Can an explosion-proof flammable and toxic gas alarm be used without a safety barrier?
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As the title suggests, can an explosion-proof flammable/toxic gas alarm be used without a safety barrier? To the best of our knowledge, explosion-proof instruments can prevent explosions inside the instrument enclosure from spreading outside it. If an intrinsically safe gas alarm without a safety barrier is being handled in a flammable and explosive environment without power isolation (4-20mA), is there a risk of explosion if the cover of the device is opened? The alarm needs to have its gauge zeroed out; how can this be done without power? If there is a fault in the wiring, could the components inside get damaged due to the lack of a safety barrier? Please help me understand this????
Explosion-proof instruments do not require a safety barrier, and it is not possible to open them for live debugging on site
Since it’s all 24VDC, it’s not that easy to damage the components.
No safety barrier is required; after the cabinet is powered off, the cover can be opened on-site to remove the gauge, which can then be taken to the maintenance room for zero calibration. Considering issues related to zeroing and maintenance, modern alarms generally come equipped with remote controls, eliminating the need to turn off the power and open the cover.
The landlord should study carefully the structure of the intrinsically safe system. Also, which explosion-proof alarms these days still require the cover to be opened for adjustment? Isn’t it usually some kind of induction tuning using magnetic strips or something like that?
To zero the alarm, a standard gas at the lower concentration limit must be released first. How do you supply air to the alarm at the scene? Are there any workwear and sample gases available? It’s better if there aren’t any; that way, there’s no need to adjust several seedlings around........ {:2_45:}
Why is a safety barrier needed for explosion-proof devices? If a safety barrier can be used, why not opt for an intrinsically safe type? Think about these two questions.
Well, it’s really necessary to study hard*. When it comes to instrument design, one must first be aware of the various risks involved. Buying the wrong type of instrument isn’t considered a major risk; the biggest risk is choosing the incorrect explosion-proof design, as that could lead to an explosion on site and put one in danger. So for beginners, it’s essential to know how to select explosion-proof instruments; otherwise, it’s better to do something else that is safer
This post was last edited by qugd on 2019-7-25 at 10:59. The original poster had better gain a thorough understanding of explosion-proof regulations and explosion-proof designs. A safety barrier is an essential component of a foolproof safety circuit. In contrast, flameproof instruments use physical safety isolation measures to enclose components with electrical hazards in an environment capable of withstanding internal electrical explosions, eliminating the need for electrical isolation components between the instrument and the circuit. As for your question regarding whether opening the flameproof enclosure while it is still powered on in order to maintain flameproof instruments could damage the components, I can tell you with certainty that generally such actions do not damage the components. However, if sparks are generated and the conditions on site are suitable, the entire device could be damaged, yet the components themselves will remain unharmed. For flameproof instruments, without shutting down the power supply, who told you that it’s possible to open the flameproof enclosure on site for operation? Have you read the operation manual for the flameproof instrument?
For explosion-proof types, there’s definitely no need to add a safety barrier; it’s useless anyway, as it simply can’t drive three-wire instruments； In an explosion-proof combustible and toxic gas detector, there are definitely intermediate wiring terminals between the components; adding a switch fuse on the 24V positive wire will prevent the components from being damaged.