Stopping the water flow is easier said than done.

Snapped an operating stem one night while flushing fire hydrants, one of the jobs my FD did. City dispatched a water department crew and after an hour with nobody showing up we tried to cap off the 5” outlet. The rites of futility as I called it. All we accomplished was to get soaked.

Between the pressure and volume it was destined to fail.

quote:

Originally posted by tatortodd:

quote:

Originally posted by Hildur:
I'm just relaying what the maintenance guy told me. He was quite clear that the pumps just can't be turned on and off.

All that water pressure compounded with gravity has to go somewhere. That somewhere is backfeeding into the pump systems which are designed for water to go out, not in and would damage them. Then there's the issue of what to do with all the excess water returning to the pump station and holding pools.

That's his explanation and it made sense to me.

Perhaps the place he worked was configured like that, but it's idiotic.

Pumps can be turned off with an ESD. It can be as simple as a button near the pump to as complex as the pump and button in 2 locations miles apart. I've done both.

Backfeeding is prevented by check valves which are an off the shelf item and available in low, medium, high pressure designs.

These pumping stations use 5 to 10 MEGAWATTS of energy. Are you suggesting that someone can throw a switch and the whole system will shut down without any negative repercussions?

How expensive is a check valve that allows for 1k+ gpm and can handle a psi over 600? Aren't these pipelines 18-24"? Does a check valve for that even exist?

quote:

Originally posted by Hildur:

quote:

Originally posted by tatortodd:

quote:

Originally posted by Hildur:
I'm just relaying what the maintenance guy told me. He was quite clear that the pumps just can't be turned on and off.

All that water pressure compounded with gravity has to go somewhere. That somewhere is backfeeding into the pump systems which are designed for water to go out, not in and would damage them. Then there's the issue of what to do with all the excess water returning to the pump station and holding pools.

That's his explanation and it made sense to me.

Perhaps the place he worked was configured like that, but it's idiotic.

Pumps can be turned off with an ESD. It can be as simple as a button near the pump to as complex as the pump and button in 2 locations miles apart. I've done both.

Backfeeding is prevented by check valves which are an off the shelf item and available in low, medium, high pressure designs.

These pumping stations use 5 to 10 MEGAWATTS of energy. Are you suggesting that someone can throw a switch and the whole system will shut down without any negative repercussions?

How expensive is a check valve that allows for 1k+ gpm and can handle a psi over 600? Aren't these pipelines 18-24"? Does a check valve for that even exist?

Someone doesn't physically throw a switch. It's a button (might be a big red phyical button or a digital button on a PLC screen) that shuts it down with zero repercussions to the pumps and associated switch gear.

Yes, check valves exist all the way up to to at least 60". A check valve would be significantly less money that tearing up a pump. Your hypothetical 1000 gpm and 600 psi is under $2500.

quote:

Originally posted by tatortodd:

A check valve would be significantly less money that tearing up a pump. Your hypothetical 1000 gpm and 600 psi is under $2500.

For shits and giggles I tried finding a check valve that met that criteria. Here's the best I could find: https://www.mscdirect.com/prod...ls/76616218?fromRR=Y

$58k for 400psi and no gpm specs. Still cheaper than a new pump but doesn't meet the psi req. as most of these systems are 600-1k psi of pressure at the pump.

quote:

Originally posted by Hildur:

quote:

Originally posted by tatortodd:

A check valve would be significantly less money that tearing up a pump. Your hypothetical 1000 gpm and 600 psi is under $2500.

For shits and giggles I tried finding a check valve that met that criteria. Here's the best I could find: https://www.mscdirect.com/prod...ls/76616218?fromRR=Y

$58k for 400psi and no gpm specs. Still cheaper than a new pump but doesn't meet the psi req. as most of these systems are 600-1k psi of pressure at the pump.

You wouldn't have a 24" pipe or valve for a mere 1000 gpm (8" for 1000 gpm and 24" would be for 15,000 to 20,000 gpm). There isn't a GPM spec as valves are spec'd on pressure, and when comparing two vendors one of the factors engineers look at is pressure drop across the valve.

^^^^^^^^^^^^
I guess you learned all this at Purdue while I was reading about the condition of man. The power of water is incredible. Holding a fire hose when it is on full blast gives you a bit of an idea. Storm surge from a landfalling hurricane is impressive as well. Poor planning all around.

quote:

Originally posted by Hildur:


I'm not sure what kind of shutoffs there are but clearly by the water pressure it's not something a guy with a wrench can do in a couple minutes. Shutting down the pumps isn't as simple as throwing a switch and it's very costly to turn on and turn off.

Costly ? Maybe so . But easy as throwing a switch ? If you know where the switch is , sure .

quote:

Originally posted by Hildur:

quote:

Originally posted by tatortodd:

A check valve would be significantly less money that tearing up a pump. Your hypothetical 1000 gpm and 600 psi is under $2500.

For shits and giggles I tried finding a check valve that met that criteria. Here's the best I could find: https://www.mscdirect.com/prod...ls/76616218?fromRR=Y

$58k for 400psi and no gpm specs. Still cheaper than a new pump but doesn't meet the psi req. as most of these systems are 600-1k psi of pressure at the pump.

If they are taking water from a lake they would have to have back flow prevention in place so there's no possibility of contaminating the lake. So there are check valves in place.

Yeah, a localized kill switch (at the pump) and the breaker in the electrical room. Either way, fairly easy to shutdown.

I'm thanks Tatortodd, my PSI guess way way low.

You guys ski much? Snow making is 4” lines….

“The violent eruption of water occurred when a snowmaking hydrant was snaped after a skier skied into it.”

Link has video of the lady describing the safety bar being blown up by the water and then her flying up off the chair lift.

So she did not jump as originally reported.
She was blown off the chair.

Link

They should have parked a snow groomer over the gusher before advancing the chair.

What a shit-show.

quote:

Originally posted by Cookster:
They should have parked a snow groomer over the gusher before advancing the chair.

What a shit-show.

By the time they get a cat over there, they would've already shut off the water flow. Its not like those drivers are sitting around during operating hours, not to mention they're likely parked over in maintenance or, mid-mountain, which is a ways off.

that's like the reverse of a winning lottery ticket

you know you're having a bad day when ...

--------------------------------------------

quote:

Originally posted by feersum dreadnaught:
You guys ski much? Snow making is 4” lines….

You're only seeing a small portion or a very simple system...

The overall hydrant piping network can be quite complex with large diameter main lines and small diameter branches from mainline to hydrant. The large diameter mainline can originate in a pump house like this .

quote:

Originally posted by shovelhead:
Stopping the water flow is easier said than done.

Snapped an operating stem one night while flushing fire hydrants, one of the jobs my FD did. City dispatched a water department crew and after an hour with nobody showing up we tried to cap off the 5” outlet. The rites of futility as I called it. All we accomplished was to get soaked.

Between the pressure and volume it was destined to fail.

The system in the story is fed by pumps . Pumps can be turned off . Valves can be closed , etc. Municipal water systems are a completely different story .

quote:

Originally posted by corsair:

quote:

Originally posted by trebor44:
What, no shut off valve? No STOP loading? Put a 'bucket' over it! There are so many solutions that it defies imagination! Put then you have to have humans capable of THINKING! Gotta love that 'snow making' equipment!

A bucket?!?...you see how much pressure is shooting out of that pipe? It was high-enough to release a ski and it nearly launched the next rider as the water column pushed up against his snowboard. Then there's the next guy who was left dangling from his chair and may have passed-out

There are many kinds of buckets. I used the back of the bucket on my excavator to deflect the geyser resulting from a broken 2” air vent line on a six inch line with over 170 psi. I suspect he wasn’t talking about a Home Depot orange five gallon Homer bucket.

That's crazy and the lift keeps feeding the chairs right into the water bath. Imagine you are drifting right into it and there's nothing you can do to stop it.

quote:

Originally posted by downtownv:
That's crazy and the lift keeps feeding the chairs right into the water bath. Imagine you are drifting right into it and there's nothing you can do to stop it.

I would have jumped off. I still can't figure out why the operator kept putting people directly in the jet?

Certainly a terrible situation for those riding the ski lift, but I just wanted to jump into the thread & state how impressed I am at the wide and varied expertise of our members here in Sigforum. I learned many interesting facts about engineering and water pressure which I did not expect to learn upon opening this thread. And that happens frequently on this forum.

Thank you to our forum members, the owner (para) and the moderators for creating this home. It’s a collection of great people from all over the world but also represents characteristics that make America great. Happy to be a member here.