In flow dividers, there is always a difference between the upstream and downstream pressure. This is due to pressure drops that occur during the operation of the flow divider. In this article, we explain what they are, why they happen, and which precautions can be taken to reduce them.
What pressure drops are
Pressure drops in hydraulic flow dividers are pressure differences that occur due to the movement of the gears and the flow of fluid through the divider itself. Typically, pressure drops in a standard flow divider range between 20 and 40 bar, depending on the displacement and the rotation speed.
In the case of a flow divider with a motor, the pressure drop is higher because, during the dividing phase, the divider also has to drive the motor.
Causes of pressure drop in flow dividers
In a flow divider, the factors affecting pressure drop are:
- Restrictions in the piping
In this case, the pressure drops are caused by the friction of the oil against the walls of the pipes. It is therefore important to ensure that the pipe dimensions are suitable for the flow rates and the type of fluid that needs to pass through them. - Rotation speed
When the flow sent to the divider is high, the gears must rotate at very high speed, which results in greater pressure drops. - Oil viscosity
The use of high-viscosity oils creates greater resistance to flow, increasing pressure drops.
How to reduce pressure drops
Let’s now look at the precautions that can be taken to minimize pressure drops and achieve lower energy consumption:
- Properly size the system
It is important to properly size the flow divider, ensuring that the piping and components are suitable for the flow to be managed. - Use multiple inlet ports
Vivoil flow dividers are equipped with multiple inlet ports (one for every two outlets, so if the component has 6 sections, there are 3 inlets; if it has 8, there are 4), and all the inlets are internally connected.
We chose to structure our range this way to optimize and simplify the selection process, giving users the opportunity to take advantage of the inlets and reduce pressure drops.
All the inlets are internally connected, so any unused ports can always be plugged. However, it is advisable to use multiple inlets to reduce pressure drops. In our flow divider catalogs, you will find guidelines on the flow rates that require the use of more than one inlet.
Parameters to follow to avoid excessive pressure drops
To avoid excessive pressure drops, we recommend not exceeding the following values for each inlet:
- Group 0 flow dividers: do not exceed 15 liters
- Group 1 flow dividers: do not exceed 40 liters
- Group 2 flow dividers:
- If the inlet is ¾ inch BSPP (British Standard Pipe Parallel): do not exceed 80 liters
- If the inlet is 1 inch BSPP (British Standard Pipe Parallel): do not exceed 120 liters
- Group 3 flow dividers:
- If the inlet is 1 inch BSPP (British Standard Pipe Parallel): do not exceed 200 liters
- If the inlet is 1¼ inch BSPP (British Standard Pipe Parallel): do not exceed 360 liters
Want to know more?
In our flow divider guide, you’ll find all the information you need to choose, customize, and use the component best suited to your project, common issues—including cylinder misalignment—and how to identify them.
If you have noticed pressure drops and want to know how to prevent them, contact us.
We’re here to help!