Normally open and normally closed fire dampers. Design and use of fire dampers for ventilation systems

Increasing urban density makes it necessary to build multi-storey buildings. According to modern regulatory requirements, all of them must contain systems fire protection. This applies not only to residential buildings, but also to public and industrial buildings.

It is worth paying attention to the fact that according to statistics, about 85% of deaths in a fire occur from the influence of combustion products on the body. Their distribution depends on the speed of movement of air masses from one point of the building to another. To reduce smoke from the entire structure during a fire, smoke protection systems are developed and installed, which include fire dampers for ventilation systems.

What are these elements of the ventilation network? Let's take a closer look at what types of valves there are, how they are selected and how they are installed.

Purpose of fire dampers

In accordance with regulatory documents A fire damper for general ventilation, air conditioning and heating systems is a device for preventing combustion products from entering rooms or removing them from the site of a fire.

Fire damper for ventilation in some modifications it is used to remove smoke, gas, or combustion products from residential and public premises, vestibules, corridors, elevator shafts and other places.

In general, according to technical literature, fire damper is called remotely or automatically controlled device for blocking ventilation ducts or openings in the building envelope. How are valves classified and what types are they?

Classification of fire dampers

Fire dampers, which are produced for use in modern systems ventilation are classified into two main categories. Each of them is intended for its own field of application and differs in design and location. Valves are:

1. NC (normally closed), which include smoke and used in the supply air exhaust systems smoke ventilation. Their purpose is to remove smoke and gases after a fire. IN in good condition the valve in them is in closed position and air does not pass through the valve. After a fire occurs and fire alarm the valve opens under the action of a servo drive or any other control devices and smoke is removed through it using ventilation.
2. BUT (normally open). The fire ventilation valve from this group is designed for installation in general ventilation systems, air heating or air conditioning to protect against smoke ingress. In the normal state, the valve in it is open and air moves freely through the ventilation system. After the alarm is triggered, the valve closes, which prevents the possible penetration of smoke from the fire into adjacent rooms. One of the popular devices of this type is the fire damper KLOP-1.

Double acting valves are also available. They combine the characteristics of the two groups considered. The device closes in the event of a fire, to protect against smoke penetration into adjacent rooms, and automatically opens after a fire. Normally closed valves are also called smoke valves.

One of the characteristics of all valves is the fire resistance limit, which characterizes the time that its integrity is maintained when exposed to fire.

Valves are also produced and divided according to climatic design. For example, there are frost-resistant devices that are designed to operate in low temperature conditions. There are also marine devices that are designed to operate in conditions of aggressive humid sea air.

Valves are also classified according to installation method into:

• wall;
• duct.

The difference is indicated in the name itself: wall ones are installed directly in the enclosing structures without connecting to the ventilation network, duct ones are connected to air ducts.

Regulation

Servo drives are now used to regulate the position of the dampers. They are controlled by applying voltage to the device. They are produced in several types with different modifications. Not all of them are suitable for fire-fighting and fire-retarding ventilation.

It should be noted that previously a normally closed valve, which was called a fire-retardant valve, allowed the use of spring actuators with a thermal lock and a fusible insert. It was triggered when the temperature increased, when the fusible link was destroyed and the valve slammed shut. But due to the fact that it cannot be controlled remotely, their use is not allowed in today's current regulatory documents

Valve selection

To select a valve, several characteristics are taken into account:

• type and purpose - smoke exhaust or fire damper;
• fire resistance limit, which is the main characteristic that determines fire and technical properties devices; it can be found in the documentation for a specific product;
• dimensions that depend on the air duct, installation location and air speed;
• the type of actuator that drives the valve flap;
• resistance;
• price.

All characteristics are selected during design based on many factors. Also, do not forget about the resistance on the fire damper, which determines the pressure loss in the network and, as a consequence, the need to choose a more powerful fan. Resistance is calculated using the same principles as for other devices in the ventilation network.

Each product has a local resistance coefficient that is used in the calculation. The aerodynamic characteristics of each valve type are different. This is also one of the factors that influence the choice. All data for each valve is usually indicated in the manufacturer’s catalogs, which must be reviewed during design.

Where are the fire dampers of the ventilation system installed?

There are regulations and requirements to determine valve installation locations. The location of the device depends on its purpose. Fine open valves, which act as fire-retarding barriers, are usually located in or near the building envelope. There are three wiring diagrams fire dampers:

• directly in a wall or other enclosing structure, with air ducts connected to the device;
• at some distance from the enclosing structures, but the section of the air duct from the valve to the wall or other element must have a fire resistance rating no less than the valve itself;
• in a building structure without connection to air ducts, such a valve ensures the flow of air between adjacent rooms.

Normally closed (smoke) dampers are most often installed in smoke ventilation ducts. They must also have the required level of fire resistance, and the external part that is visible from the room can be closed decorative grilles or other elements.

The selection of fire dampers during design is an important part of ensuring the safety of a building. Selecting the right and high-quality equipment can save lives and preserve property during fires.

Since May 1, 2009, new regulatory requirements have been introduced in Russia for the drives of fire dampers in ventilation and smoke protection systems!

Part 2 Art. 138 “Technical regulations on requirements fire safety» prohibits the use in ventilation and air conditioning systems of fire-rated normally open (formerly called fire-retarding) valves with a spring drive and a thermal switch (fusible link), since such a drive cannot be controlled remotely and the thermal switch as part of the drive is the main temperature-sensitive element, and not a backup one , as required by the regulations.

According to SP 7.13130, actuators (drives) of fire-prevention normally closed (including smoke) valves of supply and exhaust smoke ventilation systems (must maintain the specified position of the valve damper when the power supply to the drive is turned off. Distinctive feature of the indicated systems, including several valves with addressable control, is the presence of two specified damper positions - “open” (for example, on the fire floor) and “closed” (on other floors), which the drive must provide in any case of power supply circuit voltage shutdown, in including emergency ones.

This requirement actually prohibits the use of electromechanical drives with a return spring on fire protection
normally closed and smoke valves, since when the voltage is removed from them, only one specified position of the damper is ensured - “open”. This requirement is satisfied by fire-prevention normally closed (including smoke) valves with electromagnetic drive or a reversible electric drive, which controls the activation signal
is the supply of voltage to the drive. These actuators provide specified “open” and “closed” damper positions when the power supply is turned off.

various types

must provide the minimum required resistance to smoke and gas penetration.

You can familiarize yourself with the Federal Law “Technical Regulations on Fire Safety Requirements” on the RG website
Appendix A (mandatory). Scheme of bench equipment for testing the fire resistance of fire-retarding valves of ventilation systems of various sizes. Appendix B (mandatory). Scheme of bench equipment for testing the fire resistance of fire-retarding valves for the protection of technological openings Appendix B (mandatory). Scheme of bench equipment for testing the fire resistance of smoke valves
Fire safety standards NPB 241-97
"Fire dampers for ventilation systems. Test method for fire resistance"

(approved by the Chief State Inspector of the Russian Federation for Fire Supervision,

put into effect by order of the GUGPS of the Ministry of Internal Affairs of the Russian Federation dated July 31, 1997 N 52)

Fire dampers of ventilation systems. The test method for fire resistance

Introduced for the first time

1 area of ​​use These standards establish a fire resistance test method for fire dampers:;

fire retardant - for ventilation systems

for various purposes

fire-retardant - to protect technological openings in enclosing building structures;

smoke - for emergency smoke ventilation systems.

These standards are not intended to cover fire resistance tests:

fire-retarding valves to protect transport technological openings;

smoke valves of emergency smoke ventilation systems serving one room. The establishment of fire resistance limits for fire dampers is carried out in order to determine the possibility of their use in accordance with the fire safety requirements of regulatory documents (including certification).

GOST 6616-91. Thermoelectric converters GSP. Are common

5.3. The pressure drop across the test sample during thermal exposure should be 70 +- 5 Pa for fire dampers and 300 +- 6 Pa for smoke dampers. Taking into account the specific functional purpose of the valves, the specified values ​​can be changed in accordance with the customer’s technical documentation.

6. Bench equipment and measuring equipment

6.1. The bench for testing valves consists (Appendices A, ,) of a furnace with dimensions (internal) of at least 1.2 x 1.1 x 0.7 m with an opening for installing valves, a system for maintaining and regulating excess pressure on the sample, connecting lines for mating the test sample with the above system.

The system for maintaining and regulating excess pressure consists of a fan with piping and control dampers, a measuring section with a flow meter diaphragm.

The stove must be equipped with liquid fuel nozzles in the number necessary to provide the required thermal effect in accordance with 5.1 and 5.2.

Specifications elements of the system for maintaining and regulating excess pressure and connecting lines must be selected taking into account the maximum permissible values ​​of gas flow through a closed valve according to 4.2.5 and the pressure drop across the test sample according to 5.3.

6.2. The test bench is equipped with means for measuring temperature, gas flow and pressure.

6.2.1. To measure temperature use thermoelectric converters(TEP) type THA (technical conditions in accordance with GOST 6616), nominal statistical characteristics and limits of permissible deviations e.m.f which must correspond to GOST R 50431 or TPE with individual calibration.

6.2.2. To measure the temperature in the furnace, three TECs with electrode diameters from 1, 2 to 3 mm are used. The number and placement of TEC relative to the heated surface of the test sample are given in Appendices A, ,.

6.2.3. To measure temperatures on the unheated surfaces of a fire-retarding valve, its sealing unit in the furnace opening and in the outlet section of the valve (only for valves protecting technological openings), TECs with electrode diameters from 0.5 to 0.7 mm are used.

The method of attaching TECs to these surfaces should ensure temperature measurement accuracy within +- 5%.

The number of TECs and their installation locations are indicated in Appendices A and B.

6.2.5. The flow of gases is measured using standard flow metering diaphragms in accordance with Regulations 28-64.

It is allowed to use non-standard diaphragms to measure gas flow if they have calibration characteristics obtained in the prescribed manner.

6.2.6. Temperatures are recorded using instruments with a measurement range from 0 to 1300 °C, accuracy class not lower than 1.0.

6.2.7. To measure the pressure drop across the flow meter diaphragm, differential pressure gauges with an accuracy class of no more than 1.5 are used.

6.2.8. Time is recorded with a stopwatch with a measurement error of no more than 30 s during one hour of testing.

7. Preparation for testing

7.1. Two valve samples of the same size are subject to fire resistance testing.

For channels of the same type with different standard sizes, valves whose equivalent diameter differs from the maximum by no more than 25% are subject to testing.

Depending on the design features, the number of valves to be tested may be increased.

7.2. Samples of valves supplied for testing must comply with design documentation. The degree of compliance is established by input control, in which:

the completeness of each sample is determined;

the dimensions of the valve, the size of the gaps between the seating surfaces of the body and the valve of the sample and other dimensions that determine the nature of the behavior of the valve during its testing are measured;

The compliance of the component parts with the design ones is determined, and the quality of their condition is visually monitored.

The incoming inspection data is entered into the test report.

7.3. Before testing, the operation of all structural components is monitored for each sample.

To check the valve, it is necessary to perform at least 50 valve operation cycles, during which the damper completely closes (fire-retarding valves) or opens (smoke valves) its flow area.

7.4 To carry out the test, the sample in the closed position is installed on the stand (Appendices A, ,).

Density ventilation duct attached to the test sample, the amount of leaks and air leaks must be determined in advance and amount to no more than 10% of the maximum permissible gas flow rate according to 4.2.5 of these standards.

7.5. Immediately before testing, the air permeability of the sample is determined. In this case, the measuring section of the ventilation duct attached to the sample is connected to the suction pipe of the fan. By throttling the fan, at least 5 pressure differentials are created across the sample, uniformly spaced between 0 and 700 Pa.

The flow meter measures the air flow rate corresponding to each value of the pressure difference passing through the leaks in the sample structure. Then reverse the thrust, created by connecting the measuring section to the discharge pipe of the fan, the pressure drop across the valve changes in the opposite direction, and the measurement is repeated in a similar sequence.8.4. During testing the following is recorded:

1) the moment of operation of the automatic drive of the sample and its thermal drive (only for fire-retarding valves);

2) the temperature in the furnace and on the unheated side on the outer surfaces of the sample body, the adjacent air duct (with a thermally insulated valve body), the body seal assembly in the furnace opening, the gas temperature in the outlet section of the valve (only for fire-retarding valves protecting technological openings);

3) the moment of occurrence and characteristic features loss of density (destruction, extreme deformation of the seal assembly of the sample body, including the formation of through cracks, burnouts and peeling of the seal, leading to leakage flue gases and the appearance of a flame from the unheated side);

4) flow rate and temperature of the gas flow passing through the leaks in the sample structure.

Measurements of temperatures, flow rates and pressures at each control point should be carried out at intervals of no more than 2 minutes.

8.5. Tests shall be carried out to the occurrence of one or two (if necessary) limit states of the valve design in accordance with Section 4 of this document.

9. Processing and evaluation of test results

9.1. The reduced resistance of the sample to smoke and gas permeation S_kl.pr is determined by averaging the measurement results according to the formula

1 n 2 S = --- Sum(P /G)(po /po), kl.pr n i=1 kli kli i 20 where P - overpressure on the sample in the i-th dimension, Pa;

kli G - flow rate of gas filtered through the leaks of the sample in the i-th kli dimension, kg x s(-1);

ro is the density of the gas filtered through the leaks of sample i in the i-th dimension, kg x m(-3);

po - gas density at a temperature of 20°C, kg x m(-3);

20 n is the number of measurements during the test time.

The reduced resistance of the sample to air permeation is determined by the same formula using the measurement results in accordance with 7.5 of these standards.

9.2. The fire resistance limit for each sample is determined in hours or minutes from the moment one of the limiting states occurs.

9.3. The actual fire resistance limit of the valve is taken at the minimum of the values ​​​​established in testing samples.

9.4. In designating the fire resistance limit of a valve, the test results lead to the nearest smaller value from the series of numbers given in 4.2.1.

10. Test report

1) name of the organization conducting the tests;

2) name and address of the customer;

3) characteristics of the test object;

4) test method;

5) test procedure;

6) testing equipment; 7) test results; 8) evaluation of test results.

11. Safety precautions

11.2. Persons familiar with the

technical description and operating instructions for the test bench..
11.3. Before testing, it is necessary to check the reliability of the connections of the bench equipment.
The main regulatory document establishing the classification and scope of application of fire dampers in ventilation systems is currently SNiP 41-01-2008 “Heating, ventilation and air conditioning”. In accordance with this document, ventilation and smoke protection systems should provide:
— fire safety normally closed valves in exhaust and supply smoke ventilation systems and systems for removing smoke and gas after a fire from premises protected by gas aerosol or powder fire extinguishing installations.

In accordance with NPB 241-97, the designation of the fire resistance limit of fire dampers includes letters corresponding to the rated limit states and a number representing the time (min.) to achieve one of the rated limit states, the first in time. Two types of limit states of the valve are taken into account: E - loss of density; I - loss of thermal insulation ability. For example, the entry in the certificate EI 60 means that the fire resistance limit of the valve is 60 minutes. based on signs of loss of density and loss of thermal insulation ability, regardless of which of the two signs is achieved earlier.

The loss of thermal insulation capacity I of fire dampers is characterized by an increase in the temperature of the valve body and the body seal assembly in the opening of the structure on the unheated side to a given maximum permissible value, and the loss of density E is characterized by a decrease in the valve resistance to smoke and gas permeation to the minimum permissible value or the formation of through cracks in the valve body seal assembly or holes through which combustion products or flames penetrate.

The test modes for fire-rated normally open (NO), smoke and fire-rated normally closed (NC) valves differ from each other, therefore the entry in the certificate regarding the possibility of using the valve as a smoke or NC valve is made based on the test results for the corresponding mode. For example, the entry in the certificate “Smoke ventilation valve for buildings and structures KDM-2 with fire resistance limit: in NC valve mode -EI 30; in smoke valve mode - EI 90, E 90" means that the valve can be used as a fire safety normally closed and smoke valve in accordance with the requirements of SNiP 41-01-2008, in which the fire resistance limit of these valves is characterized by the letters EI, and as a smoke valve in accordance with NPB 241-97, where the fire resistance limit of smoke dampers is characterized by the letter E.

The scope of application of fire dampers in explosion-proof design is regulated by SNiP 41-01-2008, PUE, GOST R 51330.99, GOST R 51330.13-99, etc. In addition to fire safety certificates, these valves must have a certificate for compliance with explosion safety requirements.

The company produces fire dampers for various functional purposes in accordance with SNiP 41-01-2008:

— fireproof normally open NO.
- smoke
— fireproof normally closed NC.

The valves are manufactured in “wall” and “channel” types. “Wall” type valves KDM-2 (KLAD-2) and KLOP-3 have one connecting flange; they are convenient to install in openings of walls, partitions, air ducts, suspended ceilings, enclosing structures of mines, etc. Valves of the “channel” type with rectangular cross-section KDM-2 (KLAD-2), KLOP-1 (regular and explosion-proof version), KLOP-2, KLOP-3 and KOM-1 have two flanges for connection to air ducts on one or both sides. "Duct" KLOP-1 round section standard versions are manufactured with two flanges ( flanged valves) and with nipple connection (nipple valves). Type of climatic modification of all fire dampers U3 (KLOP-1 valves of “marine” version M2) in accordance with GOST 15150-69. The valves can be installed indoors with ambient temperatures from -30°C to +40°C in the absence of direct exposure to precipitation and moisture condensation on the damper. Environment should not contain aggressive vapors and gases in concentrations that destroy metals, paint and varnish coatings and electrical insulation.

Fire protection normally open (fire retardant) valves
, KLOP-2, KLOP-3 and KOM-1 are designed to prevent the spread of fire and combustion products through air ducts, shafts and channels of ventilation and air conditioning systems of buildings and structures for various purposes. In accordance with clause 5.14 of SNiP 21-01-97*, fire safety valves are used to fill openings in fire barriers with a standardized fire resistance limit (fire walls, partitions and ceilings). These valves are open under normal conditions (without a fire), but in the event of a fire they must close, ensuring the continuity of the fire barrier. It is recommended to select the fire resistance limit of NO valves taking into account the required fire resistance limit building structures regulated by SNiP 21-01-97*, SNiP 41-01-2008 and other regulatory documents. All types of NO valve drives, as a rule, have a thermocouple, which in electric drives is used to duplicate the automatic operation of the valve under conditions of thermal exposure to fire.

Smoke valves
, KLOP-1, KLOP-2, KLOP-3 and KOM-1 are designed for smoke exhaust ventilation systems. Smoke valves are closed under normal conditions. In the event of a fire, these valves must open to remove smoke from the smoke zone, and in other areas, for example, on other floors of the building, they must remain closed to ensure regulatory requirements by air leakage into the smoke exhaust duct. To control the damper of smoke valves, electric drives without a thermoelement are used.

Fire protection normally closed valves
KDM-2 (KLAD-2), KLOP-1, , KLOP-3 are designed for exhaust and supply smoke ventilation systems, as well as for smoke and gas removal systems after a fire in premises protected by gas, aerosol or powder fire extinguishing installations. Under normal conditions these valves are closed. In case of fire, NC valves open to ensure smoke removal or air supply into protected volumes, for example, airlocks, smoke-free staircases type H2, elevator shafts, as well as for removing smoke and gases after extinguishing a fire with gas, aerosol or powder plants. The design of NC valves and methods of controlling the damper are similar to smoke valves, the difference lies in the scope of application and certification testing regimes of these valves.