AnnotaCalc — Engineering Glass Edition

01 / THE EVERYDAY ESSENTIAL

Every unit.
One clear answer.

From quick conversions to considered engineering decisions.

40 unit categories

Area, volume & surface area

All common 2D and 3D shapes. Choose the length unit, enter dimensions, results update live.

Length Unit

2D shapes — area & perimeter

3D shapes — volume & surface area

CSTR vessel volume & wetted area

Vertical cylindrical vessel with dished heads — compute total volume, head dimensions and wetted surface for thermal sizing.

Tank Diameter D (m)

Straight Side Length L (m)

Head Type

Number of Heads

Liquid Level (m)

Head depths: 2:1 ellipsoidal = D/4, torispherical ≈ 0.169D, hemispherical = D/2, conical 30° = D/(2·tan30°). Torispherical volume factor ≈ 0.0809D³. Wetted area at partial liquid levels is approximate.

Pipe & tubing chart — vessel fill / drain

Pipe data (NPS 1/2–24, Sch 10–XXS) plus instrument tubing (1/8–1" OD, ASTM A269 walls) — reference chart, fill/drain sizing and velocity limits.

Type

Schedule

Design Velocity (m/s)

Vessel Volume V (m³)

Desired Fill / Drain Time (min)

Velocity Guidelines (liquid)

Pump suction: 0.4–1.5 m/s Gravity / drain: 0.3–1.2 m/s Pumped liquid: 1–3 m/s Waxy/slurry: 0.5–1.5 m/s Steam: 25–40 m/s Gas / air: 10–30 m/s

Pipe reference chart

Columns update for the selected schedule. Capacity shown at the selected design velocity.

ASME BPVC Sec.VIII Div.1 — minimum thickness

UG-27 (cylindrical shells) & UG-32 (heads) internal-pressure equations with typical allowable stresses.

Units

Design Pressure P

Design Temperature

Temp Unit

Vessel Inside Diameter D

Corrosion Allowance CA

Material

Component / Formula

Joint Efficiency E (UW-12)

Design aid only. Equations assume D/t ≥ 10, internal pressure only (no external pressure/vacuum). Typical allowable stresses from ASME II-D; always verify against the current Code edition and certified material data.

CSTR baffle calculation

Standard baffle sizing for agitated vessels — baffle width, wall clearance, off-bottom clearance and count.

Tank Diameter D (m)

Liquid Height H (m)

Number of Baffles

Application

Rule of thumb: baffle width w = D/10 (range D/12–D/8), wall gap ≈ 0.1w, off-bottom ≈ 0.25–1.0w. Baffles are only effective for axial/radial turbulent impellers (PBT, Rushton, hydrofoil). Do NOT use baffles with anchor or helical-ribbon impellers (laminar regime creates dead zones).

Agitator & impeller selection for CSTR

Auto-select impeller from application & viscosity, size impeller, speed, Reynolds, power and motor.

Tank Diameter D (m)

Liquid Height H (m)

Liquid Density ρ (kg/m³)

Viscosity μ (cP)

Application

Impeller Reference Table

Power estimated with turbulent power numbers (Np). In laminar regime (Re<10) for anchor/helical, P ≈ 300·μ·N²·d³. Motor sized to next standard rating. Tip-speed & P/V ranges are typical engineering guidelines.

Solids Suspension — Zwietering Correlation (just-suspended speed Njs)

Solids wt% (of slurry)

Particle size d_p (mm)

Solids density ρs (kg/m³)

S factor (geometry)

Impeller diameter (m)

Njs = S·(ν^0.1·d_p^0.2·(g·Δρ/ρ)^0.45)·X^0.13 / D_i^0.85. X = kg solids/kg liquid (basis; derived from wt%), ν = kinematic viscosity m²/s, D_i = impeller diameter m. S≈4–5 for axial turbines in fully baffled tanks with impeller clearance ≈ D_i; higher (6–7+) for poor geometry. Typical design margin N ≥ 1.15–1.3× Njs.

Rigorous Mixing — Blending Time & Intensity

Impeller type

Design speed N (rpm)

Tank D (m)

Liquid H (m)

ρ (kg/m³)

μ (cP)

Turbulent, fully-baffled: axial blend-time constant C≈5.2 (t95 = C/N when D/T ≥ 0.33), radial C≈18–30. For D/T < 0.33 blend time increases roughly as (T/D)². Mixing intensity targets: gentle 0.1–0.3 kW/m³, blending 0.3–1, solids suspension 1–2, gas dispersion 2–4 kW/m³.

Scale-Up (Constant P/V) & Motor Power Detail

Lab impeller D1 (m)

Lab speed N1 (rpm)

Plant impeller D2 (m)

Gearbox efficiency (%)

Line size & pressure drop

Darcy-Weisbach hydraulic design — velocity, Reynolds, friction factor, fitting losses, elevation, auto-size and pump-head contribution.

Fluid

Mass Flow (kg/h)

Density ρ (kg/m³)

Viscosity μ (cP)

Type

Sizing Mode

NPS

Schedule

Roughness (mm)

Max velocity (m/s)

Max ΔP/100m (bar)

Line Length (m)

Elevation rise (m)

90° LR elbows

Tees (through)

Gate valves

Globe valves

Check valves

K-factors: LR 90° elbow 0.6, tee (through) 0.6, gate valve 0.2, globe valve 6.0, swing check 2.5. Friction factor from Haaland explicit approximation of Colebrook-White. Gas results assume incompressible flow — valid when ΔP < ~10% of P1.

Electric & fired heater sizing

Heat-up / maintain / process duty → immersion element length, pad heater area, or furnace firing rate.

Duty basis

Liquid volume (m³) / flow

Density ρ (kg/m³)

Heat capacity Cp (kJ/kg·K)

ΔT (K)

Heat-up time (h)

Heater type

Electrical efficiency (%)

Safety margin (%)

Loss U·A (W/K)

Element OD (mm)

Watt density (W/cm²)

No. elements

Supply (V)

Phase

Watt-density (W/cm²) guide: water 1.5–2.5 • light oils 1.0–1.5 • heavy oils 0.4–0.8 • air/gas <1.0 • flowing water up to 5. Heated length/element = P/(π·OD·Wd·n) plus cold leads (~150 mm each end). Flammable pad-heater service: ≤4 kW/m² ATEX-rated. Furnace: fuel = P×3600/(LHV×η).

Control valve sizing — ISA-75.01 / IEC 60534-2-1

Cv for liquid (flashing/choked check) and gas/steam (compressible, Y-expansion), with cavitation flags and valve size estimate.

Service

Flow (m³/h)

Density ρ (kg/m³)

P1 (bar_a)

P2 (bar_a)

Mass flow (kg/h) [gas]

Molecular weight

T (°C)

Z

k = Cp/Cv

Vapor press Pv (bar_a)

Critical press Pc (bar_a)

Pressure recovery F_L

x_T (terminal)

Piping geometry F_p

Pressure recovery: F_L ≈ 0.9 globe, 0.85 angle, 0.55–0.65 butterfly/ball, 0.35 eccentric plug. x_T ≈ 0.7 globe, 0.35–0.6 rotary. Cavitation risk when ΔP > F_L²(P1−Pv); severe when Kc=ΔP/(P1−Pv)>0.9.

Flange pressure class — ASME B16.5

Screen a standard forged flange class against design pressure and metal temperature. Ratings depend on the exact material group, not just the class number.

Flange material / group

Nominal pipe size

Design pressure (bar_g)

Design metal temperature (°C)

Uses published ASME B16.5 material-group pressure/temperature ratings with the next-higher listed temperature, without interpolation. For screening only: verify the current licensed standard, exact alloy/heat treatment, design code, gasket/bolting, joint integrity, corrosion, temperature limits and any vendor restrictions before specification. Class 2500 is available here only through NPS 12. ASME B16.5 scope ↗ · Published rating tables ↗

Pressure safety valve sizing — API 520 / 521

Preliminary relief-area screening for gas, liquid, dry steam, external fire and thermal expansion. Select the credible cause first, then enter its independently established relief load.

Credible overpressure cause

Sizing route

Relief load W (kg/h)

Set pressure (bar_g)

Allowed overpressure (%)

Relieving temperature (°C)

Molecular weight (kg/kmol)

Liquid specific gravity

Total backpressure (bar_a)

k = Cp/Cv

Compressibility Z

Gas / steam Kd

Liquid Kd

Backpressure corr Kb

Rupture disc Kc

Steam superheat Ksh

Liquid backpressure Kw

Liquid viscosity Kv

Externally calculated loadBlocked outlet, valve failure, tube rupture, blowby, utility/power failure and overfill need a separate dynamic or steady-state load study. Enter the governing relieving load above.

Fire and thermal expansionThese routes calculate a screening load from wetted area or heat input. Confirm geometry, insulation, drainage/firefighting credit and liquid properties.

Specialist casesFlashing, two-phase, foaming, runaway reactions, polymerization and supercritical fluids need validated phase behavior and certified mass flux. This tool does not infer it.

This is a screening calculation, not a code-certified PSV specification. Confirm credible scenarios, coincident cases, accumulation allowance, relieving conditions, certified Kd/Kb/Kw/Kv/Ksh, inlet loss, backpressure, discharge piping and manufacturer certified area/capacity with a qualified relief-system engineer. Gas uses ideal-gas isentropic critical/subcritical flow; liquid assumes incompressible non-flashing flow. Steam uses the API 520 saturated-steam equation only up to 1500 psia and requires a validated Ksh. Two-phase requires independently validated mass flux. API 520 ↗ · API 521 ↗ · LESER sizing handbook ↗

Rupture disc sizing — general & fire case

Same API basis with disc discharge coefficient Kd≈0.62; no backpressure or Kb correction (burst independent of downstream).

Relief case

Relief load W (kg/h)

Burst pressure (bar_g)

Overpressure (%)

Temp T (°C / K)

Mol wt M

k

Z

Coeff Kd

Sp. gravity (liquid)

Backpressure (bar_a)

Vessel D (m)

Max liquid height (m)

Head shape

Env. factor F

Latent heat (kJ/kg)

Kd 0.62 typical (vendor range 0.61–0.68). Liquid overpressure normally 10–25%. Rupture discs respond to burst (not backpressure), so Kb = 1 always. Check manufacturer venting coefficient (Kv) for disc + SA-vent combinations. Fire case uses the same 21,000·F layout equation as PSV with a disc instead of a spring SRV.

Packed bed design — pressure drop

Ergun (granular catalyst beds) and Generalized Pressure Drop Correlation / GPDC (random & structured packing) with flood check and tower sizing.

Type

Sup. velocity u (m/s)

Gas ρ (kg/m³)

Gas μ (cP)

Particle d_p (mm)

Bed voidage ε

Bed height (m)

Gas flow (Nm³/h)

Gas ρ (kg/m³)

Liquid flow (m³/h)

Liquid ρ (kg/m³)

Liquid μ (cP)

Packing

Tower D (m) [0 = auto @ 70% flood]

Bed height (m)

Ergun: ΔP/L = 150(1−ε)²/ε³·μu/d_p² + 1.75(1−ε)/ε³·ρu²/d_p. GPDC: flow param X = (L/G)√(ρG/ρL); Y = G²Fpμ^0.1/(ρGρL g). Flood line fit Yf = 10^(−1.668−1.085X−0.297X²); design ≤70–80% flood (approx ΔP 0.3–1.0 in H&sub2;O/ft). Packing factors are approximate — confirm with vendor. 70% flood ≈ 0.6 in H&sub2;O/ft.

Insulation thickness — hot & cold

Radial-conduction solution with external convection: cap surface temperature (safety) or limit heat loss (hot); prevent condensation (cold).

Service

Pipe OD (mm)

Process temp (°C)

Ambient (°C)

External h (W/m²K)

Material

Max surface temp (°C)

Max heat loss (W/m) [0 = none]

Ambient dew point (°C)

Conduction through single-layer cylindrical insulation + surface convection/radiation (h default 9 W/m²K still air). For cold service use vapor-tight closed-cell materials (PUF/PIR/cellular glass/elastomeric) with sealed joints; surface must stay ≥ dew point +0.5 K to avoid condensation. k values are typical at ~50°C mean — confirm with manufacturer.

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Every unit.
One clear answer.

Area, volume & surface area

2D shapes — area & perimeter

3D shapes — volume & surface area

CSTR vessel volume & wetted area

Pipe & tubing chart — vessel fill / drain

Velocity Guidelines (liquid)

Pipe reference chart

ASME BPVC Sec.VIII Div.1 — minimum thickness

CSTR baffle calculation

Agitator & impeller selection for CSTR

Impeller Reference Table

Solids Suspension — Zwietering Correlation (just-suspended speed Njs)

Rigorous Mixing — Blending Time & Intensity

Scale-Up (Constant P/V) & Motor Power Detail

Line size & pressure drop

Electric & fired heater sizing

Control valve sizing — ISA-75.01 / IEC 60534-2-1

Flange pressure class — ASME B16.5

Pressure safety valve sizing — API 520 / 521

Rupture disc sizing — general & fire case

Packed bed design — pressure drop

Insulation thickness — hot & cold

Every unit.One clear answer.

Area, volume & surface area

2D shapes — area & perimeter

3D shapes — volume & surface area

CSTR vessel volume & wetted area

Pipe & tubing chart — vessel fill / drain

Velocity Guidelines (liquid)

Pipe reference chart

ASME BPVC Sec.VIII Div.1 — minimum thickness

CSTR baffle calculation

Agitator & impeller selection for CSTR

Impeller Reference Table

Solids Suspension — Zwietering Correlation (just-suspended speed Njs)

Rigorous Mixing — Blending Time & Intensity

Scale-Up (Constant P/V) & Motor Power Detail

Line size & pressure drop

Electric & fired heater sizing

Control valve sizing — ISA-75.01 / IEC 60534-2-1

Flange pressure class — ASME B16.5

Pressure safety valve sizing — API 520 / 521

Rupture disc sizing — general & fire case

Packed bed design — pressure drop

Insulation thickness — hot & cold

Every unit.
One clear answer.