Master ISO 13857: Core Guidelines for Machinery Safety Distances | SICK Academy

Preface

Safety distances are designed to prevent operators from reaching hazardous zones under specific working conditions. Whether for global & domestic compliance or physical protection of staff limbs, configuring safety distances in accordance with ISO 13857 is an indispensable step in machinery risk reduction.This article systematically interprets the definition rules and practical field applications of safety distances specified by ISO 13857.

1. Standard Basics: What Is ISO 13857?

ISO 13857:2019 Safety of machinery — Safety distances to prevent hazard zones being reached by upper and lower limbs is a dedicated international standard for defining safety distances in machinery protection. Its identical domestic counterpart is GB/T 23821-2022.

Core Functions of the Standard

1. Specify standardized safety distance values for guard structures to block upper/lower limbs from hazardous zones, covering industrial and non-industrial environments.

2. Provide distance requirements to stop lower limbs from freely entering danger areas.

3. Apply to personnel aged 14 and above, matching most industrial workforce scenarios.

Nature of Safety Distances

Safety distances create physical separation between protective barriers and hazardous zones to eliminate limb contact risks. They serve as critical executable measures to mitigate risks after machinery risk assessment.

2. Full-Scenario Application Rules of Safety Distances

2.1 Overhead Reach Protection

Scenarios are categorized by hazardous zone height:

• High-risk condition: Hazard zone height ≥ 2700 mm

• Low-risk condition (low injury severity & low occurrence probability): Hazard zone height ≥ 2500 mm

2.2 Reaching Over Protective Structures

Three critical parameters must be matched simultaneously:

• hh: Height of the nearest hazardous point accessible by upper limbs

• hps: Height of protective structure

• Sh: Horizontal safety distance to the nearest hazardous point accessible by upper limbs

Parameter Selection Principles

1. If calculated values fall between table figures, adopt a larger safety distance, taller guard structure or adjusted hazardous zone height; interpolation between listed values is forbidden.

2. Additional protective measures are mandatory if the protective structure height is less than 1400 mm.

2.3 Restricted Curved Reach

Safety distances are determined based on limb support positions:

• Only shoulder & armpit restricted movement: ≥ 850 mm

• Arm supported up to elbow: ≥ 550 mm

• Arm supported up to wrist: ≥ 230 mm

• Arm & hand supported up to knuckles: ≥ 130 mm

2.4 Reach Through Openings

Classified by opening dimensions (square side / circle diameter / slot width):

• Finger access (e ≤ 4 mm): Safety distance ≥ 2 mm

• Hand access (10

• Arm & shoulder access (30

Special provision for slots: If slot length ≤ 65 mm to block thumb penetration, the minimum safety distance can be reduced to 200 mm.For irregular openings: Use the minimum value of equivalent circle diameter, square side width or slot width as the judging benchmark.Warning: Slots wider than 180 mm, square/circle openings larger than 240 mm allow full-body entry and require complete enclosure guards.

2.5 Lower Limb Reach Protection

Only applicable when upper limbs cannot reach the opening:

• Toe access (e ≤ 5 mm): Safety distance = 0 mm

• Full foot access (35

• Leg access (toe to hip, 95

3. Practical Calculation Cases for Safety Distance Verification

Case 1: Calculate guard height hps with known hh & Sh

Assumptions:

• Hazard zone height hh = 1500 mm

• Horizontal safety distance Sh = 800 mmCalculation Steps:

1. Select the next higher listed hh value (1600 mm, safer than 1400 mm for 1500 mm actual height)

2. Confirm Sh = 800 mm

3. The corresponding required protective structure height hps = 1800 mm

Case 2: Calculate horizontal safety distance Sh with known hh & hps

Assumptions:

• Hazard zone height hh = 2300 mm

• Protective structure height hps = 1500 mm(Table lookup to obtain qualified horizontal safety distance per standard data)

4. SICK’s Professional Capability in Machinery Risk Assessment

As a global leading supplier of sensor and safety solutions, SICK Safety Service delivers full-lifecycle services including risk assessment, safety concept design, installation commissioning and final compliance verification. We have 115 certified risk assessment engineers providing worldwide support.

Risk assessment is not just a document for audits; it is the primary safeguard for operator safety and legal compliance evidence for manufacturers.

We support equipment manufacturers, system integrators and end-users with these typical demands:✅ Complete risk assessment to meet CE certification for new machinery✅ Safety validation after equipment retrofits✅ Formal risk assessment reports for customer factory audits✅ Plant-wide systematic machinery safety upgrading