Environmental Engineering Reference
In-Depth Information
Door frames are an integral part of doorway security because they anchor
the door to the wall. Door frames are typically constructed from wood or
steel, and they are installed such that they extend for several inches over the
doorway that has been cut into the wall. For added security, frames can be
designed to have varying degrees of overlap or wrapping. This overlap can
make prying the frame from the wall more difficult. A frame formed from
a continuous piece of metal (as opposed to a frame constructed from indi-
vidual metal pieces) will prevent prying between pieces of the frame.
Many security doors can be retrofit into existing frames; however, many
security door installations require replacement of the door frame as well as
the door itself. Bullet resistance per the Underwriters Laboratory (UL) 752
standard encompasses the resistance of the door and frame assembly both;
thus, replacing the door only would not meet UL 752 requirements.
Valve Lockout Devices
Valves are utilized as control elements in water and wastewater process pip-
ing networks. They regulate the flow of both liquids and gases by opening,
closing, or obstructing a flow passageway. Valves are typically located where
flow control is necessary; they can be located inline or at pipeline and tank
entrance and exit points. Valves serve multiple purposes in a process pipe
network, including
• Redirecting and throttling low
• Preventing backlow
• Shutting off low to a pipeline or tank (for isolation purposes)
• Releasing pressure
• Draining extraneous liquid from pipelines or tanks
• Introducing chemicals into the process network
• Serving as access points for sampling process water
Valves are located at critical junctures throughout water and wastewater sys-
tems, both on-site at treatment facilities and off-site within water distribu-
tion and wastewater collection systems. They may be located either above or
below ground. Because many valves are located within the community, it is
critical to provide protection against valve tampering. Tampering with a pres-
sure-relief valve, for example, could result in a pressure buildup and potential
explosion in the piping network. On a larger scale, addition of a pathogen
or chemical to the water distribution system through an unprotected valve
could result in the release of that contaminant to the general population.
Various security products are available to protect aboveground vs. below-
ground valves; for example, valve lockout devices can protect valves and
valve controls located above ground. Vaults containing underground valves
