True, but some people in this thread stated that pressure has nothing to do with waterflow, which is nonsense.
Plumbing Supply Issue
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True, but some people in this thread stated that pressure has nothing to do with waterflow, which is nonsense.
James:
Thanks for your detailed response, it was very informative.
But I can't help but notice the lack of the variable called "volume" in all those equations. If the pump cannot move enough water to fill the pipe then your pressure would be NIL.
For eg: you have a 12" dia water main. The pump driving the water through can only produce 12 gallons per minute of water at 50 psi. The water main would only be about 1/4 full and there'd be pretty much zero pressure on any tap connected to the main.
For eg: you have a 5 gallon bucket with no bottom on it. You have a 5 gallon bucket intact with which to fill the no bottom bucket. I don't care how fast you are, you'll never be able to fill the no bottom bucket and create "pressure" inside it.......
(and yes I realize that at some point you would hope that the demand on the water would decrease to the point that the pump or supply could fill the main and thereby create the 60 psi pressure).
Thanks for your detailed response, it was very informative.
But I can't help but notice the lack of the variable called "volume" in all those equations. If the pump cannot move enough water to fill the pipe then your pressure would be NIL.
For eg: you have a 12" dia water main. The pump driving the water through can only produce 12 gallons per minute of water at 50 psi. The water main would only be about 1/4 full and there'd be pretty much zero pressure on any tap connected to the main.
For eg: you have a 5 gallon bucket with no bottom on it. You have a 5 gallon bucket intact with which to fill the no bottom bucket. I don't care how fast you are, you'll never be able to fill the no bottom bucket and create "pressure" inside it.......
(and yes I realize that at some point you would hope that the demand on the water would decrease to the point that the pump or supply could fill the main and thereby create the 60 psi pressure).
I'm saying that saying one has "low water pressure" is incorrect. Pressure is constant in system. You could have the slowest filling bucket in Toronto, but if you put a pressure gage on your faucet, you will see 60 psi. Contrast that to a bucket that fills up in an instant, you still have the same 60 psi.
Q= velocity x Area
Velocity is a function of pressure, though I can't say that I know the equation off hand.
Pressure = force / area
Force = mass x acceleration
Force = mass x Delta V / Delta t
Here's a site that explains it better than I can...
http://www.1728.com/flowrate.htm
The point is that everyone and his brother is fixated on "pressure". You hear all the time, "we have low water pressure in the house" You don't have low water pressure, you have low flow.
You could put a pressure gage on Granny's house in Riverdale that was built in 1900 and the house has orginal rigid pipe plumbing and her pressure would be the same as your house built in Mississauga in 2009 - 60 psi. Yet Granny's bucket would take half an hour to fill up and yours 30 seconds. Why? Because Granny's pipes are almost plugged solid with corrosion that has resulted in the cross section of the pipe being reduced, hence the flow is reduced, hence it takes longer to fill the bucket.
The priciniples of hydraulics on a car are the same. The brake pressure is constant in each brake circuit. That's why they switched way back when from brakes that were actuated with a cable (that were never the same at all the wheels no matter how many hours you devoted to balancing the tension in each cable) to a simple hydraulic pipe in which the pressure was constant. You get the same pressure at each wheel very simply and easily.
P = F (pounds)/ A (square inches)
It's the force that you need to brake.
F = P * A
Pressure is created at the Master Cylinder in a car where you have a steel piston of a smaller diameter in a cast iron cylinder. Since the area of the piston is small, pressure becomes very great.
At the calipers, it's the other way round.
You transmit the pressure using the Hydraulic fluid via the steel pipes. Now you need force to slow the car, so your pistons in your caliper are much larger in diameter.
(If you've ever taken a caliper and a master cylinder apart, you know what I'm talking about.)
Force = Pressure x Area
It all comes down to the Theory of the lever. Hydraulics are nothing more than a lever.
http://www.1728.com/flowrate.htm
The point is that everyone and his brother is fixated on "pressure". You hear all the time, "we have low water pressure in the house" You don't have low water pressure, you have low flow.
You could put a pressure gage on Granny's house in Riverdale that was built in 1900 and the house has orginal rigid pipe plumbing and her pressure would be the same as your house built in Mississauga in 2009 - 60 psi. Yet Granny's bucket would take half an hour to fill up and yours 30 seconds. Why? Because Granny's pipes are almost plugged solid with corrosion that has resulted in the cross section of the pipe being reduced, hence the flow is reduced, hence it takes longer to fill the bucket.
The priciniples of hydraulics on a car are the same. The brake pressure is constant in each brake circuit. That's why they switched way back when from brakes that were actuated with a cable (that were never the same at all the wheels no matter how many hours you devoted to balancing the tension in each cable) to a simple hydraulic pipe in which the pressure was constant. You get the same pressure at each wheel very simply and easily.
P = F (pounds)/ A (square inches)
It's the force that you need to brake.
F = P * A
Pressure is created at the Master Cylinder in a car where you have a steel piston of a smaller diameter in a cast iron cylinder. Since the area of the piston is small, pressure becomes very great.
At the calipers, it's the other way round.
You transmit the pressure using the Hydraulic fluid via the steel pipes. Now you need force to slow the car, so your pistons in your caliper are much larger in diameter.
(If you've ever taken a caliper and a master cylinder apart, you know what I'm talking about.)
Force = Pressure x Area
It all comes down to the Theory of the lever. Hydraulics are nothing more than a lever.
Lots of confusion, or confusing going on.
You only have pressure if you have a closed or restricted system. Pump water into an open container and you have no pressure (at the top). So pipe size is only an issue when there is water flow, and water flow volume will depend on the size of the pipe, the restrictions on water exiting the pipe, and the pressure applied to force water into the pipe, and the volume being supplied. You can have a high volume pump which does not produce high pressure (low head pump for example) which would not even give you a trickle from a tap on the second floor. Yet it could move thousands of gallons per hour on a lift of 2 - 4 feet. Or you can have a pump that will shoot water at a high enough pressure to cut steel, but if you hooked it to your plumbing system it would not pump enough water to flush your toilet. The big difference though...if you have a closed system of pipes, the first pump would do nothing, and the second one would eventually blow your pipe system apart, or you might punch a hole in your finger when you turn a tap on...although pressure would dissapate very quickly, it would not be pleasant.
Back to the OP and the question. Submersible well pumps usually operate in the range of 5 to 6 gal/min, and provide a pressure in the 30 - 50 lb/sq.in range. Yours may be operating at the low end of that or lower, or as others have pointed out there may be restrictions in flow, etc. If the tap starts out flowing stronger and then drops off quickly you might infer flow restrictions (if no other water is running anywhere in the house). If your flow rate goes up and down then you might want to check the pressure tank and/or the limit control system/switch (settings for low and high) If neither of these apply then you might want to check the pump output, pressure and flow.
Or more simply, check the pump output and pressure, the pressure tank, and the limit control thingy anyway. That will simplify things.
You only have pressure if you have a closed or restricted system. Pump water into an open container and you have no pressure (at the top). So pipe size is only an issue when there is water flow, and water flow volume will depend on the size of the pipe, the restrictions on water exiting the pipe, and the pressure applied to force water into the pipe, and the volume being supplied. You can have a high volume pump which does not produce high pressure (low head pump for example) which would not even give you a trickle from a tap on the second floor. Yet it could move thousands of gallons per hour on a lift of 2 - 4 feet. Or you can have a pump that will shoot water at a high enough pressure to cut steel, but if you hooked it to your plumbing system it would not pump enough water to flush your toilet. The big difference though...if you have a closed system of pipes, the first pump would do nothing, and the second one would eventually blow your pipe system apart, or you might punch a hole in your finger when you turn a tap on...although pressure would dissapate very quickly, it would not be pleasant.
Back to the OP and the question. Submersible well pumps usually operate in the range of 5 to 6 gal/min, and provide a pressure in the 30 - 50 lb/sq.in range. Yours may be operating at the low end of that or lower, or as others have pointed out there may be restrictions in flow, etc. If the tap starts out flowing stronger and then drops off quickly you might infer flow restrictions (if no other water is running anywhere in the house). If your flow rate goes up and down then you might want to check the pressure tank and/or the limit control system/switch (settings for low and high) If neither of these apply then you might want to check the pump output, pressure and flow.
Or more simply, check the pump output and pressure, the pressure tank, and the limit control thingy anyway. That will simplify things.
(and believe me, I'm NOT arguing, just curious....)
But don't you need some sort of volume of material in order to create any type of pressure?
To use your master cylinder example: if the mastercylinder is only half full, no matter how hard you press the pedal you won't get sufficient pressure to activate the wheel cylinders/calipers to create stopping....pressure.....
Now I understand v= velocity, but again, don't you need volume to create velocity and pressure?
I thought that's why pumps were described as 350 cfm at 60 psi etc. Same as ventilation fans, x cfm at y static pressure.
Now, if your plumbing system is full and your lines are 1/2" dia you could achieve the 60 psi. But if you have 1", and the pump doesn't move enough water to fill the system, then wouldn't the pressure be a lot less?
Menken posted before I did but he kind of explained it and his examples were what I was thinking of. The high pressure water jet cutting systems out there can cut steel 4" thick but they don't move a LOT of water, just under very high pressure through a very narrow nozzle.
Another little interesting law of physics....
It is physically impossible to draw water higher than 32 feet since the water will cavitate (boil) and can not be drawn.
You can however push it as high as you would like to go, provided your pump has the balls to do it.
This is why well pumps must be at the bottom of a well and not up on top.
It is physically impossible to draw water higher than 32 feet since the water will cavitate (boil) and can not be drawn.
You can however push it as high as you would like to go, provided your pump has the balls to do it.
This is why well pumps must be at the bottom of a well and not up on top.
cfm = flow
cfm = cubic feet per minute, or more accurately ft3/ min
Pressure is the pressure at which the pump is operating.
Washing machines for example need a certain water pressure orelse their automatic valves will not close properly.
Am I the only one wondering why you have a tap under the sink? Not being snarky, just never seen that before.....
Check to make sure that you have sufficient pressure in your pressure tank. You may have to adjust the pressure switch or add air to the tank. If it is a diaphragm tank add pressure to the gap above the diaphragm. Follow manufacturers instructions.
If you don't have a pressure tank you may have a variable speed pump motor and this also will have a pressure control. Your plumber should know this unless he does not work on well systems very much.
If you don't have a pressure tank you may have a variable speed pump motor and this also will have a pressure control. Your plumber should know this unless he does not work on well systems very much.
Am I the only one wondering why you have a tap under the sink? Not being snarky, just never seen that before.....
We had it put in recently. We use it to fill the hot tub in winter, by running a garden hose from the kitchen to the hot tub. It is more convenient than using a hose outside. The old faucet you could attach the hose to directly, but the new restricted faucet does not have the threads for the hose.
That is also how I know that the pump is not the problem, because the tap underneath produces plenty of flow.
Seems like we've found that the replacement tap is the problem. You could go to a salavage place like Habitat for Humanity's Restore and buy a decent used one........
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