MEP Design Requirements for Central Sterile Processing Areas

Successful outcomes from surgical procedures in a hospital rely, in part, on the ability of the central sterile processing suite to provide equipment and materials in an efficient, reliable, and sterile manner.  Similarly, the central sterile processing suite relies on the mechanical, electrical, and plumbing systems serving the area to be reliable and to meet all infection control requirements.

Central sterile processing suites utilize sinks, ultrasonic cleaners, pass-thru washers, cart washers, and sterilizers to process and clean surgical tools and materials.  To allow this equipment to function properly, the building’s water, sanitary drainage, compressed air, steam, exhaust, and electrical systems must be designed in accordance with the wash equipment manufacturer’s requirements.  In most cases, additional domestic water treatment such as water softeners and reverse osmosis generators are required to insure that minerals and impurities in the domestic water do not affect the sterilization process.  It is also important that the central sterile processing equipment be served from the emergency power system of the facility to insure that processing can continue during power interruptions or for emergency cases during extended power outages.

As the materials are processed, they must travel in a “dirty” to “clean” path to prevent cross contamination.  Conversely, air flow in the HVAC system must follow a “clean” to “dirty” path and appropriate pressure relationships between spaces must be provided by the air supply and exhaust systems.  Pressure differential sensors are necessary to notify staff, and provide documentation for regulatory agencies,  that proper pressure relationships are maintained between “clean” and “dirty” spaces at all times.

In addition to pressure relationships, the HVAC system must be designed to provide comfortable space temperatures for the central sterile processing staff.  In the decontamination area, the staff wears personal protection garments for extended periods of the work day.  Therefore, a lower space temperature may be desired to keep staff comfortable as they perform their tasks.

Relative humidity also must be controlled and monitored by the HVAC systems.  The ideal relative humidity level in the central sterile processing area is 50%.  If the relative humidity in the space is too high, condensation can occur on the stored products and equipment.  This can lead to the growth of harmful microbes.  If the relative humidity in the space is too low, the materials can be excessively dry which can interfere with the sterilization process.

It is important to involve a consulting engineer during the planning of a construction project or an upgrade to existing sterilization equipment in the central sterile processing area.  Service interruptions in this area can affect the facility’s ability to perform surgical procedures in the operating suite.  With proper planning, extended shut-down periods can be avoided and infection control requirements can be maintained during all phases of construction.

If you would like more information regarding the design of mechanical, electrical, and plumbing systems for central sterile processing areas or if you would like assistance with an upcoming project, please contact Eric Sellers, PE at or (717) 845-7654.

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