Safety Distance Calculator (ISO 13855)

Free Engineering Tool

Calculate the minimum mounting distance between a safety light curtain and the hazard zone. Based on IEC/ISO 13855:2010 — the international standard for positioning safeguards relative to human approach speeds.

S = K × T + C

S = Minimum safety distance (mm)

K = Approach speed: 2,000 mm/s (hand/arm), 1,600 mm/s (whole body)

T = Total system response time = light curtain response + machine stopping time

C = Penetration allowance: 8×(d−14) mm for d ≤ 40 mm; 850 mm for d > 40 mm

where d = detection capability (resolution) of the light curtain in mm

Enter Your Parameters

ENT Model (Resolution)

Approach Type

Light Curtain Response Time (ms)

ENT range: 6.0–30.8 ms (varies by beam count)

Machine Stopping Time (ms)

Typical: 50–500 ms — verify with machine manufacturer

ISO 13855 Result

Minimum Safety Distance

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Total Response (T)

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Penetration (C)

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This calculator provides reference values per ISO 13855:2010. Always verify with your machine’s actual stopping performance measurement and a qualified safety engineer before finalizing installation. Machine stopping time must be measured, not estimated.

Worked Example: ENT-14 on a Mechanical Press

Configuration: ENT-14 with 32 beams (resolution d = 14 mm), light curtain response time = 10.2 ms, machine braking time = 100 ms.

S = 2,000 × (0.0102 + 0.100) + 8 × (14 − 14) = 2,000 × 0.1102 + 0 = 221 mm

At 221 mm from the press opening, the ENT-14 provides finger-level detection while allowing comfortable operator reach. A competitor unit with a 12 ms response time would require 244 mm for the same press — every millisecond of response time adds 2 mm of required safety distance at hand approach speed.

Quick Reference: Common Configurations

Application	Model	Machine Stop	Safety Distance
Mechanical press (fast stop)	ENT-14	80 ms	181 mm
Mechanical press (typical)	ENT-14	150 ms	321 mm
Hydraulic press (hand guard)	ENT-25	200 ms	509 mm
Press brake (near-distance)	ENT-14	50 ms	121 mm
Robotic cell (body detection)	ENT-45	300 ms	1,347 mm

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