Gear Pump for Resins and Paints
Industrial production of paints, varnishes and polymer resins demands low-shear pumping, contamination-free operation and batch-to-batch volumetric precision. The FB Bombas FBE (external gear) and FBEI (internal gear) lines cover the full range — from low-viscosity liquid resins up to pigmented pastes above 50,000 SSU.
What pump to use for resins, paints and varnishes?
For transferring resins (epoxy, polyester, alkyd), industrial paints and varnishes, the ideal pump is the FBE external gear or FBEI internal gear — both operate at viscosity up to 100,000 SSU without shearing the product. FBEI offers lower pulsation for premium paints. Materials: cast iron, carbon steel or 316 stainless depending on corrosiveness.
Why is low shear important for resins?
Resins and paints are shear-sensitive fluids — high speed at centrifugal vane edges breaks molecular chains, separates pigments, generates foam and changes final product viscosity. Gear pumps operate at low rotation (300-1,150 rpm) with laminar flow, preserving product integrity. The FBEI has even lower shear.
Does the FBE/FBEI handle high-viscosity resins?
Yes. For resins up to 10,000 SSU, FBE 1/2" to 3" runs at direct 1,150 rpm. Above 10,000 SSU (cured resins, heavy polymers), rotation drops to 300-700 rpm via reducer or pulley, and the internal FBEI becomes preferred for ultra-viscosity performance. Total range: up to 100,000 SSU.
Resin and paint classes: rheological profile
Industrial resins and paints are highly heterogeneous in rheological behavior. Unfilled epoxy resins have viscosity between 800 and 15,000 cP at 25 °C — Newtonian at low temperature, with exponential reduction when heated for cure. Unsaturated polyester resins range from 200 to 2,000 cP and are sensitive to prolonged shear, which can trigger premature polymerization. Alkyd resins, the classic base of varnishes and industrial paints, sit between 1,500 and 25,000 cP depending on drying degree. Finished industrial paints (synthetic enamels, modified alkyds, two-component epoxies, PUs) typically operate between 1,000 and 8,000 cP but contain suspended pigments that behave as non-Newtonian fluids: apparent viscosity decreases with increasing shear rate (thixotropic behavior). Wood and metal varnishes have lower viscosity (300-1,500 cP) but many contain flammable solvents, requiring anti-spark casing material and special sealing. Concentrated pigments (master-batches) and pastes used in color dispersion reach 50,000 cP — a range where only gear pumps are viable. Centrifugals fail from hydraulic infeasibility, piston pumps produce unacceptable pulsation in filling lines, and lobe pumps have precision limitations at low flow.
Why low shear is critical in resins
Polymer resins are long molecular chains, often with molecular weights above 10,000 Da, and finished-product performance depends on chain integrity. A pump operating at high shear (rates above 10,000 s⁻¹) can mechanically break the polymer chains, reducing average molecular weight and compromising properties such as gel time, post-cure mechanical strength, final paint gloss and storage stability. The FBE external gear pump typically operates at shear rates between 500 and 3,000 s⁻¹ — within the safe envelope for most commercial resins. For sensitive formulations (high-MW unsaturated polyester, functionalized epoxy, pure PU), the FBEI internal gear line reduces shear to 200-1,200 s⁻¹ thanks to the multi-chamber continuous geometry with no single-point meshing region. The FBEI's second advantage in this application is very low discharge pulsation — typically below 5% of mean value versus 15-25% in external gear. In automated dispersion lines, precision filling and catalyst dosing, this is often the decisive criterion. Volumetric efficiency reaches 90-97% at sustained viscosity above 500 cP.
Construction materials by resin family
Alkyd resins, unmodified epoxies and conventional synthetic paints are compatible with cast iron ASTM A48 CL30 and carbon steel ASTM A216 WCB — standard FBE configuration with average 7-10 year service life. Unsaturated polyester resins with styrene can attack iron over time (formation of ferrous complexes that alter color), so carbon steel or stainless is preferable depending on customer specification. Functionalized epoxy, acrylic acid, pure PUs (isocyanate pre-polymers) and water-based pigments require AISI 316 stainless casing (ASTM A743 CF8M). Free isocyanate is particularly aggressive to iron and produces localized corrosion points that contaminate the batch. Water-based paints (acrylic emulsions, latex) also require stainless because ferrous oxides may contaminate color. For resins containing flammable solvents (xylene, toluene, acetone, MEK), correct specification includes anti-spark coupling guard (bronze or aluminum), magnetic-coupling sealing (zero leakage) and ATEX Zone 1 or 2 certification per the plant zoning. FBE and FBEI are supplied in ATEX configuration per factory specification.
- Alkyd and synthetic paints — cast iron / carbon steel
- Unsaturated polyester with styrene — carbon steel or 316 stainless
- Functionalized epoxy and acrylic acid — 316 stainless mandatory
- Isocyanates and PU pre-polymers — 316 stainless + special seal
- Water-based paints (acrylic, latex) — 316 stainless to preserve color
- Flammable solvents (xylene, MEK) — ATEX + anti-spark
- Concentrated pigments (master-batch) — FBEI + enlarged clearances
CIP cleaning, color change and short batch
Paint factories often work in short-batch regime (500 to 5,000 liters) with fast color changes — a line can process 8 to 15 different colors per shift. In this scenario, correct pump configuration matters as much as the technology itself. The FBE with inspection cover facilitates manual cleaning between batches, with typical color-change time of 15 to 45 minutes. For automated lines with CIP (Clean-in-Place), FBE or FBEI in AISI 316 stainless with interior finish Ra ≤ 0.8 µm allows chemical cleaning without disassembly. The standard CIP cycle involves solvent circulation (xylene, butyl acetate or alcohol per the resin), followed by rinsing with the next color's solvent and final purge. Pumps with large internal reservoirs or textured surfaces retain residue and contaminate the next batch — the reason why FBEI with continuous-chamber geometry has operational advantage. On high-rotation lines (cosmetics, automotive varnishes, custom colors), it is common to specify a dedicated pump per color or per resin family to eliminate cleaning time. FB Bombas supplies compact FBE 1/2" to 1" assemblies in single-unit configuration, facilitating this plant architecture.
FB Bombas in the Brazilian paints and resins industry
FB Bombas has served the main Brazilian manufacturers of industrial paints, varnishes and polymer resins since the 1970s-1980s. FBE and FBEI lines are installed in paint factories for construction, automotive, marine, anticorrosive for oil & gas and industrial for structural steel — in configurations ranging from compact 1/2" assemblies for pigment dosing to 4" units for bulk resin transfer between tanks. The real technical differentiator in this market is the combination of two factors: local availability of parts (gears, seals, shafts) manufactured in Cabreúva, Brazil, and the possibility of custom specification for reactive applications (PU, two-component epoxy, acrylic acid) that imported manufacturers (Viking, Maag, Hidex) serve only with 6 to 9 month lead time. FB delivers the same specification in 25 to 40 calendar days. For replacement of end-of-life imported pumps, FB's application engineering provides dimensional analysis of the current pump, equivalent FBE/FBEI specification and base-adaptation design within 72 hours. Direct technical contact (+55 11 4898-9200) connects the buyer with the responsible engineer, via FB engineering in Cabreúva-SP.
Frequently Asked Questions
Which pump should I use for two-component liquid epoxy resin?
For component A (epoxy base) and component B (amine hardener) at viscosities between 500 and 5,000 cP, FBEI in AISI 316 stainless is the correct choice — low shear preserves reactive functionalities, low pulsation allows precise dosing, and stainless prevents ferrous-ion contamination that could catalyze premature polymerization. For real-time mixing lines, one dedicated FBEI per component ensures exact volumetric ratio.
Do gear pumps degrade the resin polymer?
In correct operation, no. The FBE typically operates at shear rates between 500 and 3,000 s⁻¹, a safe range for commercial resins (alkyd, conventional epoxy, saturated polyester). For sensitive formulations (high-MW unsaturated polyester, pure PU, special acrylic), the FBEI reduces shear to 200-1,200 s⁻¹. Polymer degradation occurs when the pump is undersized, forced beyond the maximum rotation in manual Table 2 or operated above design pressure.
Can I pump paint with pigment without clogging the pump?
Yes, as long as the pigment is properly dispersed and particle size is below 100 microns. FBE handles pre-dispersed pigments in finished paints; for concentrated pastes (>30% pigment) or high-load master-batches, FBEI with enlarged clearances is preferable. In all cases, a suction filter sized to prevent agglomerate or settled-particle ingress is recommended.
Does the FBE work for water-based paint (latex)?
Yes, but requires AISI 316 stainless specification. Water-based paints contain acrylic or vinyl emulsions with neutral to slightly alkaline pH, compatible with 316 stainless. Cast-iron or carbon-steel casing would generate oxides that alter product color — especially in light shades. Standard sealing is type 21 mechanical seal with EPDM elastomer (water-resistant).
How to specify a pump for varnish filling lines with flammable solvent?
The correct specification includes four elements: AISI 316 stainless or hardened carbon casing; magnetic-coupling sealing (zero leakage) or double mechanical seal with nitrogen purge; anti-spark coupling guard (bronze or aluminum); ATEX Zone 1 or 2 certification per plant zoning. Electric motor must be Ex-proof compatible with atmospheric gas (IIA, IIB or IIC) and solvent ignition temperature.
What is the average CIP cleaning time between color changes?
For standard FBE in carbon steel: 30 to 60 minutes, depending on contamination degree and solvent compatibility. For FBEI in 316 stainless with Ra ≤ 0.8 µm finish: 15 to 35 minutes, reducing dead time by up to 50%. For high-rotation lines (cosmetics, custom varnishes), common practice is a dedicated pump per color, fully eliminating the cleaning cycle.
Can FB Bombas replace a Viking or Maag in a paint factory?
Yes. FBE and FBEI have direct dimensional compatibility with Viking, Maag, Hidex and RZR in DN 1/2" to 4". Send the nameplate, process data (resin, viscosity, temperature, flow, pressure) and current base design to comercial@fbbombas.com.br — application engineering returns an equivalent FBE/FBEI specification within 72 hours, with typical 25-40 day lead time versus 6-9 months for direct import.
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