Explosion proof online alkali concentration detector is an important monitoring equipment for high-risk scenarios such as chemical and chlor alkali industries. Its selection should take into account explosion-proof compliance, working condition adaptation, and performance stability. Below is a breakdown of the purchasing logic from the core dimensions to help you accurately match your needs.

1、 Set a safety bottom line first: precise matching of explosion-proof level and area

Explosion proof performance is the selection criterion, which must strictly correspond to the hazardous area level and medium characteristics of the production site. According to the GB 3836.14 standard, Zone 0 (continuous presence of explosive gases) requires the use of intrinsically safe (Ex ia) equipment, Zone 1 (occasional occurrence of explosive gases) can be adapted to explosion-proof (Ex d) or increased safety (Ex e), and Zone 2 (short-term presence) can be relaxed to ordinary explosion-proof type.

At the same time, it is necessary to clarify the gas group and temperature group: high-risk media such as hydrogen require Class IIC equipment, while conventional alkanes can choose Class IIB; The surface temperature of the equipment should be lower than the self ignition temperature of the medium. For example, T6 grade (≤ 85 ℃) is preferred in chlorine gas environments. It is necessary to verify the validity of the equipment explosion-proof certificate to avoid "fake explosion-proof" products. The certificate must include full certification of the GB 3836 series.

2、 Adaptation to working conditions: Locking of medium and environmental parameters

1. Accurate adaptation of medium characteristics

The concentration range of alkaline solution directly determines the measurement principle: conductivity method can be selected for low concentrations of 0-16% (such as Shanghai Xuantian SJT-6000A), and electromagnetic induction method is preferred for high concentrations of 25-50%.

The material selection should be corrosion-resistant and durable: if the NaOH content is below 20%, it can be made of polypropylene, and if it is highly corrosive or at high temperatures (>80 ℃), it should be upgraded to PTFE or 316L.

2. Adaptation to environmental conditions

The temperature compensation range should cover the actual working conditions (Shanghai Xuantian SJT-6000A equipment covers 0-100 ℃), and the built-in PT1000 sensor can dynamically correct temperature deviation. Choose IP68 protection level for outdoor installation, and at least IP67 should be met in the workshop to avoid the impact of acid and alkali splashes and dust.

3、 Anchor performance key: accuracy and functionality adapted to production requirements

Measurement accuracy needs to match control standards: environmental compliance scenarios require ± 1.5% accuracy, while pharmaceutical, electronics, and other fields require ± 0.05% level equipment. The response time should be ≤ 5 seconds to ensure the capture of concentration fluctuations caused by process mutations and avoid safety risks caused by lag.

The automation function needs to be connected to the existing system: standard 4-20mA analog signal and RS485 interface (Modbus protocol) to ensure seamless integration with DCS/PLC; The scenario that requires a linked dosing system should have PID control logic and relay output, supporting high and low limit alarm interlocking.

4、 Calculating comprehensive costs: Operations and services cannot be ignored

Priority should be given to equipment with high maintenance frequency and long lifespan. Sensor lifespan should be over 2 years, and calibration convenience is equally important. Equipment that supports two-point calibration and on-site calibration can reduce downtime for maintenance.

Key supplier service capability: Localized technical support is required, with a fault response time of ≤ 4 hours; Brands with industry application cases (such as chlorine absorption tower projects in chlor alkali enterprises) are more reliable, and can refer to user feedback from mature brands such as Shanghai Xuantian and E+H.

Summary: We need to follow the principles of "safety first, working condition adaptation, performance matching, and service guarantee", and comprehensively evaluate the explosion-proof level, medium characteristics, and automation requirements in order to select an explosion-proof online alkali concentration detector that combines safety and economy.