Although it’s been a while that CAD programs were supposed to automate the creation of irrigation plans, it looks like they’re finally doing so in a usable way. We can create graphics that auto-calculate (mostly), pipe sizing (mostly), pressure loss calcs (mostly). Why “mostly”? Because the plan is schematic, so pressure loss won’t be what’s really there, line pressure varies over time, the graphics often need to be “tickled” to get them to update… but overall, it’s much better than it was!
A brave new world
Before, each number had to be manually calculated and typed in. This required looking up pipe runs on a sizing chart, not a fun thing for humans to do. But for a computer… no problem. Although I suspect that the computer is calculating pressure loss dynamically, no chart involved. Computers are good at math, after all.
The other really cool thing here is that we can, with a moderate level of geekiness, create graphics that plug into plan data to display information, more than would have been done by hand. The best example is pressure at the valve, something reviewers never asked for, but now part of asking for things that look very engineered but probably aren’t so much in reality.
I even discovered a Crash! Boom! bug doing this project, the kind where everything just disappears. Fixed in an update, luckily. After project submittal, unfortunately.
What? There may not be 58.85 PSI at that valve when it’s installed? Well, no. It assumes that line pressure never fluctuates – a pretty good assumption in this case because we’re using a custom pump to pull water out of the pond.
But what if more than one station is open? They’re drip stations, after all, so this can be done. That increases the flow in the main line, therefore the friction (no problem as long as flow does not exceed 5 feet per second).
And what about in ten years, when there may be deposits in the lines? Or when the emitters have some wear on them and may not put out exactly 2.00 gallons per hour each.
Then there’s a bit of slope here, not enough to really affect things since the main line runs along a more or less level path – but water gains or loses 0.433 PSI per vertical foot. Enough to move that 58.85 to… something else. I dread the day the bureaucrats add this factor into the calculations!
The really funny thing here is that once the system has been tested and adjusted by experts, the people who follow them may not be. A manager fiddling around, a gardener, someone’s geeky kid. You just never know. At least the irrigation controller senses water flow, weather, environmental factors and programs itself to optimize watering. Unless someone changes the parameters for the plants. If the controller thinks it’s watering lawn, it will put down more water than for ground cover. Since it only knows what it’s told, this could get interesting…
But darn if that computer AI stuff still doesn’t look cool and give instant design feedback! It warns if a valve isn’t connected to the system (just because you drew a pipe doesn’t always mean it actually hooked up to the valve). It says if there’s not enough pressure, it knows irrigation catalogs, it’s parametric so you can say what the limits are and it will follow your instructions: nothing less than 3/4″ diameter? OK! No half inch pipe, done.