# delay to control the of quantity water ?

#### abhimanyu143

Joined Aug 25, 2014
211
Hello
I am trying to make microcontroller based system that controls the quantity of water.
Flow Rating of water pump is 300L/H
Requirement of system : eject water near about 10 ml than stop
I don't understand according to flow rating How many second delay can be eject 10 ml water ?

#### spinnaker

Joined Oct 29, 2009
7,830
A 300 liter per hour flow rate and you can't figure how long it will take to eject 10ml? Really?

I would think that is very simple math that you should have learned in grade school. Or I missing something?

Is this RRTESH posting under a different account?

#### bertus

Joined Apr 5, 2008
22,264
Hello,

300 Liter per hour = 300 / 3600 Liter per second.
This is about 83.3333 mLiter per second.
10 mLiter is 0.12 seconds of the flow.

Bertus

#### Picbuster

Joined Dec 2, 2013
1,047
No way to get this to work with a normal pump. In theory yes in the field no.
You should use a displacement pump each compartment having 10mL.
(working: take a hose place n pins on a disk and feed the hose over the pins
when disk starts to rotate is will force the water out. the distance between the pins and diameter hose will give you 10mL.)

#### Alec_t

Joined Sep 17, 2013
14,196
10 mLiter is 0.12 seconds of the flow.
...assuming the flow rate is constant. However your pump can't start and stop instantly, so the flow rate won't be constant, so the pump will have to run longer than 0.12s. How do you plan to measure the amount of water actually dispensed?

#### abhimanyu143

Joined Aug 25, 2014
211
[QUOTE post: 941058, member: 217914"]...assuming the flow rate is constant. However your pump can't start and stop instantly, so the flow rate won't be constant, so the pump will have to run longer than 0.12s. How do you plan to measure the amount of water actually dispensed?[/QUOTE]
I have device that show the quantity of water in liter. I need not exact 10ml but it should be near about 10 ml

#### spinnaker

Joined Oct 29, 2009
7,830
[QUOTE post: 941058, member: 217914"]...assuming the flow rate is constant. However your pump can't start and stop instantly, so the flow rate won't be constant, so the pump will have to run longer than 0.12s. How do you plan to measure the amount of water actually dispensed?
I have device that show the quantity of water in liter. I need not exact 10ml but it should be near about 10 ml[/QUOTE]

It is going to depend on the accuracy of the pump is what Alec was trying to say. You just might pump far more than 20ml by the time the pump shuts off. No way to tell if it suits your needs without more data on the pump or simply trying it.

#### wayneh

Joined Sep 9, 2010
17,493
It would make more sense, in my opinion, to use the pump to develop a steady head pressure - perhaps within a recirculation loop - and then control the water ejection with a solenoid valve. The one-shot displacement pump is also a good option. There's no way to deliver precisely 10mL using a pump rated at 83mL/sec (thanks Bertus), with a gauge that reads in liters.

Depending on what you are doing, you might want to look at lab equipment that is designed for repeating delivery of a set volume. Automatic pipettors, petri dish fillers, that sort of thing. No need to reinvent the wheel.