MIL-PRF-5606 Density Chart

Canvas Element Not Working, Please Check Browser Settings or Contact KasperCalc to fix the issue.

Measured values for MIL-H-5606: 100 °F to 399 °F (38 °C to 204 °C) at atmospheric pressure, 20.7 MPaG (3000 psig) and 55.2 MPaG (8000 psig).
The atmospheric curve is a straight-line fit to the four measured points and is drawn only across that range; nothing is extrapolated.

Triangles are single-lot manufacturer typical values (not measurements) at a single temperature each. The blue MIL-PRF-23699 series is shown for comparison; its dashed portions are linear extrapolations beyond its 41–158 °F measured range.

Data from: NADC-79248-60 (Conte & Hammond, 1980), DTIC ADA081597, Table 2 (measured); MIL-PRF-23699 data from NIST IR 8263, Table 23.

Toggle data sets by clicking the legend.

MIL-PRF-5606 Density Calculator
Degrees (°F):
Degrees (°C):
Density (kg/m³):  
Density (lb/in³):  
Density (lb/gal):  
Density (lb/ft³):  
Specific Gravity*:  
Specific Gravity**:  
Specific Gravity***:  
°API****:  
MIL-PRF-23699 (kg/m³):  

Calculator valid 100.4 °F to 399.2 °F (38 °C to 204 °C), atmospheric pressure, using the linear fit to the NADC measurements. The MIL-PRF-23699 row is shown only within that fluid's 41–158 °F measured range.

Specific Gravity is a Contentious Unit

* SG based on static density of water of 1000 (kg/m³) *

** SG based on static density of water of 998 (kg/m³) **

*** SG based on temperature dependent density of water ***

**** °API gravity at current temperature, referenced to water at 60°F (999.01 kg/m³): °API = (141.5 / SG60°F) − 131.5 ****

Density of MIL-PRF-5606 Petroleum Hydraulic Fluid
About This Data

The density values are the MIL-H-5606 columns of Table 2 in NADC-79248-60 (Conte & Hammond, Naval Air Development Center, 1980, DTIC ADA081597), tabulated at 38, 93, 149 and 204 °C (100, 200, 300 and 400 °F) at atmospheric pressure, 20.7 MPaG (3000 psig) and 55.2 MPaG (8000 psig). The report does not state the measurement method, the specification revision (MIL-H-5606 predates the MIL-PRF designation) or the lot tested, and it gives no uncertainty.

The smooth atmospheric curve is the least-squares straight line through the four atmospheric points, ρ = 869.517 − 0.71295 · T°C kg/m³, used only between 38 °C and 204 °C. It departs from the tabulated values by at most 1.2 kg/m³. No density data below 38 °C were found in the sources used, so the chart and calculator are not extended below 100.4 °F or above 399.2 °F.

MIL-PRF-5606 is a petroleum-based (mineral oil) aircraft hydraulic fluid, dyed red. The triangles on the chart are single-lot "typical" values taken from manufacturer data sheets for products sold against the specification; they are not measurements made for this site and carry no stated uncertainty. MIL-PRF-5606H sets no finished-fluid density limit.

MIL-PRF-5606 — Density vs. Temperature
Temp (°C) Temp (°F) Density (kg/m³) Density (g/cm³) Density (lb/gal) Density (lb/ft³) 20.7 MPaG (kg/m³) 55.2 MPaG (kg/m³) Linear fit, atm. (kg/m³)
38100.48430.8437.03552.63856874842.4
93199.48020.8026.69350.07818840803.2
149300.27640.7646.37647.69785810763.3
204399.27240.7246.04245.20750779724.1

Columns 3–6 are the NADC-79248-60 Table 2 atmospheric-pressure measurements; 20.7 and 55.2 MPaG columns are the same table at elevated pressure. Last column: straight-line fit to the atmospheric points. Measured lot and specification revision are not stated in the report and no uncertainty is given.

Manufacturer Typical Values (not measurements)
Source Printed value Temp (°C) Density (kg/m³)
Nyco Hydraunycoil FH 51 TDS0.870 (units not stated; taken as g/cm³)20870
Mobil Aero HF SeriesSG 0.872 (15.6/15.6 °C)15.6871.1
Chevron Hydraulic Oil 56060.87 kg/l15870
ROYCO 756/756A7.261 lb/gal (reference temperature not stated on sheet)15.6 (60 °F convention)870.0

SG converted with water at 60 °F (999.01 kg/m³); lb/gal converted with 1 kg/m³ = 0.0083454 lb/gal. Single-lot typical values, no uncertainty stated.

MIL-PRF-5606 vs MIL-PRF-23699

MIL-PRF-5606 is a petroleum (mineral oil) hydraulic fluid; MIL-PRF-23699 is a polyol-ester turbine engine oil. Over the temperatures where both have data, MIL-PRF-5606 is the less dense fluid, by roughly 135 kg/m³ (about 14 %).

Temp (°C) Temp (°F) MIL-PRF-5606 (kg/m³) MIL-PRF-23699 (kg/m³) Difference (kg/m³) Difference (% of 23699)
541.0—1003.4——
2068.0—992.1——
38100.4842.4978.5136.113.9 %
40104.0841.0977.0136.013.9 %
50122.0833.9969.5135.614.0 %
60140.0826.7962.0135.214.1 %
70158.0819.6954.4134.814.1 %
93199.4803.2———
149300.2763.3———
204399.2724.1———

MIL-PRF-5606 values use the linear fit to the NADC-79248-60 atmospheric measurements, 38–204 °C only. MIL-PRF-23699 values are interpolated from NIST IR 8263 Table 23, 5–70 °C only. "—" means the fluid has no measurement at that temperature (extrapolated values are deliberately not used). The two datasets come from different sources, labs and pressures (NIST ~83 kPa; NADC atmospheric), so small differences should not be over-interpreted.

Sources
  • A. A. Conte Jr. and J. L. Hammond, Development of a High Temperature Silicone Base Fire-Resistant Hydraulic Fluid, NADC-79248-60, Naval Air Development Center, Warminster PA, 5 Feb 1980. DTIC ADA081597. apps.dtic.mil/sti/tr/pdf/ADA081597.pdf. Table 2 (MIL-H-5606 columns), accessed 12 Oct 2026.
  • US Department of Defense, MIL-PRF-5606H, Performance Specification: Hydraulic Fluid, Petroleum Base; Aircraft, Missile, and Ordnance, 7 June 2002. everyspec.com. Identification of the fluid; no finished-fluid density limit.
  • NYCO, Hydraunycoil FH 51 Technical Data Sheet (TDS_FH51-1E11), 2020. aircraftspruce.com/catalog/pdf/FH51TDS.pdf. Typical density.
  • ExxonMobil, Mobil Aero HF Series product page. mobil.com. Typical specific gravity; HF vs HFA column assignment unverified.
  • Chevron, Hydraulic Oil 5606 Product Data Sheet, Jan 2024. Chevron PDS. Typical density (general-purpose industrial/marine oil that claims to meet MIL-PRF-5606H).
  • LANXESS, ROYCO 756/756A Data Sheet, effective 6 Jan 2017. ROYCO 756 data sheet. Typical density in lb/gal.
  • Bruno et al., Thermophysical Properties of Polyol Ester Lubricants, NIST IR 8263, 2019. doi.org/10.6028/NIST.IR.8263. MIL-PRF-23699 comparison data (Table 23).

The NADC report does not state the specification revision or lot of the MIL-H-5606 tested, and gives no measurement uncertainty. Manufacturer values are single-lot typicals.

Cite This Work