dual counterbalance valve 1

[RobertHasty]

Could You help me out with some thoughts regarding a dual counterbalance valve size?

By looking at a datasheets from various manufacturer's, both of the CB's screwed in a dual housing are designed for the same flow.

As far as I know, it's not good to oversize the CB valve.

Therefore, I would always put a different CB on a rod and cap side of the cylinder due to the cylinder's areas ratio.

For example, if I have a cylinder with cap and rod side area ratio 2:1, I would install different CB valves on rod and cap side whose rated flow has the same ratio.

But it's much more convenient to install a dual counterbalance valve to avoid pilot line plumbing. But there is no such valve which has two CB's rated for different flow. At least, I didn't find such.

What are Your thoughts on this?

 

[Oldhydroman]

Hi Robert

The problems with over-sizing come about when the valve is massively over-sized for the flow. The typical 2:1 variation you get with cylinder area ratios isn't normally enough to consider the valve on the annulus port to be "over-sized".

If it's critical for your operation, or if you have a much greater speed in one direction, then you could look at the Sun Hydraulics counterbalance valves. Within any particular cavity size they will offer the standard flow rate valve as well as options for:semi-restrictive, restrictive and ultra-restrictive. These are effectively smaller valves in the same size cartridge - making the [very convenient] dual body a workable solution for you.

DOL

 

[RobertHasty]

Hello Oldhydroman, thanks for reply.

The problems with over-sizing come about when the valve is massively over-sized for the flow. The typical 2:1 variation you get with cylinder area ratios isn't normally enough to consider the valve on the annulus port to be "over-sized".

If it's critical for your operation, or if you have a much greater speed in one direction, then you could look at the Sun Hydraulics counterbalance valves. Within any particular cavity size they will offer the standard flow rate valve as well as options for:semi-restrictive, restrictive and ultra-restrictive. These are effectively smaller valves in the same size cartridge - making the [very convenient] dual body a workable solution for you.

.

OK, I'll try to put the things "in numbers" to make it easier for me.

I also look into SUN products when dealing with counterbalance valves. Let's consider CBCG valve. He is rated for 60 L/min flow.

If I have a 30 L/min pump and cylinder with 2:1 ratio, this would be a good valve for cap side because I then 30 & 60 L/min flow on that side, and at that flow this valves still makes reasonable pressure drop.

But if I put it on rod side where I have 15 & 30 L/min flow, this valve doesn't make much pressure drop at 15 L/min.

OK, I know I have some other valves (semi-restrictive, restrictive etc.) which go in the same cavity, but I would like this to clarify it for me theoretically.

 

[kcj]

Are you looking at pressure drop charts with the valves fully open? That is for sizing for maximum flow.
By nature, the counterbalance restricts by being partially open. The spool orifice goes from 0 to that maximum flow.
Granted, the metering is not as precise at low openings, but this is not like sizing a proportional valve or servovalve.

I would go overthe application with your Sun rep, but if I understand your question, I don't think you will have an issue.

 

[RobertHasty]

Hello, I just realized the geniality of SUN's counterbalance valves.

They have a different free flow and piloted flow. For example, CBBD and CBBG are both sized for the same free flow (through check valve), but different piloted flow.

Somehow I didn't see that by now. And by knowing that fact, I realize that a lot of optimization can be done by using these valves.

 

[hsbcn]

What's the position of the valve port when you're checking? Open, partially open or closed?

My focus is on petrochemical valves for corrosive applications.

 

[RobertHasty]

What's the position of the valve port when you're checking? Open, partially open or closed?

Hello hsbcn, I'm not quite sure what do you mean....