On Sat, 17 Feb 2018 18:09:10 +0000, (Roger Hayter)
wrote:

Harry Bloomfield wrote:

I tend to save a few of the cheap cleaner squirty bottles, to
re-purpose these for spraying thin oil and even water to spray cool a
weld down. Trouble is they soon seem to fail to spray.

Problem - often they stop spraying or don't spray as well as they did.
Thinking it might be a failing none return valve I spent a bit of time
investigating them and found that the reason they stop, is that they
get air in the trigger operated pump. The pumps or not self priming
they need to be full of liquid to work. Once air is drawn in they fail.

The fix - put a finger tip over the jet outlet, to act as a one way
valve and pump a few times to expel the trapped air.

All the ones I've seen have a one way valve and *are* self-priming.
But they are designed for particular liquids (mainly differing in
polarity and viscosity) and can fail by wear, distortion, debris, or
using the wrong liquid. If you can get it to work by manually priming
it that is good, but if the one way valve fails even when primed then it
still doesn't work. Best regarded as one or two uses only when used
with unsuitable liquids. For instance, I have found that polythene
(mainly) spray mechanisms intended for water soon fail when used with
100% isopropanol.

The question we should be asking is, what happened to refills? It
breaks my heart when I throw a sprayer bottle (bathroom/kitchen
cleaner, anti-mould spray etc) away, recallling the time when you
could at least buy a refill to fit the same sprayer. Plus, all those
little bits of plastic in the trigger mechanism -- and did someone
mention springs? -- are deadly for marine life if such items find
their way into the oceans.

MM