Protective devices for production equipment. Technical means of ensuring labor protection

At workplaces, the main technical means of labor protection of collective protection are protective and blocking devices. Protective devices are used to exclude the impact on workers of harmful and dangerous production factors. They are divided into protective, blocking, safety, special, brake, automatic control and signaling, remote control(GOST 12.4.125-83).

Protective devices - this is a protective barrier between dangerous, harmful factors and a person: casings, screens, shields, visors and barriers, etc.

They can be stationary, mobile, removable, mobile and motionless. Requirements for fences are set out in (GOST 12.2.062-82), SSBT.

“Production equipment. Protective fences. The fence should be equipped with comfortable handles, shooting brackets, and the surface should be painted in a signal color with a warning sign.

Blocking is called a set of methods and means designed to prevent emergency and traumatic situations. According to the principle of operation, they are divided into: mechanical, electronic, electromagnetic, electrical, combined, etc.

Blocking devices exclude the inclusion of the mechanism without means of protection (the casing is removed).

Rice. 3.1.1. Scheme of the safety interlock using a photocell:

1 - light source; 2, 4 – lenses; 3 - a beam of parallel light rays; 5 - receiver of light rays; 6 - control relay; 7 - amplifier.

Rice. 3.1.2 Scheme of radioactive auto-blocking:

1 - Geiger tube; 2 - thyratron lamp; 3 - control relay; 4 - emergency relay.

Blocking devices serve as a means for opening magnetic sensors when exposed to electromagnetic fields above the permissible values on workers and their surroundings (response time - 0.01 sec.). Blocking devices can act to block the activation of the pedal, handle, drive when a person or his body parts (arm, leg) is in the danger zone (photoelectric effect).

Special safety devices include:

traps in elevators and stairways, electric shock protection system, block locks, limiters for rotation or movement of goods, etc.

Safety devices are designed for automatic shutdown of equipment in case of emergencies in operating equipment due to exceeding the permissible operating parameters: excess of speed, pressure, temperature, electrical voltage, mechanical loads, etc. (safety valves, bursting discs, fusible links, etc.).

Brake devices designed to slow down or stop moving equipment or parts thereof in the event of hazardous production factors (working, parking, emergency braking).

Light and sound alarm warn about the inclusion of the mechanism in the work, about the work in the danger zone, about reaching the maximum concentration harmful substances in the working area, extreme temperatures or pressure in installations (combined - light and sound alarm).

Locks

Locking devices are used for the safe operation of equipment and production processes by forcing the interaction of interconnected parts of equipment or parameters technological processes.

The most widely used guards are interlocked with the drive of the machine, which ensures that the power to the drive is turned off at the moment the guard is removed. In the presence of interlocking guards, it is impossible to start the machine without a guard, since in this case the drive power circuit is in an open state.

In the case when it is necessary to stop the machine (its mechanism) when the operator or individual parts of his body approach the danger zone, protective interlocks are used, consisting of a signaling device and an actuator. As a signaling device, for example, photocells illuminated by a beam are used: a decrease in their illumination when crossing the beam activates the blocking.

In some cases, push-out (movable barrier connected to the working mechanism) or retracting hands of the operator from working area devices at the onset of a dangerous moment. In the latter case, bracelets are put on the operator's hands, connected by a rod or wire to the actuator. A significant disadvantage of such devices is that the operator has excessive tension and nervousness in anticipation of the moment of their operation and impact on the hands.

To prevent the operator's hands from getting into the danger zone, two-handed switching is also used: the starting circuit is closed only if the start buttons (or handles) are pressed simultaneously with both hands.

Signaling

Alarm is a means of warning employees about the occurrence of certain events. According to its purpose, the alarm system can be operational, warning and identification; but the method of information - sound, visual, combined (light and sound) and odorization (by smell). For visual alarms use light sources (lighting a lamp, flashing light, etc.), light displays, backlighting of measuring instrument scales, backlighting on mnemonic diagrams of a particular area; for sound- sirens, horns or calls.

Operational alarm is needed in the conduct of technological processes, where, according to safety conditions, control of time, temperature, pressure is required. The signaling is widely used in the construction of automatic lines (without the participation of an operator). To do this, use various measuring instruments equipped with contacts. Contact closure occurs at certain values of controlled parameters.

Operational signaling is also used when coordinating individual actions of workers. Found widespread use iconic signaling transmitted by hand, for example, when coordinating the actions of a crane operator and a slinger.

Warning signal necessary to warn of the presence or occurrence of a hazard. For this, various posters and inscriptions are used, as well as sound and light signals actuated from sensors that register deviations from the normal course of the technological process. Light and sound signals are given immediately before the onset of danger. In some cases, they warn if any node has failed. This is to prevent an accident that may occur if other parts of the unit continue to operate.

Identification signaling is designed to highlight one or another equipment, its parts or work areas that are dangerous or require special attention. For these purposes, a signal color system is used according to GOST 12.4.026–2001 "SSBT. Occupational safety standards system. Signal colors, safety signs and signal markings. Purpose and rules of use. General technical requirements and characteristics. Test methods". This standard establishes the following signal colors: red, yellow, green, blue. To enhance the visual perception of safety signs and signal markings, signal colors are used in combination with contrasting colors - white or black. The semantic meaning, scope of signal colors and their corresponding contrasting colors are given in Table. 4.2.

Table 4.2

Semantic meaning, scope of signal colors and their corresponding contrasting colors

signal color	semantic meaning	Application area	Contrasting color
	immediate danger	Prohibition of dangerous behavior or action
	immediate danger	Identification of immediate danger
	emergency or dangerous situation	Message about emergency shutdown or emergency condition of equipment (technological process)
	Fire equipment, fire protection equipment, their elements	Designation and identification of locations fire fighting equipment, fire protection means, their elements
	Possible danger	Designation of possible danger, dangerous situation
		Warning, danger warning
	Safety, safe	Message about the normal operation of the equipment, the normal state of the technological process
	Help, rescue	Designation of the evacuation route, first aid kits, cabinets, first aid equipment
	Prescription to avoid danger	Requiring mandatory action to ensure safety
	indication	Allowing certain actions

Adopted and put into effect by the resolution of the State Standard of the Russian Federation of September 19, 2001 No. 387-st.

General requirements

The main technical requirements for the design of safety (blocking) devices are given in section 7.2 of STO 34.01-30.1-001-2016.

In accordance with the requirements of the Rules on labor protection during the operation of electrical installations, safe conditions when working in electrical installations must be ensured through the implementation of organizational and technical measures. In this case, when the voltage is removed by turning off the voltage by switching devices, measures must be taken to prevent their erroneous or spontaneous switching on.

Compliance with this requirement is difficult due to design features equipment, as well as due to the existing risk of erroneous or unauthorized influence on switching devices when using existing blocking and locking devices.

Safety (locking) devices must ensure safe and effective fixation of the disconnected position of the switching device from spontaneous and unauthorized switching on, and allow to eliminate the risks of injury associated with non-compliance with the requirements of the NTD when preparing the workplace and performing work in existing electrical installations.

In each structural subdivision of the branch/department of the SDC servicing electrical installations, a list of the nomenclature and the scope of staffing with interlocking devices for teams for repair and maintenance should be developed. maintenance RU PS, TP / RP and approved by the head of the structural unit.

When performing work on overhead lines by several teams, an expander pad should be used to block the disconnected position of switching devices (LR, etc.) with a working locking device or use a blocking cable on the drives of switching devices, disconnectors with a faulty or missing locking device.

To do this, the foreman of each team must install its own lock with a unique key on the expander pad or blocking cable, while putting the line, equipment into operation is possible only after all teams have removed their locks.

This method of blocking disconnectors should exclude the possibility of switching on (supplying) voltage to workplaces with possible risks of errors by operational personnel keeping records of the number of teams working on the line, or errors in the production of uncoordinated work in electrical installations and should be used, as a rule, in the elimination of massive emergency outages.

Substation equipment 35 kV and higher with damage identified during the investigation of accidents and during operation, incl. factory defects

Type switches VMT-110B/1250UHL1 (manufactured in 1988), VMT-220B-25/1250UHL1 (manufactured in 1992)

The most frequent causal damage to circuit breakers of the VMT-110B/1250UHL1, VMT-220B-25/1250UHL1 types for the period from 2012 to 2016 were:

Destruction of a porcelain tire type PMVO-110;

Burnout or coil short circuit of on/off coils;

Violation of tightness (glass, valve, res. seals);

Damage to arc chutes and insulating rods;

Failure of the mechanical parts of the PPRK drive, el. engine, springs

Conducting poor-quality adjustment of controlled parameters during MW repairs also negatively affects the increase in the number of failures of this equipment.

In order to improve the reliability of operation of circuit breakers of the VMT-110B/1250UHL1, VMT-220B-25/1250UHL1 types, the following measures should be taken:

Checking the condition of porcelain covers of switches of the VMT 110-220 kV type during all types of repairs (current, medium, capital) with the MIK 1M measuring complex or other ultrasonic non-destructive testing devices in order to identify the development of internal defects in porcelain at the initial stage;

Engineering inspections of operated circuit breakers of the TDC type in order to identify defects in porcelain tires;

Application for repairs for adjusting the switch of modern devices such as PKV, MKI, MIKO, etc. with appropriate training of personnel in methods of working with devices;

When carrying out all types of repairs (current, medium, capital), measurement of the insulation resistance of the winding of the electric motor for winding the springs of the drive PPrK;

Checking the accumulated resources of all TDC-type circuit breakers and reviewing the period (reducing the period) of the average and major repairs of circuit breakers of this type;

When conducting overhauls replace porcelain covers on circuit breakers of the PMVO-110 type manufactured by Uralizolyator (Kamyshlov) with a service life of more than 20 years, replace fixed contacts in the chamber, oil in the circuit breaker columns, dismantle and check the pulley mechanism, the integrity of the pulley mechanism housing, replace coils switching on and off with a service life of more than 20 years;

Annually, before the onset of a period of sub-zero outdoor temperatures, carry out an audit of the heating system for TDC-type circuit breakers.

Voltage transformers 110-220 kV type NKF
(NKF-110-57 HL1,NKF-220-58)

Most common causes damage to HP of NKF type for the period from 2012 to 2016 were:

wear, aging insulation;

depressurization;

manufacturing defect.

In order to improve the reliability of operation of TN 110-220 kV type NKF, the following measures should be provided:

carrying out extraordinary checks of the resistance of the ground loop of the substation within the time limits established by the technical manager of the branch of the SDC;

reducing the frequency of testing and thermal imaging control of HP, operated with excess of the standard service life;

replacement of NKF-type HP with more modern ones (anti-resonant, low-oil or gas);

carrying out at least 1 time in 2 years high-voltage tests of TN 110-220 kV of the NKF type, which have been in operation for 25 years or more, with the measurement of current and no-load losses;

carrying out at least once every 2 years a chromatographic analysis of gases dissolved in oil of 110-220 kV voltage transformers with a service life of 25 years or more;

Do not let the silica gel in the air-drying filter get wet.

Surge arresters 110 kV type OPN-110/84,
OPN-U-110 / 84-2 of the manufacturer CJSC "Plant of energy protective devices", St. Petersburg)

During the period from 2012 to 2016, 68 cases of damage to surge arresters of 110 kV and above, which have been in operation for less than 5 years, were recorded in the subsidiaries and dependent companies of PJSC Rosseti, in 13 cases, arresters manufactured by the Plant of Energy Protective Devices in St. Petersburg were damaged in 13 cases.

The main causes of damage to the arrester of the manufacturing plant "Plant of energy protective devices" in St. Petersburg were:

design defect (11 cases);

atmospheric surges (thunderstorm) - 2 cases.

The most frequent cases of emergency shutdowns that led to damage to the arrester were:

tightness failure - a manufacturer's defect in terms of the use of low-quality materials, as a result of which the column of varistors was moistened when the sealing of the connection of the upper flange with the polymer coating of the surge arrester was violated;

internal breakdown in polymer insulation caused by a manufacturing defect.

In order to improve the reliability of the operation of the OPV by the CJSC Plant of Energy Protective Devices, St. Petersburg, the following measures should be envisaged:

provision of accelerated thermal imaging control and inspection of surge arresters;

organization of measurement and control over the magnitude of the conduction current;

organization of claims work with CJSC Plant of Energy Protective Devices;

On all paths of movement of floor-transport equipment (steel trucks, slag carriers, iron carriers, bogies, etc.), limit switches are provided to automatically turn off the movement mechanisms of the specified equipment (taking into account possible movement by inertia). In addition, limit stops are installed on all tracks of the floor-transport equipment.

Each converter slew drive motor is equipped with a brake that allows the converter to be held in a stationary position in the event of a power outage. The mechanisms for vertical movement of the tuyeres are equipped with switches and stops, which exclude the possibility of the tuyeres falling into the converter.

All cranes are equipped with the following safety devices:

stops that limit the movement of the crane, installed on the crane tracks at the ends of the spans, as well as limit switches installed on the mechanisms for moving the crane, turning off the movement mechanism when the crane approaches the stop at a distance of at least half of the braking path of the movement mechanism;

Limit switches that turn off the mechanisms of movement of cranes when they approach each other;

Emphasis on the bridge of the crane and limit switches that limit the progress of the trolley;

stops on trolleys and limit switches that limit the upward movement of hooks.

The places of installation of safety devices are given in table 3.2.

Table 3.2 - Safety devices

Name of devices

Installation location

1.1. Electric gate valve with remote control

1.2. Explosive relief valves

1.3. Grounding of metal non-current-carrying: parts of electrical equipment

1.4. Lightning protection

1.5. Water seals to ensure a reliable seal when water is turned off

1.6. Devices providing a constant operating pressure of oxygen on the low side

1.7. Seals to prevent air leakage at all movable joints of the gas exhaust tract of the converter operating under vacuum

1.8. Travel limiters for overhead cranes and semi-portal filling machines operating on the same track

1.9. Load limiters for all cranes, allowing overload by no more than 25%

1.10. Stops that prevent the scoops from moving off the trolleys

At the oxygen outlet, wires from the shop manifold to the converter

Gas outlet

Converter, lance, chimney electric drives

Gas outlet

Oxygen regulation unit

Converter exhaust path

Semi-portal cranes, filling machines

Overhead cranes, semi-portal charging machines

Scrap trucks

The installation locations of interlock devices are shown in Table 3.3.

Table 3.3 - Locking devices

Name of funds

Installation location

1. Converter

1.1. Blockage that excludes the introduction of the lance when the converter is tilted

1.2. Interlock to lift the lance and cut off the oxygen supply when the oxygen pressure in front of the lance decreases, the water flow for cooling the lance decreases, or the temperature of the outgoing water rises

1.3. Interlock to ensure lifting of the lance from the converter in the event of a sudden power outage

1.4. Switches preventing the possibility of the tuyere falling into the converter

1.5. Blocking that prevents the lowering of the lance and oxygen supply to the converter when the water supply to the boiler or gas cleaning is stopped or reduced below the minimum allowable value, as well as water temperature leaving the caisson above the allowable limit

1.6. Blockage that prohibits breaking the skirts of the boiler in the presence of carbon monoxide in the flue gases

1.7. Gas duct blocking:

Supply of steam to the candle in front of the afterburner and turning off the gas supply to the pilot burner in case of an emergency stop of the smoke exhauster or a vacuum drop to it, as well as in case of any emergency termination of the melt purge;

Prevention of oxygen supply for the next purge of the melt in the event of a malfunction of the pilot burners;

Shutdown of the oxygen supply to the lance after the start of its rise when the purge is stopped (normal and emergency)

1.8. Interlocks that exclude the possibility of controlling the movement of floor-transport equipment (steel trucks, scrap trucks, sling trucks, etc.) simultaneously from two points

1.9. Interlocks that exclude the possibility of controlling the equipment simultaneously from different points (remote control from a computer, local control)

1.10. Blocking, including smoke exhauster control systems after "ignition" of the melt

1.11. Blocking that excludes the supply of oxygen to the workshop and to the converter in the event of a power outage to the workshop

Lance lifting-lowering drive

Lance drive

Lance Drive, Oxygen Control Unit

Skirt lift drive

Gas ducts

Gas exhaust paths of converters, units for regulating the supply of oxygen to tuyeres

Oxygen supply control unit, tuyere lifting drive

Posts, control panels for floor-transport equipment

Stations and equipment control panels

Converter exhaust ducts

Oxygen expansion station. Nodes of regulation

The use of barriers.

To create safe working conditions, all open moving parts of equipment located at a height of 2.5 m or less from the floor level or accessible for accidental contact by workers from service sites, as well as counterweights that are not placed inside the equipment, are protected by a solid or mesh fence with mesh sizes 20x20 mm. Fencing is removable, resistant to corrosion and mechanical stress.

All guards have interlocks with equipment triggers that prevent the operation of the equipment when the guard is removed.

All platforms located at a height of 0.6 m or more from the floor level, stairs, open pits, walkways, openings in the ceilings are equipped with railings or solid concrete and metal fences with a height of at least 0.9 m. openings with sturdy covers or decks laid flush with the floor .

In the converter span, the enclosing devices are:

Slag removal shields (under the working platform along the tracks of the slag carrier, steel carrier);

Solid guard (converter turning drive);

Railings with solid sheathing along the bottom (working platform, drive maintenance platforms, oxygen supply machine maintenance platforms, cooling boiler maintenance platforms, gas cleaning, etc.).

Corrosion protection of pipelines.

Corrosion is the destruction, erosion of solids caused by chemical and electrochemical processes. It leads to loss of strength, hardness, plasticity, tightness, which in turn can lead to accidents.

There are gas ducts in the BOF span, in which, during BOF melting, build-ups and holes are possible during the movement of gas, which can lead to collapse of gas duct structures, and, consequently, to accidents and injuries. To avoid this and ensure high corrosion resistance, it is necessary to use special corrosion-resistant materials.

So, for example, to protect the welded joints of pipelines, it is recommended to use a special corrosion-resistant, heat-resistant material. They are lined with the inner surfaces of the pipes. In this case, first, the lining is made with a thin-walled sleeve made of corrosion-resistant steel, which is installed offset from the end of the pipes and welded to the pipe body with circumferential seams, and the lining of the inner surface of the pipe between the welded sleeve and the end of the pipe is performed by surfacing a corrosion-resistant material, then inside the surface pipes include a partially lined surface coated with a heat-sensitive corrosion-resistant material, such as glass enamel or polymer, and the pipes are connected by welding.

Protection against thermal radiation.

In the places of passage of steel carriers, iron carriers with liquid metal, slag carriers with liquid slag, as well as in places exposed to heat radiation, thermal protection of the metal structures of the building and equipment is installed. All columns along the path of the steel locomotive to a height of up to 8 m are lined with refractory bricks, beams and platforms above the steel locomotives are protected by special screens made of stainless metal or water-cooled screens (beams above the converter).

To protect the metal structures of the building and the equipment located above the converter, the converters are completely covered, which ensures the capture of the torch formed during loading of scrap metal and pouring cast iron. Scoop scoops and cast iron pouring ladles with elongated toes are provided to provide shelter of the required dimensions and provide technology for loading scrap metal and pouring cast iron and in order to remove the crane cables from the flare knockout zone. To protect workers from radiant heat and possible emissions of smelting products, the converters are completely covered from the zero mark to the mark above the skirt of the boiler-cooler of converter gases.

The openings in the shelter on the side of the melting drain are equipped with sliding gates.

Converter control panels are located offset relative to the converter neck.

A set of measures is provided for additional thermal protection of the main converter control posts, including glazing the post with heat-absorbing glass, protecting the outer wall of the post facing the converter with reflective screens (aluminum sheets S\u003d 1.5 mm), supply of conditioned air to the post from the central ventilation station through a heat-insulated air duct. It is also possible to install a movable protective screen made of a polymer film with a metallized coating between the glazing elements. The screen is installed between two window blocks with the same glazing at a distance of 5-20 mm from each of the glazing elements.

Sampling and measurement of metal temperature is provided with a thermal probe without knocking down the converter with automatic recharging of sensors. For manual sampling, a mechanized trolley with a heat shield is provided.

Maintenance of the steel tapping hole is provided from a special platform equipped with a protective screen. The windows of the control cabin of the semi-portal machine are made of durable heat-shielding glass and are equipped with special protective screens. The cabin is thermally insulated and equipped with air conditioning.

The device of aspiration systems.

The flue gases formed during the blowdown in the converter are completely captured, cooled, cleaned at a wet type gas cleaning unit and transferred to the installation for using converter gases.

To prevent converter gases from being knocked out through technological openings in the boiler-cooler of converter gases, they are cut off by nitrogen ejectors.

To capture fugitive emissions generated during loading of scrap metal and pouring pig iron into the converter, tapping of metal, draining slag from the converter, complete shelter of the converters is provided with individual removal of captured gases to the central gas cleaning station of the converter shop.

Noise and vibration protection.

To reduce noise and vibration levels, sealing of control posts with a sound-absorbing lining of the internal surfaces of enclosing structures, soundproof shelters for noisy units of units is provided.

The use of three-layer panels is envisaged as the enclosing structures of the built-in premises and control posts in the converter bay. The internal surfaces of walls and ceilings, if necessary, are lined with sound-absorbing materials. Joints are sealed using rubber and polyurethane gaskets.

Reduced noise characteristics from converter span equipment are provided. Measures are provided for sound insulation and sound absorption in the sources of noise, on the way of its propagation.

The full cover of the converter ensures noise reduction at the work site and in the span along the melting process. To do this, it is proposed to use a converter casing containing a frame, rear and front panels mounted on it, and two sidewalls forming a convective channel, a cover, air outlet slots, holes in one of the sidewalls for heating pipes connected to the heating element. The air outlet slots are made in the cover and the upper part of the front panel in the form of “louver” type slots, the flanges are bent out of the casing.

Steel and slag carriers are not sources of increased noise. The only source of noise is the sound siren, which is turned on when they move, in accordance with safety requirements.

To protect against vibration, vibration isolating and vibration-absorbing devices are used, as well as means of remote control, automatic control and signaling.

The cranes of the converter shop do not provide for the installation of high-voltage converters, which makes it possible to eliminate the vibration of their bridges. The cranes are fed through thyristor converters installed indoors on the floor of the workshop.

Ventilation.

Natural ventilation.

In connection with the release of significant amounts of heat, dust (especially finely dispersed, floating in the air) and gases in the oxygen-converter shop, organized air exchange is important for creating favorable working conditions. Natural ventilation is the main means of combating industrial hazards. With its help, it is possible to provide huge air exchanges, sometimes reaching tens of millions of cubic meters per hour. The implementation of such air exchanges by means of a mechanical ventilation device would require significant costs, large expenditures of electrical and thermal energy, and would be very difficult to operate.

The main advantages of aeration are insignificant (compared to mechanical) costs and noiselessness.

When designing and manufacturing machines and equipment, it is necessary to take into account the basic safety requirements for the personnel serving them, as well as the reliability and safety of the operation of these devices.
When carrying out various technological processes in production, hazardous zones arise in which workers are exposed to dangerous and (or) harmful production factors. An example of such factors is the risk of mechanical injury (injury resulting from the impact of moving parts of machinery and equipment, moving products, objects falling from a height, etc.), the danger of electric shock, exposure various kinds radiation (thermal, electromagnetic, ionizing), infrared and ultrasound, noise, vibration, etc.

The work contains 1 file

Introduction.

When carrying out various technological processes in production, hazardous zones arise in which workers are exposed to dangerous and (or) harmful production factors. An example of such factors is the danger of mechanical injury (injury as a result of exposure to moving parts of machinery and equipment, moving products, objects falling from a height, etc.), the danger of electric shock, exposure to various types of radiation (thermal, electromagnetic, ionizing), infra - and ultrasound, noise, vibration, etc.

The dimensions of the danger zone in space can be variable, which is associated with the movement of parts of equipment or vehicles, as well as with the movement of personnel, or constant.

As already mentioned above (Chapter 13), collective and individual protective equipment is used to protect against the effects of hazardous and harmful production factors. Here we consider the main means of collective protection, which are divided into protective, safety, blocking, signaling, remote control systems for machines and equipment, as well as special ones.

Protective means of protection, or fences, are devices that prevent a person from entering the danger zone. Fencing can be stationary (non-removable), movable (removable) and portable. In practice, fences are made in the form of various nets, gratings, screens, casings, etc. They must have such dimensions and be installed in such a way as to exclude human access to the danger zone in any case.

When installing fences, certain requirements must be met:

fences must be strong enough to withstand the impact of particles (chips) that occur during the processing of parts, as well as accidental impact of maintenance personnel, and securely fastened;

fences are made of metals (both solid and metal meshes and gratings), plastics, wood, transparent materials (organic glass, triplex, etc.);

all open rotating and moving parts of machines must be covered with guards;

the inner surface of the railings should be painted in bright colors (bright red, orange) so that it is noticeable if the railing is removed;

it is forbidden to work with a removed or defective guard.

Safety devices are devices that automatically turn off machines or units when any equipment parameter goes beyond the permissible values. This link is destroyed or does not work when the operating mode of the equipment deviates from normal. A well-known example of such a link is electrical fuses (“plugs”) designed to protect the electrical network from high currents caused by short circuits and very large overloads. Such currents can damage electrical equipment and wire insulation, as well as cause a fire. The fuse works as follows: the current passes through a thin wire (fusible link), the cross section of which is designed for a certain maximum current. When overloaded, the wire melts, turning off the faulty or current overloaded section of the network.

Examples of devices of this type are: safety valves and bursting discs installed on pressure vessels to prevent accidents; various braking devices that allow you to quickly stop moving parts of the equipment; limit switches and lift limiters that protect moving mechanisms from going beyond the established limits, etc.

Blocking devices exclude the possibility of a person entering the danger zone or eliminate the dangerous factor for the duration of the person's stay in the danger zone. According to the principle of operation, mechanical, electrical, photoelectric, radiation, hydraulic, pneumatic and combined blocking devices are distinguished.

The use of photoelectric blocking devices in the construction of turnstiles installed at the entrances of metro stations is widely known. The passage through the turnstile is controlled by light beams. In case of an unauthorized attempt to pass through the turnstile of a person to the station (no magnetic card is presented), he crosses the light flux incident on the photocell. A change in the light flux gives a signal to the measuring and command device, which activates the mechanisms that block the passage. With authorized passage, the blocking device is disabled.

Various signaling devices are designed to inform personnel about the operation of machines and equipment, to warn about deviations in technological parameters from the norm or about an immediate threat.

According to the method of presenting information, there are sound, visual (light) and combined (light and sound) signaling. In the gas industry, an odor (by smell) alarm about a gas leak is used, mixing smelling substances with the gas.

Depending on the purpose, all alarm systems are usually divided into operational, warning and identification. Operational alarm provides information about the course of various technological processes. For this, various measuring instruments are used - ammeters, voltmeters, pressure gauges, thermometers, etc. Warning alarms are activated in case of danger. In the device of this signaling, all the above methods of presenting information are used.

Identification signaling is used to highlight the most dangerous units and mechanisms of industrial equipment, as well as zones. Signal lights warning of danger, the “stop” button, fire fighting equipment, current-carrying tires, etc. are painted in red. Elements of building structures that can cause injury to personnel, intra-factory transport, fences installed at the boundaries of hazardous areas are painted in yellow , etc. Signal lamps, evacuation and emergency exit doors, conveyors, roller tables and other equipment are painted green. The use of identification coloration of various cylinders is discussed in Chap. 21.

In addition to the distinctive color, various safety signs are also used, some of which are mentioned in Ch. 21. These signs are applied to tanks, containers, electrical installations and other equipment.

Remote control systems are based on the use of television or telemetry systems, as well as visual observation from sites remote at a sufficient distance from hazardous areas. Controlling the operation of equipment from a safe location allows you to remove personnel from hard-to-reach areas and high-risk areas. Most often, remote control systems are used when working with radioactive, explosive, toxic and flammable substances and materials.

In some cases, special protective equipment is used, which include two-handed switching on of machines1, various ventilation systems, noise suppressors, lighting devices, protective earth and a number of others.

1 Two-handed switching on of machines and equipment is carried out by two handles by means of two starting elements, which excludes accidental starting of these devices.

In cases where collective means of protecting workers are not provided or they do not give the desired effect, they resort to individual means of protection, which are discussed in previous chapters.

A common part.

Protective devices.
Protective devices play an important role in creating safe working conditions. Fences are arranged to isolate the moving parts of machines, machine tools and mechanisms, places where flying particles of the material being processed fly out, dangerous voltage-carrying parts of equipment, zones of high temperatures and harmful radiation, areas where an explosion can occur due to a violation of the technological process. Manholes, openings, various channels in production premises and on the territory of the enterprise are protected to prevent people from falling into them. The design of the fencing of working platforms located at a height should prevent people and heavy objects (tools, materials, etc.) from falling from a height. To prevent accidental entry of a person into the danger zone, the protective devices are blocked when the machine is started.
Safety devices.
Safety devices serve to prevent accidents and breakdowns of individual parts of the equipment and the associated danger of injury to workers.
Accidents and breakdowns can occur due to various technical reasons, determined by the nature of the equipment. They can be caused by an overload of equipment or the transition of its moving parts beyond the established limits, a sudden excessive increase in steam, gas and water pressure, temperature, an increase in speed, or electric current. The cause of the accident may be an explosion or ignition of some substances. Safety devices automatically operate, turning off the equipment or its assembly when any of the specified parameters goes beyond the permissible values.
Brake devices.
Braking devices provide the ability to quickly stop production equipment or its individual elements, being an important means of preventing accidents and accidents, especially during contact work between a person and a machine. The choice of a braking system, based on safety requirements, is justified by the calculation of the braking time or braking distance, depending on the specific features of the equipment and its operating conditions.
Danger alarm.
The alarm system is a means of warning workers of impending danger. Signaling devices include light and sound signals, symbolic signaling and various indicators of liquid level, pressure, temperature. Safety devices and safety interlocks automatically eliminate the hazard. Light and sound signals are given immediately before the onset of danger. In some cases, they warn if any unit of the unit has not worked. This is done in order to take timely measures to eliminate the malfunction, preventing an accident that can occur if other parts of the unit continue to work. Such signals warn a person about his approach to the danger zone.
Gaps and safety dimensions.
For the purpose of labor safety in the maintenance of technological equipment, ensuring the safety of buildings and structures, preventing accidents during the operation of various types of transport, lifting and transport vehicles, and in some other cases, the system of safety equipment provides for the regulation of gaps between industrial buildings and structures, machines and various devices and setting safety margins.
The gap and safety dimensions are usually understood as the minimum allowable distances between objects, of which one or both represent a potential hazard that can easily manifest itself at smaller distances between them. For specific production conditions, gaps and safety clearances are established by the relevant standards, technological design norms, general and special safety rules.
Remote control.
Remote control of units, machines, machine tools and various technological processes allows you to take a person out of the danger zone and make his work easier. Remote control is especially important as a means of safety in the production and use of explosive, toxic, flammable substances and in the processing of radioactive materials. Also of great importance is the use of remote control of shut-off and control valves when they are located in hard-to-reach, flammable and other areas in which a long stay of service personnel is unacceptable.
Signal colors and safety signs.
Signal colors and safety signs should raise attention to the danger in a timely manner, they remind workers of the need to comply with certain requirements, help quickly and safely navigate when performing various production operations and repair work.
Requirements for signal colors and safety signs are established in GOST 12. 4. 026-01.
Installation, installation, rearrangement and placement of stationary and desktop equipment in existing workshops, sections and other production facilities are carried out according to approved technological layouts agreed with the relevant departments of the enterprise. Layouts for the placement of equipment and installations with the use of fire-explosive and hazardous chemicals or having sources of radiation of harmful production factors are subject to approval by local sanitary and fire authorities before approval.
The plan specifies:
- the name of the premises, workshops, sections, etc., the scale of the image;
- overall dimensions of the premises, indicating the coordinate axes, the location of windows and doors;
- fire and explosion safety categories for each room, indicating the location of explosive mixtures by category and group;
- points of connection of engineering networks and communications - heating, ventilation, water supply and sewerage, compressed air, high-voltage and low-voltage electrical networks, etc., to which the installed equipment should be connected;
- dimensions and installation location of the equipment, its number on the layout, the list of equipment to be installed, the location of workplaces, etc., and the image of the equipment is drawn along its contour, taking into account the extreme movements of moving parts, opening doors and the use of long workpieces;
- stationary handling vehicles;
- places of storage of materials, products;
- sanitary equipment and ventilation installations;
- passages and driveways with indication of vehicles;
- fire extinguishing means (fire hydrants, fire extinguishers);
- a brief description of installed equipment, quantitative characteristics for power supply, ventilation, water (supply and drain), compressed air, etc.
These characteristics are summarized in the table;
- quantitative characteristics of harmful chemicals released into the air and water (per unit of time);
- methods of neutralization and utilization of harmful chemicals in water and air.

Classification and coloring of containers
(t.l. - thousand liters)
1. Pipelines. Liquids and gases transported through the pipeline are divided into ten enlarged groups, in accordance with which the identification color of pipelines is established:
Water is green.
Steam red.
Air is blue.
Combustible and non-combustible gases - yellow.
Acids - orange.
Alkalis - purple.
Liquid mountains. and negor. - Brown.
Other substances - grey.
Warning (signal) colored rings are applied to pipelines.

2. Gas holders. High pressure gas holders (up to 40 MPa) are used to create a high pressure gas supply; gas holders low pressure- for storing gas reserves, smoothing pulsations, separating mechanical impurities and other purposes.

3. Vessels for liquefied gases. Liquefied gases are stored and transported in stationary and transport vessels (tanks) equipped with highly efficient thermal insulation. Stationary tanks are manufactured with a volume of up to 500 tons. and more, trans-s vessels - usually up to 35 tons. Appropriate inscriptions and distinctive stripes are applied on transport vessels

4. Boilers. This is a device that has a furnace, heated by the products of the fuel burned in it and designed to heat water or produce steam with a pressure above atmospheric.
When working with boilers, the greatest danger is an explosion. When the boiler explodes, instantaneous evaporation of water under pressure and at a temperature above 100 ° C occurs, because due to the explosion, the pressure in it drops to atmospheric pressure. With the instantaneous evaporation of water, a huge amount of steam is formed (1 liter of water, turning into steam, increases in volume by 1700 times), which causes great destruction.

5. Cylinders. They are used for storage and transportation of compressed liquefied and dissolved gases at temperatures from -50 to +60°C and various pressures.
Cylinders are made of small (0.4-12l), medium (20-50l) and large capacity (80-500l). At the neck of each cylinder, on the spherical part, the data are knocked out: the trademark of the manufacturer; date (month, year) of manufacture (test) and year of the next test; working and test pressure (MPa); cylinder capacity (kg); OTK stamp - designation of the current standard.
Cylinders for compressed gases accepted by filling plants from consumers must have a residual pressure of ≥0.05 MPa, and cylinders for dissolved acetylene - ≥0.05 and ≤0.1 MPa. Residual pressure allows you to determine which gas is in the cylinders, check the tightness and its fittings and guarantee that no other gas or liquid enters the cylinders.

Causes of cylinder explosions:
1. Excessive overfilling of cylinders with liquefied gases. Because Since liquids are practically incompressible, when the temperature of the cylinder rises, they expand and evaporate, which leads to very high pressures.
2. Significant overheating or hypothermia of the walls of the cylinder. Overheating causes softening of the wall material and a decrease in their mechanical strength, supercooling causes brittleness of the wall material, which also leads to a decrease in strength.
3. The ingress of oils and other fatty substances into the internal cavity of cylinders filled with oxygen, leading to the formation of explosive mixtures.
4. Formation of corrosion and rust inside the cylinders. Rust particles entrained in the gas escaping from the cylinder can create a spark due to friction and the buildup of static electricity. For this reason, before filling, oxygen cylinders are washed, degreased with solvents (dichloroethane, trichloroethane).
6. Incorrect filling of cylinders, leading to the formation of explosive atmospheres (for example, when filling hydrogen cylinders with oxygen).

Cylinder marking

Gas name	Balloon coloring	Inscription text	Lettering color	Stripe color
Acetylene		Acetylene
		Compressed air
Carbon dioxide		Carbon dioxide
Oxygen		Oxygen
				Brown
	brown
Argon pure		Argon pure
All other combustibles		Name of gas