🚀 go-pugleaf

In article <2011@randvax.UUCP> lacasse@blaise.UUCP (Mark LaCasse) writes:
>I'm not sure if washing machine, sprinkler, or other binary
>solinoid valves would suffice the original poster, but
>what I would like and can't find are PROPORTIONAL valves
>of some sort.  Something like a gate value with a stepper
>motor attached.  Something that can take water at 80 PSI.
>(Which leaves out $100 each heating system zone valves.)
>
A good (and cheap) way to handle this was suggested by someone else a 
couple of months back when this was discussed (it seems to come up 
regularly).

The plan is this: Get a number of on/off valves, and add flow restrictors 
to them.  The flow restrictors should be set such that the flow through 
each valve is twice the flow through the previous valve ie. 1gpm, 2gpm, 
4gpm, 8gpm, 16gpm, 32gpm, 64gpm etc. What you have then is a digital to 
analog converter which puts out water instead of electricity. We all 
learned that electrical current through a conductor is analagous to water 
flow through a pipe, so I guess this is a natural extension of that 
theory.

BTW, if you need finer control, you could start the binary series at a 
lower flow rate (1/4 gpm, 1/8 gpm, etc.). It really doesn't matter where 
you start as long as the rates douple for successive valves.

Another advantage to this is that once the flow restrictors are set up, 
you will have precise and PREDICTABLE flows. Wit a proportional valve 
connected to a stepper motor, you will have to do a lot of experimentation 
to determine the proper settings for desired flow rates.

Sorry for the long posting, but I hope it helps.
    Phillip
--
Phillip M. Vogel, President             | #include <standard_disclaimer.h>
Bartal Design Group, Inc. Englewood, NJ | (201)567-1343   FAX:(201)568-2891
UUCP: killer!crlabs!bartal!phillip      | Domain: phillip@bartal.crlabs.com
      ^^^^^^of questionable reliability these days