# Constant water pressure

1. Aug 16, 2008

### sfcd_123

hi i m new in this forum...n i have come to take some suggestion....

i m plaaning to make a water supply which willl give some specified guantity supply(like 500 ml,250 ml) everytime.....bt the main problem occuring is the water pressure in the outlet....the water pressure is not same all the time because the height is changing....so is there any system or set up to keep the pressure same though the height is changing....

i have a plan......if i take a midium size tank and make hole at bottom and input a small dia pipe and take it to another small tank which have its top level is same of the bottom of previous tank..than the small tank will always filled with same height..so can i get constant water flow????the pipe will b small so i think the pressure of big tank will b less....plz help quickly....

i have to submit this proposal in 2 days....plz...:(:(

2. Aug 16, 2008

### Staff: Mentor

I'm not very clear on what you mean by the water pressure changing - is the outlet moving?

I'm thinking of an active system, with pressure sensors and valves.

3. Aug 16, 2008

### Loren Booda

Reminds me of a water clock where the flow of water (proportional to pressure) needed to be constant.

4. Aug 16, 2008

### Loren Booda

To quote http://en.wikipedia.org/wiki/Water_clock" [Broken]:

"...water flowed from the top tank to the bottom tank via a float regulator that maintained a constant pressure in the receiving tank."

Last edited by a moderator: May 3, 2017
5. Aug 16, 2008

### sfcd_123

i mean i should have constant water flow in a pipe from the small tank...i have to fullfill a glass of water same amount everytime approximately at sametime whether the pressure is different....thats why i need same flow of water..the flow of water will b controlled by a valve...

6. Aug 16, 2008

### sfcd_123

the water will be situated at a small tank and when i need water i just open the valve for a certain amount of time and the output must b same quantity everytime....

7. Aug 17, 2008

### brewnog

Why not just use a simple mechanical bar optics type system: Look at how 25ml and 50ml measures of spirits are dispensed at a pub. The same quantity of liquid is measured regardless of how full the bottle is.

This is achieved very simply with a measuring cylinder which is moved between two positions. The measuring cylinder has two valves: one on the top, and one on the bottom. With the cylinder in one position, the top valve is open and the bottom closed. (This allows fluid to flow from a higher reservoir into the cylinder to fill completely, and cannot be overfilled). The cylinder is then moved to its lower position, where the top valve closes and the bottom valve opens. (This stops the flow from the reservoir, and drains the contents of the cylinder into your chosen receptacle).

Easy.