Banner EZ-SCREEN­ Safety Light Curtain Systems - Manual (Page 8)

Examples: Appropriate Applications
EZ-SCREEN Type 2 are typically used, but is not limited to, the following applications (dependent on machine risk assessment):
• Small assembly equipment
• Automated production equipment
• "Table-top" robotic work cells
• Component insertion/"pick-and-place" machines
• Small packaging machines
• Equipment and process protection (non-personnel safety
• Applications that could result in only slight (normally reversible) injuries (such as bump, bruise, knock-down, trapping but not crush-
ing, minor cuts and abrasions, etc.)
Examples: Inappropriate Applications
EZ-SCREEN Type 2 may NOT be used with the following machinery or inappropriate applications:
• As a primary safeguard in frequently accessed hazardous situations that could result in serious injuries (normally irreversible, includ-
ing death).
• In any case where Control Reliability, Category 3, Category 4, or Type 4 AOPD (active opto-electronic protective device) have been
mandated. See EN ISO 13849-1, IEC 61496-1, or other appropriate standard.
• Any machine that cannot be stopped immediately after a stop signal is issued, such as single-stroke (or “full-revolution”) clutched
machinery.
• Any machine with inadequate or inconsistent machine response time and stopping performance.
• Any machine that ejects materials or component parts through the defined area.
• In any environment that is likely to adversely affect photoelectric sensing efficiency. For example, corrosive chemicals or fluids or
unusually severe levels of smoke or dust, if not controlled, may degrade sensing efficiency.
• As a tripping device to initiate or reinitiate machine motion (PSDI applications), unless the machine and its control system fully comply
with the relevant standard or regulation (see ISO 12100-2, IEC 60204-1, IEC 61496-1, or other appropriate standard).
If an EZ-SCREEN Type 2 is installed for use as a perimeter guard (that is, where a pass-through hazard may exist), the dangerous
machine motion can be initiated by normal means only after the safeguarded area is clear of individuals and the EZ-SCREEN Type 2 has
been manually reset.
Control Reliability and Safety Categories
To summarize the expected safety circuit performance in high-risk situations, requirements of Control Reliability (OSHA 29CFR1910.217,
ANSI B11.19, and ANSI/RIA R15.06) and Category 3 and Category 4 (EN ISO 13849-1) demand that a reasonably foreseeable, single
failure does not lead to the loss of the safety function, and does not prevent a normal or immediate stop from occurring. The failure or the
fault must be detected at or before the next demand of safety (e.g., at the beginning or end of a cycle, or when a safeguard is actuated).
The safety-related part of the control system then must issue an immediate stop command, or prevent the next machine cycle or hazard-
ous situation until the failure or fault is corrected.
The effect of ANSI/RIA R15.06, ANSI B11.19, and EN ISO 13849-1 is to set a baseline for situations in which a minimum level of per-
formance has been mandated or in cases where a risk assessment has determined a need for Control Reliability, Category 3 or Category
4 level of performance.
In lower-risk safety applications, safeguards and safety circuits do not require the level of performance and fault tolerance described by
Control Reliability, Category 3 or Category 4. Applications involving situations that could result in a slight or normally reversible injury
(e.g., only requiring first aid, as defined by OSHA 29CFR1904) can be solved by EN ISO 13849-1 Category 2.
EN ISO 13849-1 Category 2 does not require the same level of performance and fault tolerance as required by Control Reliability, Cate-
gory 3 or Category 4. Safety-related parts of control systems designed to Category 2 “shall be designed so that their function(s) are
checked at suitable intervals by the machine control system.” This allows a single fault to lead to the loss of the safety function between
the check [test] of the system, but the loss of safety function is detected by the check. By comparison, in a system designed to EN ISO
13849-1 Category 4, a single fault or an accumulation of faults will not lead to a loss of the safety function.
While EN ISO 13849-1 generally applies to the machine level, IEC61496-1/-2 specifies requirements for the design, construction and
testing for two levels or “types” of active opto-electronic protective devices (AOPDs) or light curtains (light screens). “Type 2” and “Type
EZ-SCREEN® Type 2 Light Screen Instruction Manual
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