Author Topic: Manual gauge for calibration  (Read 719 times)

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Offline SLOweather

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Re: Manual gauge for calibration
« Reply #25 on: July 14, 2018, 06:33:21 PM »
How accurate is your 500 ml measurement?

Offline dport

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Re: Manual gauge for calibration
« Reply #26 on: July 14, 2018, 06:42:11 PM »
How accurate is your 500 ml measurement?

In my opinion, very accurate.  I used a 500ml water bottle (actually labeled as 500ml) for the test.  I had a whole case.  The actual amount varied VERY slightly from bottle to bottle.  However, I dumped all the water out of one bottle, then measured exactly 500ml using a measuring cup for liquids that held 500ml. I poured this back into the water bottle and it filled it to the exact spot the rest of the bottles were filled to.

Offline CW2274

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Re: Manual gauge for calibration
« Reply #27 on: July 14, 2018, 06:45:03 PM »
Now, the question is, do I even bother adjusting the screws? My calibration tells me I'm low by about 2% on my gauge.

Definitely not would be my view. Best not to touch the factory settings at all IMO. It sounds like you're as close as you're ever going to get in practical terms to checking that the calibration of the gauge is properly within spec.

  Also to note is that I averaged 4 inches per hour rate during my test.  Perhaps if I used a rate of 2 inches per hour I would be at 0% error.  Who knows.
You averaged 4" per hour or started at 4? I start at 4 and by the time the jug is empty, it's about 1" per hr.

I averaged about 4 inches an hour.  It started north of 6 inches an hour.  All said and done it took 16 minutes to dump all 500ml of water.  Averages to about 3.4 inches an hour if you do math. So, I take back my original 4 inch per hour mark :)

Most of the rain we get from May through August is in the form of thunderstorms with heavy rainfall rates.  I wanted it to be as accurate as possible for those instances.
Wow, that's cookin'. If I were you, I'd drop the average rate down to 1-2" and see what you get then. At that toad choking rate, you may have had some spill out, and maybe not, but I'd slow it down to be sure.

Offline dport

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Re: Manual gauge for calibration
« Reply #28 on: July 14, 2018, 06:57:20 PM »
Now, the question is, do I even bother adjusting the screws? My calibration tells me I'm low by about 2% on my gauge.

Definitely not would be my view. Best not to touch the factory settings at all IMO. It sounds like you're as close as you're ever going to get in practical terms to checking that the calibration of the gauge is properly within spec.

  Also to note is that I averaged 4 inches per hour rate during my test.  Perhaps if I used a rate of 2 inches per hour I would be at 0% error.  Who knows.
You averaged 4" per hour or started at 4? I start at 4 and by the time the jug is empty, it's about 1" per hr.

I averaged about 4 inches an hour.  It started north of 6 inches an hour.  All said and done it took 16 minutes to dump all 500ml of water.  Averages to about 3.4 inches an hour if you do math. So, I take back my original 4 inch per hour mark :)

Most of the rain we get from May through August is in the form of thunderstorms with heavy rainfall rates.  I wanted it to be as accurate as possible for those instances.
Wow, that's cookin'. If I were you, I'd drop the average rate down to 1-2" and see what you get then. At that toad choking rate, you may have had some spill out, and maybe not, but I'd slow it down to be sure.

I literally can't make the hole any smaller (sounds like a personal problem).  I used a pin and punctured one little hole in the bottom of the water bottle.  May have to find something other than a water bottle. 

Offline CW2274

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Re: Manual gauge for calibration
« Reply #29 on: July 14, 2018, 07:02:57 PM »
Now, the question is, do I even bother adjusting the screws? My calibration tells me I'm low by about 2% on my gauge.

Definitely not would be my view. Best not to touch the factory settings at all IMO. It sounds like you're as close as you're ever going to get in practical terms to checking that the calibration of the gauge is properly within spec.

  Also to note is that I averaged 4 inches per hour rate during my test.  Perhaps if I used a rate of 2 inches per hour I would be at 0% error.  Who knows.
You averaged 4" per hour or started at 4? I start at 4 and by the time the jug is empty, it's about 1" per hr.

I averaged about 4 inches an hour.  It started north of 6 inches an hour.  All said and done it took 16 minutes to dump all 500ml of water.  Averages to about 3.4 inches an hour if you do math. So, I take back my original 4 inch per hour mark :)

Most of the rain we get from May through August is in the form of thunderstorms with heavy rainfall rates.  I wanted it to be as accurate as possible for those instances.
Wow, that's cookin'. If I were you, I'd drop the average rate down to 1-2" and see what you get then. At that toad choking rate, you may have had some spill out, and maybe not, but I'd slow it down to be sure.

I literally can't make the hole any smaller (sounds like a personal problem).  I used a pin and punctured one little hole in the bottom of the water bottle.  May have to find something other than a water bottle.
You may have missed what I said earlier, I used putty, rope putty to be exact (any will work), to put over the hole to reduce the diameter. Takes a little time to get the flow you want, but you will.

Offline dport

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Re: Manual gauge for calibration
« Reply #30 on: July 14, 2018, 07:07:26 PM »
Now, the question is, do I even bother adjusting the screws? My calibration tells me I'm low by about 2% on my gauge.

Definitely not would be my view. Best not to touch the factory settings at all IMO. It sounds like you're as close as you're ever going to get in practical terms to checking that the calibration of the gauge is properly within spec.

  Also to note is that I averaged 4 inches per hour rate during my test.  Perhaps if I used a rate of 2 inches per hour I would be at 0% error.  Who knows.
You averaged 4" per hour or started at 4? I start at 4 and by the time the jug is empty, it's about 1" per hr.

I averaged about 4 inches an hour.  It started north of 6 inches an hour.  All said and done it took 16 minutes to dump all 500ml of water.  Averages to about 3.4 inches an hour if you do math. So, I take back my original 4 inch per hour mark :)

Most of the rain we get from May through August is in the form of thunderstorms with heavy rainfall rates.  I wanted it to be as accurate as possible for those instances.
Wow, that's cookin'. If I were you, I'd drop the average rate down to 1-2" and see what you get then. At that toad choking rate, you may have had some spill out, and maybe not, but I'd slow it down to be sure.

I literally can't make the hole any smaller (sounds like a personal problem).  I used a pin and punctured one little hole in the bottom of the water bottle.  May have to find something other than a water bottle.
You may have missed what I said earlier, I used putty, rope putty to be exact (any will work), to put over the hole to reduce the diameter. Takes a little time to get the flow you want, but you will.

Fair.  Though, with most of our rain coming at heavy rates during the summer, I feel confident that my VP2 is at least not under reporting significantly like some others have stated.  For reference, my unit was shipped in early June 2018. 

May do some additional testing tomorrow once I can slow the flow of my calibration device. 

Offline CW2274

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Re: Manual gauge for calibration
« Reply #31 on: July 14, 2018, 07:11:24 PM »
Now, the question is, do I even bother adjusting the screws? My calibration tells me I'm low by about 2% on my gauge.

Definitely not would be my view. Best not to touch the factory settings at all IMO. It sounds like you're as close as you're ever going to get in practical terms to checking that the calibration of the gauge is properly within spec.

  Also to note is that I averaged 4 inches per hour rate during my test.  Perhaps if I used a rate of 2 inches per hour I would be at 0% error.  Who knows.
You averaged 4" per hour or started at 4? I start at 4 and by the time the jug is empty, it's about 1" per hr.

I averaged about 4 inches an hour.  It started north of 6 inches an hour.  All said and done it took 16 minutes to dump all 500ml of water.  Averages to about 3.4 inches an hour if you do math. So, I take back my original 4 inch per hour mark :)

Most of the rain we get from May through August is in the form of thunderstorms with heavy rainfall rates.  I wanted it to be as accurate as possible for those instances.
Wow, that's cookin'. If I were you, I'd drop the average rate down to 1-2" and see what you get then. At that toad choking rate, you may have had some spill out, and maybe not, but I'd slow it down to be sure.

I literally can't make the hole any smaller (sounds like a personal problem).  I used a pin and punctured one little hole in the bottom of the water bottle.  May have to find something other than a water bottle.
You may have missed what I said earlier, I used putty, rope putty to be exact (any will work), to put over the hole to reduce the diameter. Takes a little time to get the flow you want, but you will.

Fair.  Though, with most of our rain coming at heavy rates during the summer, I feel confident that my VP2 is at least not under reporting significantly like some others have stated.
Okey dokey... Would not be my choice, but not my PWS either.

Offline Mattk

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Re: Manual gauge for calibration
« Reply #32 on: July 14, 2018, 07:12:19 PM »
A 1ml syringe is a handy tool (as opposed to an eye dropper) to initially get a rough feel for tipper operation, then feed a measured amount of water (measured using graduated glass cylinder) through the gauge and initially multiple runs at varying time spans trying to emulate the most appropriate rain rate. As a home made dripper, a garden variety adjustable irrigation dripper works fine. What I use as a counter to count the tips is an old WMII console.

For a 0.2mm tipper I run 425ml and top off the last tip with a syringe then compute the adjustment noting that you shouldn't adjust the whole adjustment if it is large as the dynamics of the tipper will change and you will get an over adjustment. If you require say a 18% adjustment (not uncommon) then go maybe 2 full turns of the screws then run the test again.       

Offline dport

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Re: Manual gauge for calibration
« Reply #33 on: July 14, 2018, 07:17:03 PM »
Now, the question is, do I even bother adjusting the screws? My calibration tells me I'm low by about 2% on my gauge.

Definitely not would be my view. Best not to touch the factory settings at all IMO. It sounds like you're as close as you're ever going to get in practical terms to checking that the calibration of the gauge is properly within spec.

  Also to note is that I averaged 4 inches per hour rate during my test.  Perhaps if I used a rate of 2 inches per hour I would be at 0% error.  Who knows.
You averaged 4" per hour or started at 4? I start at 4 and by the time the jug is empty, it's about 1" per hr.

I averaged about 4 inches an hour.  It started north of 6 inches an hour.  All said and done it took 16 minutes to dump all 500ml of water.  Averages to about 3.4 inches an hour if you do math. So, I take back my original 4 inch per hour mark :)

Most of the rain we get from May through August is in the form of thunderstorms with heavy rainfall rates.  I wanted it to be as accurate as possible for those instances.
Wow, that's cookin'. If I were you, I'd drop the average rate down to 1-2" and see what you get then. At that toad choking rate, you may have had some spill out, and maybe not, but I'd slow it down to be sure.

I literally can't make the hole any smaller (sounds like a personal problem).  I used a pin and punctured one little hole in the bottom of the water bottle.  May have to find something other than a water bottle.
You may have missed what I said earlier, I used putty, rope putty to be exact (any will work), to put over the hole to reduce the diameter. Takes a little time to get the flow you want, but you will.

Fair.  Though, with most of our rain coming at heavy rates during the summer, I feel confident that my VP2 is at least not under reporting significantly like some others have stated.
Okey dokey... Would not be my choice, but not my PWS either.

Limited resources here at the moment.  Like I said, will try to create a new calibration device tomorrow to slow the flow. 

Offline ct

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Re: Manual gauge for calibration
« Reply #34 on: July 15, 2018, 01:18:11 AM »
To calibrate you could do this without a calibrator.  Level gauge especially direction tippers line up . Get a medicine dropper and adjust tippers to tip 4.2 ml per tip. Factory is 4.282 ml per tip, it's 1 or 2" per hr rate. 

My metric (0.2mm) Davis rain gauges tip at 4.8 ml on one side and 3.6 on the other.  I know this is intentionally done that way by Davis.  Are you saying it is better to adjust the screws so each side tips with the same volume of water?

Online ValentineWeather

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Re: Manual gauge for calibration
« Reply #35 on: July 15, 2018, 06:48:02 AM »
A 1ml syringe is a handy tool (as opposed to an eye dropper) t

Thanks for the term syringe correction... I have always called the device that came with my Novalynx a dropper when it's a medicine syringe with much larger opening vs a needle syringe. 

https://www.amazon.com/Ezy-Dose-Calibrated-Medicine-Syringe/dp/B0040HH7VO/ref=sr_1_4_s_it?s=hpc&ie=UTF8&qid=1531651958&sr=1-4&keywords=10%2Bml%2Bmedicine%2Bsyringe&th=1
« Last Edit: July 15, 2018, 06:55:06 AM by ValentineWeather »
Randy

Offline johnd

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Re: Manual gauge for calibration
« Reply #36 on: July 15, 2018, 07:37:28 AM »
Thanks for the term syringe correction... I have always called the device that came with my Novalynx a dropper when it's a medicine syringe with much larger opening vs a needle syringe. 

How it works is that such syringes in medical or lab use are almost always used with a separate disposable needle. The fitting between syringe and needle is typically what's called a Luer fitting (probably Luer Slip in this case rather than Luer Lock). So what you have there is very likely a medical syringe but supplied without the disposable needles.
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Online ValentineWeather

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Re: Manual gauge for calibration
« Reply #37 on: July 15, 2018, 08:14:28 AM »
I see.  :-)  I've went through 2 of these because the black etched numbers wear off.
Randy

 

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