Count the pumping events

September 15, 2009 6:43 AM

I need to count how many times a sump pump runs in a given period. The sump pump pumps water out of a hole on the ground, it is activated by a float switch - so generally speaking it pumps the same amount of water out each time it runs (the volume of water from the top 'on' level to the lower 'off' level). I want to know how much water is being pumped per week/month/whatever.

I figure that since the pumping amount is (approx) the same each activation, if I knew how many times to runs (and it's about 4-6 times per day) I can work out the total pumped amount.

Is there a sensor or method you can suggest to do this?
Or to measure the pumped water volume directly maybe?

I'm on a tight budget, so I've been thinking of 'no-cost' solutions like balancing something on the pipe (which vibrates alot) or listening for the sound with a laptop set to record, but I hoping the hive mind can come up with a brilliant idea for me.

Thanks.

posted by Xhris to Technology (12 answers total)

What is the outlet pipe like? Is there a potential to place a flap at the end of the outlet, which would be moved by each surge of pump water? If so, you can rig some sort of motion detector to a shaft attached to that flap.
posted by Midnight Skulker at 6:48 AM on September 15, 2009

I think you'd want to time how long it runs in a certain period. I think most sumps are constant speed, so time of run x rate = volume.
posted by electroboy at 6:50 AM on September 15, 2009

Does it make a distinct sound? You could set up a pc down there and a cheapo mic and set it to record for a given time. Then load the wave file into a sound editor and look for the distinctive peaks that indicate the pump is running.
posted by ian1977 at 6:51 AM on September 15, 2009

umm, yeah you already had that idea. :-P
posted by ian1977 at 6:51 AM on September 15, 2009

This probably isn't the most efficient solution, but you could pick up a Kill A Watt type device and measure the draw of the pump when it's running and when it's not. They should be very different. If you have the total power used by the device, assuming that it has a fairly constant load, you could calculate the time it was running.
posted by aaronbeekay at 6:51 AM on September 15, 2009 [1 favorite]

At a surplus place I found a counter that incremented every time a magnet got close to it. If you can see the float switch this might work. The sump probably fills with water more or less continuously so there isn't a problem with the switch chattering. You could build a fork to trip a switch when the float rises and falls, too, or sense the change from float present to float not present by a bunch of different means depending on what's at the surplus place.

If the float switch circuit is accessible you could sense its changes of state directly, as the pump does.
posted by jet_silver at 7:09 AM on September 15, 2009

Well, you could start with something like this auto switch. This will turn something on every time your pump turns itself on.

Next you need this analog counter that will increment every time voltage is applied.

It runs on 24 vdc, so you'll need one of these to drop the voltage down.

I'm not entirely sure, but I think this counter would accept the AC line level voltage without an adapter.
posted by davey_darling at 7:23 AM on September 15, 2009

A cheap hour meter plus knowledge of how much water your motor pumps per hour (direct measure or read off of pump) will give pretty accurate results.

Or if you can find a mains power electric clock for free/cheap (freecycle/craigslist?) then you could just wire it down stream of the switch.
posted by Mitheral at 7:54 AM on September 15, 2009 [2 favorites]

cheapest: measure the outflow of water with a bucket of known volume that you would empty at a known interval.
posted by kuujjuarapik at 8:03 AM on September 15, 2009

What about a pc fan with a pair of magnets on them, running in the flow stream, with a hall sensor on the outside to a pc (through an arduino board or somesuch). Essentially a homemade turbine meter.
Also, see here, maybe you can find something used on ebay...:
http://www.247able.com/scp/Flow/Turbine_Flow_Meters.html
http://www.roxspur.com/flow/total/water.php
posted by defcom1 at 8:48 PM on September 15, 2009

some more suggestions here:
http://cr4.globalspec.com/thread/12196/Looking-for-cheap-domestic-flow-meter
posted by defcom1 at 8:53 PM on September 15, 2009

All you people suggesting an Arduino to implement a COUNTER need to be slapped, hard. And we complain that windows has code bloat.

If you're any good with electronics (i.e. can solder together a simple circuit, much simpler than anything arduino-related) then you can buy a simple counter chip (like a 4020) and hook it up to the float with a reed relay and magnet. Hook up LEDs to the output pins and you can see the count in binary. Total cost: under $5, plus a 5V supply.

If that's too hard but you can assemble a kit, there are many.

Otherwise, you can buy off-the-shelf discrete event counters, like this one. Arrange it so that the float cuts the "doorway beam" and you get a count of that.

Or get a mechanical counter and arrange it so that the float trips it.

Using a Kill-A-Watt to record total power consumption from the pump is also an excellent idea - not so much a count of draninings but a direct reading of water volume pumped.
posted by polyglot at 10:34 PM on September 15, 2009