Which FB pump to use — decision by fluid and condition
Four families, four decisions. Start with fluid, cross through temperature and end on flow. Each answer links directly to the matching series.
TL;DR — Straight answer
If the fluid is organic thermal oil up to 350°C → FBOT. If it's clean or turbid process liquid up to 260°C → FBCN. If it's viscous fluid (oil, asphalt, viscous chemical) with acceptable standard pulsation → FBE. If the same application requires reduced pulsation → FBEI.
Option A
Criterion 1: fluid
The first filter is always the fluid
When to use
- Water / liquid process → centrifugal
- Thermal oil → FBOT (dedicated)
- Oil, asphalt, viscous fluids → gear (FBE or FBEI)
- Corrosive viscous chemical → gear with magnetic coupling
Option B
Criterion 2: temperature + flow
Second filter tunes the series within the family
When to use
- Up to 260°C + any flow → FBCN
- 260°C to 350°C + thermal oil → FBOT
- Up to 350°C + viscous → FBE
- Up to 232°C with external jacket + low pulsation → FBEI
Quick selection by fluid
| Criterion | Criterion 1: fluid | Criterion 2: temperature + flow |
|---|---|---|
| Clean or turbid water up to 260°C | FBCN (standardized centrifugal) | Flow up to 2,200 m³/h · head up to 135 m |
| Organic thermal oil up to 350°C | FBOT (dedicated to thermal oil) | Mandatory dual sealing · no abrasives |
| Viscous oil or asphalt | FBE (external gear) | 30 to 100,000 SSU · up to 350°C · up to 390 m³/h |
| Process with pulsation-critical downstream | FBEI (internal gear) | Absolute volume control · integrated relief valve |
| Fire protection (NFPA 20 / NBR 10897) | Fire skid (FBCN + jockey + diesel) | Pre-assembled system with automatic panel |
| Application outside the grid | Custom (engineered solutions) | Engineering on demand |
Clean or turbid water up to 260°C
Criterion 1: fluid
FBCN (standardized centrifugal)
Criterion 2: temperature + flow
Flow up to 2,200 m³/h · head up to 135 m
Organic thermal oil up to 350°C
Criterion 1: fluid
FBOT (dedicated to thermal oil)
Criterion 2: temperature + flow
Mandatory dual sealing · no abrasives
Viscous oil or asphalt
Criterion 1: fluid
FBE (external gear)
Criterion 2: temperature + flow
30 to 100,000 SSU · up to 350°C · up to 390 m³/h
Process with pulsation-critical downstream
Criterion 1: fluid
FBEI (internal gear)
Criterion 2: temperature + flow
Absolute volume control · integrated relief valve
Fire protection (NFPA 20 / NBR 10897)
Criterion 1: fluid
Fire skid (FBCN + jockey + diesel)
Criterion 2: temperature + flow
Pre-assembled system with automatic panel
Application outside the grid
Criterion 1: fluid
Custom (engineered solutions)
Criterion 2: temperature + flow
Engineering on demand
The method: three questions, in this order
First question: what is the fluid and what is its viscosity at the real pumping temperature? That single answer already splits the catalog in half — above 500 SSU the path is positive displacement (FBE/FBEI); below 100 SSU, centrifugal (FBCN). The 40 °C catalog viscosity misleads: the same oil can be ten times more viscous on a cold winter start.
Second question: what is the continuous operating temperature? Up to 260 °C, the FBCN serves with proper sealing. From 260 to 350 °C, the service defines the series — organic thermal oil calls for FBOT; hot viscous fluids call for FBE with a heating jacket. Third question: circuit flow and pressure, which position the model within the series and show whether the pump runs near its best efficiency point.
Before requesting a quote, assemble the minimum data sheet: fluid, viscosity at pumping temperature, operating temperature, flow, differential pressure (or head), available NPSH and materials required by the process. With these seven data points, engineering sizes the pump in a single iteration — without them, every quote is a guess with margin.
How to decide without doubt
What if the application fits two possible series?
Classic case: viscous process fluid up to 260°C. Could be FBE (positive displacement) or FBCN (centrifugal). The decisive factor is usually specific viscosity: above ~200 SSU the centrifugal loses efficiency and FBE PD wins. Below that, FBCN with proper materials resolves at lower cost.
How to choose between FBE and FBEI?
Both are PD gear pumps. FBE (external) offers a wider size range (1/8" to 6") and temperature (350°C). FBEI (internal) offers reduced pulsation. If the downstream process accepts standard pulsation, FBE. If it requires smooth transfer (precise dosing, reactor injection, volumetric metering), FBEI.
What if I don't know the exact fluid viscosity?
Send what you know — trade name, operating temperature, origin (refinery? process?) — and the application engineer helps estimate. FB manuals have selection tables by viscosity in SSU. For known commercial fluids (Mobiltherm, Therminol, Chevron oils, CAP asphalt), selection is direct.
Can I use the same pump for two different fluids?
Only if both fall within the pump's operating window (temperature, viscosity, chemical compatibility). For two separate applications, two dedicated pumps are usually better — swapping sealing materials due to inter-process leakage typically costs more than an extra pump.
Still undecided?
The FB application engineer reviews your process condition — fluid, temperature, flow, viscosity — and points to the right series.
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