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Thread Finder

Enter a caliper measurement and, if you have it, the thread pitch / TPI and seal clue. The tool ranks candidate threads from the Armadillo dataset (13 families, 90+ sizes).

SOFT soft seal   MECH mechanical seal
Tapered threads (BSPT / NPT) change diameter along their length - always confirm taper and, where possible, mate against a known coupling before replacing.

Soft-Seal vs Mechanical-Seal Selector

Pick a thread family to see exactly how it seals, what the mating half needs, and whether a soft element (O-ring / bonded seal / washer) or a metal-to-metal (mechanical) contact does the sealing.

Quick reference - how each connection seals

FamilySeal methodTypeSeat / element

Cylinder Calculator bore & rod side

Enter cylinder geometry and duty. Outputs are computed for both the bore (full piston) side and the rod (annulus) side. Choose metric or imperial units per field - switching a unit auto-converts the value. Defaults are pre-filled for a quick start.

ResultBore sideRod sideUnit
Area
Volume
Force
Time (full stroke)sec
Velocity
Outflow
Ratio (bore : rod): 1
Area = pi x R^2 (bore), pi x (R^2 - r^2) (rod) · Volume = Area x stroke · Force = Pressure x Area · Time = Volume / oil flow · Velocity = stroke / Time · Outflow = flow / ratio (bore), flow x ratio (rod) · Ratio = Area(bore) / Area(rod). Theoretical values - real output is ~10-15% lower after friction & back-pressure.

Fluid Power Calculators pump · motor · line velocity

Standard hydraulic formulas. Choose metric or imperial units per field - switching a unit auto-converts the value. Results show metric first. Press each button to calculate.

Cylinder force (push / pull)

Cylinder speed / required flow

Pump input power

Motor torque & output power

Oil velocity in line

Pump output flow

Recommended oil velocities: pump suction 0.6-1.5 m/s, pressure lines 2.2-4.5 m/s, return lines 3-4.5 m/s. Real cylinder output runs ~10-15% below theoretical after friction & back-pressure.

Flow Rate Nomograph flow + dash size → velocity

Enter the flow rate and select the hose dash size. The tool draws the line across the nomograph and reads off the resulting fluid velocity, with a safe-range check and estimated pressure drop.

Guide only - based on the viscosity of normal hydraulic fluids. Recommended velocity: pressure lines 2.2-4.5 m/s; suction & return lines 0.58-1.5 m/s. Pressure-drop estimate uses Darcy-Weisbach for a smooth hose, assuming oil density 870 kg/m3 and viscosity 32 cSt (ISO VG32 at ~40C). Velocity = flow / bore area, using SAE nominal hose IDs.

Reference Tables

Full thread-dimension tables loaded into the finder. Dash size, male OD, female ID, pitch/TPI and seal type.

Hydraulic hose dash sizes (SAE nominal ID)

Dash number = nominal ID in sixteenths of an inch.

DashFractionNominal ID (in)Nominal ID (mm)

TPI to pitch (mm) - thread gauge chart

TPI28272420191816141211.5118
Pitch mm0.910.941.061.271.341.411.591.812.122.212.313.18

How to Measure & Identify (5-step method)

  1. Investigate - check for markings and country of origin. Europe -> DIN/BSP; USA -> NPT/JIC/UNO/ORFS; UK/AU -> BSP; Japan -> JIS.
  2. Visual inspection - parallel or tapered threads? O-ring or washer seal present? Cone seat concave or convex?
  3. Measure threads - caliper the OD of male / ID of female threads. Use a thread gauge for TPI, or measure crest-to-crest pitch, or count threads in 1/4 inch x 4.
  4. Seat angle - use a seat gauge (some fittings have dual 37/45 deg seats).
  5. Conclude - match every criterion (diameter + pitch + seat type + angle). Final check: mate against a known coupling.

1. Measure male thread OD

OD across the crests (outside) of the male thread

Close the caliper jaws over the outside of the male threads. Record the largest diameter (the thread crests).

2. Measure female thread ID

ID across the roots (inside) of the female thread

Use the inside jaws of the caliper across the female port. Record the diameter at the thread roots (the widest inside measure).

3. Measure pitch / count TPI

pitch count threads in 25.4 mm (1 inch) = TPI

Either measure crest-to-crest (pitch, mm) or count the number of thread crests in one inch (TPI). A thread gauge is quickest.

4. Identify the seat / sealing angle

37/45 flare metal cone 24/30 cone DIN / JIS flat / ORFS soft O-ring

Check the seat with a gauge: a metal cone (37/45 flare or 24/30 cone) seals mechanically; a flat face with an O-ring is a soft seal.

BSP, Metric, American and Japanese sizes can look almost identical - you must match all criteria (diameter + pitch + seat type + angle), not just diameter. Diagrams are schematic guides only.
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