F-Gas Environmental Leak Monitoring System
For monitoring fluorinated greenhouse gas emissions, protecting you and protecting the environment
With the introduction of the f-gas regulations to prevent and reduce emissions of fluorinated greenhouse gases covered by the Kyoto Protocol, OX-AN Gas Detection Ltd have launched the Environmental Leak Monitoring System.
The system provides audible and visual warnings of the presence of fluorinated greenhouse gases within a specified area in buildings around evaporators, chiller cabinet’s etc and outside plant including condensers and recovery systems.
A key feature of the system is the data logging of events for companies and organisations to be able to provide documented evidence of good practice in the charging, discharging and maintenance of refrigeration systems, heat pumps and other systems covered by the f-gas regulations with key elements of the regulations introduced on the 4th July 2007.
The system is intended for use on commercial and industrial applications with the control system fitted in a plant room or other centralised location. The sensors specific to the gas used on site are hard wired back on 4-20mA loops, warning devices such as beacons and sounders are wired back to the central control panel in mains cabling.
Features include:
- Up to 4 × USB based signal capture modules (total 32 sensors)
- Up to 4 × USB based relay modules (total 24 relays)
- .NET based software using Windows XP native USB drivers
- 1024×768 Touchscreen interface
- Individual sensor inputs software configurable for R-134A and other gases
- 4 configurable alarm levels
- 33 configurable Output Groups
- Sound Alarms
- Relay specific Mute
- Sensor specific Isolate
- Sensor value logging
- Alarm logging
OX-AN Environmental Leak Detection Monitors are typically configured prior to delivery and commissioning
PC Software
The OX-AN Environmental Leak Detection Monitoring software is designed to run on Windows XP system (SP2) with .Net framework v3.0. which is installed on the panel PC that supports the signal capture and relay modules.
The software comprises:
- PC based application
- PC XML configuration files
- Signal Board PIC18F2550 Firmware
- Relay Board PIC18F2550 Firmware
F-Gas Monitor Technical Information & Examples
1. Quickjump Links to Technical Information
2. Clickable Screenshots of OX-AN's F-Gas Monitor
Click on the screenshots in the table below to see the larger version
This monitoring screen view shows a system set up to monitor 15 channels for R134A and 2 channels for oxygen depletion. During normal running the monitoring screen displays the location text, alarm levels, sensor value and isolate status for both R-134a and O2 sensors. This is the normal viewing screen
The Outputs tab displays the current state of the relay outputs connected to the system. During normal running the tab shows the location text and relay state for all relays
The Diagnostics tab provides a visual and textual indication of the connected Sensor and Relay boards. It is important that the number of connected boards is correctly specified in the system settings. A fault condition occurs if any configured boards are missing from the system
This screen shows the system output for a RED alarm state
The system enters fault state if communications are lost with configured Relay or Signal Boards
Configuring relay outputs the screen shown here. To change a setting the engineer would select the appropriate line in the relay list and then modify the parameters using the property sheet on the right hand side of the tab
This screen shows the configuration of Input-Outputs
As an example, in the setup shown here, Relays 1, 2 and 3 will be set to ON if Output Group 7 is activated
User operation
During normal operation (i.e. not during configuration) the OX-AN Environmental Leak Monitoring System is designed for operation via a touchscreen interface.
Touchscreen buttons
Three touchscreen buttons provide the main functionality:
Sound Alarms
Activates all relays allocated to the Sound Alarms Output Group
Mute
Deactivates, for a specified time period, all relays which are activated but set as mutable NOTE Any subsequent level 4 alarms will reactivate muted outputs
Reset
Resets all alarm levels
Alarm Levels
Each alarm level changes the corresponding line in the sensor list.
Alarm Level 1 Line background LIGHT GREY
Alarm Level 2 Line background AMBER
Alarm Level 3 Line background FLASHING AMBER and AMBER ALARM WARNING visible
Alarm Level 4 Line background RED and RED ALARM WARNING visible
Fault
The system enters fault state if communications are lost with configured Relay or Signal Boards.
Fault state is also entered if the user enters configuration mode or show actual values.
Isolate
The Isolate warning message is shown if any active sensor is isolated. In isolated state the sensor does not cause any output activity (i.e. no relays are activated).
System Configuration
The system provides 4 configurable alarm levels for each sensor input. Each of these alarm levels can be programmed to activate an individual Output Group (up to 33) which, in turn, may contain up to 24 relays.
Configuring Sensor Inputs
The Input tab screen is shown below; the system allows on site configuration of sensors. To change a setting the engineer would select the appropriate line in the sensor list and then modify the parameters using the property sheet on the right hand side of the tab.
The configurable input parameters are:
For each sensor
1. Isolated Isolation state, when true sensor does not trigger alarm levels
2. Sensor Type R134a or other
3. Active Set true if sensor is present (if false sensor is ignored)
4. Location Text Text shown as sensor location in log
5. Samples Per Reading Number of samples used in calculating the sensor value
6. 4mA Value Offset for zero
7. 20mA Value Offset for full scale
8. Sensor Value Step Size Delta for changing the screen display
For each sensor Alarm Level
1. Alarm Level The level above (or below for O2 ) which the alarm is generated
2. Hysteresis The percentage which is added to the alarm level for state changes in non-latching alarms
3. Latching Value Set true to make alarm latch
4. Output Group The Output Group for this sensor’s alarm level
5. Alarm Text The alarm text for this sensor’s alarm level
To change a setting the engineer would select the appropriate line in the relay list and then modify the parameters using the property sheet on the right hand side of the tab.
The configurable output parameters are:
1. Location Text - The text displayed in the Output tab of the monitoring screen
2. Mute - If set true, the relay is switched off when system is muted
Configuring input-outputs
The Input-Output tab is used to change the contents of the Output Groups. The engineer would select the appropriate line in the Output Group list and then modify the parameters using the property sheet on the right hand side of the tab
Output group editing
The system allows the engineer to set the Output x value. An output group means that the output (Relay) will be set to ON when the Output Group is activated.
Sound alarms output group
Output Group 33 is the Sound Alarms Output Group. This Output Group is triggered when the Sound Alarms button is pressed.
Configurable system parameters
The configurable system parameters are:
Data Logging
1. File Update Period - The time between log samples in seconds
2. File Change Period - The number of days for each log file
System Settings
1. Mute Time - The time in seconds to deactivate mutable relays
System Hardware
1. Number of Sensor Boards - The number of Sensor Boards (these must be present)
2. Number of Relay Boards - The number of Relay Boards (these must be present)
3. System Start up Delay - Number of seconds to wait at system start-up before triggering alarms
Sensor level logging
The system continuously logs the value of all sensors to a CSV file located in C:\R134AMonLog. The disk files are named as R134aMon_yyyymmddhhmmss.csv where yyyymmddhhmmss specifies the creation date.
Samples are written to the log file at a predetermined time interval as well as whenever an alarm occurs.
The format of the CSV file is:
Date,Time,S1 Type,S1 Value,S2 Type,S2 Value,S3 Type,S3 Value ….. up to number of sensors
05/09/2007 23:36:47 R134a 27.99 R134a 31.1 R134a 24.88
If a sensor is isolated, “Isol” is written immediately before the sensor type.
If the sample is written in response to an alarm the sensor data is followed by the alarm data, for example, if sensor 4 enters alarm level 2 state the CSV file will contain 2 additional entries immediately after the sensor value entries:
S4: Sensor 4 location text
AlarmLevel2: Level2 Alarm Text
Start new log
The menu option Logging>Start New Log closes the current log file and begins writing samples to a new log file.
Hardware
A block diagram of the hardware used in a 2 Signal Board/ 2 Relay Board OX-AN R-134a Leak Detection Monitor is shown here:
The Uninterruptible Power Supply (UPS) powers all of the hardware components of the OX -AN Environmental Leak Monitoring System.