While water hydraulics have mainly been applied in industrial and marine contexts, they can also be effectively used in mobile equipment by adding antifreeze to the water. Using propylene glycol, which lowers the freezing point without compromising environmental safety, is an alternative. An example of this is a refuse collection truck that employs water as the main hydraulic fluid.
The cost advantages of Automotive Lift Repair Orlando water-based hydraulic fluids extend beyond the lower price of the fluid and its disposal. Since water-based fluids consist of 10 parts water to one part synthetic additive, mixing 5 gallons of additive with water yields 100 gallons of water-based fluid. This is significantly easier to store than two 55-gallon drums, leading to cleaner and more organized warehousing and reduced transportation costs.
Additional potential savings include enhanced worker safety, as water-based fluids are non-toxic and non-flammable. These characteristics can also lead to lower insurance rates for plants, and clean-up costs are reduced since granular absorbents or absorbent socks are not needed.
However, to prevent freezing in water-based fluids, antifreeze is necessary, but care must be taken in the choice of substance. While ethylene glycol, commonly used in automotive antifreeze, is toxic and non-biodegradable, propylene glycol offers a safer alternative, albeit at a higher cost and requiring slightly greater concentrations to achieve the same freezing point depression.
To mitigate freezing risks, keeping the fluid in constant circulation and using hoses, which provide better insulation than metal tubing, are effective strategies.
System Sealing
Two common concerns with Automotive Lift Repair Orlando water hydraulic systems are bacterial growth and maintaining proper additive concentrations. Sealing the system from atmospheric exposure helps control bacterial growth. Adding an antibacterial agent can further prevent bacterial buildup when air is excluded. Sealing also keeps out airborne contaminants, which often lead to component failure.
A sealed reservoir addresses another issue found in many hydraulic systems: water ingress. While dissolved suspended water contaminates hydraulic oil, in a water-based system, the main concern is the alteration of additive concentration. Water ingress is still undesirable, but its impact is less severe than in oil-based systems.
There is a misconception that water-based systems need constant monitoring to maintain additive concentration. Water evaporates from the reservoir more quickly than additives do, leading to increased concentration levels. Therefore, when new fluid is added, samples of the existing fluid should be analyzed to determine how much additive is needed to restore the correct balance.
In a sealed system, the evaporation issue is nearly eliminated. Any fluid lost through leakage is a mixture of water and additive, maintaining concentration levels. To replenish the system, a pre-mixed solution of water and additive can simply be added to the reservoir.
Special Considerations
Automotive Lift Repair Orlando Water hydraulic systems boast a high power-to-weight ratio and cleanliness, making them ideal for applications like rib-cutting saws in meat processing plants. These saws, powered by water hydraulics, are lightweight and easy to maneuver, enhancing ergonomics and productivity. In contrast, pneumatic or electromechanical drives would be bulkier and less practical.
However, if not properly designed, water-based hydraulic systems can be more susceptible to pump cavitation. To prevent this, it is important to ensure adequate porting and passageways to maintain fluid velocities below 20 ft/sec—ideally under 15 ft/sec in pressure lines, 2 to 3 ft/sec in suction lines, and below 5 to 10 ft/sec in return lines. Higher return velocities can cause foaming when the fluid re-enters the reservoir. Additionally, components should be appropriately sized to avoid rapid pressure and velocity changes, which can cause dissolved air to precipitate and result in cavitation-like damage.
Another key consideration is that major Automotive Lift Repair Orlando components should be specifically designed for use with water-based fluids, rather than retrofitted from oil-compatible versions. While tubing, hoses, and fittings can typically match those used in oil systems, pumps, valves, and actuators for water applications have notable differences.
Valves for Water-Based Systems
Valves designed for water-based fluids often feature seals that separate metal parts to prevent direct contact, as water does not provide the same full-film lubrication as oil. In oil valves, lapped spools can be employed because oil creates a lubricating film. In contrast, metal surfaces in motion in water-based valves are separated by bearing-type materials, as water’s lower viscosity allows it to leak through the clearances found in non-packed oil service valves.
Automotive Lift Repair Orlando Water service valves are generally larger than their oil counterparts, which has hindered the broader adoption of water hydraulics. However, improvements in valve sizing and reductions in price—now only about 3% higher than oil valves—make them more appealing, especially considering the potential cost savings associated with water-based systems.
Automotive Lift Repair Orlando Cartridge valves fitted into cast iron bodies and lapped-spool interchangeable cartridges are also available. For proportional control, special materials replace seals to prevent stick-slip operation.
The spool in a valve for oil service can move directly within the valve body, whereas proportional valves for water-based systems often use a spool that operates within a cast sleeve, which is softer and thus more prone to wear. Both components are hardened to reduce wear rates, and valves for water fluids have longer lands to minimize leakage.
Addressing Fluid Leakage
Fluid leakage remains a persistent challenge in many hydraulic systems. New seal materials, designs, and O-ring face-seal fittings have been developed to combat this issue, but it still occurs due to misapplication, improper installation, or a lack of understanding. Even though leakage is often unacceptable, it is more manageable in systems using water-based fluids.
Internal leakage can be equally wasteful. Lapped-spool valves are designed to allow some leakage to create the necessary oil film for lubricating moving parts, but this can lead to carburization of the oil from heat generation. Typically, internal leakage is directed back to the tank, transforming mechanical energy into heat rather than useful work. Using stainless steel spools with PTFE seals in water-based valves eliminates the need for clearance, which in turn removes internal leakage.
Automotive Lift Repair Orlando Packed-spool valves can also reduce leakage and eliminate the necessity for pilot-operated check valves. When a valve centers in an all-ports-blocked condition, there’s no port-to-port leakage, preventing cylinder drift.
Beyond the immediate costs associated with fluid leakage, the disposal of leaked fluid can become problematic. Discharging hydraulic oil into plant effluent systems incurs significant removal and disposal costs. As cleanup and disposal expenses rise and oil prices fluctuate, water-based hydraulics present a viable solution to environmental challenges.