Explosion-Proof Scales: Intrinsically Safe or Regular?
In dusty processing workshops, next to storage tanks in oil refineries, and in raw material batching zones of chemical workshops, explosion-proof scales are essential to ensure safe and precise measurements in production. Poorly chosen scales, due to vehicle unavailability, can incur expensive production downtimes and, due to explosive environments, can cause fire ignition, safety accidents, and possible regulatory non-compliance.
Nonetheless, many companies struggle with identifying the differences and safety applications between “Regular Explosion Proof” and “Intrinsically Safe” scales. This article tries to present a selection scheme that focuses on the practical side of industrial applications to effectively address your needs.
Key Differences
To choose the right explosion-proof scale, you must first understand the differences in core characteristics between intrinsically safe (IS) and regular explosion-proof types, as this directly determines whether the equipment can meet production needs.
Working Principle
| Type | Principle | Details |
| Intrinsically Safe | Energy Control at Source | All electrical units of the equipment have design features and adjustments made so as to reliably and strictly minimize the voltage, current, and stored energy in the circuitry. The stored energy, even in the worst case of equipment failure (short circuit), or damage to the elements, is so low that the electric spark produced is incapable of igniting the various explosive materials that may be present in the workshop. |
| Explosion-Proof | Physical Isolation of Explosion | Explosive-resistant high-strength cast steel and thick-walled aluminum alloy housing provide high resistance to external explosions. By precise gap and length control, even if there is a small explosion inside, the housing is guaranteed to “contain” the explosion flame and high temperature. |
Classification and Selection of Hazardous Areas
Gas Environment
Hazardous locations are divided into the following three zones based on the frequency and duration of the occurrence of explosive gas atmospheres:
| Zone | Standard | Selection |
| Zone 0 | Areas where explosive gas atmospheres occur continuously or exist for long periods (more than 1,000 hours/year) | Only Intrinsically Safe type is applicable |
| Zone 1 | Areas where explosive gas atmospheres may occur during normal operation (10-1,000 hours/year) | Both types are applicable |
| Zone 2 | Areas where explosive gas atmospheres are unlikely to occur during normal operation; if they do occur, they are only occasional and short-lived (less than 10 hours/year) | Both types are applicable |
Dust Environment:
Hazardous areas are divided into the following three zones based on the frequency and duration of the occurrence of combustible dust/air mixtures, as well as the thickness of dust layers:
| Zone | Standard | Selection |
| Zone 20 | Areas where combustible dust is continuously or frequently present during normal operation, in quantities sufficient to form combustible dust-air mixtures and/or potentially form uncontrolled and extremely thick dust layers | Only Intrinsically Safe type is applicable |
| Zone 21 | Areas where, during normal operation, dust may be present in quantities sufficient to form combustible dust-air mixtures but are not classified as Zone 20 | Both types are applicable |
| Zone 22 | Areas where, under abnormal conditions, combustible dust clouds occasionally appear and only exist for a short time, or combustible dust occasionally accumulates, or dust layers may exist and generate combustible dust-air mixtures | Both types are applicable |
To sum up, intrinsically safe electronic scales have a wider range of uses—they can cover everything from high-risk areas to regular hazardous scenarios, and can often handle more dangerous environments. Explosion-proof scales, which rely on physical explosion isolation design, provide enough protection for ordinary explosive environments.
Maintenance Costs and Service Life
For chemical and oil refining enterprises, the maintenance costs and service life of explosion-proof scales directly affect the whole-life cycle costs, and the two types of equipment differ significantly in this regard:
| Type | Maintenance | Service Life |
| Intrinsically Safe | No frequent inspection of shell tightness or replacement of seals is required | 5-7 years |
| Regular Explosion-Proof | The shell needs to be disassembled quarterly to check the sealing status, and seals must be replaced once a year (if the shell is deformed due to collision, additional explosion-proof performance testing is required) | 3-5 years |
Data Storage and Traceability:
The oil refining and chemical industries have high environmental and safety supervision standards. Data weighing net storage requirements (e.g., raw material consumption and finished product output) for auditing purposes. Also, consider the two kinds of explosion-proof scales for data analysis capability.
Intrinsically safe explosion-proof scale：
Most mainstream intrinsically safe devices have a data storage option for 99 sets, automatic, and manual weighing time and weight value record options.
Regular explosion-proof scales：
Most entry-level standard explosion-proof scales have a storage capability of 50 sets, indicating weight value records, and data recording is limited.Core Points for Selecting Explosion-Proof Scales
Compliance Certifications
Explosion-Proof Certification: For domestic uses, the scale needs to have the “GB 3836 Series Certifications” and have the explosion-proof seal clearly marked.
Accuracy Certification: It needs to fulfill the OIML Class III standard so that the weighing errors are within acceptable limits for industrial production.
Material Certification: Stainless steel, explosion-proof scales with material test certificates need to eg. 316 stainless steel. These scales resist acids and alkalis, and are also gas and oil corrosion resistant so they can survive solvent erosion in chemical workshops and humid oil refinery environments, which enhances the service life of the equipment.
Supplier Services
Customization Service: Suppliers that provide customization services can change the parameters and the functions of the explosion-proof scales to fit enterprise requirements such as hazardous area classification and the weighing range. This helps the scales fit better in real working conditions.
Warranty Service: There should be at least a 1-year warranty service during which remote troubleshooting for equipment failure applies. For more complicated problems, onsite staff can be arranged to assist in maintenance.
After-Sales Service: There should be routine follow-up to check how the explosion-proof scales are functioning. If problems arise, a competent team should be ready to provide professional solutions in a timely manner optimally.
Conclusion
Ultimately, it’s never a matter of “which one is better” but “which one is better suited for your factory area.” Considering the working conditions of your factory, and by following this guide, you can choose an explosion-proof scale that optimizes safety and efficiency. This guides you to lower operational costs and cost-effective safety barriers during processing and production.
