For water-glycol fire-resistant hydraulic fluids, a viscosifier is essential to thicken the water-glycol blend and achieve the required viscosity and lubricity for hydraulic system operation — while maintaining fire resistance and thermal stability.
🧪 What a Viscosifier Does in Water-Glycol Fluids:
- Increases the kinematic viscosity (typically to ISO VG 32–46)
- Enhances film strength and lubrication
- Improves shear stability and pumpability
- Maintains compatibility with water, glycol, and anti-wear additives
✅ Preferred Viscosifiers for Water-Glycol Hydraulic Fluids:
| Viscosifier Type | Description | Performance Notes |
|---|---|---|
| Polyalkylene Glycol (PAG) | Water-soluble synthetic polymers | Excellent fire resistance, stable in aqueous systems |
| High molecular weight Polyethylene Glycol (PEG) | Used in combination with water/glycol base | Readily soluble, biodegradable |
| Water-soluble acrylic copolymers | Shear-stable, tailored thickening profile | May be used in more specialized fire-resistant blends |
| Cellulose ethers (e.g., HEC) | Occasionally used in legacy fluids | Less common due to poor shear stability and oxidation resistance |
🔥 Why Not Use Oil-Type Viscosity Modifiers?
Because this is a water-based system, traditional viscosity index improvers like OCP or PMA are not soluble and not compatible. You must use water-soluble polymers.
💧 Target Viscosity:
- Water-glycol fluids are usually formulated to ISO VG 32–46
- Typical base mix: ~35–45% water, ~35–50% glycol, ~10–15% viscosifier + additive package
🏭 Example Formulation Base (by weight):
| Component | Weight % |
|---|---|
| Deionized Water | 35–45% |
| Diethylene Glycol (DEG) or Triethylene Glycol (TEG) | 35–50% |
| PAG or PEG viscosifier | 10–15% |
| Additive Package (anti-wear, rust inhibitor, biocide, etc.) | 2–5% |
⚠️ Considerations When Choosing:
- Solubility in water-glycol
- Fire resistance compliance (e.g., HFC fluid ISO 6743/4 Type HFC)
- Biostability (microbial resistance)
- Thermal and oxidative stability
- Compatibility with system elastomers and metals
📌 Summary:
| Property | Good Viscosifier Should Provide |
|---|---|
| Water solubility | ✅ |
| Fire resistance | ✅ |
| Shear stability | ✅ |
| Lubricity aid | ✅ |
The best viscosifier for water glycol fire-retardant hydraulic fluid is polyurea. Polyurea is a synthetic polymer that is known to be superior in its fire retardant properties. It forms a surface layer that resists the penetration of flames, preventing the spread of fire in a hydraulic system. Polyurea is also an excellent choice because it provides excellent viscosity retention in extreme temperatures. In addition, it is a cost-effective solution that offers superior corrosion protection.
Polymer polyether KE products are copolymer of ethylene oxide and propylene oxide ,which is called PAG for short.
KE – 1 is mainly used in Water – ethylene glycol fire resistant hydraulic fluid,with excellent water-soluble, thickening, lubricating, antiwear and shearing properties,as well as good temperature resistance, fire resistance, and can provide good oil film strength, effectively protecting the hydraulic pump.
Chemical Formula: R(C2H4O)X(C3H6O)YH
It can be used for base oil which can blend water-based synthetic metalworking fluid,also widely used in steel, foundry, mines, etc area.
A Viscosifier is used to increase the viscosity of a fluid, making it thicker and more resistant to flow. In the case of water glycol fire-retardant hydraulic fluid, a viscosifier is used to enhance its lubricating properties, improve its ability to resist shear, and ensure that it functions effectively in high-pressure hydraulic systems.
One commonly used viscosifier for water glycol fire-retardant hydraulic fluid is a polymer called polyacrylate. Polyacrylate is a synthetic polymer that can be added to water glycol fluid to increase its viscosity and improve its lubricating properties.
Polyacrylate is particularly suitable for use in water glycol hydraulic fluids because it is compatible with water and glycol, and does not react with the fire-retardant additives present in the fluid. Additionally, polyacrylate is resistant to thermal degradation, providing consistent viscosity across a wide range of temperatures.
When polyacrylate is added to water glycol hydraulic fluid, it forms a stable, high-viscosity gel-like structure that helps to ensure efficient lubrication and minimize wear and tear on hydraulic system components. The viscosifier also provides increased film thickness, improving the fluid’s ability to separate moving parts and reduce friction.
Overall, the viscosifier enhances the performance and stability of water glycol fire-retardant hydraulic fluid, allowing it to effectively transmit power and withstand the demands of high-pressure hydraulic systems.