Hydraulic Valve - Which Type? Want to control 2 inputs to 1 output - Page 1
Forum section: electronics / projects

author: JBionics
author_rank: Newbie
timestamp: November 23, 2012, 07:44:14 am
content: I have 2 pressurized liquids. I'd like to be able to electronically control which which liquid is pumped to a single output. Electronically switching between the two.I'm not too familiar with hydraulic valves, so I'm not sure which type of valve I need.Any info you can share?

author: Kremmen
author_rank: Super Contributor
timestamp: November 23, 2012, 09:03:01 am
content: A solenoid valve, or actually 2 of those. If you don't mind doing the solenoiding with mains power, then a cheap option could be to use one from a washing machine water inlet. They usually have up to 3 individually controllable valves in one lump. But there are other kinds, subject to your specific requirements, such as whether the fluids are corrosive, poisonous, hot or whatever.

author: IanB
author_rank: Super Contributor
timestamp: November 23, 2012, 11:50:01 am
content: If your need is for an industrial application you need to talk to a mechanical engineer. The electronic (actuator signal) side of valves is somewhat standardized in terms of signal levels, but the mechanical side has various considerations including material of construction, fluid handled, required flow rate, isolation pressure, leak tolerance, speed of operation, fail safe behavior, etc.In a homebrew situation where you are throwing something together as a hobby you can easily wing it and just choose something suitable from a parts catalog, but more care is required in a commercial setting.

author: JBionics
author_rank: Newbie
timestamp: November 23, 2012, 06:36:25 pm
content: Thanks for the pointers!If I wanted the functionality in a single valve, what type of valve would I be looking for?I'm a bit confused by the nomenclature. 3 way valve, 2/2 way valve, etc.

author: Bloch
author_rank: Unknown
timestamp: November 23, 2012, 06:50:15 pm
content: Quote from: JBionics on November 23, 2012, 06:36:25 pmI did a Google search for youhttp://en.wikipedia.org/wiki/Valve#Three-port_valves

author: robrenz
author_rank: Super Contributor
timestamp: November 23, 2012, 11:50:53 pm
content: A "hydraulic valve" is intended for hydraulic oil or oil/water emulsions. It depends on the lubricity of the fluid to operate properly and also expects highly filtered fluids. If you are passing something else thru it you need to look for valves compatible with those fluids.

author: SeanB
author_rank: Super Contributor
timestamp: November 24, 2012, 05:12:47 am
content: You do need to tell us what fluid you are mixing, as well as the temperature and the pressure. Many times you will have to use 2 separate poppet valves with an actuator, and will need an air supply to drive the actuators. The actuators will each have a 3/2 way valve to operate them. If you want to blend then you will need proportional actuators for each valve, and these fit on top of the valve, just needing air ( filtered and at 6bar) along with a 24V supply and the input 0-10v signal. Then you control each valve from 0-100% to blend.

author: G7PSK
author_rank: Super Contributor
timestamp: November 24, 2012, 04:27:42 pm
content: From your question I am not sure that you need a 2 or 3 way valve but more likely 2 single valves, but what is the presure and what are the flow rates etc.Try this forum.http://www.physicsforums.com/forumdisplay.php?f=101This company supplies many forms of valves.http://www.pvl.co.uk/solenoid_valves.html?utm_source=BMON%20AdWords&utm_medium=CPC&utm_campaign=PressureThis is the link for Danfoss who are a leader in the manufacture of such valves etc.http://www.valveselector.danfoss.com/selector.aspx?v=gb

author: PbFoot
author_rank: Contributor
timestamp: November 24, 2012, 04:58:58 pm
content: Hi,I worked a lot with these types of valves in my previous job. I agree that one for a dishwasher to laundry machine will be by far the cheapest. You can get much heavier duty ones made of brass or stainless, but they are costly - at least $100 to start, and go much higher.As already mentioned, your selection will depend much on what the fluid is. If it's just water or mild detergents then a dishwasher one will do fine. If you are dealing with petrochemicals or something weird, you may need teflon construction etc. (Which will cost a fortune.) Also, pressures, leak tolerance, rebuildable or disposable types need to be considered. What is your application exactly?Try Eaton for washing machine type valves, or Asco for industrial quality valves.-PbFoot

author: G7PSK
author_rank: Super Contributor
timestamp: November 26, 2012, 03:41:50 pm
content: You can get industrial solinoid valves for less than a $100 here are some at around the £50 mark in the UK.http://secure.thorite.co.uk/vnax2d1150919/Process-valves-and-control/Process-valves/Burkert-process-valves/Solenoid-process-control-valves/c-1-391-1064-1059-781/Stainless steel ones are considerably more expensive but that is quite likely due to it being a UK supplier and mention St/St to many people here in the UK and they expect the price to be high so many suppliers oblige.http://secure.thorite.co.uk/vnax2d1150919/Process-valves-and-control/Process-valves/Burkert-process-valves/Stainless-steel-process-control-valves/c-1-391-1064-1059-782/