Yes, the silicone oil commonly used for heating in temperature control units (TCU) is dimethyl silicone oil (polydimethylsiloxane, PDMS). The commonly used viscosities are 50cSt, 100cSt, 350cSt, or 500cSt (kinematic viscosity at 25℃).
Why Dimethyl Silicone Oil?
Dimethyl silicone oil (polydimethylsiloxane) is the most widely used heat transfer medium in temperature control units for the following reasons:
- Excellent thermal stability: It can work stably for a long time in the range of -50℃ to +200℃, and up to 315℃ in closed systems.
- Low volatility: It produces minimal smoke at high temperatures, ensuring high safety.
- Chemical stability: It barely reacts with acids or alkalis, leading to a long service life.
- Good fluidity: It maintains low viscosity even at low temperatures, guaranteeing circulation efficiency.
- Superior thermal conductivity: It can transfer heat quickly and evenly.
Viscosity Selection Guide
The recommended viscosities of dimethyl silicone oil for temperature control units depend on the application temperature range:
| Viscosity (cSt@25℃) | Applicable Temperature Range | Features |
|---|---|---|
| 50cSt | Within 200℃ | Low viscosity, good fluidity, suitable for general heating. |
| 100cSt | Widely applicable | Standard viscosity, excellent comprehensive performance, most commonly used. |
| 350cSt | High-temperature applications | Higher viscosity, suitable for stable heat transfer above 200℃. |
| 500cSt | High-temperature stability | High viscosity, suitable for occasions requiring oil film strength retention. |
Selection Recommendations
- Routine laboratory/industrial applications: Prioritize 100cSt for a balance of fluidity and thermal stability.
- High-temperature applications (>180℃): Recommend 350cSt or 500cSt to reduce volatilization loss.
- Low-temperature environments: If frequent cooling to below room temperature is required, consider 50cSt for better low-temperature fluidity.
Notes
- The viscosity value refers to the kinematic viscosity at 25℃ (unit: cSt, centistoke). Viscosity decreases significantly as temperature rises.
- Product performance varies by manufacturer. Choose regular brands and confirm technical parameters.
- Avoid mixing impurities during use. Check oil quality regularly and replace if necessary to maintain optimal performance.
Summary: The silicone oil used for heating in temperature control units is mainly dimethyl silicone oil. The most commonly used viscosity is 100cSt. For high-temperature applications, 350cSt or 500cSt is optional, and 50cSt is suitable for low-temperature environments.
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