actually be a bit smarter to set the bios to shut the machine off when the cpu temp hits a certain temp , you can set it very low like 80c. if theres ever a leak the cpu temp will rise and the machine will shut off well before the cpu hits any dangerous temp

[manikyath]

i've never seen them made 'as a finished product' but i dont presume building one to be difficult.

that said.. wouldnt you want to trigger an alert if the fluid level drops at all, rather than an emergency stop at critical levels?

 

either way, i presume the way to do this is to have some sort of 'floater' in the reservoir, preferrably something that does not react with your fluid, and is not prone to flaking off.

then you can mount a microswitch trough one of the top filler ports, that is pressed by the floater. you could then, if the floater sinks below the level where it presses the switch, either activate some sort of warning circuitry (flashing LED, buzzer, etc.) or use something like an arduino to communicate to the computer.

[DJ46]

Since water is always at least a bit conductive you could make a simple sensor with two probes that keep a relay on if they're connected.

If you used copper wire you wouldn't even be mixing metals in the loop. Drilling holes into an acrylic plug on top of a reservoir and sealing them around the wires should be simple enough.

It would have to be quite precise as even a small leak can break a component.

The problem I can see happening is if the water level in the reservoir moves during boot up/shut down it could trigger accidentally. Though now that I think about it if you set the level at the lowest typical level while running it wouldn't matter if the water level rises slightly after shutting the PC down as it would stay connected.

 

The more I think about it the more I'm considering trying something like this out when I finally end up building the loop I'm currently gathering parts for.

[Yoshi Moshi]

I'm surprised something pre-built like this doesn't already exist.? I can't find anything.

 

I like the idea of setting something up so that if the CPU gets to hot shut off the system. My only concern with this method is that if I have a small leak, and fluid slowly leaks out, it may take some time for the CPU to reach that temperature setpoint of shutting off the system. Meaning I think too much fluid would leak out before it shuts off, and a liquid level switch might turn off the computer with less fluid required to leak out. I could do something like if the fluid in the reservoir depletes by like 10 mL, shut off the system.

[For Science!]

1 hour ago, Yoshi Moshi said:

 

I mean, it does exist

 

https://koolance.com/liquid-level-sensor-70mm

 

the only thing is that it is reactive in the same way as CPU temperature is, and if liquid has indeed leaked, it probably already wreaked havoc in the system.

[Yoshi Moshi]

that looks great! But like you said that's a travel distance of 77 mm. Do you know of something that is smaller, like less than 10 mm?

[For Science!]

25 minutes ago, Yoshi Moshi said:

that looks great! But like you said that's a travel distance of 77 mm. Do you know of something that is smaller, like less than 10 mm?

https://koolance.com/infrared-liquid-level-sensor-sen-lvlir01

 

Dunno, this looks like less travel.

[DJ46]

10 hours ago, Yoshi Moshi said:

that looks great! But like you said that's a travel distance of 77 mm. Do you know of something that is smaller, like less than 10 mm?

It actually looks like the travel is 70mm, with a cap 7mm thick on top.

You could get a reservoir tall enough that >76mm of it are left exposed and it triggers as soon as the water level dips even slightly.

 

I wouldn't use it as a signal that tells the PC to shut down. My recommendation would be to have it switch off a relay. You'd need to be quite into electrical engineering to make the circuit though.

 

I don't yet have experience with a watercooling loop, so I don't know whether the water level changes while starting/stopping the pump and how.

Personally, I'd implement it in a case that has the PSU relocated and connected to the rear of the case with an extender (like a lot of mITX cases). You cut these wires and have them go through a relay. Through some circuitry you should be able to get the sensor to control that relay.

The end product would work like this:

- If the water level is normal then no liquid is leaking and the sensor in the reservoir keeps the relay switched on.

- If the water level dips even slightly the signal from the sensor changes and the relay kills power to the PSU, instantly switching the PC off. This might lead to file loss but it should prevent as much damage to the components as possible.

- There should be a relay available that requires to be manually reset after being turned off. This would prevent it from turning back on if the water level rises after the pump stops (if that is what happens).

 

With this implementation you could also have a switch in paralel with the relay that keeps the PSU connected to the mains and just turn off the switch whenever you leave the PC running unsupervised so that the relay can cut power to the PSU. This would prevent a shutdown during BIOS updates, if the system springs a leak somewhere where damage to the components is unlikely and sacrificing the motherboard is unnecessary.