How much time will this take?

These facts and figures are all 'arse about face' as we say in the UK.

I suggest you work out what you actually want to do first....then try and work out how to do it.

Do you need a specific volume ? (20L?)

Does this have to go down the drain at a specific rate? Or in a specific time?

If so what are the existing limiting factors...drain size etc.

Once we know exactly what you want to achieve and preferably, why, a solution may be forthcoming.

That Cat is back hold on to your hat!

"The water will come from a water tank through a 2 feet long straight PVSC pipe 2" in diameter. "

Are we to assume the pipe is vertical or is it horizontal? Makes a world of difference.

You could do an experiment of two as Tom Edison did as plastic drain pipe is pretty cheap.

The pipe will be horizontal. One end of the pipe will go into the drain and the other end of the solenoid valve will be open ended (i.e. in the water tank). So water will enter through the solenoid valve when the valve is open and go through the pipe into the drain.

Im trying to figure out how long it will take for 20 gallons to enter into the drain once the valve is open. The valve needs to be adjustable using the relay timer so that anywhere from 0-20 gallons of water can be flushed down the drain. Hope that clarifies some things.

The internal orifice of the solenoid is likely to be the limiting factor.

Is it a big direct acting solenoid or one with a pilot hole ? (eg it relies on the pressure to open the valve, the solenoid merely opening a small piolt hole)

Try it and see is still the best option ... different solenoids can give very different flows and even manufacturers data may not be right.

Del

Don't you hate it when "Guests" post questions, replies ask for more information, "Guests" reply with a little more information, replies ask for more information, and you never hear from "Guest" again?

hi ,

Based on the information given and assuming the tank height 5 (Five ) meters , the time taken to empty 20 gallons of water should be between 4 to 5 seconds. Higher the height of the tank , lesser time required to empty the tank.

regards

basanta

Orifices? Reynolds numbers? Surface finish? etc?

My old Chief Engineer, who was once an analyst and theoretician, used to say - Once you have an engine, forget all the calculations and analysis, it's quicker to let the engine tell you what it is going to do.

Your set up is so simple, why not build a prototype?

Georgee

Bravo... exactly !

When it doubt...try it out

You said it Mr Cat...

This is simple and cheap. Set it up and time it.

Absolutely.

And when you build your prototype, keep in mind the shape of the tank, particularly in the area of the drain. If there isn't any baffling, Coriolis will kick in and turbulence will ensue.

You can probably find the pipe coefficients you need on the internet, but the valve C_v (I think this is the correct term) may be a little tougher. The manufacturer may have the information.

You also haven't told what the tank height and diameter is, which is necessary to calculate the flow rate. What's the height of water? Will it drain out completely? Will 20 gal. flow from 1000 gal in the tank?

Need more information, then the differential equation describing the flow can be written.

Flow rate will depend upon pressure if you're below choke flow which I assume you will be. Since the source of your water is from a water tank, it could vary considerably if the lower level of the tank is close to the same level as the solenoid valve. This is only important if you require an exact amount of water each time.

Have you heard of the 'dip-stick' test? Well try my 'bucket-test'.

Take a bucket , fill with water, mark bucket with marker at every gallon. Discharge the water out in bucket for 1 sec. calculate quantity of gallons . Repeat 2/3 times till you get accurate. Divide 20 gallons by calculated gallons/sec & "presto" - you found out the time taken to discharge 20 gallons thru 2 feet long straight PVSC pipe 2".

Next Question?

'Next Question?'

Where do I buy a 2" bucket hole?

You put a few holes in a drawer a while back. If none of them are big enough, put in a larger one.

Cheers..I'd forgotten where I put 'em!

Nice Question. My bucket doesn't have that big a hole 2" so I cannot offer him. He has to find his.