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Technical Data Sheet
Skydrol® LD4 Fire Resistant Hydraulic Fluid

  • Aviation hydraulic fluid

Product Description

Skydrol LD-4 was introduced in 1977 , and is well known around the world. At the time of its introduction it was a breakthrough product, solving problems of valve erosion and thermal stability common in earlier fluids. Its excellent thermal stability under real world conditions has given it a reputation as the gold standard among Type IV fluids. Skydrol LD-4 features low density, excellent thermal stability, valve erosion prevention, and deposit control.

Typical Properties

PropertyTest MethodTypical Value, Units
Acid Number (mg KOH/g) 0.10 Maximum
Appearance Clear, oily liquid
Autoignition TemperatureASTM D 2155400 °C (752 °F ) Minimum
Color Purple, essentially equivalent to intensity and hue standard
Elemental Content 
     Calcium 10 ppm, Maximum
     Chlorine 50 ppm, Maximum
     Potassium 30 ppm, Maximum
     Sodium 10 ppm, Maximum
     Sulfur 1185-1540 ppm
Fire Point 
     COC 177 °C (350 °F ) Minimum
Flash Point 
     COC 160 °C (320 °F ) Minimum
Moisture 0.20 % Maximum
Particle Contaminationa 
     15-25 micron size 5,700 Maximum
     25-50 micron size 1,012 Maximum
     50-100 micron size 180 Maximum
     5-15 micron size 32,000 Maximum
     Over 100 micron size 32 Maximum
Pour Point -62 °C (-80 °F ) Maximum
Specific Gravity 
     @ 25°C/25°C 1.003-1.013
     @ 38°C (100°F) 10.65-11.65 cSt
     @ -54°C (-65°F) 2000 cSt Maximum
     @ 99°C (210°F) 3.66-4.00 cSt

aNAS 1638 particle counts per AS4059F

Eastman and its marketing affiliates shall not be responsible for the use of this information, or of any product, method, or apparatus mentioned, and you must make your own determination of its suitability and completeness for your own use, for the protection of the environment, and for the health and safety of your employees and purchasers of your products. No warranty is made of the merchantability of fitness of any product, and nothing herein waives any of the Seller's conditions of sale.

2/28/2018 11:35:39 AM