Existing types of vacuum ejectors
You can categorize vacuum ejectors by three main factors: the number of vacuum stages, the physical principle used to create the vacuum, and how they are mounted.
Single-stage and multi-stage ejectors
Ejectors are divided into two categories, single-stage and multi-stage, depending on the number of vacuum stages they have.
Single-stage ejectors simplify the vacuum generation process by completing it in one step, but this limits the level of vacuum they can achieve.
Multi-stage ejectors use a sequence of stages to build up the vacuum. This process makes them more efficient, as they can reach higher vacuum levels with a lower supply pressure.
Venturi vacuum
Using the Venturi effect, which is derived from Bernoulli's law, Venturi vacuum generators work by accelerating compressed air through a constricted nozzle. This causes the air's pressure to drop, creating a low-pressure zone that generates suction by pulling in the surrounding air.
Thanks to their simple and versatile characteristics, Venturi vacuum generators are a great choice for about 80% of applications. For more specific tasks, particularly those involving fragile or porous materials, other systems like contactless vacuum grippers may be a more appropriate choice.
Individual and block-mounting type vacuum ejectors
There are two main ways to mount vacuum generators: individually or in a block.
For tasks that only need one ejector, individual mounting is the best choice because as it is simple and cost-effective.
When you need to group multiple ejectors together for central control, block mounting is the most suitable solution. This method makes good use of space and allows you to manage the entire system efficiently with an industrial communication system like a fieldbus.
By combining valves and ejectors into a single, compact unit, SMC's hybrid systems provide enhanced flexibility. This integration not only simplifies the control of applications needing both positive and negative pressure but also helps to streamline machine design. With industrial communication protocols such as IO-Link, these units also make it possible to have remote and flexible vacuum control.
Key applications of vacuum ejectors
Vacuum ejectors are highly versatile and work well in many different situations. They are especially useful for:
- Systems that do not need a lot of vacuum flow.
- Point-to-point handling using single or multiple vacuum grippers
- Places where a central vacuum supply is not available
What are the benefits of using vacuum ejectors instead of other vacuum generation systems?
Industrial vacuum ejectors offer the following key benefits:
- Maintenance-free and versatile mounting: Because they do not have moving parts, they require no maintenance and offer versatile mounting options.
- Installation in any position and at any point in the application: These units are flexible and can be installed anywhere in the system.
- High response speed and vacuum generation: They have a quick response time and can reach the required vacuum level in an instant.
- Compact and lightweight: Their small size makes it easy to use.
- No heat generation: They do not generate heat that affects the surrounding environment.
- Energy-saving functions: They have built-in features that help them use less energy.
- Additional integrated functions: They also include extra features that make controlling and monitoring the system much easier.
Factors for choosing vacuum ejectors
The choice of the right vacuum ejector depends on several important factors:
- Nozzle and Diffuser Design: The size of these components is a crucial factor that impacts both the suction flow rate (speed) and the vacuum level (strength). Smaller nozzle diameters produce a stronger vacuum but with a lower flow rate. On the contrary, a larger nozzle size results in a higher flow rate but a weaker vacuum.
- Requirements for Suction Flow and Vacuum Pressure: When selecting your system, you must first determine the required suction flow (air volume) and the desired final vacuum pressure. Remember that the system's response time (how quickly it reaches the desired vacuum) is impacted by both the chosen flow rate and the pipe's diameter.
- Leakage Considerations: The shape, porosity, or other characteristics of a workpiece can cause leaks that negatively impact a system's performance. For applications with potential leaks, SMC recommends using a lower vacuum pressure setting and an ejector with a greater suction capacity to compensate for these leaks and ensure successful operation.
