FBEFBEI
FBE vs FBEI — external or internal gear?
Two positive-displacement families from FB Bombas. The choice depends on viscosity, tolerable pulsation and installation geometry.
TL;DR — Straight answer
FBE (external gear) offers a wider flow and temperature range (up to 350°C) in a compact footprint. FBEI (internal gear) delivers reduced pulsation via the gear-within-gear principle — ideal when downstream process is sensitive to flow variation.
Option A
FBE
External gear · wide range
up to 350°C
When to use
- Flow up to 390 m³/h
- Viscous fluids (up to 100,000 SSU)
- High temperature (up to 350°C)
- Compact footprint from DN 1/8" to 6"
Option B
FBEI
Internal gear · reduced pulsation
absolute volumetric control
When to use
- Pulsation-sensitive downstream process
- Dosing and precise transfer
- Viscous fluids with low noise
- Optional heating jacket (steam 185°C / thermal oil 232°C)
Side by side
| Criterion | FBE | FBEI |
|---|---|---|
| Principle | External helical gears (driver + driven) | Gear-within-gear (external rotor + internal gear) |
| Pulsation | Standard for PD (acceptable in most applications) | Reduced — equidistant seal between teeth |
| Size range | DN 1/8" to 6" | Models from 1" to 4" (GG, HJ, HL, KK, LQ, LS, M, AS, AK, AL) |
| Flow | Up to 390 m³/h | Wide range — consult catalog |
| Head | Up to 220 m | Per model |
| Temperature | Up to 350°C | Heating jacket: steam 185°C/10bar · thermal oil 232°C/10bar |
| Relief valve | Optional | Integrated (overpressure protection) |
| Typical weight | Per model | 9 kg (GG1) to 272 kg (M4) |
| Standard | API 676 | API 676 |
Principle
FBE
External helical gears (driver + driven)
FBEI
Gear-within-gear (external rotor + internal gear)
Pulsation
FBE
Standard for PD (acceptable in most applications)
FBEI
Reduced — equidistant seal between teeth
Size range
FBE
DN 1/8" to 6"
FBEI
Models from 1" to 4" (GG, HJ, HL, KK, LQ, LS, M, AS, AK, AL)
Flow
FBE
Up to 390 m³/h
FBEI
Wide range — consult catalog
Head
FBE
Up to 220 m
FBEI
Per model
Temperature
FBE
Up to 350°C
FBEI
Heating jacket: steam 185°C/10bar · thermal oil 232°C/10bar
Relief valve
FBE
Optional
FBEI
Integrated (overpressure protection)
Typical weight
FBE
Per model
FBEI
9 kg (GG1) to 272 kg (M4)
Standard
FBE
API 676
FBEI
API 676
How to decide in practice
Start with pulsation. If the pump feeds dosing nozzles, sensitive filters or a fine control loop, the FBEI has a structural advantage: the gear-within-a-gear principle delivers smoother flow, with less vibration transmitted to the piping. For general transfer of viscous fluids — oils, resins, asphalt — the FBE covers a wider flow and temperature range (up to 350 °C) in a more compact footprint.
The second filter is the physical and thermal envelope. The FBE offers more construction variants, including a heating jacket for fluids that solidify when cold, and spans 1/8 in to 6 in. The FBEI covers 1 to 4 in sizes in three casing configurations, with dimensions documented in the technical manual — when the goal is standardizing the fleet on few configurations, that simplifies the spares inventory.
A technical tie is broken by the real operating point. Send engineering the viscosity at pumping temperature, the flow and the differential pressure of the circuit: sizing will show which of the two series runs with margin — not at its limit — for your application.
Frequent technical questions
Why choose FBEI over FBE if the principle is similar?
When the downstream process is pulsation-sensitive — precise chemical dosing, reactor injection, transfer to a metering system — internal gear reduces pulsation via the equidistant seal formed by teeth between suction and discharge. For simple industrial transfer, FBE is sufficient.
Does FBE reach higher temperatures than FBEI?
Yes. FBE operates up to 350°C fluid (with proper mechanical seal and specific materials). FBEI supports an external heating jacket for steam up to 185°C/10 bar or thermal fluid up to 232°C/10 bar — that is external heating, not the pumped fluid.
What is the FBEI installation alignment tolerance?
Per the FBEI manual: radial deviation under 0.05 mm and angular under 0.6°. Pumps leave the factory pre-aligned, but transport and handling typically misalign — re-alignment is mandatory after final-base installation.
Do both follow API 676?
Yes. Both FBE and FBEI are manufactured per API 676 (Positive Displacement Pumps, Rotary) — design, materials, inspection and test requirements.
Still undecided?
The FB application engineer reviews your process condition — fluid, temperature, flow, viscosity — and points to the right series.
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