Rain Gauge

curlyandshemp

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curlyandshemp
Join Date
Jul 2005
Location
Toronto
Posts
1,903
Can anyone recommend a rain gauge to interface to a Clgx PLC as either a digital or analog signal?

We have a rural customer that is expanding their plant , thus, increasing water usage. At the moment they store processed well water into holding tanks. They want to acquire rain water and wish to have the water treatment plant switch between well water and rain. I have been researching rain gauges and most are wireless for home weather stations or stand alone units connected to ground irrigation systems .
 
Most of these devices are tipper bucket style with a reed switch contact. They are easily interfaced to most PLC I/O and you simply count the pulses to determine mm of rain (number of pulses per millimetre / inch / whatever is generally specified for the device).

I have modified the cheap home weather station ones before, accuracy is not as good as the more expensive meteorological ones but really depends on your accuracy requirements.
 
In my opinion, all you need is a bucket, a level probe (3 rods for high, low and PE) and a level relay.

When bucket is full of rain water, you start the water treatment plant with rain water. When bucket is empty (no rain water), you start the water treatment plant with well water.
 
nonuke said:
In my opinion, all you need is a bucket, a level probe (3 rods for high, low and PE) and a level relay.

When bucket is full of rain water, you start the water treatment plant with rain water. When bucket is empty (no rain water), you start the water treatment plant with well water.
Click to expand...

And who empties the bucket between rain events?

I should have read the OPs post properly, I just focused on the rain gauge bit. If you want to measure how much rain has fallen, then a tipper gauge is the tool you need.

I assume the rain water is being captured in storage tanks. If you want to preferentially run the plant with rain water from the storage tanks turn surely all you need is a level sensor in one of the rain tanks. When it hits the full level, switch the plant to use the stored rain water. Switch back to bore water when the tank gets to an empty level.
 
Saffa said:
And who empties the bucket between rain events?

I should have read the OPs post properly, I just focused on the rain gauge bit. If you want to measure how much rain has fallen, then a tipper gauge is the tool you need.

I assume the rain water is being captured in storage tanks. If you want to preferentially run the plant with rain water from the storage tanks turn surely all you need is a level sensor in one of the rain tanks. When it hits the full level, switch the plant to use the stored rain water. Switch back to bore water when the tank gets to an empty level.
Click to expand...

That is exactly what I said. I used the word bucket and you used the word storage tank.
 
This is a bucket.
wNESwSpznrQL7qfRbL6lF28Vah0FSKyEGFVIxx-J9Tn9VTLoYtLjwgpRLxVGYUQibV4zSPuaTnbaqPpD4ol7Uz4yZTCPFzbLOG9xoo8_jiWJxNqTcOFLnt2g=w384-h384-nc


But my apologies for misunderstanding, we both had the same idea just different words!
 
shawn_75 said:
http://www.rainwise.com/products/detail.php?ID=6760

This seems like an appropriate device.

Shawn
Click to expand...

Yes, I have the plastic version of the Rainwise gauge (http://www.rainwise.com/products/detail.php?ID=6697&Category=Rain_Gauges:Wired&pageNum_cart=/products/index.php) wired to a digital input on my Click PLC, and it works great. The gauge's tipping bucket operates a magnetic reed switch with a 100 ohm resistor in series, generating a pulse on each tip (0.01" rainfall). I don't know what the resistor is for, but probably it has to do with the LCD display unit that's included with the gauge. Anyway, it has no effect on the Click interface.
 
Saffa said:
This is a bucket.
wNESwSpznrQL7qfRbL6lF28Vah0FSKyEGFVIxx-J9Tn9VTLoYtLjwgpRLxVGYUQibV4zSPuaTnbaqPpD4ol7Uz4yZTCPFzbLOG9xoo8_jiWJxNqTcOFLnt2g=w384-h384-nc


But my apologies for misunderstanding, we both had the same idea just different words!
Click to expand...

You are correct. This are Storage Tanks made by the company where I work.
I should have known the word.

Juice Storage Tanks.jpeg
 
Thanks all.
As I stated this is a rural plant, processes apples , has a roof surface area over 100,000 sq ft and sends a lot of rain water onto the ground. They have 7 large underground storage tanks for processed water to use in the plant. Primary source of water is from wells, and the wells cannot keep up with demand. This is why they want to capture and treat rain water.
Just needed something to indicate when it is raining so that the well pumps can stop and rain water is then diverted from drain to the water treatment plant.
 
curlyandshemp said:
Just needed something to indicate when it is raining so that the well pumps can stop and rain water is then diverted from drain to the water treatment plant.
Click to expand...

i think having a gauge is useful for monitoring how much rain has fallen or for estimating the rain water yield. But from a process perspective I'd say the rainwater needs to go to a storage tank before you divert it to the treatment plant. You will not get a nice steady flow which could prove problematic for the plant. Buffering this in a set of tanks connected to the guttering would negate this problem.

The other thing you need to be careful of: rainwater is typically devoid of all minerals and hence has no alkalinity and a very low pH. Your treatment process needs to be capable of dealing with this if they have quality criteria for the treated water.

What might be better option is to shandy the rain water with the bore water so you're not presenting two vastly different water sources to the plant.
 
Saffa said:
i think having a gauge is useful for monitoring how much rain has fallen or for estimating the rain water yield. But from a process perspective I'd say the rainwater needs to go to a storage tank before you divert it to the treatment plant. You will not get a nice steady flow which could prove problematic for the plant. Buffering this in a set of tanks connected to the guttering would negate this problem.

The other thing you need to be careful of: rainwater is typically devoid of all minerals and hence has no alkalinity and a very low pH. Your treatment process needs to be capable of dealing with this if they have quality criteria for the treated water.

What might be better option is to shandy the rain water with the bore water so you're not presenting two vastly different water sources to the plant.
Click to expand...

thanks for that, yes I did not explain the setup too well, a holding tank fed by well water or rain water is sent to the water treatment plant.
 

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