Automotive Lift Repair Tampa Florida Hydraulic reservoirs are essential for storing the fluid needed to operate hydraulic systems. Familiarizing yourself with the various types and understanding how to select the appropriate reservoir for a specific application will help ensure the optimal performance of hydraulic components and systems.
In addition to holding enough fluid to meet the system’s fluctuating demands, hydraulic reservoirs also offer:
– A large surface area to facilitate heat transfer from the fluid to the surrounding environment.
– Sufficient volume to allow returning fluid to decelerate from high velocities, enabling heavier contaminants to settle and allowing entrained air to escape.
– An air space above the fluid to accommodate air that bubbles out.
– Access for removing used fluid and contaminants from the system and adding new fluid.
– A convenient mounting surface for other system components when feasible.
While these functions are traditional, emerging trends may deviate from the norm. For example, modern hydraulic system designs often require significantly smaller reservoirs compared to conventional guidelines. Since most systems require special consideration, it’s crucial to consult industry standards for minimum guidelines. The Recommended Practice ANSI/(NFPA)/T3.16.2 outlines essential minimum design and construction features for reservoirs.
Sizing a Hydraulic Reservoir
The first consideration in sizing an Automotive Lift Repair Tampa Florida hydraulic reservoir is determining its volume. A common rule of thumb states that the reservoir’s volume should be three times the rated output of the system’s fixed-displacement pump or the mean flow rate of its variable-displacement pump. For instance, a system with a 5-gpm pump should have a 15-gal. reservoir. It’s important to note that this is merely a guideline for initial sizing. The National Fluid Power Association (NFPA) states, “Previously, three times the pump capacity had been recommended.
Regardless of whether you follow the traditional guideline or the trend towards smaller reservoirs, be mindful of factors that could impact the required reservoir size. For example, large circuit components like accumulators or cylinders may necessitate a larger hydraulic reservoir to ensure the fluid level remains above the pump inlet, irrespective of pump flow.
High ambient temperatures can also require larger reservoirs unless a heat exchanger is used. Consider the substantial heat generated within an Automotive Lift Repair Tampa Florida hydraulic system, which occurs when the system produces more power than the load consumes. A common scenario is when the system operates for extended periods with pressurized fluid flowing over a relief valve.
Thus, reservoir size is often primarily determined by the highest fluid temperature and the highest ambient temperature. The smaller the temperature difference, the larger the surface area (and thus volume) needed to dissipate heat from the fluid to the environment. If ambient temperature exceeds fluid temperature, a water-cooled or remote-mounted heat exchanger will be necessary to cool the fluid.
For applications where space is at a premium, heat exchangers can significantly reduce the required size (and cost) of hydraulic reservoirs. Remember, the reservoir may not always be full, which means it may not dissipate heat through its entire surface area.
The Automotive Lift Repair Tampa Florida reservoir should have an additional space equal to at least 10% of its fluid capacity. This extra space accommodates thermal expansion of the fluid and gravity drain-back during shutdown while still providing a free fluid surface for deaeration. According to NFPA/T3.16.2, the maximum fluid capacity of the reservoir must be permanently marked on its top plate.
Advantages and Disadvantages of Smaller Hydraulic Reservoirs
There is a growing trend to specify smaller hydraulic reservoirs for economic benefits. Smaller reservoirs are lighter, more compact, and less costly to manufacture and maintain than their traditional counterparts. Additionally, they reduce the total volume of fluid that can leak from a system, which is environmentally beneficial.
However, specifying a smaller reservoir requires modifications to compensate for the reduced fluid volume. For instance, since a smaller reservoir has less surface area for heat transfer, a heat exchanger may be needed to keep fluid temperatures within acceptable limits. Moreover, contaminants have less opportunity to settle, necessitating high-capacity filters to capture particles that would otherwise settle in the reservoir sump.
One of the most significant challenges of smaller reservoirs is the removal of air from the fluid. Traditional reservoirs allow air to escape before the fluid is drawn into the pump inlet. A smaller reservoir may lead to aerated fluid being drawn into the pump, potentially causing cavitation and subsequent damage or failure.
To mitigate this issue, consider installing a flow diffuser that reduces the velocity of return fluid (typically to 1 ft./sec.), helping to prevent foaming, agitation, and potential pump cavitation from flow disturbances at the inlet. Another option is to use an angled screen in the reservoir to collect small bubbles, allowing them to combine and rise to the surface more easily.
Preventing aerated fluid from entering the pump is best achieved by carefully considering fluid flow paths, velocities, and pressures during hydraulic system design.
Exploring Reservoir Design Configurations
Automotive Lift Repair Tampa Florida Hydraulic reservoirs come in various design configurations. Rectangular reservoirs are common, typically featuring a hydraulic power unit with a pump, electric motor, and other components mounted on top. Consequently, the top of the reservoir must be structurally robust to support these components, maintain alignment, and minimize vibration. An auxiliary plate may be mounted on top for additional support. A significant advantage of this configuration is easy access to the pump, motor, and accessories.
A current Automotive Lift Repair Tampa Florida design trend involves vertically mounting the electric motor, with the pump submerged in hydraulic fluid. This design conserves space, as the reservoir can be deeper and occupy less floor space than traditional “bathtub” models. Additionally, this submerged-pump design eliminates external pump leakage, as any fluid leaks directly into the reservoir. Moreover, it dampens noise since the hydraulic fluid absorbs much of the pump noise.
An alternative configuration places the Automotive Lift Repair Tampa Florida hydraulic reservoir above the pump and motor, which combines atmospheric pressure and the weight of the fluid column to help flood the pump inlet, reducing the risk of cavitation. The reservoir’s top cover can be removed for servicing internal components without disturbing the pump and motor.