Level gauge tanks
Tank level detection switches
Tank level detection switches are mostly associated with the start of the alarm and the start of the executive response. Unlike monitoring systems, switches do not provide continuous level measurement but are used for alarms. In this article, we discuss the different types of level switches used for tank gauge applications (tank gauges). Magnetic surface switches, conductivity and field effect switches and microwave level switches are surface measuring switches. However, they are not suitable for fuel storage applications and are therefore beyond the scope of this article
Tank level detection switches
Range level switch
This type of range-level switch , also known as a “fork switch”, uses piezo crystals that continuously resonate at a known frequency in the open air. The speed at which these crystals resonate when immersed in a liquid. The principle adopted for this type of switch in preventing the tank surface from filling is that the piezo crystal is attached to two metal hooks that are in contact with the gasoline stored in the tank by changing the tank surface. When the forks, which resonate due to the connection of the piezo crystal, come in contact with gasoline, the frequency at which the nails change. If the detected oscillations are very different from the natural oscillation frequency of the crystal, its resonance frequency (damping factor calculator), it means that the crystal is exposed to an atmosphere other than air, ie gasoline, and the switch signal is activated
Displacement level switch
The dispersion surface switches work using a spring weight known as a displacement, which keeps its weight on the liquid surface in the tank. As the fluid level rises, a steel armature in which the displacement is located rises to the mechanical switch mechanism. This armature activates the magnet that activates the switch. When the fluid level in the tank decreases and as a result the displacements decrease, the switching operation is reversed
Mechanical switches use a type of lever (also used connectors and rotating rods) that move according to the level of liquid inside the tank. When the liquid reaches a certain level, the movement of the moving lever contacts the switch. When the surface moves away from the actuator surface, the placement of the lever causes the switch contacts to come apart. Mechanical switches are operated continuously because they do not rely on any factor other than the liquid level inside the tank
Optical level switch
Optical level switch The light source and detector are used to determine the presence of liquid in the storage tank. This impermeable method shines a light source on the surface of the liquid. The reflection is then detected. Examples of light sources are diodes (LEDs) or lasers. These types of switches require the detector lenses to be cleaned regularly, so these switches can have a significant inspection and maintenance
Magnetic surface switch
A magnetic surface switch can block or block electrical current by creating a magnet for two “Reed” metal strips. The presence of a magnetic field, which is provided by a magnetic float inside the tank, connects the two rods and allows current to flow through the circuit. When the magnetic float passes through the straw switch, the magnetic field is removed and they separate. This separation occurs because the stiffness of the reeds causes them to separate. Straws are usually placed in a sealed glass tube that tries to protect them from corrosion due to moisture or aggressive materials
Novel tank reservoir replacement method
The American Petroleum Institute (API) has come up with a way to over-identify fuel storage tanks that use the tank’s external precision instruments. This method has been successfully implemented by a reputable fuel storage center in the United States. In this system, three pipes are used that work parallel to the outer part of the fuel storage tank. Among these pipes, the center one is hit at the bottom of the tank and is always made of liquid fuel inside. This pipe is also transferred to the atmosphere so that it can be assumed that the surface in the pipe is the same as the level inside the tank. Two external side pipes are connected to the central pipe at high or high level warning points
These connections are piped connections between the central pipe and the outer pipes, which will allow liquid flow from the central pipe to the outer pipe when the fuel level reaches the rust activation point, ie the connection pipe point. In the event that excessive fuel pressure is applied to the outer pipes, an alarm is activated when fuel accumulation begins at the end of the pipe. This method has many advantages over the currently approved level change methods because the tank is non-invasive and the alarm sensors are only exposed to fuel when an alarm sounds. However, the central pipe, which is constantly fueled, must be protected from external damage because if the pipe is broken, it can be damaged due to the loss of reservoir contents
Problems testing HI-Hi level switches
A control and instrumentation inspector stated that the most common type of HI level switch used is the magnetic reed type. The proof test was satisfactory without full knowledge of the switch mechanism. One of the biggest shortcomings in testing HI level switches is the lack of proper training of technicians or proper written methods for proof testing. Other problems in testing the proof of hi-level switches can be aspects such as disconnecting the float to which the switch is attached, “locking” where the float belonging to the switch is located in the fixed well
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