ᐅ How much water should or must flow from the main water supply line?

Created on: 30 Jul 2018 10:50
K
KingSong
Hello,

I have a somewhat urgent question. Our screed is scheduled to be poured on Friday. The main water line from the street enters the technical room, connected at the bracket but without a meter yet. Just behind the main shut-off valve, there is a tap installed.

The screed contractor connected the silo mixer to this tap. Both valves are fully open, but not enough water is coming through. The silo mixer requires 2000 liters per hour (530 gallons per hour).

The shut-off valve at the street is fully open. The water utility says the pressure is no more than 3 bar (43.5 psi), but the construction manager believes that even at 3 bar (43.5 psi), the line should easily supply 2000 liters per hour (530 gallons per hour).

How much flow should generally be expected here? The water utility suggests installing a pump to increase the pressure, but if the street supply can’t deliver more water, how would a pump increase the volume?

Currently, work is stalled because there isn’t enough water from the line to run the silo mixer.

Does anyone have any ideas on what we can do?

Thanks in advance, greetz Jörg
KingSong30 Jul 2018 13:02
Yes, that is probably the solution, but the installer is not available, and I definitely won’t be handling it myself.
Musketier30 Jul 2018 14:07
Such low pressure also becomes relevant for the sprinklers. They assume 4 bar (58 psi). We have a maximum of 6 bar (87 psi) here.

However, I also suspect the valve.
M
Mottenhausen
30 Jul 2018 14:52
Take a look at the external cross-sections of the main valve and the piping in general... and then the cross-section of the temporary valve, where the water flow is also diverted unfavorably around a corner. That setup cannot work.

Try this test: open both valves fully, then slowly close the main water supply valve. I estimate you can close it up to 75% without noticeably reducing the flow at the smaller valve, as this is where the actual bottleneck is.
KingSong30 Jul 2018 15:49
Then the plumber definitely messed up, since he knew the screed was coming. Why would he install a valve like that and even say the screed installers could connect to it? I could really get upset about such unnecessary nonsense.
D
Domski
30 Jul 2018 20:29
I also had a tap like that, which was more than enough for the small screed machine. However, I have 5 bar (72.5 psi) pressure before the pressure reducer here.
KingSong30 Jul 2018 20:32
Unfortunately, I don’t have a *small* screed machine, but a 17-ton (17,000 kg) screed silo mixer.