What Happens When You Put Two Double-Head Pumps in Parallel?

You have a medical device that needs both deep vacuum and high airflow, but the space is tight and noise is a major concern. A single pump that meets these specs is often too large, loud, and costly.

By connecting two compact, series-configured pumps in parallel, you can achieve both high flow and high vacuum. This setup maintains the maximum vacuum of a single pump while significantly boosting the flow rate in a quiet, space-saving package.

I recently worked with a client in the medical field who faced this exact challenge. They were developing a therapeutic device that required a deep, stable vacuum to be effective, but also needed high airflow to quickly reach that vacuum level for each treatment cycle. The machine had to be quiet and compact enough for a clinical setting. We explored several options, but the most elegant solution was a modular one that leveraged the power of parallel connections.

Why Not Just Use a Single, Larger Pump?

When you need more power, the obvious answer seems to be "get a bigger motor." Why bother with the complexity of connecting two pumps instead of finding one large one that does it all?

For applications like medical devices, a single large pump is often a poor fit. A dual-pump system offers a better balance of size, noise, redundancy, and performance than a monolithic solution.

When designing for sensitive environments, brute force is rarely the best approach. My medical client's checklist included "quiet" and "compact" right alongside the performance specs. A single, large pump that could deliver both -98 kPa and 70 L/min would likely be noisy and bulky. A dual-pump setup, however, offers distinct advantages:

• Compact Footprint¹: Two smaller pumps can often be arranged more flexibly to fit into tight spaces where one large pump cannot.
• Lower Noise & Vibration²: Two smaller motors running in a balanced state can be significantly quieter than one large, high-power motor.
• Redundancy: In a medical device, this is critical. If one pump fails, the system can still operate at reduced capacity, which is far better than a complete shutdown.

First, What is a "Double-Head Series" Pump?

The term "double-head series pump" can be confusing. To understand the parallel setup, you must first understand the high-performance building block you're working with.

This is a pump with one motor driving two separate pumping chambers. The outlet of the first chamber is connected directly to the inlet of the second, creating a two-stage vacuum system.

This internal series connection is a clever design used to achieve very deep vacuum levels³ that a single-stage pump cannot. Think of it as a relay race for air molecules.

1. Stage One: The first pump head does the initial work. It pulls air from the application and reduces the pressure significantly.
2. Stage Two: The second head takes this already rarefied air from the first stage and evacuates it further. Because it's pulling from a partial vacuum instead of atmospheric pressure, it can achieve a much deeper final vacuum level.

This design masterfully trades some maximum open airflow for a massive gain in ultimate vacuum capability⁴, making it perfect for applications that need to pull hard. Our BODENFLO BD-05T1040DU is a perfect example of this powerful design.

How Does Paralleling Them Actually Increase Flow?

You have these high-vacuum pumps, but how does connecting them side-by-side make them faster? And if one pump gives 40 L/min, do two give 80 L/min?

Connecting pumps in parallel combines their flow rates. However, the rule isn't a simple 1+1=2. Due to system physics, you get a significant boost, often around 50-70% of the second pump's flow.

This is a critical point of expertise I always share with clients to set correct expectations. While the vacuum level is determined by the strongest pump (in this case, they are identical), the flow rate⁵ is additive. You are creating two paths for the air to travel. However, the system's tubing, fittings, and the pumps themselves create resistance. This means you won't get a perfect doubling of the "free air flow" specification.

A single BD-05T1040DU provides 40 L/min. Putting two in parallel doesn't give you a guaranteed 80 L/min. A more realistic outcome, as my client discovered, is around 65-70 L/min. This is a massive 60-75% increase in speed, which is often more than enough to meet demanding cycle time requirements.

How Did This Solve the Medical Client's Problem?

It's great in theory, but what did this solution look like in a real-world medical device? Was the performance enough to meet their strict requirements?

The dual-pump solution perfectly met all the client's needs. They achieved their target flow and vacuum levels within the tight size and noise constraints of their new medical device.

Here is a breakdown of how the dual BD-05T1040DU setup solved their engineering challenge:

• Requirement: A vacuum of -98 kPa, a flow rate over 65 L/min, quiet operation, and a compact size.
• Single Pump Test: One BD-05T1040DU delivered the required -98 kPa vacuum, but its 40 L/min flow was too slow.
• Dual Parallel Solution: By connecting two BD-05T1040DU pumps in parallel, the system performance was perfect.
  • Vacuum: Remained at a powerful -98 kPa.
  • Flow: Reached over 65 L/min, meeting their speed requirement.
  • Size & Noise: The two compact pumps fit easily into the chassis and were quieter than any single pump with comparable performance.

The client was able to finalize their design, confident they had a reliable, high-performance, and quiet vacuum source.

What Are the Rules for Building a Parallel Pump System?

You're ready to try this, but you are worried about making a mistake. You know that a bad setup could be inefficient or even damage the pumps.

To ensure success and longevity, you must use identical pump models, create a perfectly symmetrical tubing layout, and ensure your power supply can handle the combined electrical load.

When I consult on these setups, I stress three non-negotiable rules for creating a balanced and efficient system. Getting these details right is the key to achieving the performance you expect.

1. Use Identical Pumps⁶: Never mix different models. The pumps must be exact duplicates to ensure they share the workload equally. A stronger pump will always overwork itself while a weaker one underperforms.
2. Symmetrical Plumbing⁷: This is crucial. The tubing from the junction (a "Y" or "T" fitting) to each pump's inlet must be the same length and diameter. The same rule applies to the outlet side. This equalizes resistance and balances the load.
3. Sufficient Power: One BD-05T1040DU is rated at 100W. Two will require a power supply that can comfortably provide 200W, plus a safety margin to handle the inrush current when both motors start simultaneously.

Is the BODENFLO BD-05T1040DU Right for This?

You need a pump that can provide extreme vacuum but is also robust enough to be used in a demanding parallel configuration. Is this model up to the task?

Yes. The BD-05T1040DU is the perfect building block for this setup. Its internal series design provides extreme vacuum, while its powerful motor and durable construction ensure high performance and reliability.

We specifically designed the BD-05T1040DU for demanding industrial and medical applications. The aluminum alloy body and head are not just for durability; they act as an excellent heat sink, allowing the pump to run for long periods under heavy load without overheating. Inside, the high-end DC brushed motor provides a long service life, and the EPDM diaphragm and valves are chosen for their resilience. Combining two of these units in parallel creates a modular performance package that is more flexible, reliable, and often quieter than a single, oversized pump.

Conclusion

Paralleling two double-head series pumps like the BD-05T1040DU is an intelligent design strategy. It achieves both high flow and high vacuum in a compact, quiet, and reliable modular system — making it ideal for demanding OEM and medical applications.

If you’re looking to integrate high-performance micro pumps into your next project, partner with BODENFLO for expert engineering support and tailored solutions.

📩 Contact us today: info@bodenpump.com
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