Looking for Pneumatic control valve information

[Cburg]

TL;DR Summary

Need a pneumatic control valve with 1/4inch ports that will operate a double acting cylinder but will also release the cylinder when all current is removed.

I am looking to find out if there is a control valve type that will move a duel port cylinder in both directions but then the current to the valve is turned off the cylinder will NOT be locked up. I thought a 5/2 double coil valve would do this but it holds cylinder when current is removed form both coils,
I am looking to open and/or close a door with the cylinder but also let a person over ride the cylinder when the control is not being used.

Thank You in advance for your help...

Cburg

 

[jrmichler]

It sounds like you need a three position, double solenoid, spring return valve. This diagram shows the terminology (but has the wrong valve porting):

You need to find a valve that:
1) When Solenoid A is energized, the cylinder is pushed one way,
and
2) When Solenoid B is energized, the cylinder is pushed the other way,
and
3) When neither solenoid is energized, the valve spool is spring loaded to the center position, where the cylinder ports are connected to each other.

Your next step is to get some pneumatic valve catalogs and start searching. This might take a while, but if you are persistent, you should find a valve.

 

[Baluncore]

If the central position needs to be floating, then both sides of the cylinder need to be connected to the tank in that position. That is because the rod has a finite volume, so the total volume of the cylinder changes as the piston moves.
It gets more complicated if, when the power is on, you want the cylinder to be held in the last adjusted position. There is then a safety consideration, will a supported load fall whenever there is a power cut.

 

[jrmichler]

So a pneumatic solenoid valve like this:

Valve is spring loaded to center, S is supply, and V is vent.

Don't worry about the valve port size. You can find fittings to adapt any valve port to any tube, hose, or pipe.

 

[Cburg]

Thanks for all your input, Sorry for my delay in getting back to you ...
Looking at the post form Jrmichler I was thinking alone the same lines.

however: When I tried that valve is would stop the rod anywhere along the full travel BUT when power is removed the rod is held in place and will not run free.

I think the valve would need to more like this:

I am thinking that when the valve has no power and is in the center position either both cylinder ports need to be joined together or both need to be connect to the exhaust.
The question is now, do they make this type of valve or do I need to look at using a second valve vent or maybe just shut the air of the supply.

Your Thoughts ...

Thanks
Cburg

 

[Baluncore]

I am thinking that when the valve has no power and is in the center position either both cylinder ports need to be joined together or both need to be connect to the exhaust.

In the central position, the two cylinder ports should be connected to the exhaust vent, while the supply is blocked.

 

[Cburg]

I agree. But is there such a valve? It appears there is a naming code that is used to ID valves but I have no clue what the code is. For example: the valve I have that is like this one ...

Is Called a ... " Pneumatic Solenoid Air Valve 4V230C-08 DC 12V 5 Way 3"

Thanks
Cburg

 

[Baluncore]

4 port hydraulic solenoid valve is similar to 5 port pneumatic solenoid valve.
Search for 4 way, 3 position, centre float, air control valve.
Cheap ... https://www.ebay.com.au/itm/393872782262?
But you must find a manufacturers data sheet, to get one with a centre float.

https://www.enerpac.com/en-au/4-way-3-position-valves/solenoid-spool-valves/VEX11

https://www.grainger.com/category/p...+and+Positions|4-Way/3-Position&filters=attrs

 

[Baluncore]

Some symbol and ordering codes are here;
https://cdn.shopify.com/s/files/1/0068/3235/7429/files/4v400-TrimantecNEW.pdf
You will need the float centre valve position "exhaust" = 30E.
Or look for a smaller port series that would work in your application and will cost less.
These may have port data and centre code in the listing.
1/8” port 4V230E-06
1/4” port 4V230E-08 Search eBay for this US $25.
3/8” port 4V330E-10
1/2” port 4V430E-15
Remember to select a solenoid voltage and verify the "exhaust" float centre.

 

[Cburg]

Thank ... Looks like l have some homework...
I will report back...