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Liquid Ethylene Density Calculator

Ready to calculate
ρ = m / V.
5 unit systems.
NIST 567.7 kg/m³ reference.
100% Free.
No Data Stored.

How it Works

01Confirm Cryogenic Conditions

Liquid ethylene exists only between −169.2 °C (triple point) and 9.2 °C (critical point). At standard temp it is a gas.

02Weigh the Sample

Mass of the liquid C₂H₄ in your tank or vessel. Accepts kg / g / mg / lb / oz / metric tons.

03Measure the Volume

Volume of the liquid in L / mL / m³ / ft³ / US gal / UK gal — corrected to the actual storage temperature.

04Apply ρ = m / V

Output in kg/m³, g/mL, lb/ft³, lb/gal — plus % deviation from the 567.7 kg/m³ boiling-point reference.

What is a Liquid Ethylene Density Calculator?

Ethylene (C₂H₄, MW 28.05 g/mol) is the highest-volume organic chemical in the world — global production exceeds 200 million metric tons per year, almost all of it polymerized into polyethylene, ethylene glycol, ethylene oxide, vinyl chloride, and styrene. Because ethylene is a gas at standard conditions (boiling point −103.7 °C at 1 atm), industrial-scale storage and shipment uses cryogenic liquid ethylene at temperatures between roughly −104 °C (atmospheric BP) and the critical point of +9.2 °C / 50.4 bar. Tank-truck loading, marine cargo accounting, polymer-feed flow control, custody-transfer metering, and quality-control density verification all depend on knowing the actual liquid ethylene density to ~0.1% precision.

Our Liquid Ethylene Density Calculator implements the foundational identity ρ = mass / volume with full unit support — accept mass in kg / g / mg / lb / oz / metric tons, volume in L / mL / m³ / cm³ / ft³ / US gal / UK gal, and report density in five unit systems: kg/m³ (SI standard for engineering), g/mL = g/cm³ (laboratory standard), kg/L, lb/ft³ (US engineering), and lb/gal (cargo accounting). Every result is compared against the NIST reference density of 567.7 kg/m³ at the 1-atm boiling point of −103.7 °C with explicit % deviation, plus smart warnings for densities outside the physical range (gas-like below 200 kg/m³, water-exceeding above 1000 kg/m³, or beyond the triple-point limit of 654 kg/m³).

Designed for cryogenic-cargo operators verifying tanker manifests, polymer plant engineers calibrating flow meters, chemical-engineering students computing densities from sampled mass and volume, custody-transfer auditors cross-checking metered values against reference data, and any researcher quantifying liquid C₂H₄ samples — the tool runs entirely in your browser, no account, no data stored.

Pro Tip: Pair this with our Molarity Calculator for solution chemistry, our Grams to Moles Calculator for stoichiometry, or our Partial Pressure Calculator for ethylene gas-phase calculations.

How to Use the Liquid Ethylene Density Calculator?

Confirm Liquid Ethylene Conditions: Liquid ethylene exists only between its triple point (−169.2 °C, 1.213 mbar) and critical point (+9.20 °C, 50.42 bar). At standard temperature (25 °C), ethylene is a gas at any pressure (above the critical T it is supercritical). Most industrial liquid ethylene is at −104 °C (atmospheric BP) or pressurized between 5-50 bar at slightly higher T.
Weigh the Sample: Mass of the liquid C₂H₄ in your tank, vessel, or sample container. The calculator accepts kg, g, mg, lb, oz, and metric tons. For tank inventory, mass is usually computed as ΔW (loaded − tare). Be precise — a 1-ton sample weighed to 1 kg gives ρ to 0.1%.
Measure or Calculate the Volume: Volume of the liquid in L, mL, m³, cm³, ft³, US gal, or UK gallons. Cryogenic tanks are dimensioned for a specific T (usually 1 atm BP); apply tank-volume corrections for temperature if measured at off-spec conditions.
Apply ρ = mass / volume: The calculator converts mass to kg and volume to m³ internally, computes density, then converts to all 5 output unit systems for cross-checking.
Read Density in 5 Unit Systems Simultaneously: kg/m³ (SI), g/mL = g/cm³ (lab), kg/L (numerically equal to g/mL), lb/ft³ (US engineering), and lb/gal-US (cargo accounting). Pick whichever your reference document uses.
Compare Against the NIST Reference: The result panel shows the % deviation from the canonical 567.7 kg/m³ value at the 1-atm boiling point. Within ±1% is excellent (typical of well-controlled cryogenic storage); ±5% likely indicates an off-BP storage temperature; >15% deviation usually indicates a measurement error or non-liquid sample.
For Off-BP Storage Temperatures: Density falls steeply with rising T — 654 kg/m³ at the triple point (104 K) → 567.7 at the BP (169.45 K) → ~480 at −60 °C → ~220 near critical (282.4 K). For T-dependent reference values, use NIST REFPROP or the IUPAC International Thermodynamic Tables — Ethylene.

How is liquid ethylene density calculated?

Density is the most-fundamental thermophysical property of a liquid — it is required for converting between mass and volume in every cryogenic-shipping, custody-transfer, and process-engineering calculation. Liquid ethylene density depends strongly on temperature and weakly on pressure (sub-critical liquids are nearly incompressible).

Reference: NIST Chemistry WebBook (Lemmon, McLinden, Friend); IUPAC International Thermodynamic Tables of the Fluid State — Ethylene; CRC Handbook of Chemistry and Physics.

Core Formula

Density ρ = mass / volume

SI standard: kg/m³. Equivalent: 1 g/mL = 1 g/cm³ = 1 kg/L = 1000 kg/m³. US engineering: 1 kg/m³ = 0.06243 lb/ft³ = 0.008345 lb/gal (US).

Liquid Ethylene Reference Density at the 1-atm Boiling Point

ρ_BP = 567.7 kg/m³ = 0.5677 g/mL = 35.44 lb/ft³ = 4.738 lb/gal (US) at T = −103.7 °C = 169.45 K, P = 1.01325 bar.

This is the most-cited value for liquid ethylene; appears in CRC Handbook, NIST WebBook, IUPAC tables, and the safety data sheet of every major industrial-gas supplier.

Worked Example — Tanker-Load Calculation

A cryogenic ethylene tanker has 1500 m³ of liquid C₂H₄ at the 1-atm BP. What is the cargo mass?

  • Volume = 1500 m³.
  • Density = 567.7 kg/m³.
  • Mass = ρ × V = 567.7 × 1500 = 851,550 kg = 851.55 tonnes.
  • Equivalent: 30,367 mol/m³ × 1500 m³ = 45.55 Mmol = 45.6 Mmol of C₂H₄.

Worked Example — Sample Density Verification

A cryogenic sample container with tare 200 g, gross weight 760 g, internal volume exactly 1.0 L. Compute density.

  • Net mass = 760 − 200 = 560 g = 0.560 kg.
  • Volume = 1.0 L = 0.001 m³.
  • ρ = 0.560 / 0.001 = 560 kg/m³.
  • Deviation vs 567.7 reference = (560 − 567.7) / 567.7 × 100 = −1.36%.
  • Interpretation: sample is at slightly elevated T (~−98 °C) or slightly contaminated; well within typical commercial-grade tolerance (±2-3%).

Liquid Ethylene Density vs Temperature (Saturated Liquid)

  • Triple point (−169.2 °C / 104.0 K): ρ ≈ 654.4 kg/m³ (densest liquid form).
  • −150 °C (123 K): ρ ≈ 632 kg/m³.
  • −130 °C (143 K): ρ ≈ 605 kg/m³.
  • 1-atm BP (−103.7 °C / 169.45 K): ρ = 567.7 kg/m³ (canonical reference).
  • −80 °C (193 K): ρ ≈ 525 kg/m³ (requires elevated pressure ~9 bar).
  • −40 °C (233 K): ρ ≈ 437 kg/m³ (requires ~18 bar).
  • 0 °C (273 K): ρ ≈ 295 kg/m³ (requires ~40 bar — close to critical).
  • Critical point (+9.20 °C / 282.4 K, 50.42 bar): ρ_c = 214.2 kg/m³ (above this, supercritical fluid).

Density vs Other C₂ Hydrocarbons (saturated liquid at 1-atm BP)

  • Ethylene (C₂H₄, ethene), BP −103.7 °C: 567.7 kg/m³.
  • Ethane (C₂H₆), BP −88.6 °C: 544.0 kg/m³.
  • Acetylene (C₂H₂), sublimes at −84 °C: 467 kg/m³ (only below triple point).
  • Liquid methane (CH₄), BP −161.5 °C: 422.6 kg/m³.
  • Liquid propane (C₃H₈), BP −42.1 °C: 581.0 kg/m³.
  • Liquid water at 25 °C: 997.0 kg/m³ (~1.76× ethylene).

Unit Conversion Reference

  • 1 kg/m³ = 0.001 g/mL = 0.001 g/cm³ = 0.001 kg/L.
  • 1 kg/m³ = 0.062428 lb/ft³.
  • 1 kg/m³ = 0.0083454 lb/gal (US) = 0.010022 lb/gal (UK / Imperial).
  • 1 g/mL = 1000 kg/m³ = 62.428 lb/ft³ = 8.3454 lb/gal (US).
  • 567.7 kg/m³ = 0.5677 g/mL = 35.44 lb/ft³ = 4.738 lb/gal (US) = 5.692 lb/gal (UK).
Real-World Example

Worked Example — Cryogenic Tanker Cargo Verification

Scenario. An ISO-tank-container of cryogenic liquid ethylene arrives at a polymer plant. The tank has internal volume 24,000 L (24 m³) at its design temperature of −104 °C; the gross weight is measured as 18,400 kg, and the empty (tare) weight is 4,800 kg.

Step 1 — Compute Net Mass.

  • m = 18,400 − 4,800 = 13,600 kg of liquid ethylene.

Step 2 — Apply ρ = m / V.

  • V = 24,000 L = 24 m³.
  • ρ = 13,600 / 24 = 566.67 kg/m³.
  • Or equivalently: ρ = 0.5667 g/mL = 35.36 lb/ft³ = 4.729 lb/gal (US).

Step 3 — Compare to Reference.

  • Reference at −103.7 °C BP: 567.7 kg/m³.
  • Deviation: (566.67 − 567.7) / 567.7 × 100 = −0.18%.
  • Interpretation: cargo density is within 0.2% of the BP reference — consistent with well-controlled cryogenic storage. Mass and volume are mutually consistent; the tanker is properly loaded.

Step 4 — Mole Inventory for Process Calculations.

  • n = m / MW = 13,600 / 28.054 = 484,750 mol = 484.75 kmol.
  • If polymerized to PE at 100% efficiency: yield = 484.75 × 28.05 = 13,597 kg ≈ 13.6 tonnes (mass conservation).
  • At a typical PE plant throughput of 50 tonnes/h, this tank supplies ~16 minutes of feedstock.

Who Should Use the Liquid Ethylene Density Calculator?

1
Verify liquid ethylene mass from tanker volume and reference density (or vice versa) at terminals, ports, and rail-car transfer stations. Cross-check against shipping documents and reconcile manifest discrepancies.
2
Convert volumetric flow (m³/h from a turbine meter) to mass flow (kg/h) for material balances, polymer-yield calculations, and feed-stoichiometry control in PE / EO / EG / PVC plants.
3
Confirm a sampled liquid C₂H₄ matches reference density (within ±2% for typical commercial grade); deviations point to elevated T, pressure issues, or contamination by ethane / methane.
4
Practice density calculations on real industrial cryogenic streams; compare to water, methane, propane to build intuition for organic-liquid densities at sub-zero temperatures.
5
Compute tank volume from required mass capacity and reference density; design margins for thermal expansion as T rises within the liquid range (567.7 → 295 kg/m³ from BP to near-critical).
6
Quantify volume released per kg in spill scenarios; compute pool depth and evaporation rate (cryogenic liquid pool spreads quickly and produces dense flammable cloud at LEL 2.7 vol%).
7
Compare a measured sample density (from pycnometer or vibrating-tube densitometer) to the NIST reference; flag samples that are off-spec by >2-3%.

Technical Reference

Compound Identity. Ethylene (IUPAC: ethene; CAS 74-85-1; UN 1038 for refrigerated liquid), C₂H₄, MW 28.054 g/mol, formula H₂C=CH₂. Simplest alkene; planar molecule with C=C double bond. Major source: steam cracking of ethane, propane, naphtha. Industrial uses: polyethylene (~60% of production), ethylene oxide → ethylene glycol (~20%), vinyl chloride (~7%), styrene (~5%), ethanol via hydration (~3%).

Phase Diagram Reference Points.

  • Triple point: T_t = 104.0 K = −169.2 °C; P_t = 1.213 mbar = 121.3 Pa. Liquid coexists with solid and vapor.
  • Normal boiling point (1 atm = 1.01325 bar): T_NBP = 169.45 K = −103.7 °C. Liquid ρ = 567.7 kg/m³; vapor ρ = 2.114 kg/m³.
  • Critical point: T_c = 282.35 K = +9.20 °C; P_c = 50.418 bar; ρ_c = 214.2 kg/m³. Above the critical T, ethylene is supercritical for any pressure.
  • Density of saturated liquid is correlated by the Span-Wagner-style equation of state implemented in NIST REFPROP and the IUPAC International Thermodynamic Tables — Ethylene, accurate to ±0.05% in the liquid region.

Saturated Liquid Density vs Temperature (NIST REFPROP).

  • 104.0 K (TP): 654.4 kg/m³
  • 120 K: 638.2 kg/m³
  • 140 K: 615.6 kg/m³
  • 160 K: 587.1 kg/m³
  • 169.45 K (NBP): 567.7 kg/m³
  • 180 K: 553.2 kg/m³
  • 200 K: 519.0 kg/m³
  • 220 K: 477.7 kg/m³
  • 240 K: 425.2 kg/m³
  • 260 K: 354.8 kg/m³
  • 275 K: 290.6 kg/m³
  • 282.35 K (CP): 214.2 kg/m³

Pressure Effect on Density (sub-critical liquid). Liquid ethylene is nearly incompressible: at constant T, increasing P from saturation pressure to 100 bar increases ρ by less than 1%. For T = 169.45 K (NBP) and P up to 50 bar: ρ ≈ 567.7 + 0.5%. For most engineering work, the saturated-liquid density at the storage T is sufficient.

Comparison Densities (SI, saturated liquid at 1-atm BP unless noted).

  • Ethylene C₂H₄: 567.7 kg/m³
  • Ethane C₂H₆: 544.0 kg/m³
  • Methane CH₄: 422.6 kg/m³
  • Propane C₃H₈: 581.0 kg/m³
  • Butane C₄H₁₀: 600.7 kg/m³
  • Liquid nitrogen N₂ (BP −196 °C): 808.6 kg/m³
  • Liquid oxygen O₂ (BP −183 °C): 1141 kg/m³
  • Liquid argon Ar (BP −185.8 °C): 1395.4 kg/m³
  • Liquid water (25 °C): 997.0 kg/m³
  • Liquid mercury Hg (25 °C): 13,533 kg/m³

Density Measurement Methods. (1) Pycnometer: calibrated-volume vessel; weigh full minus empty. Standard for laboratory work; accuracy ±0.1% with care. (2) Vibrating-tube densitometer (Anton Paar, Mettler): resonant frequency of a U-tube changes with sample density. Accuracy ±0.0001 g/mL (industry standard for QC). (3) Hydrometer: buoyancy-based; reads density off a calibrated scale. Accuracy ±0.5%. (4) Buoyancy weighing (Mohr-Westphal balance): weighs a sinker in the liquid. Accuracy ±0.05%. (5) For cryogenic liquids, commercial densitometers must be jacketed and pre-cooled; alternative: weigh a known volume of liquid in a bath at controlled T.

Safety, Hazards, and Handling. Ethylene is highly flammable (flash point −136 °C, autoignition 450 °C, flammable range 2.7-36 vol% in air, MIE 0.07 mJ — extremely low static-spark ignition energy) and a simple asphyxiant (no toxic effects, but displaces O₂). Cryogenic liquid contact causes severe frostbite (boil-off generates dense vapor that hugs the ground). Major hazards: BLEVE (boiling liquid expanding vapor explosion) if a pressurized liquid tank is fire-impinged; static-spark ignition during cryogenic transfer; oxygen-deficient atmosphere in confined spaces near a leak. Required: bond/ground all transfer equipment; use cold-resistant PPE (face shield, cryogenic gloves, sleeves); flammable-gas detector (set 10% LEL alarm); never seal a heated cylinder. Storage: refrigerated to −104 °C at near-atmospheric pressure (LIN-jacketed tanks) or at +5 to +10 °C under 50-100 bar pressure (less common; energy cost). Reference SDS: Praxair / Linde / Air Liquide / Air Products ethylene SDS — all align on these specifications.

Conclusion

Liquid ethylene density is a one-formula calculation (ρ = m/V) with industrial implications at every scale — from a 1 mL laboratory sample to a 24,000 L ISO-tank to a 100,000-tonne marine cargo. The key references to remember: 567.7 kg/m³ at the 1-atm BP of −103.7 °C is the canonical value cited in CRC, NIST, IUPAC, and every supplier SDS. Liquid ethylene exists only in the cryogenic range from the triple point (104 K, ρ_max ≈ 654 kg/m³) to the critical point (282.4 K, ρ_c ≈ 214 kg/m³); above the critical T it is supercritical, not a true liquid.

Three pitfalls worth flagging: (1) Confusing ethylene (C₂H₄, the polymer feedstock) with ethylene oxide (C₂H₄O, oxirane — a different compound with very different density 882 kg/m³) or ethanol (C₂H₆O, density 789 kg/m³ at 25 °C) is a documented incident-causing error. (2) Density is highly T-dependent — a 10 °C rise from BP gives ~3% density drop; for off-BP storage use the NIST REFPROP equation of state, not the BP reference. (3) Liquid ethylene is highly flammable (LEL 2.7%, MIE 0.07 mJ — extremely low) and a simple asphyxiant; cryogenic skin contact causes severe frostbite. Always handle with proper PPE, bonding, grounding, and cold-resistant equipment.

Frequently Asked Questions

What is the Liquid Ethylene Density Calculator?
It implements the foundational identity ρ = mass / volume for liquid ethylene (C₂H₄, the polyethylene feedstock and highest-volume organic chemical worldwide). Mass inputs accept kg / g / mg / lb / oz / metric tons; volume in L / mL / m³ / cm³ / ft³ / US gal / UK gal. Outputs density in kg/m³ (SI), g/mL = g/cm³, kg/L, lb/ft³, and lb/gal (US) simultaneously, with explicit % deviation from the NIST reference of 567.7 kg/m³ at the 1-atm BP (−103.7 °C). Smart warnings flag unphysical results.

Pro Tip: Pair this with our Molarity Calculator for solution chemistry.

What is the density of liquid ethylene?
567.7 kg/m³ = 0.5677 g/mL = 35.44 lb/ft³ = 4.738 lb/gal (US) at the 1-atm boiling point of −103.7 °C (169.45 K). This is the most-cited reference value, appearing in CRC Handbook, NIST WebBook, IUPAC International Thermodynamic Tables, and all major industrial-gas supplier SDS. Density varies strongly with temperature: 654 kg/m³ at the triple point (104 K), falling to ~290 kg/m³ near the critical point (282.4 K). For non-BP storage, use NIST REFPROP for the T-dependent reference value.
Why is liquid ethylene less dense than water?
Water at 25 °C is 997.0 kg/m³; liquid ethylene at the BP is 567.7 kg/m³ — about 57% the density of water. Two reasons: (1) molecular mass — ethylene MW 28.05 g/mol vs water MW 18.02 g/mol; ethylene is heavier per molecule but molar volumes differ. (2) molecular packing — water has hydrogen bonding that holds molecules tightly in a structured network (high density at 4 °C); ethylene has only weak van der Waals forces, allowing larger intermolecular spacing in the liquid. The molar volume of liquid ethylene at BP is 28.05/0.5677 = 49.4 mL/mol vs water 18.02/0.997 = 18.1 mL/mol.
At what temperature is ethylene a liquid?
Ethylene is a liquid only at cryogenic temperatures. The full liquid range spans from the triple point (T = −169.2 °C, P = 1.2 mbar) to the critical point (T = +9.2 °C, P = 50.4 bar). At standard room temperature (25 °C) and any pressure, ethylene cannot exist as a true liquid — above the 9.2 °C critical T it becomes a supercritical fluid. Atmospheric BP = −103.7 °C is the most common operating point for industrial liquid ethylene storage; high-pressure (~50 bar) storage at slightly elevated T (e.g. −10 °C) is also used but rarer.
How does liquid ethylene density change with temperature?
Density decreases monotonically with rising T, with steeper drop near the critical point. NIST REFPROP values for saturated liquid: 654 kg/m³ at −169 °C (TP) → 567.7 at −104 °C (BP) → 519 at −73 °C → 425 at −33 °C → 355 at −13 °C → 214 at +9 °C (CP). Rule of thumb: ρ falls ~3% per 10 °C rise near the BP; falls ~10% per 10 °C near the critical point. For precise off-BP work, use NIST REFPROP or the IUPAC ethylene equation of state.
How do I convert kg/m³ to g/mL or lb/ft³?
1 kg/m³ = 0.001 g/mL = 0.001 g/cm³ = 0.001 kg/L (factor of exactly 1000). 1 kg/m³ = 0.062428 lb/ft³ (lb/ft³ = kg/m³ × 0.062428). 1 kg/m³ = 0.0083454 lb/gal (US); 1 kg/m³ = 0.010022 lb/gal (UK / Imperial). Examples for liquid ethylene at BP: 567.7 kg/m³ = 0.5677 g/mL = 35.44 lb/ft³ = 4.738 lb/gal (US). The calculator displays all 5 unit systems simultaneously so you can pick whichever your reference document uses without manual conversion.
Is the density at the boiling point the same at all pressures?
Liquid ethylene density depends primarily on temperature; pressure has a small (≤1%) effect for sub-critical liquids. The 567.7 kg/m³ reference value is the SATURATED-LIQUID density at exactly 1 atm and the corresponding BP of −103.7 °C. Compressing liquid ethylene at constant T from 1 atm to 50 bar increases ρ by less than 0.5%; this is the basis of the "incompressible liquid" approximation in most engineering calculations. For storage at elevated P and T (e.g. 50 bar, +5 °C — close to the critical point), use NIST REFPROP for the precise ρ — pressure effects become significant near the critical point.
How do I compute the mass of ethylene in a cryogenic tank?
m = ρ × V. Workflow: (1) measure or read the tank volume V (in m³, L, gal, or whatever unit); (2) read the storage temperature; (3) look up ρ at that T from NIST REFPROP (or use 567.7 kg/m³ if at the 1-atm BP); (4) multiply. Example for 24,000 L = 24 m³ at BP: m = 567.7 × 24 = 13,625 kg = 13.6 tonnes. The calculator inverts this for QC: enter measured mass and volume → check if computed ρ matches the reference (within ±2% for typical commercial-grade liquid ethylene).
How is liquid ethylene shipped and stored industrially?
Two main approaches. (1) Refrigerated atmospheric (BP) storage: liquid at −104 °C and ~1.0-1.1 bar in vacuum-jacketed cryogenic tanks (like LNG tanks). Used for large-volume terminals (50,000-100,000 m³) and ISO-tank containers (20-25 m³). Reference density 567.7 kg/m³. (2) Pressurized storage: liquid at near-ambient T (5-15 °C) under 50-100 bar in thick-walled steel pressure vessels. Used for smaller volumes; less energy-intensive but limited tank size. Density falls to ~250-300 kg/m³ depending on T-P. Marine shipping: ethylene carriers (LEC) typically use refrigerated atmospheric storage with auxiliary cooling; smaller cargo uses pressurized cylinders.
What's the difference between ethylene, ethylene oxide, and ethanol?
Three distinct compounds. Ethylene (C₂H₄, ethene, MW 28.05): the polymer feedstock; gas at room T; liquid only at cryogenic T (BP −103.7 °C); ρ_liq = 567.7 kg/m³. Highly flammable. Ethylene oxide (C₂H₄O, oxirane, MW 44.05): a 3-membered-ring epoxide; liquid at room T (BP +10.7 °C); ρ = 882 kg/m³ at 10 °C. Highly toxic, mutagenic, carcinogenic. Used as sterilant and PE-glycol precursor. Ethanol (C₂H₆O, ethyl alcohol, MW 46.07): liquid at room T (BP +78.4 °C); ρ = 789 kg/m³ at 25 °C. Beverage alcohol and industrial solvent. Mixing these up has caused serious industrial incidents — the names are similar but the densities, hazards, and uses are completely different. Always check CAS numbers (74-85-1 ethylene, 75-21-8 ethylene oxide, 64-17-5 ethanol).
What are the main safety hazards of liquid ethylene?
Three main hazards. (1) Flammability: flash point −136 °C; autoignition 450 °C; flammable range 2.7-36 vol% in air; minimum ignition energy 0.07 mJ (extremely low — a static spark can ignite). Use intrinsically safe equipment, bond/ground transfer lines, ban smoking/open flames within 50 m. (2) Cryogenic burn / frostbite: liquid at −104 °C contacts skin → instantaneous tissue freezing. Required PPE: cryogenic-rated face shield, gloves, full sleeves, no exposed wrist gap. Never handle vessels barehanded. (3) Asphyxiation: ethylene displaces oxygen — at 12 vol% O₂ unconsciousness, at 6 vol% death within minutes. Use O₂ monitors in confined spaces. Boil-off vapor (~0.5 kg/m³) is heavier than warm air at first and pools at floor level before warming up. Never enter a confined space with possible ethylene leak without breathing apparatus. BLEVE risk: a pressurized liquid tank exposed to fire can rupture catastrophically — emergency depressurization or water-spray cooling required.

Author Spotlight

The ToolsACE Team - ToolsACE.io Team

The ToolsACE Team

Our ToolsACE chemistry team built this calculator to handle the cryogenic-cargo, polymer-feed, and laboratory measurement workflows that need an accurate <strong>liquid ethylene density</strong>. Ethylene (C₂H₄, MW 28.05 g/mol) is the highest-volume petrochemical in the world (>200 Mt/yr global production), and it is shipped and stored as a liquid at cryogenic temperatures. The fundamental identity is <strong>ρ = mass / volume</strong>; the calculator accepts mass in kg / g / mg / lb / oz / metric tons and volume in L / mL / m³ / cm³ / ft³ / US gal / UK gal, then reports density in <strong>kg/m³ (SI), g/mL = g/cm³, kg/L, lb/ft³, and lb/gal</strong>. Each result is compared against the <strong>NIST reference density of 567.7 kg/m³ at the 1-atm boiling point (−103.7 °C)</strong> with an explicit % deviation. Smart warnings flag unphysical densities (gas-like &lt; 200 kg/m³, water-exceeding &gt; 1000 kg/m³) and densities outside the liquid range (between 654 kg/m³ at the triple point 104 K and ~217 kg/m³ near the critical point 282.4 K).

NIST Chemistry WebBook (NIST Standard Reference Database 69)CRC Handbook of Chemistry and PhysicsStandard cryogenic engineering references

Disclaimer

Density ρ = mass / volume. Liquid ethylene (C₂H₄) exists only between its triple point (−169.2 °C, 1.213 mbar) and critical point (+9.20 °C, 50.42 bar); above the critical point ethylene is supercritical, not a true liquid. Reference density 567.7 kg/m³ at the 1-atm BP (−103.7 °C); density varies strongly with T (654 at TP → 214 at CP). Use NIST REFPROP for off-BP T-dependent reference values. Liquid ethylene is highly flammable (LEL 2.7%, MIE 0.07 mJ — extremely low ignition energy) and a simple asphyxiant; cryogenic contact causes severe frostbite. Never confuse with ethylene oxide (C₂H₄O, 882 kg/m³, toxic carcinogen) or ethanol (C₂H₆O, 789 kg/m³). References: NIST Chemistry WebBook (Lemmon, McLinden, Friend); IUPAC International Thermodynamic Tables — Ethylene; CRC Handbook of Chemistry and Physics.