this post was submitted on 30 Jun 2024
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In the US for example the standard is 110V for voltage and 80psi for water. In Europe, voltage is 220V, is water pressure different there too?

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[–] [email protected] 29 points 4 months ago (1 children)

Water operates more like DC voltage so there isn’t really a need for a standard. You just need enough to get to your shower head.

[–] [email protected] 7 points 4 months ago (1 children)

That’s an interesting analogy. But just like too much current can melt a wire, I would assume there’s some upper limits to keep it from bursting pipes and fittings?

[–] [email protected] 8 points 4 months ago (1 children)

I think it’s 80psi/20psi to code.

[–] [email protected] 5 points 4 months ago (1 children)

But which regions code are you referring to?

[–] [email protected] 5 points 4 months ago

US. I’d be surprised if anywhere was allowing more than 80psi.

20psi is really low so this value may have different variations. I’m on a well pump and before I replaced it I was getting down to 20psi. It barely dribbled out of the 2nd floor shower head. I now have the pump set to 60/40 with a 50psi restriction valve. This seems to be the sweet spot.

I’m not in plumbing and won’t know how to look this stuff up.

[–] [email protected] 28 points 4 months ago* (last edited 4 months ago) (2 children)

Afaik water pressure is variable based on each city's design needs.

[–] [email protected] 26 points 4 months ago* (last edited 4 months ago)

Everyone else is focusing on whether the rest of the world uses metric and not that fact that water pressure at a given faucet or shower head will be governed by bernoullis equation which will take 99 things into account such as:

The max height of the water reservoir

The height of your faucet

The design of the pipes leading from the reservoir to your faucet

Air pressure

The pumps in the system

Etc

[–] [email protected] 5 points 4 months ago

And the location of the house/apartment. Houses higher up have lower water pressure and in apartment buildings the upper floors have lower pressure than bottom floors. 1bar of pressure lifts water 10 meters high. When constructing heating lines on a new building we might have the heating on on the first 3 floors despite the ends of the pipes leading to upper floors still being open and half of the building missing. The water wont spray out as long as we keep the pressure low enought that it doesn't rise to where the pipes end.

[–] [email protected] 21 points 4 months ago* (last edited 4 months ago)

Noggie here. Code dictates a minimum of 2Bar (~30psi), but it's usually between 3-6 bar.

The pressure at my house was recently measured as I had some plumbing work done, and in my 2nd floor bathroom it clocked in at around 5 bar (75ish psi, I think)

[–] [email protected] 12 points 4 months ago

Here in the UK the legal minimum is 1 bar per 10m of elevation. But usually the tap will have between 2 and 4 bars of pressure. Older buildings might only have 1 bar ofc. And by older I mean stuff that was built centuries ago and proper modern water supply is impossible to install.

[–] [email protected] 9 points 4 months ago

My house is operating at around 3,5-4 bar after the pressure regulator. Since I have no gauge I can‘t deliver the pressure of the supply. I guess it is around 6 bar. Small town in Germany.

We also have mandatory check valves since a couple of years to prevent water from entering the supply from the buildings in case the pressure drops.

[–] [email protected] 8 points 4 months ago* (last edited 4 months ago) (2 children)

Not European, but I think they might not use PSI since that's Pounds per Square Inch. I believe they use Pascals/ Bar.

[–] [email protected] 16 points 4 months ago (1 children)

In Germany at least I think th most popular unit is Bar

[–] [email protected] 2 points 4 months ago

Portugal is the same.

[–] [email protected] 9 points 4 months ago (1 children)

Doesn’t really matter the unit of measurement. Kinda like hp/ps or lb-ft/nm, there are equivalents. I’m more interested in the values, but you do have a valid point there.

[–] [email protected] 5 points 4 months ago

Well, you're asking about other countries and literally no one knows what PSI is :)

[–] [email protected] 8 points 4 months ago

Australia uses kilopascals rather than PSI. Our standard is 500kPa which works out at around 72 PSI.

[–] [email protected] 6 points 4 months ago* (last edited 4 months ago) (1 children)

The most common one is bar. 1 bar is roughly the atmospheric pressure.

An older German unit was atü, 0 atü is atmosperic pressure

Edit: sorry I misunderstood the question

[–] [email protected] 0 points 4 months ago (1 children)

So, a hole in a bucket? Doesn't sound right.

[–] [email protected] 1 points 4 months ago (1 children)

Gauge pressure not absolute

[–] [email protected] 1 points 4 months ago
[–] [email protected] 4 points 4 months ago (2 children)

In europe they mostly use Bars as the unit of measurement.

Mostly water pressure is around 1-2 bars as a minimum, but there are still places using different standards, for example the old style gravity-fed UK watersystems with sub 1 bar pressure, but those are not very common anymore.

Most domestic sanitary products in the EU are designed to be used on 1-5 bar pressure.

I read somewhere the domestic water pressure to be between 4-6 bar, however not sure how realistic it is accross the whole EU and also what you got at the mains and what you got when opening the faucet is two different numbers.

[–] [email protected] 2 points 4 months ago (2 children)

A bar is 100,000 Pa or 100.000 Pa. Why not use KPa? Why set a separate unit to be 1E+05?

[–] [email protected] 2 points 4 months ago

Because 1 bar is almost atmospheric pressure. Oddly enough I've never seen anyone use kPa, weather forecasts often use hPa (instead of mbar) to report atmospheric pressure.

[–] [email protected] 1 points 4 months ago

No idea what is the story behind it, or if there is a practical reason.

[–] [email protected] 1 points 4 months ago (3 children)

Will any pressure below 1 bar work at all? Wont it just suck the air in instead?

[–] [email protected] 2 points 4 months ago

These pressures are all gauge pressure, not absolute pressure. 1 bar gauge pressure would be about 2 bar absolute.

[–] [email protected] 2 points 4 months ago (1 children)

1 bar is enought to lift water 10 meters up. The pressure gauges reads zero at atmospheric pressure.

[–] [email protected] 1 points 4 months ago

Ahh, relative pressure

[–] [email protected] 1 points 4 months ago* (last edited 4 months ago)

The gravity systems in this case are not pressurized. They just have a water tank in the loft/airing cupboard and the hight of the tank determines the pressure. 0.1 bar for every 1 meter height. You open the faucet and gravity pushes out the water.

Its a nightmare, I used to live in UK and these systems are barely enough for anything really.

[–] [email protected] 4 points 4 months ago (1 children)

80psi

different there too?

Of course, because psi exists only inside Usa. The real world does not use body parts for measurement anymore ;-)

[–] [email protected] 2 points 4 months ago (1 children)

I use Torque per cubic foot.

[–] [email protected] 3 points 4 months ago (1 children)

Stork's foot or crocodile's?

[–] [email protected] 2 points 4 months ago (1 children)
[–] [email protected] 1 points 4 months ago

Old man still got any pressure?

[–] [email protected] 1 points 4 months ago (2 children)
[–] [email protected] 4 points 4 months ago (1 children)
[–] [email protected] 3 points 4 months ago

What genius decided to denote the difference by using three shades of the exact same colour?

[–] [email protected] 3 points 4 months ago (2 children)

Is that substantial though or is it like calling 120V something like 110V/115V?

[–] [email protected] 2 points 4 months ago

It doesn't matter one bit. The actual voltage from the wall varies, and devices are build to operate under a fairly wide margin.

[–] [email protected] -2 points 4 months ago (2 children)

Hes just being pedantic. Reality is US houses get a +120v and a -120v supply. Combine them is how you get 240v.

[–] [email protected] 3 points 4 months ago

There’s lots of pedantry going on in this thread rather than attempting to understand the spirit of the question.

[–] [email protected] 2 points 4 months ago* (last edited 4 months ago) (1 children)

sorry dude thats not right. first off houses recieve AC power which cycles between positive and negative at 60hz ~120v rms in north america. they achieve a potential difference in voltage by basically taking a phase of power, splitting it into two lines and then lagging one line by 90° usually with the use of capacitance from what i was taught back in the day(Good ol ELI the ICEman). this phase shift now gives you a potential difference between those two lines of 240v and 120v between phase and ground. need to use phasor algebra with AC power. when dealing with 3 phase power you still wouldnt just add 120v plus 120v when going phase to phase, you would multiply 120v by the square root of 3 which gives you 208v.

[–] [email protected] -1 points 4 months ago (1 children)
[–] [email protected] 1 points 4 months ago

oop, not my intention but youre right