I'm a farmer. I have a state licence to spray RUP's, altho I stick to the 'Caution' chemicals I still wanted the education. Spray my beans & corn every year.
For the common tank mixes on these crop chemicals, I dump in one type for broadleaves, one for grasses, an oil to make the chemical stick to the leaves, and some granular fertilizer to help it all work. (Many brand-named all-in-one weed killers are actually just a premix of the ingrediants I use - at more cost.)
This solution MUST be agitated to mix it all together & to keep it suspended in the water.
The labels on all the chemicals I use tell me to agitate for 15 minutes (or more) before going out & spraying - and I need to follow the label or I can get fined.
Perhaps your chemicals are different; I don't know and I'm sorry I presumed to know. /forums/images/graemlins/smile.gif However, I sure would want an agitation line from the pump to the tank to properly keep my solution in suspension. Agitating the tank is very important to keep the solution properly suspended with most weed killers.
This line is typically the pressure regulator overflow, which is needed to keep a sprayer at the proper pressure of (for my chemicals) around 20-30#. Some of the RUP insect sprays require 60# pressure. If you spray my types of weed sprays at 60#, it causes very tiny micro-droplets that drift for hours on the wind & kill the neighbors crops or garden. If I were to spray the insect killers at 20# of pressure, it would not properly create the droplet cloud & would not kill the insects. In either case I'm wasting my time & money to not get the job done, & possibly cause problems for my neighbors. You can't regulate that pressure very well by stopping & starting the pump - you need a regulator to handle the shock loads & legally apply spray according to the label. So accurate pressure regulation is very important to properly apply the chemicals & you need a dedicated regulator to do so.
The pump itself gets subject to very high shock loads, and needs a bypass of some type. At full throttle & on agitae-only my pto pump runs 60#, I've seen it hit 90# once when the overflow line plugged. Then again when I am spraying at fast idle it has a hard time getting over 20#. This is _with_ a regulator, I can't imagine what I would do to the pump without a regulator. Anyhow, for the safety of the pump, it needs a bypass regulator - as stated, blown seals & hoses & the like.
As I see it, there are 3 very important reasons to be using a pressure regulator. They are available in any farm supply store, I thought around $20 but I could be wrong, and sure will save wear & tear on the pump & hoses, as well as help you to properly apply the chemical so it does the work you want without wasting it or harming others or the environment.
Note - I am not familiar with small electric sprayer pumps, perhaps they are built with a 'closed center' design & are built to supply the proper pressure & deadhead themselves? I do not know. I would still like an agitation line even so just to keep the solution in suspention.
Different strokes for different folks, but for me this is what is required by law, & the only way I would feel comfortable using chemical sprays.
--->Paul
