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b1 Space Pressure Monitors
b1 Remote Pressure Monitor
b1 Space Pressure Sensors
The Guardian series room/space pressure monitoring systems can be utilized a number of ways as illustrated below:
Standalone Pressure Monitoring
Both the SPM-3000 and SPM-4000 Guardian Room/Space Pressure Monitors can be used as standalone systems that provide local indication of the supply and exhaust/return airflow control system’s ability to maintain the room/space pressurization requirements. The room/space status is locally indicated via high intensity LED’s identifying operational mode as being either active or off; and the room/space pressure level being either normal or in an alarm condition. Activation of either a high pressure or low pressure alarm will trigger a local audible alarm which can be silenced by pressing the panel mounted “Alarm Acknowledge” button.
Pressure Monitoring with Network Communication
Both the SPM-3000 and SPM-4000 Guardian Room/Space Pressure Monitors have network capability. The diagram below shows the SPM-4000 networking to both a building management system as well as a PCI model RPM-2000 Remote Pressure Monitor (i.e. Nurses Station). Interface with a building management system can be performed either with analogue inputs and outputs (0 to 10vdc or 4 to 20mA) or through a network interface utilizing either BACnet®-MS/TP or LonWorks® protocol. The communication channel for interfacing the room pressure monitors with the remote pressure monitor uses a native BACnet® communication port. PCI’s RPM-2000 Remote Pressure Monitor is capable of monitoring up to 24 individual room pressures.
Comprehensive Room/Space Condition Monitoring
The SPM-4000 Guardian Infinity Room/Space Pressure Monitor also offers the ability to monitor and alarm room air changes per hour, room temperature and room humidity. The SPM-4000 can interface with the building management system to provide room operating conditions and alarm statuses over the building’s information network using either BACnet®-MS/TP or LonWorks® protocol. Alarm setpoint levels can be programmed locally or via the building management system.
Constant Volume With Pressure Control
The SPM-4000 Guardian Infinity Room/Space Pressure Monitor has optional three mode (P-I-1/D) controller capability. This module can be utilized to monitor and control the room/space pressure level via the modulation of either a control damper or a fan’s variable speed drive. In the diagram below the supply airflow rate is being controlled at a constant rate (as would be the case in a hospital patient room where the requirement is to deliver enough air to assure the specified air changes per hour for the given application) and the exhaust air from the space is being varied as required to maintain the specified differential pressure.
The SPM-4000 can operate in a standalone manner or be fully integrated into a building management system and/or PCI’s RPM-2000 Remote Pressure Monitor.
Cascade Pressure Control
Cascade pressure control is a complimentary control strategy for volumetric offset control. Traditional volumetric offset control provides modulation of one airflow rate base on another airflow rate. The addition of cascade control, using PCI’s SPM-4000 Guardian Infinity Room/Space Pressure Monitor, adds the functionality of the measured space pressure “fine tuning” the volumetric offset setpoint. In the diagram below the supply airflow rate to a space is being maintained through a constant volume control loop. The exhaust airflow from the space is being modulated to maintain a constant volumetric offset thus producing the required space pressure. The offset volume required to produce the required space pressure is determined during the initial balancing and commissioning of the air volume control systems. At this point the output of the SPM-4000 cascade (reset) pressure controller is set to deliver a mid-scale (zero) output value based on the space pressure level being created and maintained by the volumetric offset control loop. The SPM-4000 pressure controller is then configured to permit an allowable maximum and minimum CFM reset range to the volumetric offset setpoint to occur. During normal operation the SPM-4000’s pressure reset controller output will stay at the mid-point (zero correction) value. Should the pressure in the space fall below or go above the required safe operational value the SPM-4000’s controller output will modulate so as to automatically reset the volumetric offset setpoint as required to bring the space pressure level back into compliance with the required safe operational value. Should the space pressure fail to be corrected with a maximum allowable volumetric offset then the SPM-4000 pressure alarm circuit will activate.
Complete integration of the SPM-4000 control and alarm functions into the building management system are available through either a BACnet®-MS/TP or LonWorks® communication network.