Well pressure tank: Does well-side supply line pressure match tank pressure?

[CobyRupert]

Water is incompressible, meaning you can’t compress it like a gas, or a foam football.

In a closed system, think of it like a metal rod, or like a cable you can push. Like hydraulic oil in a hose. A push, tap, pulse, hammer on one end will transfer the force to the other end.
Moving water has momentum that creates a force when that momentum is interrupted. That force can be reflected in the opposite direction of the original flow.
If much of that force, created in this case by water to the ballast tank reversing direction when aux valve is opened, is absorbed into a bladder (gas compressing) in a ballast tank) or passes through the open faucet, one can expect the shock load (hammer) to be lessened.

 

[Egon]

I coined the "connection". Remember Nerf Balls and bats? Soft foam. A hammer would thus be a contradiction in terms. "Hammer" connotes some range of severe impact. Below that range would be what? .. impulse? urge? bump?

Sounds like confusing the issue by an attempt to introduce new wording that does not apply to the situation.

 

[Valveman]

Water is incompressible, meaning you can’t compress it like a gas, or a foam football.

In a closed system, think of it like a metal rod, or like a cable you can push. Like hydraulic oil in a hose. A push, tap, pulse, hammer on one end will transfer the force to the other end.
Moving water has momentum that creates a force when that momentum is interrupted. That force can be reflected in the opposite direction of the original flow.
If much of that force, created in this case by water to the ballast tank reversing direction when aux valve is opened, is absorbed into a bladder (gas compressing) in a ballast tank) or passes through the open faucet, one can expect the shock load (hammer) to be lessened.

You are exactly right. If the ballast or pressure tank is inline with the main line, as when using the old galvanized type tank, the air in the tank can absorb much or all of the shock wave. However, a bladder style tank is teed off the side of the main line. This causes the resulting shock wave created when the flow in the pipe changed direction to fly past the tee to the tank at more than 3,000 feet per second. Water hammer happens so fast that nothing teed off the side of the line can catch it. In this case the shock wave would fly right past the tee to the tank and travel all the way to the faucet in the blink of an eye. The restriction of smaller pipe and the partially open faucet will slow it down some, but still reflect most of the shock wave right back towards the pump again. In a short pipe line it will still bounce back and forth several times.

I have watched gauges on pipelines that were miles long. When you shut off the pump and/or open a valve, the pressure will bounce from a strong negative to wrapping the needle around the gauge. The longer the pipeline the slower this happens. But the gauge will go from one extreme to the other every couple of seconds on a long pipeline. It can be actually kind of scary to watch and listen too as it can even shake the ground. The negative and positive pulses will get less and less with each bounce back until the friction loss in the pipe finally uses up all the extra energy.

One funny story is of a friend of mine who closed an 8" valve too quickly at the end of a 7 mile pipeline. The water blew off the MJ fitting and squirted two guys out the top man hole. It is only funny because all that got hurt was their cell phones to call for help. Lol!

 

[turnkey4099]

It will be fine, I run a line like that already, but its almost 2000 feet long. The pressure will be uniform in the whole system.

The static pressure (no water bneing drawn) will be equal. The dynamic pressure (water in use) will depend on distance the water is traveling and the altitude difference between tank and point of use (pump not running). There can be a lot of pressure lost (dynamic)_ in long runs and number of pipe fittings.

 

[SPYDERLK]

Sounds like confusing the issue by an attempt to introduce new wording that does not apply to the situation.

Yes, some are easily confused. They are prone to take a real phenomenon, awesome in its effect in large scale systems where virtually every design and operation choice has been poor, and then sensationally apply such effect, full bore with negligent regard for operating nuances and convenient moderating choices, to a guys backyard water system.

 

[cqaigy2]

The static pressure (no water bneing drawn) will be equal. The dynamic pressure (water in use) will depend on distance the water is traveling and the altitude difference between tank and point of use (pump not running). There can be a lot of pressure lost (dynamic)_ in long runs and number of pipe fittings.

I don't understand how distance would be involved.

 

[SPYDERLK]

I don't understand how distance would be involved.

"Traveling", and "dynamic", in the post you quoted is meant to indicate flowing as opposed to static. Friction increasing with distance, comes into play during flow.

 

[Egon]

Yes, some are easily confused. They are prone to take a real phenomenon, awesome in its effect in large scale systems where virtually every design and operation choice has been poor, and then sensationally apply such effect, full bore with negligent regard for operating nuances and convenient moderating choices, to a guys backyard water system.

Talk about ConFusion!
Liquid flow has parameters that are independent of system size. It is all about the change in liquid velocity.

 

[turnkey4099]

I don't understand how distance would be involved.

Pipe and fitting friction with dynamic pressure. I have an interconnect to my neighbor's well 1/4 mile away. System pressure 30/50. That runs sprinklers at his place just fine. Won't run one at my end. we are just about level for elevation between the two points.

After thinking about my original posst I realized that the static pressure will equalize for all points but varies with the elevastion. Level - all points read equal. point of use higher - the pressure will read lower.

 

[turnkey4099]

Shutting any valve off suddenly can induce water hammer (moving water hits immovable object and the momentum of the water causes pressure spikes). Because gate valves move slowly, they are less susceptible to water hammer. Solenoid operated valves, globe valves and ball valves can be shut quickly.

The solution is easy: don't quickly shut a valve on rapidly flowing water.

The pressure spikes from water hammer are hard on your plumbing, leading to premature failures.

There is a type of pump, called a hydraulic ram pump, that makes use of the pressure spike of a water hammer to convert low pressure flowing water into higher pressure water. Upside is that it uses no additional power, the major downside is that it only pumps up about 10% of the flow. Still, if you have flowing water...

All the best,

Peter

Yep. With a flowing stream they work quite well. Low output but it is outputting 24/7 so...drawback is hardly any pressure at point of use. There are homebuilt one using nothing but pipe fittings. Neighbor had one feeding his house (50 gal barrel in kitchen) Pump was almost severy hundred yards away.