Hydraulic oil becomes cloudy when it is contaminated with water above its saturation level. That is the amount of water that can be dissolved in hydraulic oil and is typically 200 - 300 ppm for mineral hydraulic oil measured at 68°F (20°C).

Water in hydraulic fluid
● Reacts with some additives to form corrosive by-products which corrode some metals.
● Leaves critical surfaces vulnerable to wear and corrosion due to reduced lubrication film-strength.
● Clogs filters and reduces the filterability of the oil.
● Increases air entrainment.
● Increases cavitation occurrence.

Water removal methods
● Polymeric filters- H20 causes the polymer to swell, trapping water within the media. Best suited for removing small amounts of H20 or H20 contamination within allowable limits.
● Vacuum distillation - Water boils at 133°F (56°C) at 25 inches Hg. At this temperature water can be removed without damage to the oil or its additives.
● Headspace dehumidification- Circulating and dehumidifying air from the reservoir headspace causes water in the oil to migrate to the dry air. It is then removed by the dehumidifier.
● Changing out the oil - Depending on system size, changing the oil may be more cost-effective than using any of the above methods of water removal.

Prevention is best cure and is cheaper than removing H20 from the oil.

Standard breather caps on hydraulic reservoirs are a major source of H20 in hydraulic power units. Replacing the standard breather cap with a hygroscopic breather will eliminate the moisture ingress and keep contamination particles out of the reservoir.

WhisperPak® HPS

The Shore Western WhisperPak® Series are acoustically treated laboratory quality hydraulic power systems designed to meet the exacting requirements of servo-hydraulic control systems. These power supplies utilize quality components and micro-clean filtration to provide trouble-free long life with minimum maintenance. A complete system of interlocks and controls allow failsafe unattended continuous operation. Low noise level and leak-free components allow use directly in the laboratory next to the test equipment. Typical applications include

  • Laboratory and Test Lab HPS
  • Large flow central HPS systems
  • Used extensively where sound attenuation is required

The low noise level is achieved by use of inherently quiet components operated as a submerged pump/motor unit(s) inside the enclosed hydraulic oil tank. Output is filtered by pulsation dampers and connected through low velocity flexible hoses to a piping interface manifold. The pumping assembly is mounted with isolators in a completely sealed, acoustically treated enclosure to eliminate airborne noise and prevent heat discharge into the surrounding environment. All possible connections, including components, utilize o-ring fittings or welded joints to eliminate external oil leaks. Units range in size from 7 gpm to 180 gpm. Standard units are wired for 380/460 VAC, 3 phase, 50/60 Hz. Other voltages and frequencies available.

WhisperPak® with insert photo
showing access panel open.

Features

  • Easy maintenance and accessibility – Access doors on end and top provide access to filtration, cooling and pressure controls. The reservoir has a full-size removable top for unrestricted access and clean out.
  • Reduced vibration – The pump-motor assembly is shock mounted inside the reservoir and is soft connected by hoses to prevent mechanical excitation of the surrounding structure.
  • Ease of installation – Smaller sizes are portable with swivel casters. Larger units are skid mounted with forklift access for ease of handling. All oil and water connectionsare located together on one end of the unit, specified at order.
  • High capacity water cooling – A water flow modulating valve monitors reservoir temperature, limiting water flow to that required to maintain a set oil temperature. The heat exchanger is over-sized to minimize water consumption while dissipating full system heat load.
  • High capacity filtration system – Designed to achieve ISO 14/11 cleanliness level consistent with the protection of critical servo components, a full-flow filter with a 3-micron replaceable element is provided on the pump discharge.
  • Electric motor controls – Controls and motor starter are mounted in a NEMA 12 oil-tight enclosure located on the end of the unit. They include control power/emergency stop switch, main pump stop/start-low/high pressure switches, run-time hour meter, indicator lights for low oil level and oil over temperature.

Options

  • Optional controls – Low oil pressure warning indicator, oil over temperature warning indicator, filter condition indicator(s) and combination fused disconnect.
  • Additional filtration – Optional 3-micron, replaceable element return line filter or kidney loop filtration can be added.
  • Special operating conditions – Systems with operation to 550 degrees F (288 degrees C) and over 5,000 psi (345 bar) available.
  • Increased flow options – Larger units can be plumbed in parallel to provide increased total flow capabilities. Total flow capacities are in increments of 60 gpm.
  • Run On Demand (ROD) PLC control system – Using a flow meter to monitor demand, as the flow of the system approaches the capacity of the active pumps, the next pump is brought online or switched from idle to run mode. Control algorithms allow proper timing for adding and reducing pump capacity avoiding instability or low frequency oscillations in the system. The system monitors pump hours and brings units on-line in a rationalized sequence to distribute the wear.