Pressure drop in a hydraulic system why is it important

[WezTec]

Hi
I would like to know why all hydraulic components relate to pressure drops. I understand that you will get a drop after whatever hydraulic component or piping is installed.

If a cylinder requires 100BAR to move and say a pressure drop through the valve of 5BAR & the pump is capable of pushing 200BAR how does the pressure drop effect the cylinder power ?

 

[Hydromechdude]

Hydraulic circuits are generally not that simple. You can have multiple pumps, valves, actuators, and a whole lot of plumbing. Gotta make sure that when it's all said and done, the pressure at the load is high enough to do what you want.

Can you lift 10 lbs? How about 20 lbs? Not really a big deal even though it's double. What about if you keep stacking up 10 lb plates? Eventually you are not going to be able to lift it. That's when it matters.

 

[WezTec]

Thank you for the response it is as I thought.

 

[kcj]

If the pump is capable of 200 bars, and load is 100, and a extra pressure drop is 50 bars, that extra 50 bars is wasted energy that must also be supplied to turn the pump (electricity, diesel fuel, etc). After that, it is converted to heat across the pressure drop instead of converted to work as the 100 bar at the load is. So now the extra energy in the form of heat must be dissipated either to ambient or through some sort of cooler, or the system runs hotter and has shorter life and less reliability.
In the 'good old days', the motor would be oversized, the cooler circuit would be oversized, and who cared about extra hardware cost and wasted energy. The system worked and the end user paid the hiddens costs.

Now, thankfully, end users care, and force the designer to care, about operating costs, heat, space, weight, and a host of other issues.

 

[IceStationZebra]

Obviously you also have to consider the flow rate. Poor plumbing doesn't matter much at low flows, but can be a significant hindrance at high flows. So generally the power available to do work will decrease as flow increases. ISZ

 

[hydtools]

The pressure drop(s) do not affect the cylinder 'power' until the pressure drop(s) add to overall pressure demand such that the total demand exceeds the pump/driver capacity. Component pressure drops, in addition to actuator pressure requirement, must be considered when figuring the total power required for the pump/driver.

Ted

 

[WezTec]

Thank you guys, this site is very interesting.