Application

Overview
Hardware Inputs
5
Siemens Industry, Inc.
Application Note, App 2920
140-1307
2015-07-07
Overview
Application 2920 controls pressurization, ventilation, and room temperature in a
laboratory room served by one single-duct supply terminal with a reheat coil, one
general exhaust terminal, and up to six fume hoods (multiple fume hood flow signals
must be averaged using an averaging and scaling module. Pressurization is controlled
by maintaining a selected difference between supply and exhaust airflows.
NOTE:
Application 2920 can be set up to operate without a supply box, or without a general
exhaust box. See the
Application Notes section for more information.
Application 2920 uses fast-acting electronic actuators for Venturi Air Valve control. A
standard 0 to 10 Vdc actuator is used for the hot water valve.
NOTE:
The LCM controls pressure, ventilation, and temperature. When these functions
conflict, the priorities are:
• Pressurization
• Ventilation (supply minimum may be overridden to maintain negative pressurization)
• Temperature (temperature control is overridden by specified flow limits for the air
terminals)
Temperature control is determined by input from the room temperature sensor.