At a glance
- Type
- Oil-lubricated screw
- Architecture
- Two-stage, intercooled
- Pressure options
- 4 / 5 bar(g)
- Drive
- Permanent-magnet VFD (VPM-B)
Overview
DUALLUBE-VPM Low-Pressure is the low-pressure member of the DUALLUBE D two-stage family. Two rotor sets share the compression with intercooling between them, and a permanent-magnet variable-frequency drive follows a load that moves. It exists for the duties that want a large volume of air at low pressure — pneumatic conveying, fermentation, fluidisation and textile air jets — which is why its model codes carry the VPM-B suffix rather than the standard VPM one.
Model range
The VPM-B low-pressure line runs from 22 to 280 kW at 4 and 5 bar(g). Model row, FAD and package contents come from the current datasheet.
Pressure
4 / 5 bar(g)
- Range
- 22–280 kW
- Suffix
- VPM-B
- Duty
- High flow, low pressure
Architecture
Two-stage, intercooled
- First stage
- Compresses to intermediate pressure
- Intercooler
- Removes inter-stage heat
- Second stage
- Compresses to final pressure
Drive
Permanent-magnet VFD
- Why
- Conveying and jet duty rarely run flat out
- Not the same as
- Standard VPM (8/10/13 bar)
- Before a quote
- Confirm the 4 or 5 bar row
Technology
Why two stages at low pressure
At 4–5 bar the pressure ratio per stage is small, so it is fair to ask whether two stages are worth it. On the flows this line covers they are: the energy bill follows the air volume moved, and splitting the compression with intercooling in between keeps the process closer to isothermal and pulls specific power down at high flow.
The VPM-B variant
VPM-B is the low-pressure form of the variable-frequency drive in the DUALLUBE D family. Rotor profile and the split of pressure between the two stages are set for 4–5 bar rather than 8–13 bar, so the inter-stage pressure ratio stays balanced across the range instead of being an off-design compromise.
What the intercooler adds
The intercooling circuit is the visible difference from a single-stage machine of the same power: an extra heat load for the compressor room to reject, and a larger footprint. Both need to be in the room layout before the machine arrives.
More technical detail
Specific power at low pressure
Two-stage machines hold their advantage in this band because the compression work is spread and intercooled, which matters more as the flow rises. The comparison that decides a project is single-stage versus two-stage at the same 4 or 5 bar duty and the same annual hours — not a nameplate comparison.
Selection logic
Set the required pressure first: 4 or 5 bar(g). Then take the actual flow at that pressure. Pick the VPM-B row at or above it, and confirm the model row and FAD on the current datasheet before quoting.
Selection & quote checklist
- the required pressure — 4 or 5 bar(g)
- actual flow at that pressure, not the nameplate figure
- the duty: conveying, fermentation, fluidisation or jets
- whether the load moves, which decides the drive
- room heat load and footprint including the intercooler
- the current VPM-B datasheet and package contents
Applications
Pneumatic conveying
Powder and pellet lines move on a large volume of low-pressure air. Pressure wants to be 4–5 bar; volume is what shifts the material.
Fermentation air
Aeration duty runs continuously at low pressure, so the running hours make the two-stage efficiency worth having.
Fluidisation
Air is used to make a bed of solids behave like a liquid. Flow is high, pressure is low and steady.
Textile air jets
Air-jet looms want steady pressure at high volume; a balance tank sits upstream of the jets.
FAQ
How is VPM-B different from VPM?
VPM-B is the low-pressure variant, set for 4–5 bar(g) applications. The two use the same variable-frequency principle but different rotor profiles and inter-stage pressure-ratio allocation, so they are not interchangeable — each is selected for its own pressure band.
Can this machine run at 8 bar?
No. VPM-B is built for 4–5 bar duty. If the plant needs 8, 10 or 13 bar, the standard DUALLUBE D page is the right series and its model rows are the ones to compare.
Is the intercooler a maintenance item?
Yes. Air-cooled intercoolers need periodic fin cleaning and water-cooled units need the water side watched for scale, so plan access to the cooler when you lay out the room.
Why not just run at 8 bar and regulate down?
Because the energy was already spent compressing to 8 bar. Holding the whole plant at 8 bar to serve a 4 bar process pays for compression the process never uses — the correction is the right pressure band, not a bigger machine.
Confirm the model row, FAD and package contents for the pressure you select.
