ANSI B151.1-2017 pdf download.Safety Requirements for Injection Molding Machines
7.4.4.2 Stop function
Each IMM shall be equipped with either a Category 0 or Category 1 stop. Category 0 and Category 1 stops shall be operational regardless of operating modes. The stop function shall operate by de-energizing that relevant circuit and shall override related start functions. For a Category 0 stop that results in uncontrolled stopping, the access time to the hazardous area shall be: (a) greater than the stopping time; or (b) prevented by guard locking device until standstill has been detected. Where required, provisions to connect safeguarding devices and interlocks shall be provided. Where applicable, the stop function shall signal the logic of the control system that such a condition exists. The reset of the stop function shall not initiate any hazardous conditions.
7.4.4.3 Emergency stop
Emergency stop shall be initiated by a single human action. In addition to the requirements in 7 .4.4.2 for stop functions, emergency stops shall meet the following requirements:
a) it shall override all other functions and operations in all modes;
b) power to the machine actuators, which causes a hazardous condition(s)， shall be removed as quickly as possible without creating other hazards (e.g，by the provision of mechanical means of stopping requiring no external power, by reverse current braking for a Category 1 stop);
c) reset of an emergency stop circuit shall not initiate a restart;
d) it shall function as either a Category 0 or a Category 1 stop. Where a Category 0 stop is used for the emergency stop function and provided by other than the main disconnecting means, it shall have only hardwired electro-mechanical components. Where a Category 0 or a Category 1 stop is used for the emergency stop function, final removal of power to the machine actuators shall be ensured and shall be by means of electro- mechanical components; Exception: Electronic logic (hardware or software) that meets NFPA 79 requirements can also be used.
e) emergency stop pushbuttons shall be located at each operator control station or where motion can be initiated and at other locations where emergency stop is required;
f) pushbutton-type devices for emergency stop shall be of the self-latching type and shall have positive (direct) opening operation.
g) emergency stop devices shall not be flat devices or graphic representations based on software applications; .
h) It shall not be possible to restore an emergency stop circuit until the emergency stop device has been manually reset. Where several emergency stop devices are provided in a circuit, it shall not be possible to restore that circuit until all emergency stop devices that have been operated have been reset;
i) actuators of emergency stop devices shall be colored RED. The background immediately around pushbuttons and disconnect device actuators used as emergency stop devices shall be colored YELL OW. The actuator of a pushbutton-operated device shall be of the palm or mushroom-head type. The RED/YELLOW color combination shall be reserved exclusively for emergency stop applications.
7.4.6 Interlocks
Safeguarding devices incorporated into safety circuits in accordance with Type I, II and II described below shall be used as specified in the relevant sub-clauses. Alternatively, the safety related parts of the control systems shall be in accordance with the required performance levels (PLr) as specified in a documented risk assessment. If the principles of safety circuits specified below are applied, the calculation of the PL achieved is not required. Resetting a safeguarding device of the safety related parts of the control system in or of itself shall not restart the machinery or cause a hazardous situation. The integrity of the safety reset function shall be consistent with the risk assessment for single or multiple reset devices. When electromechanical components are used to meet the following requirements, the main shut-off device, as well as the position sensor, shall be proven in use or well-tried components.ANSI B151.1-2017 pdf download
