@PRZEM Do you run the risk of becoming the family "go-to" guy/girl (or help desk) when you learn a special skill? Or is that potentially a good thing? I had a brother-in-law who would come with my sister to visit and take care of all of the handyman type things while he was supposedly "on vacation." Tightening loose latches, repairing our screen door, and other kinds of marvelous things.
That jogged my memory, while working on refrigeration systems , we had this epoxy stick http://www.laco.com/repair-sealants/heat-seal-stik/ , it looked like a big green crayon, you cleaned up around the leak, then heated the pipe (150C??), and just rubbed the "crayon" on the leak, I used it once when there was no access for soldering and it's pretty strong as the refrig system could get to > 200Psi.
Another product I found in my old refrig kit is "RedEpoxy" , this is a two part epoxy you mix up seperately, then apply it to a warmed section of pipe, then apply heat till it goes gold, takes a minute, and it's good for 300psi. http://www.highsidechem.com/redepoxy.html
Both of the above can be obtained from a HVAC shop and are specifically designed for high pressure leak fixes. You also have a range of kneadable epoxies similar to marine-tex like this one http://www.laco.com/repair-sealants/epoxy-stik-/ personally I've had mixed results with kneaded epoxies, they tend to be porous.
Also, to make an analogy between the eductor and a transistor, you'd have to go to the (relatively uncommon) common base configuration. In this configuration, the "bias" voltage would be the water pressure being fed by the water supply to one of the legs of the Y connection (aka transistor's collector). The other leg of the Y connection would be the base. The bottom of the Y, which spits our the supply water plus whatever the pump sucks up, is the emitter.
So what happens is that as water pressure is applied to the "collector" of this pump, some "base" current will flow (into the transistor, current from ground through the base), and the sum of collector and base current flows out the emitter. But notice, no voltage gain here, just as there isn't any pressure gain in an eductor.
A regular water faucet is probably a more typical analogy to a transistor, say in emitter follower (common collector) configuration. Water pressure is applied at the "collector," and then a relatively small effort at the faucet's tap (base) will cause a large change in "emitter" water flow. The pressure of the water out of the faucet won't exceed the pressure of the water feeding the faucet, just as in an emitter follower amp, but you'll get large gains between effort applied at the tap and the amount of water flow and pressure out of the faucet.
Eductors can be super efficient pumps, e.g. for de-flooding, if you feed them, say, with typical firemain pressures.
Marine-Tex is an epoxy putty that has myriad uses around boats. A guy I used to work for that owned a 30' Egg Harbor said he'd know someone that used it to fix a crack in an intake manifold. The engine heat helped it to set quicker!
If forced into the hole I'd expect it to set up and remain in place.
Yep you pretty much have it in your last paragraph. The nozzles I use are orange, and bought from a $1 shop in Buffalo (on one of my visits to the US).
(I've not heard of "hydraulic monitor" before but now we have google! I do recall seeing them used on a History channel show, some sort of gold? mining operation)
You also need two lengths of 1/2" hose , about 3' long, with the click-lock fittings at each end. (I use PVC tubing instead as it's more flexible)
So you basically split the water supply into two using the Y piece with the valves, sometimes you need to turn off one or both of nozzle and suction; and have a 3' length of hose for each of the nozzle and ejector.
Ok "adobe" just seems to be dried dirt? domestic water pressure should cut that OK (without resorting to a pressure cleaner) (we have "silcrete" in the western parts of Australia , it's like asphalt!)
You need to make a deep corner in your excavation, this is the sump, the suction unit shoud be contrived to be 1/2" above the bottom, so it doesnt suck onto the bottom of the sump, a small piece of wire netting (1/2" holes or smaller) (like used in aviaries) can be used to form a basket around the bottom , this also catches big chunks that might cause blockages. You would normally leave the suction unit in the one place.
If it's a flat pond or has many low spots you might need to move the suction unit around a bit. I've usually emptied ponds down to ~ 1-2" with the pond pump first. The wire mesh basket prevents damage to any fish you might accidentally try to suck up.
Avoid hydrostatic issues by discharging the water a long way from the pond and waiting several days after heavy rain.
The venturi is fine sucking air, it generally works best sucking half air and half muddy water . You will spend half your time cutting and the other half chasing the mud into the sump.
A secondary issue is what to do with the pile of mud and muddy water at the exit hose , if diverted to a shallow tub , you can then recover about half of the volume of dirt. Or maybe a large piece of shade cloth? or weed mat?
I am having trouble visualizing how all this connects together. We have a pond which could probably use a vacuum.
I also use something like a hydraulic monitor for cutting under the sidewalk. (a plastic nozzle with a taper on it.)
I need to fix some sprinklers, but with the drought here in Northern CA, the adobe soil is like brick. The monitor would cut it, exept all the water pools in the adobe, and has to be pumped out.
I know about venturis from the rocket group I am president of. These things work on air or other fluid. (I have a 19th century textbook on the subject.)
What I can not visualize is how the venturi connects to the monitor and can move the silty mud that backs up in the hole. Where does the Y valve fit in. Does this connect to the water supply with one leg to the venturi and the other to the monitor? If the venturi port is sucking in air, what keeps it from being clogged?
The ejector has a variety of names , e.g. venturi, aspirator.
if you search on ebay for " pond suction -cup " you will find some pictures of e.g. a "mud sucker" and a "pond mini-vac"
You can make one yourself by starting with say a 1" plastic tee, and screwing in a reducing bush with a hose adapter and a hose tail (for a nozzle) . I used to make them myself, (then discovered I could buy better ones for less than the $30/hr to make them! )
Continuing the electronic analogy theme of the original blog...
An ejector is very much like a transistor , you push a current of fluid into the "base" , this causes it to suck up stuff through the "collector" and eject the sum of both flows out the "emitter" (a PNP might be easier to visualise) . Homebuilt ones might have a HFe of 1 to 5 , store bought units maybe 10 to 50
I think the same way , and about $30/hr seems a sensible threshold.
I mow my own lawn with a ride-on mower ,because it takes me 30 min to get it in and out of shed (even if the gardener drives it) , but I leave all the edge trimming , pruning and weeding to him.
With plumbing sometimes its half and half, its silly to pay someone $100/ hr to dig holes , so at least you can dig holes/ lift pavers etc so when the plumber arrives his billable time is short. Sometimes after doing all the prep, you find you can fix it yourself. Irrigation systems are a good example of this.
(BTW I'm in Australia) Recently I needed an ultrasound , the nearest diagnostic imaging company, about 10kms away, wanted ~$400 and couldn't do it for a month. But a private hospital some 50km's away could do it for free the same day.
Given that I already had to drive somewhere, the 80km extra round trip distance amounted to 90 mins of my time in order to save $400, So that's $266/hr , way more than $30/hr
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.