Suction Filter Sizing 1

[BEMPE16524]

Hi All,

I have a system like this:

-variable displacement pump maximum 360cc.
-operating pressure 200-220 Bar
-Calculated system flow at 1800RPM at 220 Bar is 648 lpm.
-the pump is needed to run a hydraulic motor only.
-the pump and the hydraulic motor location may not be too far apart (around 2 meter max, using flex hose)

What should be the flow rating of my suction filter? Should I use the 648 lpm as reference? T.I.A

R.Efendy

 

[TugboatEng]

Don't do it. Hydraulic systems only benefit from very fine filtration. This can't be done on the suction side. Use full flow filters rated at system pressure or use filters on the servo/replenish/cooling pump circuit.

Otherwise, your tank shouldn't be contributing wear particles to the system. There should be no benefit to a suction filter provided you follow some basic cleanliness practices.

 

[BEMPE16524]

TugboatEng, are you saying I shouldn't put any filter at the suction?
At the moment I have already selected a high-pressure filter after the pump which suit the operating pressure and flow.

R.Efendy

 

[TugboatEng]

From an operator's standpoint, we see no benefit from additional filters. They only add cost to both to purchase and lifecycle. Starving the pump suction can cause damage much more rapidly than particle wear. It's ok to use a strainer that can catch rocks and large debris but is coarse enough that it will not require service within the lifetime of the machine. Otherwise, focus on making the reservoir large enough that fluid moves slowly enough that large particles can't get picked up by the pump. Our most reliable systems don't use suction strainers or suction filters. Our most reliable systems use the filters on the servo pumps but I think they also have better design over the other systems.

 

[BEMPE16524]

TugboatEng, that make sense. Thanks for your view.

R.Efendy

 

[73lafuite]

Hello,
Is your installation working? Or is it a project?
A 360 cm3/t open circuit pump is not recommended when there is only one hydraulic motor to drive.
As my colleagues indicate, you should not put a filter on the suction, but in addition you must take constructive measures to guarantee a correct pressure difference between suction and drain in all situations: cold oil, variations in displacement brutal, fitting below the oil level in the tank, suitable drain ø and length, etc. And it may also be necessary to take constructive measures to avoid problems of boosting the hydraulic motor during transient phases.
Why don't you use a closed circuit pump? It's more environmentally friendly because you use 5 times the oil.
Cordially

 

[BEMPE16524]

73lafuite thanks for your view.
Yes, this is considered as a new project. we have been dealing with same situation before but with smaller pump and still working fine.

So this was the previous project:
- 100 HP electrical motor (no electrical soft start), 3000V/60Hz/1700-1800RPM
- main pump - 131 cc with auto mechanical soft start at pump exit. pump is fixed displacement.
- operating pressure 210 Bar.
- to drive a hydraulic motor
- has a suction filter (565 lpm, 20 micron, 200psi max)
- has a pressure filter (565 lpm, 5 micron, 414 Bar max)

Our next project (as we discussed here):
- 335 HP electrical motor (with electrical soft start), 3000V/60Hz/1700-1800RPM
- main pump - 360cc (with pressure/flow control, no mechanical soft start).
- operating at 200-220 Bar.
- to drive a hydraulic motor of 355cc max
- pressure filter no issue.

we have to use open circuit because the operator will be far away from the system and need time to recover the whole unit to fix. during the recovery process, the unit may still work with help from the compensator on the tank (continuously pushing the oil to the hydraulic line) and we need the tank in case of hydraulic totally loss, sea water can still be filled up into the tank as an emergency medium until the system is recovered to the surface.

R.Efendy

 

[73lafuite]

Hello,
I understand your application better. It seems to me that the Rexroth A10Vs do not go up to 360cm3/t. Parker makes a 360cm3/t PV pump. But this pump could not work at 1800RPM and 100% flow rate if suction pressure is same as crankcase pressure. Only at 95% of max flow.
Personally using such a pump with 335HP scares me. The speed at the distribution window is very high and therefore premature wear cannot be ruled out if the conditions are not ideal. For open circuit I would put 2 pumps in tandem assembly. For suction and discharge hoses it will be less expensive and more standard. With a little imagination we could divide by 2 the flow brewed in the tank and therefore the volume of the tank.
I remain convinced that a closed circuit solution is much more reliable and simple. Why not ask suppliers who have this experience. Example Rexroth/bosch, Sauer Danfoss, Linde?
Good luck.

 

[BEMPE16524]

73lafuite,

I've checked with Eaton/Danfos, they have PVWS-360M-07R0001R02SV0A-LR00A2F model for 360cc. and for hydraulic motor, I've seen Rextroth has the 355 cc which should be enough for us. and yes, we are not running at max flow and pressure, that's why I've confident to run the configuration as it is (إن شاء الله).

Thanks for your point/view.

R.Efendy