ANSI/BHMA A156.28-2000 pdf free download.RECOMMENDED PRACTICES FOR MECHANICAL KEYING SYSTEMS.
1. SCOPE
The scope of ANSI/BHMA A156.28-2000 is limited to mechanical key bitting, cylinder pinning and multiplex
key systems.
The purpose of ANSI/BHMA A156.28-2000 is to recommend the approach to selecting the optimal keying system, once the type of cylinder has been selected by other criteria.
This recommended practice is not intended to provide sufficient information for a full understanding of master key systems.
Various types of cylinders have varying levels of security and performance to which other standards may apply. These include ANSI and Underwriters Laboratories standards.
2. GENERAL
Master keying is the process of combinating (or programming) a group of locks or cylinders, so that each is operated by its own change key as well as by a master key for the entire group. This process increases convenience but has two negative effects on the lock or cylinder:
I) Master keying decreases the security of the cylinder by making it easier to pick and by increasing the number of keys which operate it.
2) In the most common cylinder mechanisms, master keying may make the cylinder more susceptible to mechanical failure by adding more moving parts.
3. DEFINITIONS. The following definitions are taken from The Professional Glossary of Terms
Relating to Cylinders, Keys and Master Keying, copyright 1982 — 1998 by the Lock Industry Standards and
Training (LIST) Council and the ALOA Sponsored National Task Group for Certified Training Programs.
3.1 Bow – The portion of a key which serves as a grip or handle.
3.2 Change Key – A key which operates only one cylinder or one group of keyed alike cylinders in a keying system.
3.3 Concealed Key Control (CKC) – A specification that all lock cylinders be marked with standard keying symbols in a location which is concealed while the cylinder is installed.
3.4 Combinate – To set a combination in a lock, cylinder or key.
3.5 Construction Core – An interchangeable or removable core designed for use during the construction phase of a building. The cores are normally keyed alike and, upon completion of construction, they are to be replaced by the permanent system’s cores.
3.6 Construction Master Key – A key normally used by construction personnel for a temporary period during building construction. It may be rendered permanently inoperative without disassembling the cylinder.ANSI/BHMA A156.28-2000 pdf free download.