Hydraulics Valves ON/OFF. Constant voltage or Latch Relay?

[JCollado]

Hello

I would like some General Ideas as to the best way to go about Controlling a Hydraulic Setup.

I will have about 14 High pressure (About 3000 PSIG) that half will be ON and half will be OFF and alternate through the test of the Components.

Anybody with experience on some similar setup?

Do I have to maintain the analog output on for the entire time I need the valves ON or should I use a LATCH type relay that will either turn it on or OFF  using negative voltage to Turn OFF and Positive voltage to Turn ON?

Are those type of Latch Relay safe to keep valve energize for UP to 15 minutes?

Note: I'm not a mechanical or Electrical engineer

Thanks

[RavensFan]

Do you have a brand/model number you can tell us for these valves?  A link to their website and instruction manual?  What kind of DAQ equipment are you using to control them?

Some valves might have an analog input of 4-20mA current or a voltage input that you can vary so that the amount of valve opening is infinitely adjustable.  In that case, all you should need is the analog output and not any relay.

Other valves may be purely solenoid and on or off in action.  They would not generally have an analog input, and you would just supply power or take away power and would thus be controlled by a relay that would be driven by a digital ouput of your DAQ modules.

[JCollado]

Just in t eh beginning Stages of planning.

I have one of the valves. SUN Hydraulics   770-724 0DB9

I will also use a proportional pressure control valve from continental but that one should not be a problem.

Is just a Solenoid operated valve that uses 24 volts to operate.

Just was thinking in general. Do you normally keep the output voltage on continuously until you need to shut it off?. I figured these would be using a lot of resources instead of turning on and off when you need to and have like a latch relay either turn it on or off depending if is positive or negative.

I figure it would be helpful to know how others done it before I start developing a flow chart of the software operation.

[JCollado]

Sorry I forgot the file.

Here are some files with their valves

[RavensFan]

These valves look like they are either on or off, and no in between.

A normal relay is enough to drive the power on/off to the solenoid.  The solenoid needs power 100% of the time to be on, and 0% of the time to be off.  (A spring returns the valve to the off position once solenoid power is removed.)  So you need a relay to switch that circuit.  There is no benefit to using a latching relay to control that circuit, and if anything it just complicates things because you'd need a way to tell the latching relay to switch back to off so that it removes the power from the solenoid circuit.

Any control relay (like those "ice cube" kind) are intended to be continuously powered if needed, and are designed to use as minimal power as possible in its own coil circuit.

If you're still uncertain as how to wire things, then I suggest contacting the manufacturer of the valves and see if they have any technical info on recommended electrical circuit diagrams.

[JCollado]

My main concern was if I need to supply the voltage continuouslly from the software or could I some how just send the voltage for a sec or two and then again when I need to turn them off.

I really know how the valves work and we use them here manually with a switch box. Just wondering how to keep them on for up to 15 minutes at a time.

Thanks for your help

[tbob · Accepted solution]

Don't be afraid to keep the relay energized for 15 minutes or even longer at a time.  Relays can handle it.  Don't use the latching type relay because if your system breaks, there is no way to unlatch it and the valve will be stuck on.  Just be sure to use a good quality industrial relay and you will be fine.

[nathand]

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JCollado wrote: 

Do I have to maintain the analog output on for the entire time I need the valves ON or should I use a LATCH type relay that will either turn it on or OFF  using negative voltage to Turn OFF and Positive voltage to Turn ON?

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Note that an analog output is not usually the right signal to use for a relay.  You should drive it with a digital output.

[JCollado]

Thanks everyone for your help.

I think with this info I can move in the right direction

[tbob]

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@nathand wrote:

Note that an analog output is not usually the right signal to use for a relay.  You should drive it with a digital output.

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I disagree.  Digital outputs usually do not have enough current drive to actuate a relay coil.  If you use a digital out, you usually have to put in some kind of interface circuit, like a ULN2003.  But there are some digital output cards specially make for driving relays.  Digital outputs are usually 5v.  Relays can be 5v, 12v, 24v, etc.  Analog outputs typically dirve more current than digital outputs, and they are voltage configurable.