I. What is a limited space? Do you encounter it in your life?
①What is a limited space?
Not designed for continuous stay, and access to the space is restricted, these spaces usually have small entrances and exits, poor ventilation, and there may be toxic, hazardous, flammable and explosive substances accumulate or insufficient oxygen content and other hazards.
②Is it possible to encounter a limited space in my life?
Limited space usually has a large enough space to allow employees to enter the work, but at the same time access is restricted, usually small mouth and stomach, is not conducive to rapid entry and exit.
Spaces with these types of characteristics are still quite common in life. For example, water towers, wine tanks, oil tanks, sewage wells, inspection wells, boilers, furnaces, silos, sewers, basements, shopping malls, underground spaces.
II. limited space is dangerous？
Limited space ventilation is poor, rushed into, is very dangerous. Oxygen deficiency or toxic gases, no matter who happens to be there, can cause harm to the body.
Danger ①: lack of oxygen
Limited space entrances and exits are small, poor ventilation, it is easy to form a low-oxygen environment. In the absence of testing oxygen levels, there is no ventilation, rashly enter, if you run into a low-oxygen environment, the oxygen concentration in the space is not enough to support normal respiration, people may be hypoxic conditions, the loss of oxygen, very dangerous.
Danger ②: Harmful gases
Common harmful gases include methane, hydrogen sulfide, and monoxide, which are also common in daily life. Methane is flammable and explosive, and hydrogen sulphide and carbon monoxide are inherently toxic. These gases are found in limited spaces with poor ventilation and can easily accumulate, and it is dangerous to enter that space hastily and run into excessive concentrations of harmful gases! The cause of these gases can originate from manufacturing processes, chemical leaks, or biological decomposition, among others. High concentrations of hazardous gases can cause acute and chronic injuries to the human respiratory system, nervous system or other organs, and can be fatal in severe cases.
III. Who will enter the limited space?
① Chemical workers: inspect and maintain chemical reactors, tanks and other containers.
② Oil and gas workers: enter storage tanks and well chambers for maintenance.
③Electricity industry workers: cleaning and overhauling boilers and other equipment.
④Paper and pulp workers: Enter pulp tanks, reactors, etc. to perform mechanical repairs or process inspections.
⑤ Plumbers: install, inspect, or repair sewers, drainage systems, and pipes in buildings and municipal works.
⑥ Electricians: Install or repair electrical equipment and wiring in confined spaces.
⑦Welders: perform welding operations in confined spaces, such as inside ship hulls or storage tanks.
⑧ Water treatment plant workers: enter treatment ponds and tanks for maintenance and sample collection.
⑨ Sewer and Drainage System Maintenance Worker: Regularly inspects and cleans sewers and drainage ditches.
⑩ farm workers: enter silos to inspect grain storage or perform maintenance.
There are many other types of workers who need to enter the limited space to operate, and we will not repeat them here.
IV. What do I need to prepare before entering a limited space?
①Assess the risk and make a plan
Limited space may exist in the harmful gases, oxygen levels, physical hazards (such as mechanical injury, high or low temperature), electrical hazards, etc. Assessment, and based on the results of the risk assessment, the preparation of specific operational plans and emergency response plans.
②Acquisition of permits
③Safety training
The training should include the definition, characteristics, potential risks, personal protective equipment (PPE) to be used, and response measures in case of emergency of the limited space.
④ Personal protective equipment (PPE)
Equip with appropriate PPE based on risk assessment.This may include:
– Respirators: to prevent inhalation of harmful gases, necessary respiratory support in oxygen deficient environments.
– Protective clothing: protection against chemical contamination, flame retardant clothing, etc., selected according to the work environment.
– Safety elmets: with protective visors to prevent head injuries.
– Safety belts and lifelines: to prevent falls and aid rescue.
– Gloves and safety shoes: to protect hands and feet from chemical burns and physical injuries.
⑤ Carry a portable gas detector to do tests on ventilation and air to ensure that the concentration of harmful gases is below dangerous levels and the oxygen content is within safe limits.
⑥ Equip with effective communication equipment, such as radio or communication lines, and carry lighting equipment if there is insufficient light inside the limited space.
⑦Emergency rescue and surveillance measures: Set up one or more external guardians with rescue capability to monitor staff entering or leaving the limited space and be ready to carry out emergency rescue. At the same time, rescue equipment should be prepared, such as lifeline, rescue ladder, portable oxygen cylinders.
⑧ Marking and isolation: The limited space being operated is clearly marked and isolation measures are taken to prevent unrelated personnel from entering. Safety signs, caution tape, etc. can be used for area isolation and warning.
⑨ Tools and equipment inspection: Ensure that all tools and equipment brought into the limited space are safe and suitable for the environment and are inspected before entry. And it should be ensured that staff entering the limited space, are in good physical condition and have no health problems that would affect the safety of the operation.
⑩ Records and reports: Record every detail of the limited space operation, including the results of the risk assessment, the list of operators, the entry and exit times, the results of the air quality test, the PPE used, etc. These records are vital for subsequent safety audits and accident investigations where necessary.
V. What are the applications of gas detectors in limited spaces?
There are two types of gas detectors: fixed and portable. Here, only the portable gas detectors with higher frequency of use in limited space are described.
①Real-time detection of oxygen concentration
Normal oxygen concentration is generally 19.5% to 23.5%, higher or lower than the normal value, are harmful to the human body. Portable gas detector on and off, you can check as you go, built-in highly sensitive gas sensors, can detect the subtle changes in the surrounding oxygen, the alarm method also added a vibration function, triple alarm, more conducive to the safety of the user.
② real-time monitoring of harmful gas concentrations
Limited space common toxic and harmful gases, including but not limited to hydrogen sulfide, carbon monoxide, ammonia, etc., are toxic, will cause damage to human health. The use of gas detectors in such spaces is essential! After ventilation, only when it is determined that the concentration of harmful gases in the space is within the safety value, the operator can enter the limited space.
③ Real-time monitoring of flammable and explosive gases
Some limited spaces may also contain flammable and explosive gases, such as methane and propane. If the concentration of the accumulated flammable gas reaches or exceeds the explosion limit value, at this time, once there is an open flame or electric spark in the space, there is the possibility of a gas explosion occurring. Therefore, the operating personnel must strictly abide by the operational safety norms, use the gas alarm correctly, and in the event of an increase in the concentration of the gas, measures must be taken quickly to avoid a fire or explosion.
