Safety Light Curtain Distance Calculator

Work out safety light curtain distance instantly with clear inputs, formula shown and shareable results.

About Safety Light Curtain Distance Calculator

The minimum distance formula S = K x T + C combines how far a hand travels while the machine stops with a penetration allowance for the curtain's resolution. K is 1600 mm/s for hand approach, T is the sum of detection, control and machine stopping times, and C is 8 x (resolution - 14) for curtains coarser than 14 mm.

Formula

Minimum distance

S = K x T + C

K: 1600 mm/s hand approach, 2000 mm/s for short distances
T: Total response plus stopping time
C: 8 x (resolution - 14), zero for resolution 14 mm or finer

Worked example

With the default values below, Safety Light Curtain Distance Calculator returns Minimum safety distance of 496. Change any input above and every figure here is recalculated in your browser.

Inputs used

Machine stopping timeminimum 1 ms: 200 ms
Light curtain and control response timeminimum 1 ms: 30 ms
Curtain resolutionminimum 5 mm: 30 mm
Assumed approach speedminimum 100 mm/s: 1,600 mm/s

Results

Minimum safety distance: 496 mm
Depth penetration factor C: 128.0 mm
Total system response time: 230 ms
Hand travel during the stop: 368.0 mm

Step by step

1Values used
2Minimum distance
3Minimum safety distance= 496 mm
4Depth penetration factor C= 128.0 mm
5Total system response time= 230 ms
6Hand travel during the stop= 368.0 mm

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Preliminary estimate only. Safety distance calculation must follow the applicable standard, use validated stopping time measurements and be verified by a competent person.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Preliminary estimate only. Safety distance calculation must follow the applicable standard, use validated stopping time measurements and be verified by a competent person.

Frequently Asked Questions

How is the Safety Light Curtain Distance figure worked out?

S = K x T + C. The minimum distance formula S = K x T + C combines how far a hand travels while the machine stops with a penetration allowance for the curtain's resolution.

Why does resolution affect the distance?

A coarse curtain does not detect a finger until it is some way past the beam plane. The C factor accounts for that undetected penetration before the stop is triggered.

What values do I need to enter?

This calculator takes 4 inputs: Machine stopping time, Light curtain and control response time, Curtain resolution, Assumed approach speed. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.