Water is the basis of all life and it is essential to protect ground water and drainage systems against contamination from mineral oils. In garages, service stations and industrial processes, light liquid separators, or oil separators, prevent harmful substances from escaping uncontrolled into the environment and disrupting the hydrological cycle. However, installing an oil separator alone does not solve the problem completely. A system must be monitored continually to ensure it operates reliably. This is the only way to prevent environmental damage and avoid the associated liability risks.
Comprehensive monitoring of a system requires warning devices that detect a critical operating status in the separator and trigger an alarm before any harm can be done to the environment. The requirements are defined in European Standard EN 858-1 and form the basis for the CE mark on oil and separators. This standard defines the criteria for a device that triggers an alarm if the light liquid or waste water level is too high or the waste water level is too low.
These warning devices have the following descriptions: device to warn of excessive depth of light liquid waste or waste water or low level condition; or automatic warning devices and auxiliary devices – separator systems shall be provided with automatic warning devices.
To ensure appropriate monitoring, Pepperl + Fuchs has developed warning devices for separator systems that can be combined with a variety of sensors. These are positioned in the separator hanging from a pre-installed five metre cable. All sensors have ATEX approval and are suitable for installation in hazardous areas. They are compact and robust and do not incorporate moving parts. For areas where there are no people or supply voltages, a system with alarm trip offers around the clock protection via the GSM mobile network.
Compact intelligence
The LAL-SRW warning device for oil and petrol separator alarms is extremely compact and can be mounted in a wall box or on DIN mounting rails in any control cabinet. The device is available for two or three sensors and guarantees the comprehensive, reliable monitoring of light liquid separators. When a sensor sends a signal indicating that the operating status of the separator is critical, the control unit triggers an acoustic and visual alarm.
Built-in reliability
If the cause of the alarm is ignored after the reset button is pressed, the alarm is repeated after 24 hours for safety reasons. In addition to the sensors, all connected cables are continuously monitored. In the event of a short circuit or broken cable, acoustic and visual alarms are triggered. Remote monitoring via a decentralised alarm is also possible.
Layer thickness sensor
The capacitive sensor KVF-104-PF can distinguish between oil/petrol and water. If the layer thickness exceeds a defined maximum value, the incoming signal is sent to the LAL-SRW control unit where it is evaluated and an alarm is triggered. Thus an excessive thickness of the oil layer in the separator can be detected reliably and penetration of oil into the sewer network can be prevented.
The LAL-D-EX capacitive sensor measures the thickness of an oil film and detects a decreasing level in an oil and petrol separator. If the sensor is located in water, the transmitted high frequency signal is attenuated. However, if the sensor is surrounded by oil or air this value changes, which indicates an alarm status. The sensor detects that the oil storage quantity has reached a maximum value which could potentially damage the environment if exceeded.
Overflow sensor
The NVF-104/34PF overflow sensor was developed specially for distinguishing air from liquid. If the fluid level exceeds a defined value, the incoming signal is also sent to the LAL-SRW control unit and an alarm is triggered. This method can be reliably used to determine whether a coalescence filter is clogged, thereby preventing overflow and the resulting environmental damage.
The LAL-8-D-EX ultrasonic sensor is mounted hanging above the normal liquid level and responds immediately when a closed automatic closure device or clogged coalescence filter causes an overflow and triggers an alarm. This reduces the risk of oil separators overflowing and oil products contaminating the ground.
Sludge level sensor
The SLU-103-PF sludge level sensor differentiates between sludge and fluid, as well as monitoring the sludge level in the sludge trap or an oil separator. An alarm is triggered when a defined level is reached. This sensor detects whether the light liquid separator is already clogged with sludge, allowing reaction to protect the environment from hazardous substances.
The LAL9-D-EX ultrasonic sensor is designed for monitoring the sludge level in oil and petrol separators. The receiver detects a defined signal if the sensor is surrounded by fluid. If sludge, sand or metal particles obstruct the sludge level, an alarm situation is signalled to prevent the separator from becoming clogged with sludge, which could allow harmful substances to escape into the environment. This keeps manual checks to a minimum.
Individual configuration
The GSM warning system with SMS alarm is an efficient solution for monitoring oil and petrol separators. It is designed for applications where this type of monitoring was not previously possible for financial and technical reasons. The system ensures reliable remote monitoring around the clock and is also suitable for areas where personnel are not constantly present. If an alarm status occurs, a text message is generated and sent by SMS to up to three mobile phones via the GSM modem. This message is transmitted repeatedly at regular intervals until the cause of the alarm is rectified. Weekly status messages via SMS also provide a comprehensive overview of the status of the oil and petrol separator.
The monitoring of the system is very flexible because it can be configured individually. Up to three different sensors can be connected to this warning device. For example, oil film, overflow or sludge level sensors can be installed together to provide a comprehensive protective function for the application in question. This system is also suitable for retrofitting because these three sensors can be easily connected via a conventional 2-wire cable.
Application-orientated alarm system
There are three versions of the alarm systems available, suitable for a wide variety of applications.
For more information contact Rob Burns, P & F Products, +27 (0)11 609 8188, [email protected], www.pandf.co.za
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