Vacuum Assist Pumps: How Roots Booster Technology Speeds Up Industrial Vacuum Systems

Two coating shops run nearly identical chambers and the same rotary vane backing pumps. On paper, their vacuum systems should perform the same. Yet one shop starts its deposition cycle in a fraction of the time, runs more batches per shift, and holds a noticeably deeper process vacuum. The difference is not a bigger backing pump or a newer chamber. It is a vacuum assist pump sitting between the chamber and the backing pump, quietly doing the heavy lifting in the pressure range where the backing pump alone runs out of breath.

If your process spends too long pumping down, or your ultimate pressure stalls just short of spec, this article explains what a vacuum assist pump does, why it must be paired with a backing pump, how to size the combination, and what to look for in a manufacturer.

A vacuum assist pump is a mechanical booster built on the Roots principle. Inside the housing, a pair of figure-8-shaped (lobed) rotors spin in opposite directions at constant speed, synchronized by gears. The rotors never touch each other or the casing; they maintain extremely tight clearances while sweeping gas from the inlet to the outlet. Because there is no oil in the pumping chamber and no internal compression taking place, the machine moves large volumes of gas cleanly and quickly in the low- and medium-vacuum range.

That is exactly where it earns its name: it assists another pump. On its own, a standard Roots-type booster cannot compress gas all the way to atmospheric pressure. Bolted in series with a suitable backing pump, though, it transforms what that backing pump can do.

With no internal compression, a vacuum assist pump exhausts against the intake of a backing pump rather than directly to atmosphere. The backing pump — commonly a rotary vane pump, a dry screw vacuum pump, or a liquid ring pump — handles the roughing stage from atmosphere and then provides the discharge path for the booster.

The division of labor works because each pump operates in the range where it is most effective:

• From atmosphere down to rough vacuum, the backing pump does the work alone.
• In the medium-vacuum band, where a backing pump's effective speed drops off sharply, the booster cuts in and multiplies the system's throughput — commonly by a factor of two to ten, depending on the size ratio between the two pumps.
• At ultimate pressure, the combination typically reaches roughly an order of magnitude deeper than the backing pump could achieve on its own.

Any process that needs fast evacuation or a stable medium-to-high vacuum on a large chamber is a candidate. The most common industrial uses include:

• Vacuum metallurgy and heat treatment — smelting, brazing, sintering, and casting, where gas loads are high and cycle time drives throughput.
• Vacuum coating — PVD and CVD chambers that must reach a clean base pressure before deposition can start.
• Lithium battery and electronics manufacturing — drying, degassing, and assembly steps that run under vacuum, often on tight takt times.
• Chemical and pharmaceutical processing — paired with a liquid ring or dry backing pump, boosters handle large volumes of water vapor and solvent vapor during distillation and drying.
• Freeze drying and vacuum drying — food, pharmaceutical, and materials drying lines that cycle chamber after chamber.
• Power industry — transformer drying and oil treatment, where deep vacuum removes moisture from insulation.

Because compression work turns into heat, cooling design is one of the first specification decisions:

For large chambers or very high throughput, a multi stage roots pump arrangement — two or more boosters in series ahead of the backing pump — extends the same principle into deeper vacuum territory without changing the basic architecture.

Oversizing wastes capital and energy; undersizing leaves the process starved. Work through these questions before requesting quotes:

• 1. What is your working pressure and target pump-down time? These two numbers determine the speed you need in the booster's efficient band, not just its nameplate rating.
• 2. What booster-to-backing ratio fits the process? Ratios between roughly 2:1 and 10:1 are common. Higher ratios move gas faster but narrow the pressure window in which the booster can run safely.
• 3. What is the maximum allowable pressure difference? Check it against the pressures at which you want the booster to cut in; a bypass valve or gas-circulation cooling widens your options.
• 4. What is in the gas stream? Dust, condensable vapors, and corrosives all influence the choice of backing pump, inlet filtration, and sealing.
• 5. What utilities do you actually have? Cooling water, electrical supply, floor space, and maintenance access are mundane details that routinely decide between two otherwise equal pumps.

A booster spends its life spinning at high speed with clearances measured in fractions of a millimeter, so manufacturing precision is not a marketing point — it is the product. Zhejiang Yingpa Electromechanical Co., Ltd, which markets internationally under the InPowerVac brand, has focused on vacuum equipment since 2000 and operates production bases in Zhejiang and Hebei, including a 70,000-square-meter plant added in Taizhou in 2023.

As a roots vacuum pump manufacturer, the company runs 92 sets of machining equipment — 30 of them imported, including 32 Mazak machining centers — and backs them with a full inspection chain: a material tensile testing lab, a vacuum performance test room, a dynamic balancing lab, and three-coordinate measuring machines. Rotor profile accuracy and balance are verified before a pump ever leaves the factory.

The Roots lineup covers the configurations discussed above: vacuum assist pumps, multi stage roots pumps, gas-circulation cooled and air-cooled models, high-capacity units, and auxiliary pumps. For turnkey needs, these boosters are integrated with backing pumps into a complete vacuum pump booster system, engineered for applications from lithium battery production and semiconductors to coating, packaging, and pharmaceuticals. The same equipment serves global customers including Foxconn, Huawei, Samsung, the Tata Group, Aoyama Group, and Russian National Energy.

Before signing off on a vacuum assist pump, confirm each of these with your supplier:

• Pump-down curve or calculated cycle time for your chamber volume, not a generic datasheet figure.
• Maximum allowable pressure difference, and whether a bypass valve or gas-circulation cooling is included for early cut-in.
• Backing pump recommendation and the final ultimate pressure of the combination.
• Cooling requirements — air, water, or gas circulation — matched to your utilities.
• Sealing and materials suitable for your gas composition (vapors, dust, corrosives).
• Spare parts availability, maintenance intervals, and who provides commissioning support in your region.