These are excerpts from the OSHA guidelines that require “control reliable” controls for two-hand start systems.
According to OSHA guidelines, Programmable controllers which are used in two-hand start systems shall meet the definition of “control reliability”. This definition states that the controllers shall be constructed so that a failure within the system does not prevent the normal stopping action from being applied to the press when required, but does prevent initiation of a successive stroke until the failure is corrected. The failure shall be detected by a simple test, or indicated by the control system. This requirement does not apply to controls which have no effect on the protection against point of operation injuries. The Programmable Controllers also must default to a predetermined safe condition in the event of any single failure within the system.
The following are the OSHA paragraphs which are referred to above:
29 CFR 1910.217 (b)(13) Control reliability. When required by paragraph (c)(5) of this section, the control system shall be constructed so that a failure within the system does not prevent the normal stopping action from being applied to the press when required, but does prevent initiation of a successive stroke until the failure is corrected. The failure shall be detectable be a simple test, or indicated by the control system. This requirement does not apply to those elements of the control system which have no effect on the protection against point of operation injuries.
29 CFR 1910.217 (h)(6)(xvii) Presence sensing device initiation; Cycle control and control systems. Controls with internally stored programs (e.g. mechanical, electro-mechanical, or electronic) shall meet the requirements of paragraph (b)(13) of this section, and shall default to a predetermined safe condition in the event of any single failure within the system. Programmable controllers which meet the requirements for controls with internally stored programs stated above shall be permitted only if all logic elements affecting the safety system and point of operation safety are internally stored and protected in such a manner that they cannot be altered or manipulated by the user to an unsafe condition.
29 CFR 1910.217 (c)(5) Additional requirements for safeguarding. Where the operator feeds or removes parts by placing one or both hands in the point of operation, and a two hand control, presence sensing device of Type B gate or movable barrier (on a part revolution clutch) is used for safeguarding:
(i) The employer shall use a control system and a brake monitor which comply with paragraphs (b)(13) and (14) of this section.
These are only a few of the many regulations pertaining to this subject. For the complete OSHA regulations see the OSHA web site directly.
This page is provided for information purposes only. Compliance to any Federal regulations is the responsibility of the user.