Why is in the gas flowmeter type to a security gate
But simple components do not need to be certified, such as thermocouples, thermal resistors, switches, etc., even if no authentication is available, they can also be directly added to the safety barrier.
The safety barrier is installed in a safe place, receives signals from the danger zone, and outputs safety signals to the safety zone or danger zone. The safety gate is designed between field equipment and control room equipment of a limited energy interface, so whether the control room equipment is in normal or fault state, can ensure the safety gate through which energy is transferred to the scene equipment essential safety. Safety gratings must be used in field explosion proof areas, isolation measures may be used in non explosive zones, but safety gratings are generally used to ensure data reliability. The safety gate is the role of the field instrument plays a role of intrinsically safe. It is restricted to the scene of the energy, limiting voltage through a zener diode, resistor limiting current, thereby limiting the total energy to the scene, even if a spark, the spark energy is not enough to ignite the gas explosion scene, if the instrument just explosion-proof certification, it is necessary to use safety gate. If the instrument through this certification, the explosion-proof certification, without safety gate can (except, in a situation where there are 2 instrument wiring cavity, one is intrinsically safe authentication, a flameproof certification, this case still must add security gate)
In the design of explosion-proof safety grid application system, it is installed in a safe place and contains the intrinsically safe circuit and non intrinsically safe circuits, circuit by current and voltage limiting circuit for limiting the intrinsically safe loop energy sent to the site, so as to prevent dangerous energy non intrinsically safe circuit on intrinsically safe circuit, is an important part of safety system.
