The Basics of Vacuum Technology
Reliable, efficient, and precise vacuum systems are essential in industry. Because there are several key components – including a motor-driven pump or venturi generator, cups, tubing, valves, and fittings – that must be correctly sized to ensure effective and efficient performance, calling on JHFOSTER as your trusted partner in automation ensures proper sizing and integration of an optimal vacuum solution.
This blog will explain how pneumatic vacuum systems work, outline the key components, and discuss system design.
What is the Working Principle of a Vacuum System?
The venturi effect is the mechanism behind pneumatic vacuum generation. Based on this working principle, an air-powered vacuum is generated by forcing compressed air through an orifice (a nozzle). As the air exits the nozzle, it expands and increases in velocity before entering a diffuser to create a negative pressure, or vacuum.
How Does a Vacuum System Work?
In a pneumatic vacuum system based on the venturi effect, compressed air flows through a nozzle, then expands in the diffuser to create negative pressure at the vacuum port. When called upon, the vacuum travels through tubing and system components to the vacuum cup to perform work, such as generating suction to pick up an object or evacuating a vessel.
Sizing the Essential Components of an Industrial Vacuum System
Key components of a vacuum system include the vacuum generator, vacuum cups, tubing, valves, and fittings, which should be selected and sized based on the specifications of the application.
To ensure proper sizing of components, it is essential to understand how the combination of vacuum level, holding force, flow, and cycle times interacts. This is because the force, or weight of an object, that the vacuum system can pick up is determined by the area of the vacuum cup multiplied by the vacuum level of the generator.
To simplify this, the following formula, (.4912 x cup area x Inches Hg vacuum) ÷ 4 can be applied to sizing a vacuum cup with a 4:1 safety factor.
For example:
A 2” diameter vacuum cup has an area of 3.14 in2. If the vacuum pump or generator produces 22 inches HG vacuum, the approximate holding force of the vacuum cup would be (.4912 x 3.14 in2 x 22) ÷ 4 which equals 8.48 lbs of the vacuum holding force.
While proper sizing of a vacuum system is often misunderstood, getting it right is critical to avoiding common system flaws and inefficiencies. The experts at JHFOSTER are here to evaluate your application and ensure proper sizing.
Troubleshooting Common Design Flaws
The most common design flaw is a restriction in flow due to improper sizing of tubing, valves, fittings and other components.
To check that your system isn’t restricting vacuum flow, place a tee with a vacuum gauge near the suction port of the generator. If the gauge reads vacuum when nothing is connected to the suction cup or a vessel is not attached, then the system is restricting flow.
If you find the system is not picking up an object or evacuating a vessel fast enough, you’ll need to increase the flow path with properly sized tubing, valves and fittings. If restrictions cannot be eliminated, use a generator with a higher vacuum level and flow to provide the fastest vacuum/evacuation.
Comparing Vacuum Generator Types and Maintenance Requirements
There are two main types of vacuum generators: single-stage and multi-stage.
Single-stage: A single nozzle creates a vacuum in one step. They are best at high-flow, low-vacuum tasks like picking up lightweight, smooth parts in quick cycles. Single-stage systems blow debris out an exhaust so they do not require filters. The simple design means there are few maintenance requirements.
Multi-stage: Multiple nozzles work in stages to create higher vacuum levels for faster cycles or heavier objects. They are best for picking up heavy objects or high-speed automation. Multi-stage systems are more susceptible to clogging and require filters/filter changes. The more complex design increases maintenance requirements.
The following table highlights the key differences between single-stage and multi-stage vacuum systems.
| Characteristic | Single-Stage Vacuum Generator | Multi-Stage Vacuum Generator |
| Efficiency | Less efficient | Consume less air, higher efficiency. |
| Susceptibility to Clogging | Not as susceptible to clogging. | Require filters to reduce clogging. |
| Maintenance Requirements | Low maintenance requirements due to simple design and low risk of clogging. | More complex design, plus the use of filters, increases maintenance requirements. |
| Vacuum Level | High-flow, low vacuum level. | Higher vacuum levels. |
| Best For | Picking up lightweight, smooth objects. | Picking up heavier objects and high-speed automation tasks. |
Point-of-Use vs. Centralized Industrial Vacuum Systems
There are two major vacuum system configurations: point-of-use (or decentralized) and centralized.
Point-of-Use Systems: Smaller, more compact units placed locally at the application.
Centralized Systems: Multiple vacuum needs are managed from one central location using a delivery system of piping.
The following table compares and contrasts the two systems to help you decide which system is right for your needs.
| Characteristic | Point-of-Use Systems | Centralized Systems |
| Location | Placed at the application. | Placed in a centralized location with a vacuum delivered to individual workstations via a piping system. |
| Efficiency | Less energy efficient | More energy efficient due to demand-driven control. |
| Noise/heat | Create more noise and generate more heat at the workstation. | Less noise and heat at the application area. |
| Reliability | Downtime affects only one station. | Failure impacts multiple stations. |
| Response time | Fast response because the vacuum is on site. | May have delays as the vacuum travels through the delivery system. |
| Best for | Small tasks, when a vacuum is only needed at a few work stations. | Large facilities with multiple vacuum applications. |
Applications for Industrial Vacuum Systems
Versatile vacuum systems are used in a range of industries to accomplish many tasks. Here are just a few:
- Pick and place robots.
- Packaging lines.
- Handling of porous/non-porous materials.
- Vessel evacuation.
- Palletizing/depalletizing.
As your robotics, automation, and compressed air partner, JHFOSTER can help you integrate a properly sized vacuum system that is customized to meet the needs of your specific application. Stop wasting time and energy. Contact us today for an evaluation so we can design and integrate a vacuum system that performs efficiently and effectively, so you can start working smarter, not harder.
