I hate to ask again but new design help please !!!

[xtal01]

OK, so my "simple" lift project just keeps getting more complicated.

With the number of relays, timers and such in the control panel growing, I decided to use a PLC. This then lead to me asking myself "since you have a PLC, why not use a flow valve with proportional analog input".

With a cost of $390 for the valve and $560 for the driver board, I decided to look over the circuit again .... the mechanical version I was planning on using was $90 plus say $75 for a actuator with limit switches ( and a day or two to mate them together ). I needed two of these mechanical valves so about $330 all together with actuators.

By redesigning the circuit ( and adding one $65 solenoid valve ), I was able to eliminate one flow valve .... using just one valve for raise and lower!

I have attached a diagram of the new circuit. Can you guys look it over ( again ) and see how I did this time?

I think I have it right. From what I can tell I need to order the valve ( a Brand Hydraulics FC51 ) with a special option so I can block the Ex port and use it as a two port valve when lowering ( solenoid valve to close this port while lowering ). I till have a load check valve to hold the load while lifting ... I think it is all there.

As I said, the flow valve is a Brand Hydraulics EFC 12-10-242P ( built this # from their info at

http://www.brand-hyd.com/efc/catalog.pdf

).

Since this is a true proportional valve it will give me much more control of acceleration / deceleration. With my first ideal of a mechanical valve / actuator combination, I was at the mercy of the speed of the actuator.

I talked with there tech support a while back. The new control board is a DEC5000 ($560). I found a "new old stock" version of their old board (EC0004A) for only $180. I am trying to find out the difference it the two boards. I don't see a reason why the old board won't work ... it is still listed on their web site.

Anyway, if you guys could check me on this, I would greatly appreciate it!!!!!

Just FYI ... my wife explains to everyone that if this simple hydraulic circuit has now taken me three weeks to design you can understand why it took us three years to build a house ... and it's still not finished! To my defense, when I build a project, it usually works on the first try since I have tried to work out all the problems and look at all my options in the design phase.

Thanks so much again .... Mike

 

[hydtools]

Ah, you found the Brand EFC. Looks like the system will work.

Ted

 

[xtal01]

Awesome!

See, you can teach an old dog new tricks.

I had actually wanted to use this valve weeks ago but with two valves at $370 and then two boards at $560 plus a PLC to control everything, I just had too much invested in a "home" project. Using only one valve, a NOS ( new old stock ) board for $180 and since I already will have a PLC for the other controls ... now it looks a lot more affordable.

Did I get the "2P" option correct? If I read the literature correctly, if I get the "2P" option I can still use this valve as a 3 port valve but it will just have a different flow characteristics that the standard valve.

Thanks so much for your help!

Mike

 

[kiwitom235]

I was just thinking last week that you could easily eliminate one of the flow control valves, but I didnt have time to draw a circuit. Lucky you thought about it already! You should only ever need one flow control valve to control both up and down.

 

[kiwitom235]

OK i just noticed something. I believe you can get rid of both dump valves and place a single dump valve prior to the flow control valve? Then you can also get rid of the line connecting the CF port to tank via the dump valve?

Tom

 

[kiwitom235]

actually, ignore what I said, I may have to look into it a bit more!

 

[kiwitom235]

OK, i believe you can get rid of the dump valve on the EX port and make this a hose straight to tank.

 

[xtal01]

If I get rid of the valve on the EX port, will I not loose my control on the lowering? If the total flow in is equal to the flow out ( CF + EX ) then everything that goes in will just "dump" back into the tank.

CF to the tank would be regulated but any excess for in would just dump unregulated through EX to the tank ... I think ?????

Thanks ..... Mike

 

[xtal01]

OK ... I just put up a new post.

If you are reading this can you please look at my new post. I am having a problem figuring out if I need a special "2 port" option for this valve.

Thanks again so very much !!!!!!!!!!!!!!

Mike

 

[kiwitom235]

Hi, I believe you are incorrect as this flow control valve is pressure compensated on both outlet ports.
This means that the flow will be split no matter what the pressure is of the EX and CF port. The EX port just acts as an excess flow outlet. e.g. say you have in flow of 5lpm and adjust the flow control valve to get 1pm out, 4 lpm will go to tank through the EX port. you cant block the EX port, or else where will any excess flow go? If you block the EX port and restrict the flow to the cylinder, the valve will try and force more fluid to the EX port and blow your relief valve.

And remember, There is no difference in operation of this valve whether it is raising or lowering. Either way pressurized fluid is going in and being redistricted, and the excess flow is going to the EX port to tank.