ANSI/SPI B151.21-2003 - "Safety Requirements for Manufacture, Care and Use of Injection Blowmolding Machines"

Q: Is a blowmolding machine that has safety gates covered with expanded metal, as opposed to a solid plastic covering, in violation of this standard? In other words, does this provision mean that the covering must conform to ANSI Z97.1 (1) only when you choose to use a transparent piece of plastic, or (2) when there is any "opening" in the safety gates? Phrased another way, how is "window" interpreted in this provision--does window mean (1) a transparent covering or (2) any opening?

A: (1) A physical guard shall be used, whether it be a "lexan" (solid) or expanded metal guard. This addressed the conditioning of the articles being produced--process and cooling controls. The manufacturer, remanufacturer, or modifier determines which is appropriate (including safety) for the intended process. (2) Window means a transparent covering.

Clause 5.3.1.4 Emergency Conditions: "Activation of the Emergency Stop device shall initiate stopping and opening of the driven rolls provided that this does not create additional hazards." Clause 5.5.2 Power Loss: "Power loss shall not initiate hazardous machine motion. Restoration of power shall not restart the machine."

Q: If a power loss occurs, should driven rolls open automatically?

A: A loss of power should initiate an Emergency Stop. It is reasonable to interpret the standard as treating a power loss in the same way as an Emergency Stop with regard to opening the rolls, as described in clause 5.3.1.4. However, the roll opening time (clause 5.3.1.4.1) and stopping distance (clause 5.3.1.4.2), specified for an Emergency Stop, may not be achievable in a power loss condition due to the lack of power to control the motion.