Hydraulic oil contaminants encompass any substance that disrupts the fluid’s proper function. Air, falling under this classification, necessitates corrective measures when it becomes entrapped in the oil to avert damage to both the oil and other Car Lift Repair Tampa Florida hydraulic system components.

Air manifests in four distinct forms:

1. Free air: Trapped pockets of air within the system.

2. Dissolved air: Hydraulic oil typically holds 6 to 12 percent of air by volume.

3. Entrained air: Microscopic air bubbles, usually less than 1 mm in diameter, dispersed within the oil.

4. Foam: Air bubbles, typically larger than 1 mm, congregating on the oil surface.

Among these forms, entrained air poses the most significant issues. Addressing free air is typically achieved by pre-filling Car Lift Repair Tampa Florida components and adequately bleeding the hydraulic system during startup. Minor foam presence is usually superficial and not problematic. However, substantial foam volumes, causing reservoir overflow, can indicate a more severe air contamination or oil degradation issue.

Why is entrained air detrimental?

Negative impacts of entrained air comprise:

– Reduced bulk modulus, leading to spongy operation and inadequate control system response.

– Increased heat load.

– Diminished thermal conductivity.

– Fluid deterioration due to heightened oxidation and thermal degradation (dieseling).

– Decreased fluid viscosity, leaving crucial surfaces susceptible to wear.

– Cavitation erosion.

– Elevated noise levels.

– Decreased efficiency.

Gaseous cavitation

Car Lift Repair Tampa Florida Hydraulic oil may contain up to 12 percent dissolved air by volume. Specific conditions can prompt this dissolved air to emerge from solution, resulting in entrained air. As hydraulic oil temperature rises or static pressure drops, air solubility diminishes, forming bubbles within the fluid, known as gaseous cavitation.

Decreased static pressure and subsequent dissolved air release can transpire at the Car Lift Repair Tampa Florida pump inlet due to:

– Obstructed inlet filters or suction strainers.

– Turbulence from intake-line isolation valves.

– Poorly configured inlet (undersized diameter, excessive length, multiple bends).

– Collapsed or restricted intake lines.

– Blocked or inadequately sized reservoir breather.

Other factors contributing to decreased static pressure include fluid velocity alterations through conductors and orifices, flow fluctuations, and faulty or improperly adjusted anti-cavitation or load control valves.

External ingestion

Air entrainment can also arise from external sources. Similar to gaseous cavitation, this frequently occurs at the pump due to:

– Loose intake-line clamps or fittings.

– Porous intake lines.

– Low oil level in the reservoir.

– Faulty pump shaft seals.

Other causes of air ingestion encompass malfunctioning or misadjusted load control valves, which may draw air past double-acting cylinder glands, and return oil surging into the reservoir (installing drop pipes extending below the minimum oil level at all return penetrations can mitigate this).

I often encounter inquiries about the potential challenges that arise when transitioning between different brands or types of hydraulic oil. 

1. Complete removal of the original hydraulic oil from the system is practically unattainable.

2. Consequently, there will inevitably be some degree of blending between the original and the new oil. Ensuring their miscibility (compatibility) becomes crucial.

This predicament is not exclusive to end-users; Car Lift Repair Tampa Florida oil additive manufacturers and blenders confront similar dilemmas when conducting field trials to assess the performance of their latest formulations against established control fluids. Their strategies in addressing this challenge offer valuable insights for hydraulic practitioners.

In a documented field trial, a new oil variant underwent testing across variously sized Car Lift Repair Tampa Florida excavators and wheel loaders deployed across five distinct work sites. The protocol for oil change entailed draining the hydraulic tank, replenishing it with the new oil, operating the machinery for 10 to 15 minutes, and repeating this process until analysis indicated residual original oil content below 5%.

In practice, it was observed that achieving the targeted contamination level of 5% or less necessitated a minimum of four complete reservoir changes. This observation underscores two key points:

1. The substantial volume of oil (and consequent waste) required for four reservoir changes can be impractical, especially for large reservoirs.

2. Even with a 95:5 ratio favoring the new oil, ensuring compatibility with the original oil remains imperative.

To conduct a comprehensive compatibility study, the intrepid oil testers adopted a meticulous approach: they mixed varying proportions of the new and original oil—100:0, 75:25, 50:50, 25:75, and 0:100. These mixtures underwent storage at temperatures of -18°C, 0°C, 20°C, and 65°C for a month, with weekly inspections for any signs of precipitates or alterations. Remarkably, in this particular study, no incompatibilities were detected within the tested mixtures.

Are multiple varieties of Car Lift Repair Tampa Florida hydraulic oil crowding your oil storage area? If so, you’re not alone. I frequently receive inquiries from individuals seeking to streamline their hydraulic oil inventory but unsure of the best approach. Here’s a typical question I receive:

“We operate various hydraulic equipment such as bucket trucks, cranes, backhoes, rollback wreckers, dump trucks, and scissors lifts. I’m interested in understanding the compatibility or interchangeability of these different products to avoid causing irreversible damage. I’m bewildered by the assortment of hydraulic oils we currently use, like Warren R&O, Conoco MV-22, NAPA AW-46, AW-315, etc. Is there a resource or guide available that clarifies which oil is suitable for each application?” 

The initial step involves decoding the various abbreviations and numbers to gain a comprehensive understanding of your inventory, allowing for a comparison of like-for-like products.

Navigating this task is made complex by the utilization of various standards, with some manufacturers employing non-standard abbreviations and numbers. Examining Bob’s assortment of oils:

  • R&O or RO denotes rust and oxidation, indicating hydraulic oils with enhanced anti-rust and anti-oxidation properties. AW signifies anti-wear, denoting RO hydraulic oils fortified with an anti-wear additive package. 
  • MV represents multi-viscosity, which, as far as my understanding extends, lacks a standard abbreviation. Theoretically, MG (multi-grade), MW (multi-weight), or HVI (high viscosity index) could serve the same purpose. Nevertheless, these oils incorporate viscosity index improvers that alter the rate of viscosity change with temperature. The ISO classification is HR for VI-improved RO oils and HV for VI-improved AW oils.