Winterizing sprayers

Just wanted to mention something I was thinking about today, as I was moving a back pack sprayer into my unheated storage.

I store some of my smaller sprayers in unheated storage over the winter, and some in heated storage.

With small tank sprayers, I thought if I pumped all the water out, it wouldn’t freeze up. This isn’t necessarily the case.

Once a gun froze up and broke, even though I had run it empty. The gun was $25+.

Since then I have talked to some other growers about this and they run antifreeze through their equip. in the fall. One grower runs RV anti-freeze through equipment, which is what I did for a couple years.

This year I ran windshield washer fluid through my sprayers, because it’s considerably cheaper. The washer fluid is alcohol based, so I’m not sure how rubber seals will hold up long term, but I thought I’d try it.

Just want to mention this so some of those folks who store spray equip unheated can be aware.

Btw, it’s not every year that the freezing will break unheated equip. It was a few years before the freezing weather starting causing damage to my equip.

A word of caution on windshield washer fluid… some of it contains methanol. Methanol is not so great on Viton seals. Viton is rated fair, I think. We make diluted stocks of chemicals in the lab in methanol and store them in Viton capped vials.

The seals will swell from methanol over time, but Viton absorbs much less of the chemicals we are interested in.

So the swelling could be an issue in parts that have a moving sealed interface.


Thanks Levers.

Appreciate the chemistry caution on Viton.

Maybe I will go with simple glycol antifreeze. It’s about the same cost as RV antifreeze (which has some alcohol).

My main intent in starting this thread was to try to prevent folks feeling a false sense of security from draining their spray systems over winter, thinking this protects their equipment. Perhaps choosing the right antifreeze is just as important.

That’s interesting about viton and your lab experience. Viton seals and tubing is fairly widespread for biodiesel applications, being one of the few synthetic rubbers that biodiesel will not erode. Interesting that it is not all that great with methanol.

BTW, for several years now I have stored my pump sprayers for winter in an unheated barn. I wash them and then pump until air is coming out the nozzle. Then remove the nozzle and clip the trigger/wand on the unit so that it can drain out the open nozzle end, and so that the trigger is up with little or no hose above it. This has been working, and it often goes below freezing and below 0F sometimes in the storage area.

I looked into it briefly, and there are different “grades” of Viton/FKM rubber with the more fluorinated ones having better chemical resistance. I always assume the cheapest and lowest grade, unless told otherwise. Interestingly Viton is very impermeable to what I would consider much more aggressive solvents such as the chlorinated ethenes PCE and TCE (dry cleaning solvent).