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 — Direct 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.
FBE
External gear · wide range
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"
FBEI
Internal gear · reduced pulsation
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
| — | 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 3rd edition | API 676 3rd edition |
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) 3rd edition — design, materials, inspection and test requirements.
Still unsure?
FB's application engineer evaluates your process conditions — fluid, temperature, flow, viscosity — and points to the right series.
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