water in hydraulic oil

can you boil it off ?

Quando Omni Flunkus Moritati

the working temp for mil-h-83282 up to 205C. so i can heat it. but will the heat remove all emulsified water down to below 100 ppm ?

This article is informative,
Heat alone will not work. It helps to vaporize water but then the vapor must be flushed away from the oil with air flow across the oil surface. Spraying the oil will increase its surface area. The first thing I would try in your case is purging the vapor space of you hydraulic reservoir with dry air.

Obviously a military acft. C-130?

Once the moisture is in Your hydraulic-oil, within an active acft H-system it is impossible to remove, other than purging the system [drain/replace all fluid]. This is very tedious and expensive. However excessive H2O in Your system is hydraulic system source of severe damage: FREEZING [ice crystals, excessive viscosity, density, blockage]; BOILING [hot-pumps, air bubbles/cavitation, excessive power-draw]; CORROSION [air+moisture+steel/CRES/Aluminum]; maintenance, etc... among many-other system threats [and performance oddities] that must be eliminated, fast.

Ensure that all leaking H-system components are repaired [fluid-leaks-out, air leaks in].

Ensure H-service carts ["mules"] are purged with clean fluid within chemical limits, so they atre not a source of contaminates [wet air, particulates, etc].

Ensure new/fresh -83282 fluid is charged into Your system.

NEVER allow -5606, -87257 or 83252 to intermix, except on a very minute basis. Generally speaking, the poorest characteristics of each fluid type will dominate the mix.

Also, wherever there are gas-charged static or pressure-chamber/reservoir [IE: fluid reservoir, pre-charged cylinder, LDG Strut, tires, etc] it absolutely necessary that they be charged with verified DRY NITROGEN [as close to 100% as possible]. Dry nitrogen ensures, freedom from moisture and an inert gas environment. Any trace of moisture is less of a corrosion threat in a pure nitrogen environment [no/trace oxygen and moisture]. Also, by eliminating any compressed oxygen [~30% atmosphere] the threat for system [hot] diesel/detonation is eliminated.

I discovered a long time ago that transient maintenance on a FOB or civilian airfield with minimal military presence generally leads to maintenance short cuts such as using compressed air [ILO certified dry nitrogen] and substitute H-fluids to get a system "topped-off" [book seez it's OK, why not?!?]. Then everyone forgets what was done as an expedient... and the system [tires, struts, etc] were not re-serviced to eliminate the long-term issues/threat that the “expedient” maintenance posed [“Aw it’ll be OK”].

Some "light reading" documents/specs that you may find useful...
SAE...
AIR81 Importance of Physical and Chemical Properties of Aircraft Hydraulic Fluids
AIR737Aerospace Hydraulic and Pneumatic Specifications, Standards, Recommended Practices, and Information Reports
AIR786 Elastomer Compatibility Considerations Relative to O-Ring and Sealant Selection
AIR810 Degradation Limits of Hydrocarbon-Based Hydraulic Fluids, MIL-PRF-5606, MIL-PRF-83282, and MIL-PRF-87257 Used in Hydraulic Test Stands
AIR1362 Aerospace Hydraulic Fluids Physical Properties
AIR1899 Aerospace Military Aircraft Hydraulic System Characteristics
AIR1918 Comparison of Hydraulic System Cleanliness Procedures and Requirements for Ten Aerospace Companies
AIR4713 Chlorinated Solvent Contamination of MIL-H-5606/MIL-H-83282 Vehicle Hydraulic Systems
AIR5358 Landing Gear Shock Strut Hydraulic Fluid
AIR5693 Compatibility of PTFE Hose Assemblies With Typical Fluids Found in Aerospace Applications
AIR5829 Air in Aircraft Hydraulic Systems
ARP243 Nomenclature, Aircraft Hydraulic and Pneumatic Systems
ARP785 Procedure for the Determination of Particulate Contamination in Hydraulic Fluids by the Control Filter Gravimetric Procedure
ARP1084 External Hydraulic Leakage for In-Service Components
ARP4268 [CX] Aerospace Hydraulic System Fluid Contamination - Location of Sampling Points
ARP4285 Evaluation of Particulate Contamination in Hydraulic Fluid - Membrane Procedure
ARP5376 Methods, Locations And Criteria For System Sampling And Measuring The Solid Particle Contamination Of Hydraulic Fluids
ARP5891 Achieving Cleanliness Standards for Aircraft Hydraulic Systems During Manufacture
AS4059 Aerospace Fluid Power - Contamination Classification for Hydraulic Fluids
AS5440 Hydraulic Systems, Military Aircraft, Design and Installation, Requirements For
AS8775 Hydraulic System Components, Aircraft and Missiles, General Specification For
USAF T.O.s [unsure what NAVAIR #s might be]
42B-1-1 QUALITY CONTROL OF FUELS AND LUBRICANTS
42B2-1-3 FLUIDS FOR HYDRAULIC EQUIPMENT
42B2-1-12 ORGANIZATIONAL, INTERMEDIATE AND DEPOT MAINTENANCE - AVIATION HYDRAULICS MANUAL
42E1-1-1 ORGANIZATIONAL, INTERMEDIATE AND DEPOT MAINTENANCE AVIATION HOSE AND TUBE MANUAL

Sorry... got carried away. Gottagobacktowork.

Regards, Wil Taylor

Trust - But Verify!

We believe to be true what we prefer to be true.

For those who believe, no proof is required; for those who cannot believe, no proof is possible.

Unfortunately, in science what You 'believe' is irrelevant – "Orion"

I am thinking that a vacuum application may help remove excess water in the oil. Find a depressurizing chamber and try it out. The Air Force has altitude chambers if that may help.

It will do no good to remove the existing water in the hydraulic fluid if you do nothing to prevent it from happening again. The water in the fluid is likely produced by humid air condensing out on the inside of the reservoir air space surfaces during heating/cooling cycles. To prevent the problem from re-occurring in the future, seal the system and install a desiccant breather on the reservoir. You can also add aircraft dry-break fluid service fittings to the reservoir to add fluid without un-sealing the system.