Thermocouple wire directly in mash?

I just got a multi-meter with a thermocouple from my dad. Can I just drop the wire right in the top of hte mash and leave it, or will the liquid/ph combo not be good for this? It's made by Fluke and here's a pic:

I've got the same thermocouple on my Fluke 179 and put it directly in the mash. Not saying that it is wrong or right, but that's what I do.

Do you leave it in there the whole mash? It hasn't wonked out on you or anything, has it?

Yep, leave it in the entire mash. That way I don't have to keep taking the lid off and loosing all that heat. The thermocouple on your Fluke is a Type K which is relatively robust. The mash is not going to hurt the thermocouple.

I also use a thermocouple (K-style). I have been using it for several batches. Much easier to read the digital scale than a dial guage. The wort will not hurt the thermocouple. Mine has a braided outer sleeve. I just rinse the wire afterward. I tie the wire around the pot handle so that it sits halfway into the pot. I also use a SS nut to wrap around the tip and weight it down so it says in the middle.

From a previous life I can tell you that thermocouples are very robust and you will not hurt them.