How to Size a Vacuum System for Industrial Applications
When it comes to industrial vacuum systems, size matters — and getting it wrong can mean wasted energy, underperforming processes, or costly equipment replacements. Whether you're designing a new system or upgrading an old one, correctly sizing your vacuum system is critical to achieving the performance, efficiency, and reliability your application demands.
At Industrial Air Services, we help manufacturers and facility managers across Nashville, Knoxville, and Chattanoogaselect and install properly sized vacuum systems. In this guide, we’ll walk you through everything you need to know to size your vacuum system the right way — the first time.
Why Sizing a Vacuum System Is So Important
Many people mistakenly assume that vacuum systems work like compressed air systems — but they don’t. In fact, designing a vacuum system involves a completely different set of calculations and variables. Unlike air compressors, which add pressure, vacuum systems remove air or gas to create a pressure differential, which is what enables suction.
Incorrect sizing can lead to:
Inadequate vacuum levels (low performance)
Overworked equipment (leading to breakdowns)
Increased energy consumption
System instability
Inability to meet process requirements
Getting the size right ensures the system meets demand without wasting power or overstressing components.
Key Factors That Affect Vacuum System Sizing
When determining what size vacuum system you need, several variables come into play:
1. Required Vacuum Level
What vacuum level (measured in inches of mercury or millibar) does your application require? Some processes only need a mild vacuum, while others demand deep vacuum levels.
Vacuum is typically categorized into:
Low vacuum: 1 to 30 inHg (typical industrial uses)
Medium vacuum: 0.1 to 1 mbar (lab and process applications)
High vacuum: Below 0.1 mbar (specialized applications like semiconductors)
Knowing your target vacuum level is the first step in determining the right system.
2. Volume to Be Evacuated
Are you pulling vacuum on a sealed chamber, a continuous line, or an open system? You’ll need to calculate the total volume (in cubic feet or liters) of air to be removed. The larger the volume, the more capacity (CFM) your system needs.
3. Evacuation Time
How quickly do you need the vacuum to reach its target level? This is especially important in batch processes, packaging lines, or any system that must be ready within a specific time frame. Faster evacuation means higher pump speeds.
4. Leak Rate and System Integrity
All vacuum systems experience some leakage. For open systems or porous materials, the leak rate can be substantial. This must be factored into the sizing to maintain a stable vacuum.
5. Altitude and Environmental Conditions
Because air density changes with elevation, you’ll need to adjust for altitude — especially in facilities located in higher-elevation regions. Temperature and humidity can also affect system performance.
6. Process Type
Are you conveying material, holding parts in place, thermoforming plastics, or degassing liquids? Each process type places different demands on the vacuum system. The type of vacuum pump — rotary vane, claw, screw, or liquid ring — must match the process, not just the volume.
Steps to Size a Vacuum System Correctly
Here’s a simplified step-by-step process we follow when sizing systems for our clients:
Step 1: Define the Application
Determine the end use:
Holding/lifting
Packaging
Forming
Drying
Conveying
Degassing
Central vacuum for a facility
Step 2: Identify the Required Vacuum Level
Define the absolute pressure or inches of mercury needed for the process to function correctly. This will determine what type of pump technology is appropriate.
Step 3: Calculate Volume and Flow Rate
Measure or estimate the volume of the system, chamber, or process line. Then determine how much flow (measured in ACFM — actual cubic feet per minute) is required to reach the target vacuum level within your specified time.
Step 4: Factor in Leakage
Evaluate how much air enters the system during operation. Open processes, flexible seals, and older piping systems all introduce leakage, which adds to the required pump capacity.
Step 5: Choose Pump Type Based on Application
Different pumps are designed for different needs. For example:
Rotary vane pumps: great for medium vacuum, quiet and efficient
Claw pumps: oil-free, high-efficiency, continuous duty
Screw vacuum pumps: suitable for harsh, dirty gases
Liquid ring pumps: ideal for wet or vapor-heavy processes
Choosing the right technology is just as important as selecting the right size.
Step 6: Plan for Future Growth
Always build in extra capacity. If your production expands or your system begins to leak more over time, an undersized system will fail to meet your needs. We typically recommend sizing at 120–150% of initial demand to ensure scalability.
Common Sizing Mistakes (and How to Avoid Them)
Many businesses struggle with vacuum performance not because of faulty equipment — but because of poor sizing or misapplied technology.
Mistake #1: Using Compressor Logic to Size Vacuum Systems
Compressed air rules don’t apply. You can’t just match HP or CFM numbers and expect good results. Work with a vacuum specialist who understands the differences.
Mistake #2: Ignoring Evacuation Time
For batch or cyclic processes, how fast you can pull a vacuum is just as important as the final vacuum level. Failing to account for this causes bottlenecks and delays.
Mistake #3: Not Accounting for Leaks
Even well-maintained systems have some leakage. Ignoring this factor leads to systems that can’t hold vacuum under real-world conditions.
Mistake #4: Oversizing “Just to Be Safe”
Too large a vacuum pump will cycle inefficiently, waste energy, and potentially damage itself. Proper sizing should meet demand, not blow past it.
Let Industrial Air Services Size Your System the Right Way
At Industrial Air Services, we don’t guess — we measure, calculate, and customize every system we install. We’ll evaluate your specific application and help you choose a system that performs the way it’s supposed to, day in and day out.
We provide:
On-site system assessments
Sizing and equipment selection
Installation and integration with existing systems
Ongoing service and preventive maintenance
Central vacuum system design
📞 Call us at (615) 641-3100 to schedule a consultation or speak with one of our vacuum system experts in Nashville, Knoxville, or Chattanooga.
Don’t let an undersized or mismatched vacuum system hold your process back. Let Industrial Air Services help you get the right fit — with the performance your operation demands.
