Most hydraulic and lubrication failures are contamination failures. Particles wear components, water attacks additives and steel surfaces, and air causes cavitation and oxidation. Twin Hydraulics Engineering designs filtration and fluid-conditioning systems for mineral oils, hydraulic oils and gear oils, and is adding the Bosch Rexroth Fluid Care Unit (FLCU) to our rental fleet so you can dry and clean a system without buying the equipment.
Filtration system design
A filter is only useful if it is the right rating, in the right place, sized for the real flow. We design the whole arrangement around your machine and your target cleanliness class:
- Target cleanliness class set to ISO 4406 against the most sensitive component in the circuit — servo and proportional valves demand far cleaner fluid than a simple gear-pump circuit.
- Filter placement — suction, pressure, return, or an offline kidney loop that polishes continuously without touching the working circuit.
- Sizing for actual maximum flow, not average, so pressure drop stays low and element life stays long.
- Element selection by beta ratio rather than micron rating alone, with the correct collapse pressure for the position. We build and maintain our systems with Hengst filter elements — Twin Hydraulics Engineering is a Hengst Competence Partner for hydraulic filters and systems — and we cross-reference elements from other makes so you are not locked to whatever was fitted originally.
- Housings, indicators and breathers — simplex or duplex housings, visual or electrical clogging indicators wired to your PLC, and desiccant breathers to stop humid air entering the tank in the first place.
- Condition monitoring — particle counters and water-in-oil sensors where continuous evidence is worth more than periodic sampling.
We work with mineral oils (HL, HLP, HLPD, HVLP and HVLPD to DIN 51524), industrial gear oils, and biodegradable HEES fluids to ISO 15380. Tell us the fluid, the reservoir volume, the viscosity grade and what the machine does, and we will specify the system around it.
Fluid Care Unit (FLCU) rental — dewatering without damaging the oil
Water is the contaminant most people underestimate. It strips additives, promotes oxidation and corrodes bearing surfaces, and once oil turns cloudy the usual reaction — drain and replace — is expensive and often unnecessary.
The Bosch Rexroth Fluid Care Unit, type FLCU, removes water, gas and particles from oil while the fluid stays in service. It works by vacuum: the process chamber runs down to 50 mbar absolute, so water evaporates at low temperature instead of being boiled off with heat. That is the point — the additive package, viscosity index improvers and base-oil characteristics are not cooked out of the fluid in the process. The oil that comes back is the oil you bought, minus the water.
- Dewatering, degassing and fine filtration in one pass, connected as a bypass or into the cooling circuit.
- Typical performance: in Rexroth’s published test, one litre of water in 100 litres of HLP 46 at 40 °C is removed in roughly six hours, taking relative oil humidity from saturated back down to about 10%.
- Filter ratings of 3, 6, 10 or 20 µm, selected for the system it is cleaning.
- Flow up to 20 l/min, self-regulating according to suction resistance, with suction height to 3 m and return line pressure to 10 bar.
- Continuous fluid analysis — optional water (aqua) and particle sensors record what is happening throughout the run, so you finish with evidence rather than an assumption.
- Portable at around 150 kg on wheels, running from a 380–480 V supply, for indoor use.
Suitable for mineral oils to DIN 51524 and biodegradable HEES fluids to ISO 15380. Reference: Bosch Rexroth data sheet RE 51565.
Proving the oil is fit to reuse
Cleaning oil is only half the job. What decides whether you refill or replace is whether the fluid coming out actually meets the standard your machine needs — and that has to be measured, not assumed. We monitor the fluid before, during and after conditioning using Hengst instrumentation.
- Hengst OPM II online particle monitor. Measures contamination continuously on the light-extinction principle and displays the cleanliness class to ISO 4406:99 or SAE AS4059E. It records a purity trend rather than a single snapshot, keeps the data in its own memory, and raises an alarm when a limit is exceeded. Rated to 420 bar dynamic and 600 bar static, measuring flow 50–400 ml/min, for mineral oils, bio-oils and diesel fuel. Hengst data sheet RE 51460.
- Hengst WGM oil humidity sensor. Reads water content as relative saturation, continuously and in service. Water is usually what decides whether a charge of oil is worth saving, and a figure on a display settles that far better than holding a sample up to the light. Hengst operating instructions RE 51550-B.
The practical result: we can show you the cleanliness class and water content of your oil before conditioning and after it, so reusing the charge becomes a documented decision rather than a hopeful one. Where a system needs permanent monitoring rather than a one-off check, the same sensors can be installed and wired into your control system.
When renting a fluid care unit makes sense
- After water ingress — a failed cooler, a leaking seal, or a washdown that found its way into the tank.
- Cloudy or milky oil in a large reservoir, where replacing the charge costs far more than drying it.
- Before and after major repairs — clean fluid before a rebuilt pump goes back in, so the new unit is not destroyed by the debris that killed the old one.
- Commissioning new machines and flushing new pipework to the required cleanliness class.
- High-humidity environments and outdoor plant where moisture ingress is continuous rather than accidental.
Talk to us about your system
For a filtration design or a unit rental, tell us: the fluid type and viscosity grade, the reservoir volume, the current problem (water, particles, varnish, foaming), and any cleanliness class you must meet. We will tell you what the system needs, whether conditioning the existing charge is viable, and how long it is likely to take.
See also our hydraulic filter elements, pump and motor repair and our full range of services. Twin Hydraulics Engineering is a Bosch Rexroth Certified Excellence Distributor, certified to ISO 9001, ISO 14001 and ISO 45001, with branches in Shah Alam and Butterworth.
