Flow switch for TIG set

[500e]

Did you see this thread

https://www.mig-welding.co.uk/forum/threads/cooling-unit-and-torch-for-lorch-t220.97883/page-3

 

[AndersK]

Could a pressure switch be used instead of a flow switch, or use a contact from a relay when the pump/cooler is on (neither will be a true indication of flow but might be a cheaper option)

A pressure switch would not detect if the line is clogged. Unless you put a restriction just before the tank on the return line and the switch there. Could limit the flow though.

 

[daleyd]

A pressure switch would not detect if the line is clogged. Unless you put a restriction just before the tank on the return line and the switch there. Could limit the flow though.

That’s why I said that neither that nor the relay are a true indication of flow, but rather an indication that the pump is on (which might be good enough, maybe not depending on your POV).

 

[AndersK]

It is, if it measure pressure drop over a restriction.

 

[daleyd]

It is, if it measure pressure drop over a restriction.

Measuring across a known orifice plate is a well used method of measuring flow in process industries - not sure it would help in this application but a simple non differential pressure switch would give an indication that the pump is on, if not actual flow.

 

[AndersK]

Having an orifice directly before the tank and a non differential sensor just before it would detect flow, since pressure on other side is always 0.

Of course it would fail if said orifice gets clogged but a strain would prevent that and usually the torch gets clogged first.

 

[Munkul]

Ok so I got around to sorting this... I opened it up, had another look at the existing setup, realised it was a pressure switch (not great) but it was adjustable (better)! It just needed backed off a bit - guess the Lorch torch doesn't have much backpressure compared to some.

I then got it wired into the welder as planned - you can see the secondary lead come out of the tuchel plug that plugs into the welder.

Now, if the cooler is switched off or broken, the lack of water pressure means the welder comes up with Error 5 - overheating torch. Works perfectly as OE intended.

 

[Munkul]

@daleyd sorry I didn't end up using the relay still much appreciated though. Anyone else want it for a project?

 

[daleyd]

@daleyd sorry I didn't end up using the relay still much appreciated though. Anyone else want it for a project?

No probs mate, keep hold of it, always handy if you need to change the polarity of a switch or something. Glad you got it sorted

 

[pawsnizzy]

Does anyone know the most compact way to come off a 15mm pipe into an 8mm barb? Looked at various solutions and come up with nothing viable

Dave

 

[Munkul]

Thought I'd give a little update, and some info for anyone else doing something similar...

I've had massive problems recently with losing HF somewhere, it's been getting steadily worse. I checked over everything I could, tried an air cooled torch etc, couldn't find anything.
Express (the dealer) took the machine and torch back in, checked over, and couldn't find any faults. Got it back and it was worse than ever, nigh on unusable.

After another chat with one of their technicians, I did a little more checking, turns out that the metal flow switch plug was tracking HF into the cooler chassis, I saw it with the lights switched off. I thought I'd checked this, guess I missed it first time around.

Liam told me that these machines are designed to send HF down all of the plug pins to equalize potential differences (protecting electronics) so in practice this means making sure everything that is connected is well insulated.

I wrapped some insulating tape around the flowswitch plug, and bingo, the tracking stopped and the HF is working flawlessly again. Maybe even better than it was new, it's very strong!

 

[pawsnizzy]

Radio Spares/Farnell sell better ones cheaper - don't forget that you can have pressure with no flow, so a flow switch is the one to go for

I fitted one of these flow switches when I removed the noisy motor fan and replaced it with a quiet mains powered fan. 3D printed an adaptor to fit the existing aperture which holds the new fan and flow switch