How to choose storage devices for explosion-proof video surveillance systems?

In high-risk environments such as petrochemicals, coal mines, and gas stations, explosion-proof video surveillance systems are key facilities for ensuring production safety and preventing accidents. Storage devices, as the "data warehouse" of the system, undertake the core functions of video data collection, storage, backup, and retrieval. Unlike ordinary monitoring and storage devices, explosion-proof scenarios require more stringent requirements for the explosion-proof level, resistance to harsh environments, data reliability, and compatibility of storage devices. Improper selection may not only result in data loss due to equipment failure and inability to trace the cause of accidents, but also pose a risk of explosion if the equipment does not meet explosion-proof standards. Starting from the special requirements of explosion-proof scenarios, this article outlines the core dimensions of storage device selection and provides targeted selection solutions based on the characteristics of different high-risk environments, helping users choose suitable and reliable storage devices.

1、 The core selection prerequisite for explosion-proof video surveillance storage devices: clear scene requirements and compliance with standards

Before selecting, it is necessary to clarify the application scenario parameters and compliance standards of the storage device, which is the basis for ensuring device compatibility and security, and avoiding selection errors caused by parameter mismatches or non-compliance with standards.

（1） Confirmation of core scenario parameters

Explosion proof environment level: Storage equipment with corresponding explosion-proof levels should be selected based on the classification of explosion hazardous areas in the scene (such as chemical workshops classified as Zone 0, Zone 1, and Zone 2 according to GB 50058, and coal mines classified as gas mines and high gas mines according to MT/T 408). For example, Zone 0 (continuous presence of explosive gas mixtures) requires the selection of Ex d Ⅰ IC level or above explosion-proof storage equipment, while Zone 1 (occasional presence of explosive gas mixtures) can select Ex d Ⅱ B level or above equipment;

Video data volume parameters: including the number of cameras (such as 50-200 cameras required in chemical industrial parks), stream size (high-definition cameras typically have a stream of 4-8Mbps, while 4K cameras can reach 16Mbps), and storage duration (according to national standards, high-risk scene videos need to be stored for ≥ 30 days, and some special scenes such as coal mines need ≥ 90 days). These parameters directly determine the capacity requirements of storage devices;

Environmental operating parameters: It is necessary to confirm the temperature, humidity, dust concentration, and vibration intensity of the scene (such as the temperature in the oil storage tank area reaching 50 ℃ or above in summer, and the temperature in the coal mine underground reaching 35 ℃ and humidity ≥ 90%). These parameters determine the temperature and humidity resistance, dust resistance, and vibration resistance that the storage equipment needs to possess.

（2） Mandatory compliance standards

Explosion proof video surveillance storage devices must comply with national and industry mandatory standards. When selecting, the following certifications and standards should be carefully checked:

Explosion proof certification: In China, it is necessary to have an explosion-proof certificate issued by the National Quality Supervision and Inspection Center for Explosion proof Electrical Products (CQST), with the certification mark of "Ex", and the certification level must match the application scenario (such as in coal mines, which must comply with GB 3836.1-2021 "Explosive Environment Part 1: General Requirements for Equipment", and in chemical scenarios, which must comply with GB 3836.2-2021 "Explosive Environment Part 2: Equipment Protected by Explosion proof Enclosures" d ");

Industry specific standards: Coal mine underground storage equipment must comply with MT/T 1097-2008 "Technical Specification for Maintenance of Coal Mine Mechanical and Electrical Equipment", and petrochemical scenarios must comply with SH/T 3164-2021 "Technical Regulations for Construction of Petrochemical Instrumentation Engineering";

Data Security Standard: It must comply with GB/T 35273-2020 "Information Security Technology - Personal Information Security Specification", and have data encryption (such as AES-256 encryption) and access control (such as hierarchical permission management) functions to prevent video data leakage or tampering.

2、 Core selection dimension: comprehensive consideration from performance to adaptation

The selection of explosion-proof video surveillance storage devices should revolve around four core dimensions: capacity adaptation, reliability assurance, environmental tolerance, and compatibility matching. Each dimension needs to be evaluated in a targeted manner based on the special requirements of explosion-proof scenarios.

（1） Storage capacity: precise calculation, reserved redundancy

Insufficient storage capacity can lead to excessive video data coverage, which cannot meet the storage duration requirements; Excess capacity will increase costs, so it is necessary to accurately calculate capacity and reserve reasonable redundancy.

Capacity calculation formula

Single camera daily storage capacity (GB)=bitrate (Mbps) × 3600 seconds × 24 hours ÷ 8 ÷ 1024

Total storage capacity (TB)=Single channel daily capacity (GB) x Number of cameras x Storage days ÷ 1024 x Redundancy factor (recommended 1.2-1.5)

Example: A certain chemical workshop has 50 high-definition cameras (stream 4Mbps) that need to be stored for 30 days with a redundancy factor of 1.3. Therefore, the total storage capacity=(4 × 3600 × 24 ÷ 8 ÷ 1024) × 50 × 30 ÷ 1024 × 1.3 ≈ 76.3TB. Therefore, a storage device with a total capacity of ≥ 80TB needs to be selected.

Capacity configuration strategy

Small scale scenarios (with no more than 30 cameras): Embedded hard drive video recorders (DVR/NVR) can be selected, paired with 4-8 large capacity hard drives (such as 16TB and 20TB enterprise grade hard drives), to meet storage needs for 30-60 days;

Medium to large-scale scenarios (with 30-200 cameras): It is recommended to choose a network storage server (NAS) or a storage area network (SAN), which supports multi disk expansion (such as 16 or 24 disk slots) and can achieve a balance between capacity and reliability through RAID arrays (such as RAID5 or RAID6);

Ultra large scale scenarios (with more than 200 cameras, such as large chemical industrial parks): A distributed storage system should be selected to expand capacity through multi node clusters, with a single node supporting 12-24 disk positions. Nodes can be dynamically added according to demand to meet long-term storage needs of more than 90 days.

Precautions for hard disk selection

Explosion proof scenario storage devices need to choose enterprise grade monitoring dedicated hard drives instead of ordinary consumer grade hard drives, because:

Enterprise grade hard drives support continuous operation for 7 × 24 hours (consumer grade hard drives are mostly designed for 5 × 8 hours of operation), adapting to the uninterrupted storage needs of monitoring systems;

Has higher anti vibration and anti impact performance (such as enterprise grade hard drives with a vibration limit of up to 500Hz/2.17G, and consumer grade hard drives with 300Hz/1.5G), suitable for vibration scenarios such as mining and chemical industry;

Supports Error Recovery Control (ERC) function, which can quickly repair hard disk read and write errors and reduce the risk of data loss.

（2） Reliability: Multiple safeguards to address high-risk risks

In explosion-proof scenarios, the reliability of storage devices directly determines whether data is complete, and multiple mechanisms such as hardware redundancy, data backup, and fault warning are needed to ensure reliability.

Hardware redundancy design

Power redundancy: Choose storage devices with dual or multi power redundancy, such as chemical storage devices that need to support 220V/380V dual power input. When one power supply fails, the other power supply can seamlessly switch to ensure uninterrupted operation of the device;

Fan redundancy: Adopting a redundant fan design (such as 2+1 fans), when a single fan fails, the other fans can automatically increase speed, maintain equipment cooling, and avoid equipment downtime due to overheating;

RAID array: Select the appropriate RAID level based on data importance. For important scenarios such as coal mines and gas stations, RAID6 is recommended (allowing 2 hard drives to fail simultaneously without losing data), while RAID5 is recommended for general scenarios (allowing 1 hard drive to fail); At the same time, the hot spare function needs to be enabled. When the hard drive fails, the hot spare can automatically replace the faulty hard drive for data reconstruction, reducing data recovery time.

Data backup mechanism

Local backup: Set up backup partitions within the storage device to perform dual backups of video data from critical cameras (such as tank areas and wellhead cameras) to avoid data loss caused by single partition failures;

Remote backup: For ultra high risk scenarios such as nuclear industry and large oil and gas fields, a remote backup center needs to be established to synchronize video data in real time to remote storage devices through fiber optic or 5G networks. When local storage devices are damaged due to explosions or fires, remote backup data can be fully retained;

Scheduled backup: Set a scheduled backup strategy (such as incremental backup from 2-4 am every day) to reduce the impact of real-time backup on storage device performance, while ensuring the timeliness of data backup.

Fault warning and self-healing

Select storage devices with intelligent fault warning functions, support real-time push of warning information such as hard disk faults, power abnormalities, and high temperatures through SMS, email, monitoring platform alarms, etc., to facilitate timely processing by operation and maintenance personnel;

Some high-end storage devices have self-healing capabilities, such as automatic repair of minor bad sectors on hard drives, and automatic continuation of unsaved video data after network interruption recovery, reducing manual intervention costs.

（3） Environmental tolerance: adapted to harsh working conditions in high-risk scenarios

The harsh working conditions such as temperature, humidity, dust, and vibration in explosion-proof scenarios can seriously affect the lifespan of storage equipment, and it is necessary to choose equipment with strong environmental tolerance.

Wide temperature design

High temperature scenarios (such as oil storage tank areas and metallurgical workshops): Select storage equipment with a working temperature range of -20 ℃ -60 ℃. For some extreme high temperature scenarios (such as coking plants), wide temperature equipment with a range of -40 ℃ -70 ℃ should be selected. High temperature resistant components (such as high temperature capacitors and temperature resistant chips) should be used inside the equipment to avoid component aging and failure caused by high temperature;

Low temperature scenarios (such as northern oil fields and high-altitude mines): Choose storage devices with low-temperature startup function, support -40 ℃ low-temperature startup, and can maintain stable operation in low-temperature environments to avoid a decrease in hard disk read and write speed or device failure to start due to low temperature.

Dust resistance and waterproof performance

High dust scenarios (such as underground coal mines and flour processing plants): Choose storage devices with a protection level of ≥ IP65, with a sealed design for the device casing and dust-proof sealing rings at the interface to prevent dust from entering the device and blocking the fan or short circuiting the circuit board; At the same time, regular dust cleaning of the equipment is required (such as blowing the equipment's cooling holes with compressed air every month);

Wet or water related scenarios (such as underground oil depots and sewage treatment plants): Choose waterproof storage equipment with a protection level of ≥ IP66. The equipment shell is made of stainless steel material (such as 316L stainless steel), which is corrosion-resistant and waterproof. Waterproof joints are used at the interface to prevent moisture from infiltrating the equipment and causing short circuits.

Vibration and impact resistance performance

Frequent vibration scenarios such as mining and infrastructure: Select storage devices with anti vibration levels ≥ 50G (half sine wave, 11ms) and anti impact levels ≥ 100G (half sine wave, 2ms). The internal hard drive of the device should be fixed with shock-absorbing brackets to reduce the impact of vibration on the hard drive;

Transportation or mobile scenarios (such as explosion-proof inspection vehicles): Choose vehicle grade explosion-proof storage devices that support wide voltage inputs (such as 9V-36V), have anti bounce performance (in accordance with ISO 16750-3 vehicle vibration standards), and adapt to vibration and voltage fluctuations during vehicle operation.

（4） Compatibility and Scalability: Adapt to System Upgrades and Function Expansion

Explosion proof video surveillance systems may involve different brands and types of equipment, and storage devices need to have good compatibility and scalability to avoid system failure due to compatibility issues or insufficient scalability to meet later upgrade needs.

Device compatibility

Protocol compatibility: Select storage devices that support universal protocols such as ONVIF and GB/T 28181 to ensure that different brands of explosion-proof cameras (such as Hikvision, Dahua, and TianDi Technology's explosion-proof cameras) can be connected without the need to replace devices due to brand incompatibility;

Encoding format compatibility: Supports mainstream encoding formats such as H.264, H.265, H.265+, etc. Among them, H.265 encoding can save 50% of storage capacity compared to H.264, making it suitable for large-scale deployment of high-definition and 4K cameras; At the same time, it is necessary to support intelligent encoding technologies such as Smart H.265, which can dynamically adjust the stream according to the picture and further optimize the storage capacity.

Functional scalability

Interface expansion: Storage devices need to have rich interfaces, such as Gigabit Ethernet ports (≥ 2, supporting link aggregation to improve data transmission speed), USB 3.0 interfaces (for local data export), HDMI interfaces (for local preview), and some scenarios require support for fiber optic interfaces (such as long-distance transmission scenarios);

Intelligent function extension: supports the integration of intelligent analysis modules (such as behavior analysis, fireworks recognition, intrusion detection), which can store structured data after intelligent analysis together with video data for easy retrieval in the later stage (such as quickly locating relevant video clips through the "fireworks event" tag);

Capacity expansion: Supports hard disk expansion cabinet access. When the existing storage capacity is insufficient, storage capacity can be increased through cascading expansion cabinets (such as each expansion cabinet supporting 16 disk slots) without the need to replace the original storage devices, reducing upgrade costs.

3、 Storage device selection schemes for different high-risk scenarios

The environmental characteristics and requirements of different high-risk scenarios vary greatly, and suitable storage devices need to be selected based on specific scenarios. The following are detailed selection plans for three typical scenarios.

（1） Petrochemical scene: Explosion proof+high reliability priority

Petrochemical scenes (such as refineries, oil depots, and chemical workshops) contain explosive gases (such as gasoline and methane), and the environmental temperature and humidity are high, requiring extremely high explosion-proof levels, reliability, and temperature and humidity resistance of storage equipment.

Recommended storage device type: Explosion proof network storage server (Ex d Ⅱ C T4 Ga level)

Performance parameters: 16 disk positions, supporting RAID5/6, dual gigabit Ethernet ports, dual power redundancy, operating temperature -20 ℃ -60 ℃, protection level IP65;

Hard drive configuration: 16 16TB enterprise level monitoring hard drives with a total capacity of 256TB, supporting H.265 encoding, capable of connecting 80 4MP cameras, and meeting 30 day storage requirements;

Adaptation advantages: The explosion-proof shell can effectively prevent the leakage of internal electric sparks and avoid igniting external explosive gases; The dual power supply and RAID6 design ensure that data is not lost, adapting to the 24-hour uninterrupted operation requirements of chemical scenarios.

Attention: Storage devices need to be installed in explosion-proof junction boxes, and cable connections should use explosion-proof sealed joints; Regularly check whether the explosion-proof surface of the equipment is intact to avoid a decrease in explosion-proof level due to damage to the explosion-proof surface.

（2） Coal mine underground scene: anti dust+low-power adaptation

There is a risk of gas and coal dust explosion in the underground scene of coal mines, with a humid environment (humidity ≥ 90%), high dust concentration, frequent vibration, and limited underground power supply resources. The requirements for anti dust, anti vibration, and low-power performance of storage equipment are prominent.

Recommended storage device type: Mining explosion-proof storage recorder (Ex d Ⅰ Mb level, compliant with GB 3836.1-2021)

Performance parameters: 8 disk positions, supporting RAID5, single gigabit Ethernet port (supporting coal mine specific Ethernet protocol), wide voltage input (127V/380V/660V), working temperature -20 ℃ -40 ℃, protection level IP66;

Hard drive configuration: 8 12TB mining specific hard drives (anti vibration level ≥ 60G), total capacity of 96TB, supports H.265+encoding, can connect 40 channels of 2MP cameras, and meet 90 day storage requirements;

Adaptation advantages: The explosion-proof design for mining complies with coal mine safety standards, and its anti dust and waterproof properties are suitable for the humid and dusty environment underground; Wide voltage input adapted to different power supply voltages underground, low-power design (standby power consumption ≤ 15W) saves underground power supply resources.

Attention: Storage devices should be installed in underground chambers (such as mining area substations), away from blasting operation areas; Regularly clean the dust on the equipment casing, check the operation status of the cooling fan, and avoid equipment overheating caused by dust blockage.

（3） Gas station scenario: miniaturization+intelligent retrieval adaptation

Gas station scenarios (such as LNG refueling stations and urban gas pressure regulating stations) are relatively small in scale (with no more than 20 cameras), but they contain explosive gases and require rapid retrieval of abnormal events (such as smoking and illegal parking of vehicles), which requires high requirements for miniaturization and intelligent retrieval functions of storage devices.

Recommended storage device type: Explosion proof embedded NVR (Ex d Ⅱ B T4 Gb level)

Performance parameters: 4 disk positions, supporting RAID5, single gigabit network port, working temperature -10 ℃ -55 ℃, protection level IP65, supporting intelligent retrieval (such as event retrieval, face retrieval);

Hard drive configuration: 4 8TB enterprise grade hard drives with a total capacity of 32TB, supporting H.265 encoding, capable of connecting 16 4MP cameras, and meeting 30 day storage requirements;

Adaptation advantages: Small size (approximately 400mm × 300mm × 150mm), suitable for installation in narrow equipment rooms of gas stations; The intelligent retrieval function can quickly locate abnormal event videos, improving the efficiency of accident tracing.

Attention: Storage devices need to form a closed-loop network with cameras and monitoring hosts to avoid external network attacks; Regularly backup critical video data (such as daily backup to a USB drive) to prevent data loss caused by device failure.