Fuel System Design Guide for Hospitals
Design Guide ESS.DG.916
Introduction
Fuel systems for medical centers are characterized by generally large loads and run time
durations of 72 hours requiring substantial quantities of fuel on the site. The systems are
designed with standard components but with redundancy to avoid single points of failure. The
redundancy requires monitoring of component status and auto-switch to alternate components
when failure is indicated. These monitoring and auto-switch functions require advanced PLC
control systems. The systems are also highly monitored by BMS systems.
Large hospitals are often multi-story building designs in urban areas with generators and boilers
separated from fuel storage areas. This arrangement makes the networking and graphic
displays of the controllers especially important so that the operator can “see” what is going on
in different parts of the system.
Boiler systems in hospitals typically require diesel fuel backup to the primary natural gas fuel
source. The fuel storage systems are usually shared between the boiler and generator capacity
requirements. Codes may require that the boiler fuel feeds be limited to a certain capacity of
the stored fuel so as to allow for the generator fuel supply for the required run durations.
Fuel System Elements
The fuel system is designed to safely store fuel and transfer it to the generators when needed.
The combustible nature of diesel fuel means that the bulk fuel storage is often separated from
the generators and the buildings. However large generator sub-base tanks are sometimes used
with packaged generator enclosures. Standard Fuel System Elements will include:
- Storage Tanks: To safely store fuel for required generator run time
- M2 Duplex Pumps: To move fuel from storage tanks to point of use
- M3 Filtration Unit: To filter dirt and water from fuel during long term storage.
- M4 Tank Fill Station: To receive fuel from delivery trucks and transfer to tanks.
- M5 Day Tank Units: To store limited fuel quantities adjacent to generators.
Typical System Layout
A typical hospital fuel system layout will have a combined generator and boiler fuel system with separate pump systems for each to allow for different flow and pressure requirements.
The fuel system has single elements with single flow paths. The example does include 2 important features for backup manual operation: (a) the pump motor starter has an HOA switch with manual mode functional based on line power alone independent of control power, and (b) manual valves to bypass control valves.
A Good Design for Large Generator Sub-Base Tanks
Generator designs may provide for large sub-base tanks without supplemental fuel storage. In this design there are 2 main considerations: (a) redundant and fast receipt of fuel from delivery trucks, and (b) a filter polisher system with the ability to transfer fuel between tanks as needed.
