Flow switch for alarming

[mofox1]

I'm toying with the idea of adding a flow switch to the rig, so that I can test for low or no flow through the herms coil (ie - stuck sparge or pump not pumping).

Found this:
http://www.ebay.com/itm/231212360068

If it works out, I'll be tying it into the panel alarming - but I'll just have it tied up to a little 5V LED or something for a while, in case it either doesn't work, it's too hard to keep clean, or if I can't find a place to stick it (_on the rig_) that isn't too annoying.

Has anyone used anything similar, or seen this sort of thing in use before?
Is there a more suitable method for low flow alarming?

Pic:

 

[sponge]

You'd want something to match your control circuit voltage - ie, 24VDC or 240VAC, depending upon what you've got in your control panel.

Otherwise it would be fairly simple to wire up for low/no flow for the pump supply and an alarm.

 

[Truman42]

I was going to use something similar in my herms to switch off the 12 V supply from the PID to the SSR if I have no flow.

Many times on brew day Ive been pumping my first runnings from the MLT to the kettle and have forgotten to turn my herms power supply off. Because my probe is at the top of my herms coil and not covered by wort when theres no flow, the temp drops and the herms comes on. I dont realise until its spitting steam and boiling water out the top of the herms vessel vent hole. Then once I start the sparge Ive forgotten to turn the herms power back on.

Seemed like a good solution but i just havent got around to doing it yet.

In your case though I think you would need a normally closed switch. (That one above is normally open) So when there is flow its open but when flow stops the circuit is closed and current is supplied to your LED/Alarm warning you of this.

Im not even sure you can get them NC though so you may need to make up some sort of circuit that powers the LED/Alarm when the power is cut due to low flow. Wouldnt be hard to do, and there are members on here that would know how.
(Qldkev..Edak)

The 100V rating is maximum volts so you would have to use a transformer to supply power through it.

 

[Truman42]

Linked to something but it was wrong.

 

[mofox1]

You'd want something to match your control circuit voltage - ie, 24VDC or 240VAC, depending upon what you've got in your control panel.

Otherwise it would be fairly simple to wire up for low/no flow for the pump supply and an alarm.

Apologies - I wasn't very clear in my original post. I don't have a control panel yet. Before I go and try to work a low flow alarm into my control panel design, I would want to test out the switch in the existing system to see how it performs.

I'm certainly not running 240V AC out to a sensor on my rig, even if it was rated for it (it's not). The only way I would use it would be tied up to a relay - using whatever low volt DC power I've got, or a resistence SSR if I don't have any other requirement for DC power.

I'm more interested in the physical aspect of these devices - whether they've been used in home brew rigs before (undoubtedly), whether they gunk up, fail, or just aren't worth the hassle.

 

[sponge]

I was pretty vague in my response as well, so I'll comment on the usability. You'd just want to make sure the orifice of the flow switch isn't too small, because that's when flow switches and sensors start failing due to build up (which wouldn't be an issue with regular cleaning).

I think they'd be a good idea for being automated and shut off on a fail if you weren't there monitoring. Use that as an interlock for the SSR and pump so that both the element and pump supply cuts out, and prevents damage of the pump from no flow whilst an alarm sounds.

If you spend most of your time monitoring your brew then it probably wouldn't be worth the effort IMO.