Thread Content
Article 4.3.7 of the \"Technical Specifications for Chlorine Safety in Chemical Enterprises\" (GB11984-2024) requires that chlorine-related equipment and pipelines be equipped with diaphragm pressure gauges; the isolating fluid in such pressure gauges should be a medium that does not react with chlorine. Physical isolation is used to prevent chlorine from coming into direct contact with the sensitive core components of the pressure gauge, thereby ensuring long-term accuracy, reliability, and safety in pressure measurement. 1. Preventing chlorine from corroding core components: Chlorine is a highly oxidizing and highly toxic gas; especially when it contains trace amounts of moisture (wet chlorine), it forms hydrochloric acid and hypochlorous acid, which possess extreme corrosive properties. The core pressure-sensing components of ordinary pressure gauges, such as the Bourdon tube (made of copper alloy), will be rapidly corroded once they come into direct contact with chlorine gas. This can lead to inaccurate measurements; corrosion can render the metal inelastic, resulting in incorrect pressure readings. This causes damage to the instruments, shortens the service life of pressure gauges, and increases the frequency of replacement as well as related costs. 2. Preventing the isolation medium from reacting with chlorine: Diaphragm pressure gauges have an “isolation fluid” filled between the diaphragm and the gauge mechanism. If the isolation fluid reacts with chlorine (for example, certain organic substances or incompatible liquids), it may crystallize or precipitate beneath the diaphragm or inside the capillary, causing the pressure gauge pointer to get stuck or stop functioning. The reaction products may increase the viscosity of the isolation fluid and cause volume changes, affecting the accuracy of pressure transmission and the response time; they may also accelerate the corrosion of the isolation diaphragm, leading to its rupture. If it is not set in accordance with the specifications, using a regular pressure gauge or selecting an inappropriate isolation fluid will pose a range of serious safety and operational risks. 1. Rapid damage to pressure gauges and loss of measurement accuracy: The Bourdon tube in ordinary pressure gauges can be quickly corroded by chlorine, causing the gauge to give inaccurate readings or even become completely damaged within a short period of time (possibly a few days or weeks). If a pressure gauge gets stuck at a certain scale due to blockage or corrosion, it will provide the operator with incorrect safety signals or false information regarding the operating conditions. For example, if the actual pressure is already extremely high but the instruments show normal values, this may result in the safety valve not activating and operators failing to take action, ultimately leading to catastrophic accidents such as overpressure in the equipment, container rupture, or even explosion. 2. The risk of chlorine leakage arises from the possibility of rupture in corroded Bourdon tubes or connections. Chlorine is a highly toxic gas; even low concentrations in the air can cause coughing and difficulty breathing, while high concentrations can lead to pulmonary edema and sudden death. In the event of a leak, it can pose a serious threat to the life and health of the personnel on site, and may lead to mass poisoning incidents. The leaked chlorine can also spread outside the factory area, causing public safety incidents and environmental pollution. 3. Increased maintenance costs and downtime risks: Frequently replacing damaged pressure gauges not only increases the costs of spare parts and labor, but more importantly, the replacement process involves operations such as shutting down the system, replacing the gauge, and purging it. This disrupts the continuity and stability of production, resulting in significant economic losses.