Frequently the Food and Drug Administration, Centers for
Disease Control and Prevention (CDC), or Federal Emergency Management Agency
guidelines and mandates specify that backup power is required to guarantee
the viability of medical or laboratory equipment for critical applications.
Often, guidelines and mandates fall short of specifying the full scope of
the backup systems necessary for the applications. Equipment requirements
differ by manufacturer, which leaves equipment implementation and the
backup-power system details to be determined by the end-user or his
After an equipment implementation, one key question
frequently left to be answered by time is, “Will the equipment or system
powered by the primary and backup-power systems meet the intent and spirit
of the specified guideline or mandate?” The following two illustrations
outline the scope and issues related to real-world equipment installations.
Vaccines for Children Program
A state agency purchased one large refrigerator for
central storage of vaccines in support of the CDC Vaccines for Children
Program (VFC), and three smaller refrigerators in which to store vaccines at
three of its remote vaccination centers. Vaccines must be stored in
refrigeration, below mandated temperatures, to maintain the viability and
potency of the vaccines. The CDC states that the following three elements
are necessary for vaccine management for the VFC program:
- “proper storage and handling procedures that maintain
the viability of vaccine;”
- “procurement and ongoing replenishment of adequate
vaccine inventory;” and
- “efficient distribution of vaccines to eligible
providers, while maintaining the cold chain.”
The use of a double conversion online UPS acts like an electronic firewall between the utility or generator source and the sensitive computer and network hardware.
The CDC also states, “The management of publicly
purchased vaccine is one of the most important activities conducted by an
immunization grantee.” The CDC further defines the three main components of
the cold chain as:
- “transport and storage equipment;”
- “trained personnel;” and
- “efficient management procedures.”
The CDC also mandates that the refrigerators in which
vaccines are stored must have their internal temperatures continuously
monitored and the data logged to a level that ensures vaccines remain
viable. Finally, CDC demands, “If there is suspicion of a cold-chain failure
or evidence that vaccine has been exposed to temperatures outside the
recommended temperature range, vaccine should be marked ‘DO NOT USE,’ so
that the vaccine is not used until a response indicating that the vaccine is
still potent has been received.” The re-testing and re-certification of the
vaccine in question can be a very costly process, especially if the vaccines
must be destroyed.
The refrigerators purchased by the state agency all have
local thermal chart recorders, an RS-232 port for connection of a local PC
computer, and the ability to be monitored remotely using Ethernet local area
network (LAN) connectivity.
The three methods of monitoring temperature may seem to
be overkill; but with this design, if one of the methods becomes disabled or
unreliable, two other data sources exist against which to compare.
State facilities where these four vaccine-storage
refrigerators go have backup-power generators in the event of a utility
power loss. While many people believe these generators should be enough to
assure the viability of the vaccines, that is not the case. The local PC
connected to the refrigerators’ RS-232 port can crash during the time it
takes generators to start up. PCs must be powered by uninterruptible power
supplies (UPS) during the generator start-up period.
Additionally, the refrigerators have Ethernet ports
connected to each facility’s LAN. This situation demands that all LAN
routers, switches, modems, and servers required to facilitate the
refrigerators’ data monitoring, logging, and storage be backed up with a
central or distributed UPS to maintain LAN communication during generator
start up. To truly meet the spirit and intent of the CDC VFC guidelines for
proper vaccine storage involves a substantial engineering project, conducted
by many departments inside (and outside) the state agency.
Often, IT department engineers and managers charged with
purchasing UPS units — commonly referred to as offline or line-interactive
designs — to meet these demands. Because they are not power engineers, they
do not realize that all UPS products do not provide the same level of
protection and may not operate reliably from generator power.
Avoid these inexpensive UPS products; in critical
applications, use double conversion online, generator-compatible UPS models
with low distortion and true sine wave AC output; and that provide the
highest level of protection against the widest range of power problems while
operating from utility, generator, or internal batteries.
Childhood Lead Poisoning
The Lead Contamination Control Act of 1988 authorized the
CDC to initiate program efforts to eliminate childhood lead poisoning in the
United States. As a result, the CDC Childhood Lead Poisoning Prevention
Program (CLPPP) was established. State and local agencies collaborate with
the CDC in the prevention, detection, and Web-based tracking of lead
poisoning in children.
As part of the program, the CDC distributes a proprietary
CLPPP tracking, database, and Web-reporting software to all participating
agencies. Ongoing database reliability for this program is essential.
Directly related to the reliability is providing continuous clean power for
all database workstations, servers, and LAN communications hardware.
As an example, the CDC’s software supplier states: “The
most common cause is an abnormal shutdown of software due to a server crash,
a software crash, a computer-system crash, or a power spike. When this
happens, key files are not updated, so they can point to wrong or
non-existent data.” The critical data in the database may become corrupted
and possibly could be lost if the right corrective action is not taken.
A backup generator alone will not provide the complete
solution. With this widely distributed program, on-site backup-generator
power may not be available. A UPS must be provided as a backup-power
solution for database computers, servers, and LAN hardware. Special
attention should also be paid to the CDC’s reference to “power spikes.”
Low-cost offline and line-interactive UPS types will not provide adequate
protection, since most utility-related power anomalies are passed directly
through them to the connected equipment.
The use of a double conversion online UPS acts like an
electronic firewall between the utility or generator source and the
sensitive computer and network hardware. It regenerates ultra-clean, tightly
regulated, and uninterrupted AC power, offering the best insurance against
power related data corruption.
A simple statement recommending or mandating backup power
does not clearly define the types or level of backup systems required for a
specific program or equipment installation. Regulations, program guidelines,
and mandates, as well as risk assessments, should always be reviewed by IT
engineers and facilities departments prior to purchasing critical equipment
or software. This ensures that proper attention has been given to the
overall backup-power requirements, yielding a true up-front cost of
implementation and, most importantly, assuring compliance.
Michael A. Stout is vice president of Engineering at
Falcon Electric, Irwindale, CA, which provides a variety of backup power
products. See www.falconups.com .
The CDC details vaccine storage and handling procedures at
more about the Childhood Lead Poisoning Prevention Program at www.cdc.gov/nceh/lead/about/program.htm .