Variable Water Flow Restrictor Needed

This is the place for any magazine-related discussions that don't fit in any of the column discussion boards below.
Post Reply
rotatepod
Posts: 43
Joined: Sun Oct 14, 2007 5:34 am
Contact:

Variable Water Flow Restrictor Needed

Post by rotatepod » Tue Nov 11, 2008 7:05 am

I apologize for asking about something that probably doesn't
exist. I'll describe a product that millions of folks use, so you'll
have some idea of what I'm looking for.

Think of an inexpensive garden sprayer. Usually, they have
a plastic disk or wheel with a series of numbered holes. Each
time you turn the wheel to a different number the amount of
chemical siphoned from the attached container increases or
decreases.

I built a very small tank (about 3 quarts). It has 3/4" copper
male connectors at the inlet and outlet. Its been pressure
tested to 200 psi with no leaks. It will hold water only at
70 psi. I need a variable inline flow restrictor for the outlet
of the tank. Most regulating valves used for industrial
purposes would definitely be like swatting a fly with a
sledge hammer. Too massive and complex for my little
tank. A simple fixed flow restrictor is easy enough to
make. A plastic or metal disk with a small hole will do
the job. Any ball valve can be used as a crude flow restrictor.
Since you can't see inside a ball valve, there is no way to
know how much of the hole in the ball is open to the water
stream. I thought about putting a flow meter inline with
a ball valve. Again, most of the the flow meters I've seen
would not be practical for this project.

Its possible companies that make commercial grade (brass
and stainless steel) valves, connectors, and adapters for
garden use may sell a variable inline flow restrictor. If
so, I've never seen one.

If I can't find a manufactured product that will work, I'm going
to have try numerous fixed restrictors, until I get the flow rate
I'm looking for. To make matters worse, I don't know what
the flow rate should be without some experimentation. I can't
even guess how many times I would have to depressurize,
drain, and break the connections to my tank. That's why I
need a variable flow restrictor.

Its frustrating to know that the product you want is probably
made by a company you never heard of, from an industry
you know nothing about. That about sums up my situation
right now.

User avatar
Externet
Posts: 1840
Joined: Fri Feb 01, 2002 1:01 am
Location: Mideast USA
Contact:

Post by Externet » Tue Nov 11, 2008 8:03 am

The only part that bothers me is the 70 psi working pressure.

If you want it small, use a hose, a non metal-braided hose like for transmission fluid, oil pressure gauge, steering pump. Perhaps an under-the-sink fiberglass braided hose section.
Place it in such way that a roller turned by the thumb chokes it.

The same way a serum bottle flow is controlled, or whatever be the name in English for these thingies:

http://www.atlanticmedsupply.com/shopdi ... ation+Sets

You do not mention any electrical application for the flow valve, but could be used with a servo that could push the roller too.

Another not-that-small variable flow valve is in the heater path for an automobile heating system. It is fully variable by moving a lever and I would say it can handle the pressure. Try Honda, Toyota. They are about 2" x 1" x 1"

Or: http://www.clearpvcpipe.com/index.asp?P ... ProdID=338

Miguel
- Abolish the deciBel ! -

User avatar
MrAl
Posts: 3862
Joined: Fri Jan 11, 2002 1:01 am
Location: NewJersey
Contact:

Post by MrAl » Tue Nov 11, 2008 10:24 am

Hi,


They make valves like this for heating systems when the flow
has to be controlled or rather balanced between two radiator
systems. The flow starts out from one pump, but has to split
into two loop systems rather than one loop and the restriction
to flow might be different due to one loop being longer than the
other for example, so these valves are used to cut down the
flow from the loop with the least restriction so the flow rate can
be balanced in both loops.
They are basically a block of metal with a screw in one side
and standard pipe threads on both ends. The valve is placed
in line with the pipe with the pipes threading in both ends.
When the screw is turned one way, it moves inward and blocks
more of the flow, when turned the other way it moves outward
and allows a greater flow...not much too it and i bet you could
build one up yourself using a 3/8 diameter bolt and some careful
drilling. I dont know how much flow you are looking for so you
may even need a 1/4 inch or even 1/2 inch bolt fine thread.
I dont know how much leakage you can live with either.

I dont think they can be too expensive to buy, but then i've never
priced them. They might have them at a heating supply store or
a plumbing supply store.
LEDs vs Bulbs, LEDs are winning.

User avatar
Dave Dixon
Posts: 436
Joined: Thu May 01, 2003 1:01 am
Location: Wichita, KS
Contact:

Post by Dave Dixon » Tue Nov 11, 2008 11:37 am

Sorry I don't have time to look further into this, but my first thought was to look at Omega dot com. They have a whole section on flow measurement and control, and SOME of their prices aren't really high. Can't hurt to give it a shot. Best of luck.
While I am on here - - Thanks to all the Veterans that might read this thread!!!!!
Dave

Engineer1138
Posts: 458
Joined: Thu Feb 05, 2004 1:01 am
Location: Minneapolis, MN
Contact:

Post by Engineer1138 » Tue Nov 11, 2008 12:10 pm

Any ball valve can be used as a crude flow restrictor.
Since you can't see inside a ball valve, there is no way to
know how much of the hole in the ball is open to the water
stream,
Can't you make a scale under the valve actuator so you can see how far it's open?

User avatar
MrAl
Posts: 3862
Joined: Fri Jan 11, 2002 1:01 am
Location: NewJersey
Contact:

Post by MrAl » Tue Nov 11, 2008 12:17 pm

LEDs vs Bulbs, LEDs are winning.

Bigglez
Posts: 1282
Joined: Mon Oct 15, 2007 7:39 pm
Contact:

Re: Variable Water Flow Restrictor Needed

Post by Bigglez » Tue Nov 11, 2008 4:56 pm

rotatepod wrote:I need a variable inline flow restrictor for the outlet
of the tank.
A ball valve or needle valve would do.
rotatepod wrote:Most regulating valves used for industrial
purposes would definitely be like swatting a fly with a
sledge hammer.
I've seen some small scale ones in the local semiconductor
industry.
rotatepod wrote:Any ball valve can be used as a crude flow restrictor.
Since you can't see inside a ball valve, there is no way to
know how much of the hole in the ball is open to the water
stream. I thought about putting a flow meter inline with
a ball valve. Again, most of the the flow meters I've seen
would not be practical for this project.
Or, setting the ball valve as required in testing, then
removing it and inspecting the orifice visually.
rotatepod wrote:Its possible companies that make commercial grade (brass
and stainless steel) valves, connectors, and adapters for
garden use may sell a variable inline flow restrictor. If
so, I've never seen one.
Where are you? There's literally tons of air, gas, and fluid
control surplus locally. My favourite gold mine for odds
and ends like this would be Triangle Machine. Bring a
flashlight and don't forget they close midday on Friday's
for prayers.

User avatar
Lenp
Posts: 1416
Joined: Thu Oct 26, 2006 8:11 pm
Location: Maryland
Contact:

Post by Lenp » Tue Nov 11, 2008 6:34 pm

Rotatepod,
I'm not sure of your application or volume of flow. You say 70 psi, but what is the differential accross the valve? Maybe a small needle valve would work. I use a small panel mounted needle valve for a product I produce as vacuum control made by ARO. It is even 'calibrated' with reference markings on the valve stem and can be locked in place. There are also many flow control valves used in pneumatic controls to slow the operation of air cylinders. Most are brass or stainless steel since moisture, although undesired, is not uncommon in pneumatic systems. Check www.grainger.com and www.usplastics and www.mcmaster.com for a selection to consider. Keywords may be needle valve or flow control valve. Lastly you might consider a brass air control valve for aquarium pumps. With a little work they may be modified for your application!

Hope this helps!

Len

rotatepod
Posts: 43
Joined: Sun Oct 14, 2007 5:34 am
Contact:

Post by rotatepod » Wed Nov 12, 2008 7:29 am

I thought about the incredible variety of electrically controlled valves used
in modern cars and trucks. Mechanics often call them motors because
the valve is usually controlled by a solenoid. Typical fluid pressures in
cars are well under 20 psi, so I can't use any of this stuff.

I keep telling myself to keep this darn thing simple! I've used all different
kinds of air and water pressure control gizmos. I don't know why I'm
reluctant to go in that direction.

A graduated scale for a ball valve sounds like a good idea. Since a
ball valve opens and closes with a quarter turn, a graduated scale
would be kind of crude. It may be impossible to have some precision
without additional complexity.

Considering the length of some of my posts, it may be hard to believe that
I rarely post on any other forum. There is something very special about
the people who participate in this forum. I really appreciate all you guys!

User avatar
MrAl
Posts: 3862
Joined: Fri Jan 11, 2002 1:01 am
Location: NewJersey
Contact:

Post by MrAl » Wed Nov 12, 2008 1:10 pm

Hi again,


Did you check out the heater valve link i posted?
These are relatively inexpensive.
LEDs vs Bulbs, LEDs are winning.

Post Reply

Who is online

Users browsing this forum: No registered users and 14 guests