An undersized system will put undue wear and tear on the components of the system which will lead to increased maintenance costs. In some extreme cases a system may be so undersized that the lag pump will need to run in order to maintain the demand. An oversized system can also create problems, especially if it is a medical air system. If the system is sized too large and does not cycle enough, it could increase the possibility of having high dew point within the system.

 

Oversized systems use more water if liquid ring, more oil if oil lubricated and almost always use more electric to run the larger motors.

 

New medical air and vacuum systems are usually sized by the engineer. The engineer figures out how many outlets and inlets there are by area. Once the final count is complete, they figure out the flow requirements for each area. If there is a possibility for future expansion, the systems can be increased in size accordingly to compensate for the additional outlets and inlets.

 

Replacement air and vacuum systems are often sized to match the existing systems. Existing systems in use for 10, 20 and maybe even 30 years may have changed over time. Outlets and inlets may have been added or removed from the systems, which would have a significant effect on the requirements for the capacity of the replacement system.

 

Whenever possible, it is always recommended that a count of all the outlets and inlets are taken and listed by area because each area has a specific flow requirement. Once the information has been obtained, it will be easier to determine what system is needed to replace the existing system.

Size, it does matter!