Ankerry Yu Yang
System Introduction:
01 Overview
1.1 Necessity of System Design
Why design a bypass valve in a mechanical pressurized air supply system to control the positive pressure value of the pressurized air supply? What role can it play after a fire?
As we all know, when a fire occurs, the vast majority of casualties are not because of fire, but flue gas, with the combustion of combustibles to produce a large number of high-temperature flue gas, flue gas contains a large number of toxic and harmful substances that are not completely burned, inhaled into the body through the human respiratory tract, causing a serious threat to the safety of personnel's lives.
In order to control the spread of fire and prevent the spread of smoke. The air outlet of the pressurized air supply system can form a positive pressure in the stairwell and the fire front room, blocking harmful smoke from entering the evacuation channel. However, when the air supply volume and air supply time of the pressurized air supply system are uncontrollable, the normal escape route may be due to the excessive pressure in the front room and the fire door cannot be opened. In view of the above considerations, the Sichuan Fire Science Research Institute of the Ministry of Public Security combined with international experience to propose the data of the residual pressure value. The differential pressure control system can control the residual pressure value of the mechanical pressurized air supply system within a reasonable range required by the national standard by controlling the opening and closing of the bypass valve----- smoke-proof stairwell 40-50Pa, and the front room, the shared front room, the front room of the fire elevator room, and the closed evacuation layer (room) are 25-30Pa. This not only prevents the entry of harmful fumes, but also ensures that the fire door can be opened and closed normally when evacuation is required.
The system meets the functional requirements in relevant national standards such as GB51251 "Technical Standard for Building Smoke Prevention and Exhaust System" and GB50016 "Code for Fire Prevention of Building Design".
1.2 Application Background
1) In the event of a fire in a building, it is necessary to ensure the smoke resistance requirements of the smoke-proof stairwell, the evacuation walkway and its front room.
2) From the perspective of smoke prevention, the residual pressure of the mechanical pressurized air supply system is too low to be conducive to smoke prevention, so the higher the residual pressure, the better.
3) Because the direction of the evacuation door is opened in the direction of evacuation, and the direction of the pressurized air supply is exactly the opposite direction of the evacuation, if the residual pressure is too high, it will lead to too large a pressure difference on both sides of the evacuation door, resulting in the door can not be opened normally, affecting the evacuation of personnel and fire personnel rescue.
4) The design of the pressurized air supply system should first be based on safe evacuation.
5) At present, the pressurized air supply system itself does not have the ability to judge whether the pressurized area maintains a certain pressure, or the pressure area leaks too much, the pressure does not meet the standard, does not play a smokeproof role, or causes the evacuation door to be blocked due to excessive pressure.
6) Design and installation of residual pressure monitoring system, which can solve the fault that the pressure difference on both sides of the evacuation door is too large and the door cannot be opened normally, ensure the safe dredging of the evacuation channel, and make the pressurized air supply system in a reasonable working state, so as to provide a strong guarantee for the evacuation and rescue of personnel in the case of fire.
1.3 Design Basis
As a smoke-proof method, pressurized air supply has been widely accepted and adopted in the design of high-rise buildings at home and abroad. Regardless of domestic or foreign fire codes, there are consistent pressurization requirements, that is, in the event of a fire, the residual pressure value of the stairwell (40-50Pa) > the residual pressure value of the front room (25-30Pa) > the corridor.
When a fire occurs, the air outlet of the pressurized air supply system can make the stairwell and the fire front room form a pressure on the opposite aisle, block the harmful smoke from entering the evacuation channel of the person, ensure the normal opening of the fire door, and escort the safe evacuation of personnel when the fire occurs. However, the air supply outlet can be opened for a long time so that the pressure difference between the two ends of the fire door is too large, can not be opened normally, resulting in the serious consequences of personnel can not be evacuated, combined with the experienced countries at home and abroad on the positive pressure air supply system to do the following requirements:
※ GB50016-2014 "Code for Fire Protection of Building Design"
8.5.1 Smoke prevention facilities shall be provided in the following places or parts of the building:
1) Smoke-proof stairwell and front room;
2) The front room of the fire elevator room or the shared front room;
3) The front room of the evacuation walkway, the evacuation floor (room).
※ GB51251-2017 "Technical Standard for Building Smoke Prevention and Exhaust System"
3.4.4 The mechanical pressurized supply air volume shall meet the increasing pressure distribution of the corridor to the anterior chamber stairwell, and the residual pressure value shall comply with the following provisions:
1) The pressure difference between the front room, the closed evacuation layer (room) and the walkway should be 25Pa-30Pa;
2) The forehead pressure difference between the stairwell and the walkway should be 40Pa-50Pa;
3) When the residual pressure value of the system exceeds the allowable pressure difference, pressure relief measures should be taken.
5.1.4 Mechanical pressurized air supply system should be equipped with pressure measurement device and wind pressure regulation measures.
5.1.5 The fire control equipment shall display the opening and closing status of the blower, valve and other facilities of the smoke prevention system.
※ GB50016-2006 "Code for Fire Protection of Building Design" (the following specific system design clauses are still implemented)
9.3.3 The residual pressure value of the mechanical pressurized air supply and smoke prevention system in the smoke-proof stairwell should be 40-50Pa; the front room and the joint front room should be 25-30Pa.
※ GB500045-95 "Fire Protection Code for The Design of High-rise Civil Buildings" (2005 edition) (the following specific system design clauses are still implemented)
8.3.7 The full pressure of the mechanical pressurized blower, in addition to calculating the loss of the unfavorable ring pipe, there should be residual pressure. The remaining pressure values should meet the following requirements:
8.3.7.1 Smoke-proof stairwells are 40Pa-50Pa.
8.3.7.2 The front room, the shared front room, the front room of the fire elevator room, and the closed evacuation floor (room) shall be 25Pa-30Pa.
※ GB50098-2009 "Civil Air Defense Engineering Design Fire Code"
6.2.1 The residual pressure value of the air supply air supply in the smokeproof stairwell shall be (40-50)Pa, and the residual pressure value of the front room or the combined front room air supply system shall be (25-30)Pa.
6.2.2 The residual pressure value of the front chamber of the evacuation walkway should be (25-30)Pa.
※ National civil construction engineering design technical measures
4.10.10 When the residual pressure value of the pressurized air supply system exceeds the specified value, it is advisable to set up a pressure relief valve or bypass valve and other devices.
※ DGJ08-88-2006 "Technical Regulations for Building Smoke Prevention and Exhaust" (Shanghai)
3.3.6 When the residual pressure of the system exceeds the pressure difference, the residual pressure control valve should be set up or the variable speed fan and other measures should be adopted.
1.4 System Introduction
The residual pressure monitoring system can collect the working conditions such as the pressure change in the monitoring area in real time, and alarm prompt and record the residual pressure in the abnormal state.
When the residual pressure value of the smoke-proof stairwell or the front room reaches the overpressure monitoring value, the residual pressure detector issues an alarm signal, and the residual pressure controller opens the bypass valve on the pressure relief on the fan duct of the pressurized fan; after the residual pressure falls back to the normal interval value, the residual pressure detector sends a signal, and the residual pressure controller closes the bypass valve, and by controlling the opening of the bypass relief valve, the residual pressure value is stable within the interval value required by the specification.
The residual pressure monitoring system is composed of some or all of the equipment such as the residual pressure monitor (main engine), the residual pressure controller, the residual pressure detector, the damper actuator, the system monitoring special software, etc. And is full and higher than the functional requirements in relevant national standards such as GB51251 "Technical Standard for Building Smoke Prevention and Exhaust System", GB50016 "Code for Fire Prevention of Building Design" and GB50098 "Code for Fire Prevention of Civil Air Defense Engineering Design".
System Structure:
02 Design basis
Design Principles:
The host is set in the control center;
The controller is set in the fan box, and the ratio of the controller/damper actuator to the supply fan is 1:1;
The residual pressure detector is set in the front room for each front room, and when it is set at the stairwell, it is 1/3 and 2/3 in addition to one set each;
The list of products on the figure is:
Mainframe: 1 set
Controllers: 2 sets
Damper actuators: 2 sets
Residual pressure detector: 33 + 2 = 35 sets
Residual pressure detector sub-panel: 35 sets
System features:
Equipment Selection:
03 ARPM100/B3 Residual Pressure Monitor
Features:
1) Meet the national standard GB51251-2017 "Building Smoke Prevention and Exhaust System Technical Standards"
2) Mated with residual pressure controller, residual pressure detector, damper actuator, etc., flexibly build a large-capacity evacuation channel residual pressure monitoring system
3) The residual pressure change of the evacuation channel can be monitored through the residual pressure controller to adapt to the complex and changeable requirements of modern buildings
4) Strong anti-interference ability, can be powered over long distances
5) Provide 2 RS485 communication circuits, each circuit can be connected to 32 residual voltage controllers
04 Residual pressure detector
4.1 ARPM-S/1 residual pressure detector
4.1.1 Product Features
1) Power supply: 15-28VDC (two-bus)
2) Working current: <4mA
3) Measuring range: -1000Pa~1000Pa
4) Communication mode: two buses
5) Size: 86mm*86mm*20mm
6) Mounting hole spacing: 60mm
7) Installation: 86 box installation
8) Working temperature: -20°C~70°C
9) Storage temperature: -40 °C ~ 85 °C
4.1.2 LED display
1) Running indicator: When the device is in a communication state, the running indicator flashes.
2) Fault INDICATOR: When the device fails to self-calibrate, the fault LED is lit.
3) Alarm indicator: When the detector detects that the residual pressure difference value exceeds the set value, the alarm indicator light is lit.
4.1.3 Installation Methods
This module adopts the universal 86-box mounting method, and the horizontal mounting hole spacing is 60mm. The operating power supply of the detector is 15-28VDC, please ensure that the voltage at the end of the wiring conforms to the range of the operating power supply. A rubber hose is used to connect to the low pressure nozzle and the other end of the hose is connected to the low pressure zone. (If the equipment is installed on the low pressure side, it is connected to the high pressure nozzle with a rubber hose, and the other end of the hose is connected to the high pressure zone.) ）
4.2 ARPM-S/2 residual pressure detector
4.2.1 Product Features
1) Size: 86mm*86mm*20mm
2) Mounting hole spacing: 60mm
3) Installation: 86 box installation
4) Working temperature: -20 °C ~ 70 °C
5) Storage temperature: -40 °C ~ 85 °C
05 ARPM-C residual pressure controller
5.1 Product Features
1) Working power: AC220V 50Hz
2) Power consumption: Standby state < 3W, action state < 10W
3) Execution output: 24V (actuator)
4) Switching input: 2 channels
5) Switching output: 1 relay output
6) Communication: 1ch 2-bus, 1ch RS485
7) Communication distance: 500m
8) Installation: Din rail installation
9) Operating temperature range: -20°C~60°C
10) Storage temperature range: -30 °C ~ 80 °C
11) Ambient humidity: relative humidity ≤ 90%, no condensation
12) Protection class: IP30
13) Product conforms to: GB16806-2006
5.2 Dimensions
5.3 Connection Diagram
06 ARPM-DC24V damper actuator
1) Meet the functional requirements in the national standard GB51251 "Technical Standard for Building Smoke Prevention System" and GB 50016 "Code for Fire Prevention of Building Design" and other relevant national standards
2) Receive the command of the residual pressure controller, control and adjust the opening and closing angles of the bypass pressure relief valve
3) Selectable rotation angle, adapter, set independent running time, with manual control button
4) The DC24V working voltage is used to ensure system stability and personal safety
07 Design selection
08 Design procedures
8.1 Design Procedures
1) The system should be based on the specific conditions of the mechanical pressurization air supply system in the building, and adopt the control mode of the split design to determine the location, quantity and form of the residual pressure controller and the residual pressure detector;
2) The real-time working status and fault alarm information of the residual pressure controller and the residual pressure detector should be connected in parallel to the residual pressure monitoring system bus in the control box of the pressurized fan through the communication interface, and all kinds of information should be uploaded to the residual pressure monitor (host) in the fire control room for unified monitoring and management, display and storage, so that the duty personnel can control and understand the operation of the equipment at any time;
3) RS485 communication mode is adopted between the residual pressure monitor and the residual voltage controller, and the bus of the 485 circuit adopts the NH-RVSP-2*1.5mm2 communication cable, the communication distance is generally within 500 meters, and the residual pressure monitor can be connected to 64 residual pressure controllers;
4) The two-bus communication mode is adopted between the residual pressure controller and the residual pressure detector, and the bus of the two-bus loop adopts the NH-RVSP-2*2.5mm2 communication cable, the communication distance is generally within 500 meters, the smoke-proof stairwell, the front room floor is vertically laid, and the residual pressure controller can connect 128 residual pressure detectors;
5) The setting of the system should not affect the normal operation of the mechanical pressurized air supply system.
8.2 Setting up the premises
In places with mechanical pressurized air supply systems, a residual pressure monitoring system should be provided.
8.3 Setting the Scope
1) Each pressurized fan distribution control box should be provided with a residual pressure controller;
2) Smoke-proof stairwell and its front room are equipped with residual pressure detectors;
3) The front room of the fire elevator room or the front room of the shared use should be provided with a residual pressure detector;
4) In the front room of the evacuation walkway, the evacuation layer (room) should be equipped with a residual pressure detector.
8.4 Setting up the site
Settings for the residual pressure controller
1) The number of settings of the residual pressure controller, and the number of mechanical pressurized blowers is one-to-one;
2) The residual pressure controller should be set in the control box of the pressurized fan, and a 220V power supply is reserved in the control box as the working power supply of the residual pressure controller;
Settings for the residual pressure detector
1) The front room of the smoke-proof stairwell or the front room of the shared use should be equipped with a residual pressure detector in the front room of each floor;
2) A residual pressure detector should be provided at about one-third and two-thirds of the stairwell height (floor); or it is advisable to set up a residual pressure detector at the place where there is a pressurized air supply outlet (layer);
3) The residual pressure detector should be set in the high-pressure area (stairwell, front room area evacuation door side), 0.2 to 0.5 meters from the top wall mounting, using the base directly fixed on the embedded 86 box.
09 Design application legend
9.1 Evacuation channel residual pressure monitoring system diagram
Evacuation channel and front room residual pressure monitoring system diagram
Design Description:
(1) According to the provisions of the National Standard of the People's Republic of China GB50045-95 "Electrical Design Code for High-rise Civil Buildings", the project sets up an evacuation channel residual pressure monitoring system.
(2) The evacuation channel residual pressure monitoring system adopts the fire two bus, the communication bus (with DC24V power supply) NH-RVSP-2*2.5mm2 -SC20.
(3) ARPM100/B3 residual pressure controller should be able to display the residual pressure of the monitoring area connected to the residual pressure detector, and should be able to alarm when it exceeds the specified value of the specification.
(4) After the ARPM-C residual pressure controller receives the overpressure alarm, it can continuously adjust the opening angle of the damper actuator to relieve pressure.
(5) ArPM-DC24V damper actuator should be able to feedback the opening angle to the residual pressure controller.
(6) ARPM100/B3 residual pressure monitoring host should be able to record the status information of the residual pressure controller and the residual pressure detector connected to it, and when an alarm failure occurs, it should be able to issue an audible and visual alarm.
(7) The stairwell and the front room of the combined use are all in the smoke-proof mode of pressurized air supply, and the positive pressure air supply is provided with an air supply outlet on each floor, and the air outlet adopts a remote control multi-leaf air supply outlet, and the air supply outlet is usually closed; when the residual pressure difference of the fire changes, the residual pressure controller receives the information of the residual pressure detector and adjusts the pressure relief valve to control the residual pressure within a reasonable range.
(8) When there are 2 or more residual pressure detector pressure data in the front chamber and the difference between atmospheric pressure is greater than 30Pa, the pressure relief valve is opened in a linkage, the opening degree of the pressure relief valve is adjusted, and the rest of the pressure difference is close to the set value; when the pressure difference between the residual pressure detector pressure value in the stairwell and the pressure difference in the front chamber is greater than 30Pa, the pressure relief valve is opened in a linkage, the opening degree of the pressure relief valve is adjusted, and the remaining pressure difference is close to the set value.
(9) The construction of the system shall be carried out in accordance with the approved engineering design documents and construction technical plan, and shall not be changed arbitrarily. If it is really necessary to change the design, the design unit should be responsible for the change and approved by the drawing review agency.
9.2 Residual voltage monitoring system power distribution diagram
9.3 Floor plan of the residual pressure detector
Schematic diagram of the remaining pressure detector plane
Note:
1. Each floor of the front chamber is equipped with a residual pressure detector
2. The stairwell is equipped with a residual pressure detector at about 1/4 and 3/4 heights
3. The trachea used for pressure injection can be installed on the wall or ceiling according to the actual situation of the site
4. The residual pressure bathometer is laid vertically along the floor slab to the air room control box through N-IYSP-2x2.5m2-SC20-C
9.4 Schematic diagram of the installation of the façade of the residual pressure detector
9.5 Residual pressure monitoring system structure diagram
(1) Between the residual pressure monitor (host) and the residual pressure controller is 485 communication, the connection method is hand-in-hand connection, the linear NH-RVSP-2 * 1.5mm2, the communication distance is 500 meters;
(2) The host supports 2 RS485 communication loops, and each loop can be connected to 32 residual voltage controllers;
(3) There is two-bus communication between the residual pressure controller and the residual pressure detector, the communication distance is 500m, and the linear NH-RVSP-2*2.5mm2;
(4) One residual pressure controller can be equipped with 120 residual pressure detectors.