- For circuits requiring pressure resistance, flange tightening, and main sealing of pipe joints → Select FVMQ fluorosilicone (O-ring / gasket / molded part); if it is E85 high-alcohol gasoline or strong chemical media, priority should be given to evaluating FKM fluororubber
- For internal parts of oil circuit sensors, PCB / pins, and tiny gaps, only perform oil-gas isolation + stress buffering, without bearing fluid pressure → Fluorosilicone gel
| Fluorosilicone (FVMQ) Sealants | Excellent broad thermal range paired with fuel/oil resistance | Engine oil sensors, turbocharger air-intake lines, fuel sender seals | High raw material cost; not suited for primary structural load-bearing frame bonds. |
| Fluoroelastomer (FKM) Sealants | Highest resistance to hot synthetic oils, diesel fuel, and temperatures to 220°C | Transmission sumps, turbocharger flanges, heavy-duty engine valve covers | Reduced elasticity at extreme sub-zero temperatures (-20°C and below). |
| Two-Part Structural Epoxies / MMA | Rapid strength buildup, excellent shear strength, bonds oily metal | Quick-assembly chassis brackets, emergency hydraulic tank repair | Brittle under severe continuous shock impact if un-toughened; short working life. |
| project | Fluorosilicone rubber FVMQ | Fluosilicone gel |
| Post-curing morphology | Elastic rubber, Shore A 20–80 | Soft gel, Shore 00 – jelly-like texture |
| Gluing method | Molded precast components / RTV sealant | Liquid dispensing, vacuum sealing |
| Sealing and Positioning | Primary pressure-bearing static sealing components (O-ring / gasket / diaphragm) | Auxiliary potting, oil and gas protection, and micro-gap filling (non-pressure-bearing) |
| mechanics | Excellent tensile, tear, and compressive rebound performance; capable of withstanding flange clamping forces. | Extremely low strength and low stress; unable to withstand compressive loads. |
| Oil circuit typical locations | Fuel joint O-ring, fuel tank flange gasket, fuel pump diaphragm | Potting of the internal chip and the oil circuit connector pins of the fuel tank sensor |
| Fuel-resistant | Good; swelling: 10–25% | Similar to FVMQ – resistant to oil and gas, suitable for immersion use. |
| Key Trade-offs | Wide operating temperature range + fuel resistance; features structural sealing capability | Oil-resistant + extremely low stress – protects precision electronics; not designed for pressure-bearing applications. |
Comparison of fluorosilicone gel with similar products on the market
| brand | JOME | WACKER | Shin-Etsu | |||
| model | JOMS1800 | JOMS 3200 | JOMS 3200C | 927F | FE-73 | FE-78 |
| Single/doublecomponent | Two (1:1) | one | one | one | one | Two (1:1) |
| surface | Colorless andtransparent | Colorless and transparent | Colorless and translucent | Colorless and turbid | Colorless andtransparent | Colorless andtransparent |
| Mixed viscositymPa• s | 750 | 550 | 2200（ RI： 2.1） | 2500（ RI： 2.4） | 2000 | 700 |
| condition of cure | 25℃*24h | 150℃*30min | 150℃*30min | 150℃*30min | 125℃*2h | 100℃*2h |
| Penetration1/10mm | 30 | 50 | 50 | 50 | 65 | 65 |
| condition ofstorage | 5-30℃ | 2-8℃ | 2-8℃ | 2-8℃ | -10-10℃ | 5-30℃ |
Performance comparison of single-component fluorosilicone sealant
| brand | JOME | A research institute | DOWSIL | |||
| model | JOMS 2122 | JOMS 2123 | JOMS 2125 | 730FS | Q4-2817 | |
| Solidification type | Alcohol type | Alcohol type | Alcohol type | Ketoamine type | Acetic acid type | Acetic acid type |
| surface | White flows | White flows | White paste | White paste | White paste | Red paste |
| dynamic viscosity Pa•s | 7-10 | 20-30 | NA | NA | NA | NA |
| Table dry time min | 20 | 20 | 10 | 15 | 14 | 11 |
| hardness HA | 20 | 20 | 35 | 30 | 40 | 43 |
| tensile strength MPa | 1.0 | 1.5 | 2.6 | 2.1 | 3.0 | 4.5 |
| elongation at break % | 200 | 400 | 485 | 300 | 200 | 375 |
Oil (solvent) resistance test of fluorosilicone sealant
The change rate of hardness/volume/mass of JOMS2125 in solvent at 25℃*7d
| hardness change % | specific volumetric dilatation % | Quality gain rate% | |
| carbinol | -1 | 1.8 | 2.2 |
| glycol | -2 | 2.6 | 3.6 |
| isopropanol | -3 | 2.2 | 3.8 |
| diesel oil | -5 | 1.6 | 2.9 |
Test results of aging in 150℃ oil for 1000h
| JOMS2122 | JOMS2123 | JOMS2125 | ||||||||
| initial | After aging | change rate | initial | After aging | change rate | initial | After aging | change rate | ||
| hardness （ HA） | 201.02000.40.6 | 12.60.681250.150.33 | -37%-31.5%-37.8%-64%-45.5% | 201.54000.91.1 | 12.21.01450.420.68 | -39%-33.6%-63.8%-54%-38.2% | 352.64851.41.7 | 241.72640.71.1 | -31%-34.6%-57.4%-50%-35.3% | |
| Tensile strength (MPa) | ||||||||||
| elongation at break （%） | ||||||||||
| Shear strength(MPa) | PPS-PPS | |||||||||
| Al-Al | ||||||||||