Sprayer Gauge Question

[gberry]

We have a 130 gallon 3 point hitch sprayer that I would like some advice on the pressure gauge. We have difficulty calibrating the spray volume and I believe it is because the gauge is not accurate. When the sprayer is running the needle will bounce at least 10 psi with the vibration of the sprayer. Will a glycerin filled gauge stop this and allow us to make a more accurate pressure reading?

 

[novaman]

Yeah I would get a liquid-filled guage and the needle should do no bouncing then.

 

[gberry]

Thanks.

 

[Jogeephus]

Within reason, pressure has very little influence on your calibration. Speed is the key component.

 

[gberry]

I know. The problem was that I couldn't set a consistent pressure. I replaced the valve today and did find the liquid filled gauge helped. I also think our gauge was just bad.

Pressure does make a difference, though. At 40 PSI, our 32 foot sprayer puts out 4.3 GPM with our current spray tips, but at 60 PSI, it's 5.5 GPM.

It seems to be working well now.

 

[Jogeephus]

I think you missed my point. Yes it does make a difference but there is just so much water you can push through a tiny hole no matter how much pressure you use. With the numbers you gave, this wouldn't make but a minutes difference in field time. Pressure has a diminishing effect on output whereas speed has an exponential effect. For instance, at a speed of 5 mph and 40 psi you can put out 36 gallons but if you increase the pressure to 60 psi this will increase to 43 gallons. But if you increase the speed just 1 mph at 60 psi you will again only put out 36 gallons and this number will decrease exponentially with each mph added. I always spray at 40 psi so whether my gauge was working or not the box should be set to this figure and if I was having trouble getting my sprayer to calibrate I'd first double check my speed. If this was ok, I'd be checking my nozzle tips. If this didn't fix it I'd be looking for a mechanical/plumbing problem cause pressure just isn't going to make that much difference - within reason.

 

[gberry]

I get your point. I probably misstated my problem. It wasn't that we couldn't calibrate the sprayer so much as we have to start over fresh every time we spray. Even if we never adjusted the control valve, the gauges don't work on our old worn out tractors, so we couldn't achieve a repeatable pressure. With the new gauge, we can set to 40 or 50 psi and adjust our speed to control output as you described above. It's the problem with using equipment that we can afford.

 

[hayray]

I beg to differ on that pressure issue Joe. I have sprayed plenty of times where pressure just falls 5 PSI because of pump or by pass valve malifunction and it will dilute your calibration very significantly on pieces just as small as 20 acres. Most sprayer calibration problems are not with changing ground speed, that is easy to maintain gear and rpms for speed. I just heard of one study from Oregon where a minorly calibrated sprayer cost a producer over $40,000 per year.

 

[Jogeephus]

Well I guess we will have to agree to disagree. No matter to me but a faulty pressure gauge is the last thing I'd be looking at if I couldn't get my sprayer to calibrate properly.

 

[longtimelurker]

I guess I must be lucky changing ground speed with my sprayer never will change the GPA rate.

 

[dun]

I guess I must be lucky changing ground speed with my sprayer never will change the GPA rate.

This might change your mind but I doubt it:
http://www.teejet.com/media/a73d1d6c-9c ... s_p012.pdf

 

[longtimelurker]

I guess I must be lucky changing ground speed with my sprayer never will change the GPA rate.

This might change your mind but I doubt it:
http://www.teejet.com/media/a73d1d6c-9c ... s_p012.pdf

You are right it didn't change my mind. I'm guess I'm still lucky changing speed will never change the GPA rate on my sprayer.

 

[Jogeephus]

What kind of sprayer are you using?

 

[longtimelurker]

What kind of sprayer are you using?

I've had a redball, a demco and a fast. They all work exactly the same. Speed will not change GPA rate.

 

[1982vett]

I guess I must be lucky changing ground speed with my sprayer never will change the GPA rate.

What kind of sprayer are you using?

I've had a redball, a demco and a fast. They all work exactly the same. Speed will not change GPA rate.

Get rid of the GPS and the computer and tell us what happens.

 

[longtimelurker]

I guess I must be lucky changing ground speed with my sprayer never will change the GPA rate.

What kind of sprayer are you using?

I've had a redball, a demco and a fast. They all work exactly the same. Speed will not change GPA rate.

Get rid of the GPS and the computer and tell us what happens.

Guessing is a fools game. Chemicals and fertilizer are expensive, ravens are cheap. You can keep guessing if you would like, but I will never guess again, thanks for the suggestion however.