Parker K220LS Relief Valve 2

[HydroBuff]

Hi everybody,

I have a couple of questions on a Parker K220LS valve using an ASC mid inlet. (part number 22000667)
Would you know what the application uses would be for part number 9120092290? Can I use that in an ASC mid-inlet if I don’t have any AS compensators?

Also, I would like to know if using PLS relief (part number 9120092269) will limit my max system pressure to a certain point lower than what PLM would.

Thank you.

 

[FluidPowerUser]

Part number 9120092290 is a plug to replace the PLS spool assembly if the application doesn't require the PLS valve.

The PLS and PLM valves work together to control the main system pressure and the load sense / stand by pressure. You don't need the PLS valve if your system does not have a load sensing variable flow pump.

The PLM and PLS valves are not interchangeable, the max pressure of the PLS is only about 38 BAR and the max pressure of the PLM is 350 BAR

 

[HydroBuff]

Thank you very much, @FluidPowerUser ,

Would you also know if PLS will limit the max system pressure?
For more background, I am using an ASC type K220LS mid inlet. The only reason I used it was because that is what was available, it is not like I am using any AS type compensator spools.
Now I have this problem that no matter where my settings on the PLM are, I cannot build more than 230 bar.
I know my pump is capable of building this pressure because after removing this valve and using another I could easily build 300 bar.
This has the load sense line going directly from the LS port on the K220 to the hydraulic pump.

Thanks for your advice.

 

[FluidPowerUser]

Where are you measuring the pressure?

There are LS relief valves set to 200 BAR and with a 30 BAR margin, it will set the pump pressure to 230 BAR.

The PLS valve has a pilot section that is connected to the PLM valve. When the PLM valve opens, it vents the PLS valve and that is what limits the pump pressure.

I'm not sure if you already have this, but there are more details of the valve connections in the PDF, link below

https://www.parker.com/literature/HY17-8537-UK_K220.pdf

 

[HydroBuff]

As far as system pressure I measured directly on the work ports of the valves. Some of the workports have feed reducers installed and some do not. None of them have port reliefs. None whatsoever of the valves were capable of building more than 230 bar at the most.
For the LS valve I placed a tee into the LS line going to the pump.

Excuse my ignorance, but what exactly did you mean by an LS relief valve? Wouldn't that be the PLM valve that is a screw adjustable type valve?
And yes, I was reading the Parker config pdf, but am fairly new to some of this so its great to be able to ask an experienced engineer like you all.

Thanks for your time!
Best regards,

 

[FluidPowerUser]

Measuring the pressure at the work port will tell you what pressure the load sense relief valves are set to. The image below highlights the load sense relief valves. They can be adjusted to limit the pressure at each section and the highest pressure is the one that gets sent to the pump via the LS network.

If you add the set pressure of the PLS valve to the set pressure of the LS relief valves, that is what the pump pressure will be.

 

[HydroBuff]

Ok, I got you now. I have always called them feed reducers.
A section without any of these reliefs should reflect the value of PLM, correct?

 

[FluidPowerUser]

Yes, that's right. The PLM value will set pressure at the pump if the LS relief (feed reducers) are removed.

Does this explain why your pump pressure will not go above 230 BAR?

 

[HydroBuff]

No that doesn't really explain, because I have a section that is required to much higher pressure than the rest (300 bar) which I did not order with feed reducers because I assumed I would set that pressure with the PLM setting. The rest of the workports all need to be lower than 200 bar so I ordered feed reducers on all of them.
Accordingly, I should be able to get higher pressure at the work section without feed reducers.
I can lower the pressure on any of the sections with feed reducers and the one with feed reducers remains fixed at 230 bar unless I lower either the PLS or PLM.

 

[FluidPowerUser]

OK...

What is the pump compensator set to? That will also limit the pump pressure if it's set below 300 BAR.

The PLM valve will go to 350 BAR, although, for some reason the PDF says the maximum inlet pressure is only 330 BAR. The difference between the pump pressure and the work port pressure is the value of the PLS valve, so 350 + PLS setting.

If you are not getting to 300 BAR and there are no line reliefs or LS reliefs in the sections, then it's worth looking at the pump compensator to see if that's limiting the pressure.

 

[HydroBuff]

I really believe that I can rule out the pump causing the issue because when I use another valve with different config I can easily build all the pressure I require.
I am using electrohydraulic solenoid operation. You wouldn't suppose that some of Parkers solenoid options would in some wya limit pressure??

Thanks for your time and details.

 

[FluidPowerUser]

The electro-hydraulic pilot control valves only control the displacement of the spool and therefore the flow. If you are able to get more pressure out of the pump with a different setup, that does suggest that the Parker K220LS valve has an issue.

What are you driving to get the pressure? Can you dead head the outlet from the valve and see what pressure you get? The pump will reduce its displacement to the lowest flow required to maintain the pressure, or to the minimum displacement setting, if there is one.

Are you using the ASC inlet? If not, which one are you using?

Also, you said that you "teed" into the LS line to the pump, where else is that LS signal going?

 

[HydroBuff]

As far as where I have tried for the pressure measurement, I have tried it on several sections, deadheaded, with the same results.
I am using an ASC inlet here.

And for the tee, all I meant was a test guage teed into the LS line running directly to the pump.
I believe I will have to double check all the parts assembled on the valve and do a complete analysis to make sure there wasn't some incorret assembly.

Best Regards,

 

[HydroBuff]

Hi FluidPowerUser,

Not sure how familiar you are with these valves, but just in case this rings a bell with you, I seem to be able to build more pressure when using the LS port which is load signal that is copied, versus when I am taking it from the PL port which is uncopied load signal from the workport.

 

[FluidPowerUser]

Hello...

I am very familiar with pre compensated section valves like this one. I have 35+ years of experience in fluid power and have used Rexroth, Danfoss and Parker valves. The Parker version is really obscure with the port references and the nomenclature etc. It's just too complicated and to make things worse, the PDF and support documentation is not very clear either.

Most valves of this type just call the LS port 'X' or 'LS' and it's simple to connect that port to the pump compensator. I don't know why Parker have decided to have PL and LS and as you had said that the max pressure you could reach was 230 BAR versus the expected 300 BAR, I couldn't see how the load sense pressure or the copied pressure could account for the 70 BAR differential. I guess that's just because of the exchange of information on this forum. I didn't want to cause offence or insult your intelligence by asking dumb questions.

Anyway, are you all good now and getting the pressure you expect from the Parker valve?

 

[HydroBuff]

Just to clarify, you will not insult my limited intelligence. I am only an eigth grade school dropout trying to learn all I can by doing things. Hopefully I am not the one offending you with simple questions.

And no, I will keep on diagnosing, this is not the expected behaviour of this valve and I must determine what is going on.

Fo some reason I did get a 70 bar pressure difference and I really don't understand it yet. I will keep you all posted if I figure it out.

 

[FluidPowerUser]

OK, sounds good.

There is a fluid power forum and your questions will get a higher profile and more subjective response.

The valve forum tends to be steam valves and gate valves or ball valves. As you will know by now, pre compensated, load sensing, sectional valves are a little more complicated and questions about their operation are perhaps better answered in the fluid power engineering forum.

Don’t be afraid to ask. He who does not know, but asks, is a fool for 5 minutes. He who does not know, but does not ask, is a fool forever.

 

[HydroBuff]

Is it possible for me to move this thread? This is the first time I ever posted here.

 

[FluidPowerUser]

Yes, it’s possible, but I don’t know how. I have seen it done before. I just tried, but it kicked me out and I had to ask for access, hence the delay in responding.

 

[HydroBuff]

Would there be any way to tag the admins and ask them to do it?

Let me knwo if you have ever done that before.

Thanks!