Dynex pumps are known for their high-pressure capabilities and unique design features, especially their piston pumps that can handle a wide range of fluids, including those beyond standard hydraulic oil. These pumps are particularly noted for using metal-to-metal sealing (rather than relying heavily on elastomeric seals), which gives them an advantage in handling aggressive, low-viscosity, or low-lubricity fluids.
Dynex Pumps & Alternative Fluids:
- Type: Fixed and variable displacement checkball piston pumps
- Fluids Supported:
- Water-glycol
- Skydrol (phosphate esters – aerospace)
- Solvent-based fluids
- Low-lubricity fluids (including some synthetic esters).
- Why they work: Their checkball piston design avoids shear on seals and can function in harsh chemical or low-viscosity environments.
- Applications:
- Wellhead control systems
- Synchronous lifting systems
- Drill rigs
- Test stands
- Industrial presses
- High pressure lubrication systems
- Rock crusher control systems
- Hydraulic power units
Dynex Design Features That Support Alternative Fluids:
- All-metal internal components: Limits chemical degradation.
- Minimal elastomer use: Reduces incompatibility risks with fluids like Skydrol or synthetic blends.
- High-viscosity tolerance: Some models can be adapted for thick fluids or unusual fluid profiles.
- Seal Options: Dynex offers Viton, EPDM, PTFE, and other seal materials to match the fluid’s chemical profile.
Recommendations Before Use:
– Always refer to the Material Safety Data Sheet (MSDS) of the intended fluid and the Dynex Pump Operating Manual to assess suitability.
– When evaluating a fluid for suitability, you will need to consider the following compatibility factors: (see below for more information)
- Viscosity
- Lubricity
- Temperature
- Material Compatibility
- Seal Compatibility
- Load Pressure
– Ensure that you have the appropriate seal kit and fluid-compatible materials
Understanding Fluid Compatibility Factors:
Viscosity
This is defined as a resistance to flow, also known as drag. The lower the viscosity, the more likely the pump will have internal leakage and reduce its volumetric efficiency. The optimum range for most Dynex pumps is between 20-70 cSt. or Centistokes, except for the PF1300 and PF4300 products, as they are designed to operate on much thinner fluids.
Lubricity
All pump components that are in contact and under load during operation will experience wear. The rate of wear and life expectancy of the component parts is affected by lubrication between those components. Dynex pumps are unique because they are a single fluid design—the fluid being pumped also provides lubricity between components. Lubricity is generally related to viscosity, but two fluids with same viscosity can have different lubricity characteristics.
Temperature
Temperature can have a major impact on viscosity. Some fluids get exponentially thinner as the temperature increases, while others stabilise at certain temperature points. It is important to take into consideration what the operating temperature of the fluid is.
Material Compatibility
Depending on the fluid, there is a chance that it may react with the materials that a pump is constructed from. An example is water glycol fluids and their reaction with aluminium and other alloys, as compared to steel and stainless steel alloys. In addition to the material compatibility of the product, it is important to evaluate the compatibility with any surface finishing treatment, including paint or coatings, that could react.
Seal Compatibility
It is important to understand the fluid’s ability to work with the elastomers in the product, such as in o-rings, backup rings, and any dynamic seals (shaft seal, etc.). Fluid data sheets typically provide information on which elastomer compounds are good, fair, or not recommended.
Load Pressure for Pump
Load pressure affects not only how components of the pump are stressed, but also affects internal fluid leakage. As load pressure increases so does internal leakage. Viscosity has an impact on this. When reviewing viscosity, it is important to understand what the load pressure at the outlet of the pump will be.
In addition to these main areas of focus, you should understand the duty cycle of the application. You should also be aware of any safety or hazardous information that could affect the work environment or any operators. This is usually found on the MSDS associated with each specific fluid.
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