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A Safety Barrier is Necessary for Intrinsic Safety Flow Switch


1. What is an Intrinsic Safety Flow Switches?

Intrinsic Safety Flow Switch is one kind of Explosion Proof flow switches, it is an approach to the design of flow switch going into hazardous areas. The idea is to reduce the available energy to a level where it is too low to cause ignition. That means preventing sparks and keeping temperatures low.

It means that under the normal and fault conditions, the sparks of flow switch generated by the circuit and system and the temperature reached will not ignite the explosive mixture. The explosion-proof performance of intrinsically safe flow switch is not realized by ventilation, inflation, oil filling, explosion-proof and other external measures, but by the circuit itself, so it is intrinsically safe. For example, GE-316 series explosion-proof flow switch, adopting a passive signal dry contact, plus measures such as glue filling and sealing, so as to achieve intrinsically safe explosion-proof effect. It can be used not only in the field of petrochemical industry, but also in the underground of coal min(this product has the explosion-proof certificate in class I and class II).


GE-316 Explosion-Proof Paddle Flow Swicthes


ExibIICT6 for class II; ExibI Mb for class I

GE-316 Paddle Flow Switch is a very low cost Ex-proof flow switch, DN15 DN20 DN25, specially designed for the Flow M.


2. What is safety barrier?

Safety barrier is a energy limiting circuit between intrinsically safe explosion-proof flow switch and control room equipment, which is used to limit the electric energy supplied by the control room to the on-site intrinsically safe flow switch to the surface temperature of the instrument which can neither produce enough sparks to detonate dangerous gas nor produce enough temperature to detonate dangerous gas, thus eliminating the ignition source.


3. Why safety barrier is necessary for an Intrinsic Safety Flow Switches?

The intrinsic safety flow switch itself will not produce energy exceeding the standard requirements, but the acquisition equipment in the safety area, such as PLC or relay, may fail and lead to dangerous large current and voltage input to the danger area, so to ensure the safety of the site, it is necessary to set safety energy limiting measures for its circuit - that is, use safety barrier to limit energy.


4. What kind of safety barrier should be used for intrinsically safe explosion-proof flow switch?

In recent years, the United States, Germany and other countries have applied "parameter certification" technology for Intrinsic Safety certification, and put forward a new concept of intrinsically safe explosion-proof fieldbus. Its main feature is that users can legally combine and evaluate the intrinsic safety system for the intrinsic safety equipment and associated equipment that have been certified by parameters. That is, users can complete compatible safety design according to the technical requirements of "parameter authentication", so that the intrinsic safety equipment produced by different manufacturers can be safely hung on the same bus. At present, China's explosion-proof inspection technology institutions are also actively promoting this practice.

The parameter requirements of intrinsic safety flow switch for safety barrier are as follows:
Uo : (Maximum voltage that may output): less than or equal to 30VDC
Io  : (Maximum possible output current): less than or equal to 250mA
Po :  ( Output maximum power ): less than or equal to 2.5W

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