Author Topic: Rain Gauge Not Showing Precip (Read 14119 times)

DJMWX86 · « **on:** May 25, 2009, 04:08:46 PM »

I have a Davis VP station and my rain gauge does not show a single drop of rain or very low readings when a big storm rolls through. I compare it to another station a few miles away and they both don't even come close to the same readings. It's not clogged with debris and the tip bucket tips freely. It has no obstructions ie, tree. Does it need to be re calibrated?

offroadjosh · « **Reply #1 on:** May 25, 2009, 04:31:26 PM »

is there any thing obstructing it?? and also rain readings can EASILY vary over even half of a mile. how much does it show if you tip the tipper once? it should show a reading of .01.. if not then check all your connections. how old is this station? has it always done this, did it just start??

Josh

DanS · « **Reply #2 on:** May 25, 2009, 04:41:37 PM »

I would check that it's level also. Being off slightly will give results like you say.

Dan

tomcj2 · « **Reply #3 on:** May 25, 2009, 05:00:10 PM »

Right now I am in the middle of calibrating my rain gauge. I thought that it was reading 20% low,but now I am not sure. I am trying to put 544 grams of water through it; it should read 1 inch, but I am having problems controlling the rate of water I am putting into it. I am using a 2L coke bottle with a small hole in the cap and half way up the side to break the vacuum. I am experimenting with different sized holes.
What I think I really need is an IV drip bag that will give me better control.

Any suggestions?

DanS · « **Reply #4 on:** May 25, 2009, 05:10:45 PM »

Perhaps a different 2-liter bottle but put a small hole in the bottom, fill it holding your finger over the hole then screw the cap on tightly. Position the bottle over the rain gauge and unscrew the cap slowly to get the best flow?

SLOweather · « **Reply #5 on:** May 25, 2009, 05:41:23 PM »

1) Try to run the water through it at a constant rate of no more than say 3" an hour. That would be 20 minutes for your 544 ml.

2) Fabricate a dripping assembly with an orifice/hole no larger than 1/32". It works better if you don't have the weight of the entire column of water pressing on the orifice. That makes it hard to regulate the flow.

You could make the dripping assembly out of a 1 liter bottle cap, and then pour the measure volume through it slowly as it empties.

Or, use a slightly larger container or dish with the hole in it, and suspend or block up the bottle inverted, say half as deep as the sidewall of the dish. If the bottle is unvented, then the dish will only fill to the level of the bottle opening and stop, until enough water has drained out the orifice.

Think of this as a small scale office water cooler.

Or, I'll rent you my NovaLynx Tipping Bucket Calibrator, and Davis specific instructions. I include a RainWise electronic counter that the rain gauge plugs into, which keeps your calibration efforts from screwing up your console readings, and also keeps you from having to manually count the tips.

Chris

wxtech · « **Reply #6 on:** May 25, 2009, 06:36:33 PM »

I need a constant drip into a rain gauge. What I have set up.
1 cola bottle with a #12 drill bit hole in the cap.
2 2 feet of CAT5 outer insulation used as tubing. Strip the outer layer, discard the wires.
3 crimp the tubing lengthwise and force into the tight fit hole in the bottle cap
4 use play dough or plumbers putty to seal the tubing entry into the bottle cap
5 cut large hole in cola bottle bottom for filling.
6 use two Bulldog paper clips together to crimp the tubing or use a forceps to regulate the water flow drip rate. Squeeze the tubing almost entirely closed to get a 1 drop per second drip rate.
7 lots of duct tape to hold the bottle supported to some frame.
8 make a drip loop below the bottle cap and arrange the bottom of the loop so that drips/leaks from the bottle cap don't flow into the tipping buckets
picture below

wxtech · « **Reply #7 on:** May 25, 2009, 06:42:15 PM »

Warning. The above rig seems to be a rain maker. Sunday, I set it up and it began to rain while I was building it. Today, I changed to a larger bottle and rain started so hard the duct tape wouldn't stick.

SlowModem · « **Reply #8 on:** May 25, 2009, 06:49:55 PM »

Quote from: DanS on May 25, 2009, 04:41:37 PM

Being off slightly will give results like you say.

Dan

Hey! I resemble that remark!

SlowModem · « **Reply #9 on:** May 25, 2009, 06:51:18 PM »

Quote from: wxtech on May 25, 2009, 06:42:15 PM

Warning. The above rig seems to be a rain maker. Sunday, I set it up and it began to rain while I was building it. Today, I changed to a larger bottle and rain started so hard the duct tape wouldn't stick.

It would probably look funny, but wouldn't it be easier to use an enema bag/hose. You can regulate that flow, too, and it's all hooked up.

SlowModem · « **Reply #10 on:** May 25, 2009, 06:52:49 PM »

Quote from: DJMWX86 on May 25, 2009, 04:08:46 PM

I have a Davis VP station and my rain gauge does not show a single drop of rain or very low readings when a big storm rolls through. I compare it to another station a few miles away and they both don't even come close to the same readings. It's not clogged with debris and the tip bucket tips freely. It has no obstructions ie, tree. Does it need to be re calibrated?

You should consider getting a manual gauge and placing it beside the tipping bucket sensor. Then you can compare.

DanS · « **Reply #11 on:** May 25, 2009, 07:11:09 PM »

Quote from: Slow Modem on May 25, 2009, 06:49:55 PM

Quote from: DanS on May 25, 2009, 04:41:37 PM
I would check that it's level also. Being off slightly will give results like you say.

Dan

Hey! I resemble that remark!

That remark was initially directed at the rain gauge query but after reading the "enema bag" suggestion I'm reconsidering.

tomcj2 · « **Reply #12 on:** May 25, 2009, 07:42:08 PM »

I thank all of you for your suggestions: I will try most of them next weekend. Having moved 6 cubic yards of bark dust, getting the pool cleaned after winter, planting the flowers, and tilling and preparing an area of the back yard for grass seed, I am done for this weekend. Some long holiday weekend!! I look forward to work tomorrow; a chance to rest.

By using 2 different pop bottles, several times each, I decided that it was reading 5 to 6% low. The tipping buckets had a lot of crud in them, and I assume that made up the other 16% of the difference that I was experiencing. I will clean them every month or two in the future.

I turned the screws out 1 full turn, and I am running more "pop Bottles " through it.

A report will be posted later

DJMWX86 · « **Reply #13 on:** May 25, 2009, 10:50:43 PM »

There is nothing obstructing it. I did tip it a few times and it does read .01''. The station is about 5 years old. I can't recall exactly when this started, but I know it's been happening for quite awhile (for most of last year and this year)

wxtech · « **Reply #14 on:** May 25, 2009, 11:15:07 PM »

Quote from: DJMWX86 on May 25, 2009, 10:50:43 PM

There is nothing obstructing it. I did tip it a few times and it does read .01''. The station is about 5 years old. I can't recall exactly when this started, but I know it's been happening for quite awhile (for most of last year and this year)

If it is wireless, take your console to the ISS and carefully tip the bucket one time. The console should indicate 0.01" increase. Tip the bucket back to the original angle and the console should indicate an additional 0.01". You should get exactly 0.01" increase for every tip of the bucket.
It is possible that the magnet, the reed switch or the cable is defective. In that case, contact Davis for replacement instructions. Check the cable plug and socket for bent pins, debris, or moisture in the connector. Check for a frayed cable.
Trace the rain cable to the reed switch under the buckets. It has a plastic cover that snaps over the reed switch. You may carefully remove that cover and check the cable solder connections or if dirt or spider webs are on the reed switch. The reed switch is a glass tube with leads on each end.
PM me if you wish to call me for more information.

DJMWX86 · « **Reply #15 on:** May 28, 2009, 04:15:17 PM »

I will check it out and get back to you. In the mean time, is there a way to manually enter rain fall data in VWS so my readings can be somewhat accurate?

Anthony · « **Reply #16 on:** May 29, 2009, 08:22:16 AM »

Yes Try looking under Settings | Rainfall.

Aardvark · « **Reply #17 on:** May 29, 2009, 10:02:01 PM »

check that the rain bucket is level.

I noticed that it was pouring and no rain being recorded, so I hoofed out in the rain and found that the iss had shifted forward so slightly, but the water was going in the funnel,down on the tipper and flowing out of the tipper. I re-leveled it and it began to work right... do check that ..

IF you manually tip the tippers and the console registers, then the bucket isn't level. Other wise .. contact davis

tomcj2 · « **Reply #18 on:** May 30, 2009, 09:06:29 PM »

Quote from: Slow Modem on May 25, 2009, 06:51:18 PM

It would probably look funny, but wouldn't it be easier to use an enema bag/hose. You can regulate that flow, too, and it's all hooked up.

I tried several methods, and the enema bag worked the best. Yes it did look funny. Check it out at Axelvold's site http://www.axelvold.net/

specifically http://www.axelvold.net/mxcam/thumb.php?id=4269.

DJMWX86 · « **Reply #19 on:** June 17, 2009, 01:58:23 PM »

I checked out my Davis rain gauge by tipping the bucket to each side and it did read .01'' increase per tip however, we got rain today and just out of curiosity, I have a manual rain gauge a few feet away and compared them both and they read: Davis: .10'' Manual: .51''.
The Davis Gauge is not obstructed and debris free. I am just dumbfounded here.

d_l · « **Reply #20 on:** June 17, 2009, 02:29:14 PM »

When you tested the tip recording did you test for recording of successive tips? Perhaps it fails to record some tips when they are occurring at a modest rate (rapid tip rates may simply be too fast for any gauge to record)?

Aardvark · « **Reply #21 on:** June 17, 2009, 04:08:38 PM »

I know we've said it before.
when you are calibrating your rain guage, you need to carefully adjust both screws under the tipper and remember which direction you are moving it.

When checking why no readings:
Crud in the bucket or something plugging up the bottom of the cone
Broken reed switch
Dislodged magenet on the tipper
check that it is plugged in and there are no corrosion in the plug.
the wire isn't broken or frayed.
check that the ISS/rain bucket is perpendicular and level in two directions.
prayer and a shamman also help at times when all else fails

dalecoy · « **Reply #22 on:** June 17, 2009, 10:42:03 PM »

Quote from: DJMWX86 on June 17, 2009, 01:58:23 PM

I checked out my Davis rain gauge by tipping the bucket to each side and it did read .01'' increase per tip however, we got rain today and just out of curiosity, I have a manual rain gauge a few feet away and compared them both and they read: Davis: .10'' Manual: .51''.
The Davis Gauge is not obstructed and debris free. I am just dumbfounded here.

Just checking (no insult intended) - are you comparing console reading for "today's rain" to manual gage that was just today's rain? Or WeatherLink Storm Rain to the total manual rainfall?

DJMWX86 · « **Reply #23 on:** June 18, 2009, 10:44:46 AM »

We had been dry for about a week and I compared "daily rain" on the console (less then 24 hours) with the manual rain gauge and the manual rain gauge read 0.51'' and the console read 0.10'' after the rain stopped as I stated eariler. I tipped the bucket slowly and waited for it to show on the console then tipped it again and waited, etc. So I was not rushing it so to speak.

wxtech · « **Reply #24 on:** June 18, 2009, 10:50:52 AM »

I've read and re-read this thread several times. There's nothing that I can do without having my hands on the equipment. It will take a technician about 5 minutes to fix this. It's time to contact Davis customer service/technicians or take it to a wx eqpt tech.

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Author Topic: Rain Gauge Not Showing Precip (Read 14119 times)