【 Weak current College 】 gas extinguishing system protection automatic pressure relief design and installation (1)

1 Overview
Gas extinguishing system protection area relief vents, refers to when a gas fire extinguishing systems of fire extinguishing agent is spraying on the protection of the pressure values achieve the required value for the automatic opening pressure relief devices, pressure relief, also known as automatic pressure relief device, is equipped with gas fire extinguishing system, necessary, generally installed in the gas fire extinguishing systems for exterior or interior walls protected areas of pressure relief cavity. (For ease of presentation, this article short relief in Unity).
Fire extinguishing system with clean, good insulation properties, fire fighting speed characteristics, in fire-fighting and fire-fighting in on protection of objects and the environment without secondary pollution. It is widely used in electronic and computer room, telecommunications Center, communications, computer room, library, archives, treasures Gallery, museums, places of distribution rooms clean. In 2006, with the 2005 GB50370-extinguishing system design code for the promulgation of national standards, fire departments to increase the fire fighting equipment checks, 2007 after market on automatic pressure relief port needs also increased significantly. Due to the pressure of the product is new products, countries, sectors, there is no uniform standards. Most production release of product manufacturers or companies are only producing one type of relief. From Baidu, Google without a search site to retrieve, view, a comprehensive introduction to the pressure of application, design, installation and use of information and articles on few, the correct choice for enterprises, design, installation, use the relief port comes with a lot of problems, is not conducive to the pressure of the gas fire extinguishing in correct play their actual function and role. More than two years, I am at home and abroad all manufacturers of pressure relief port information, sample the system of collection, research and development on the product, has done a lot of testing. To enable automatic pressure relief port products in China is the correct use and development, are features of this article. In this article will inevitably exist in a number of shortcomings and defects, I sincerely look forward to our associates give correct me.

2 set the pressure of necessity
2.1 related standards with pressure relief representation of requirements, result in ambiguity.
· GB50370-2005 the gas fire-extinguishing system design code before the promulgation of national standards, national standards and norms of the fire extinguishing system must use the pressure of the provisions of the interpretation of words of fuzzy, ambiguous, resulting in fire-extinguishing systems in the practical application of the relevant design and supervision departments to properly design and oversight of the pressure of the installation and use.
GB50193-93 the CO2 fire-extinguishing system design specifications "section 3.2.6 national standard provisions description set out in article:" adopts all drown the fire extinguishing system to protect the most protection zone which are not completely closed, the doors, Windows protection zone generally have a gap exists; the gap through the window and door leaks around the carbon dioxide to prevent pressure excessive rise in space, this protection generally do not need to heptafluoropropane. ”
DBJ15-23-1999 heptafluoropropane (HFC-227ea) clean gas fire-extinguishing system design specifications "Guangdong local standards the 3.0.6 bar Pf symbols explained:" Pf-envelope withstanding intrinsic pressure allows pressure (Pa). When equipped with external door flexible door closer or spring door protection area, its opening area not less than the pressure port area calculation, not another release in the mouth. ”
DG/TJ08-306-2001 the inert gas IG-541 extinguishing system technical specifications standards provisions of Shanghai local 3.1.2 explain statement: "for tightness better protection areas requiring installation of relief. "That is protective zone tightness poor can not install the relief port.
· March 2006 GB50370-2005 the gas fire-extinguishing system design specifications "national standard published, due to the standards of public information, follow-up and printing of the lag, the Design Institute and fire departments in fact only started the year 2008 by the standards on relevant gas extinguishing system project design and supervision. But as the standard in the first section 3.2.7 and 3.2.9, term fussy to some designers and users. Provisions of section 3.2.7 "protection zones should be set pressure relief, heptafluoropropane fire extinguishing system for the pressure outlet should be located in the protection zone clear height of 2/3 or more. "So, some people think that the relief port is in the ground two-thirds of the height measured at a pressure relief holes, not a pressure relief, the provisions of section 3.2.9" spews fire protection district before venting openings extraoral should automatically close. "This again illustrates the pressure port is a normally open holes, deepened part of designers of misunderstanding.
2.2 set pressure of the real necessity
By 2005 the GB50370-gas fire-extinguishing system design code requirements, heptafluoropropane fire-extinguishing system design concentration is 8 per cent to 10 per cent. When heptafluoro release into a complete seal protection area, driven gas (nitrogen) of release and heptafluoro at 20 ° C under standard atmospheric pressure, pressure gasification enables protection area with elevated, the absorption of heat, so that part of the protection zone temperature decrease, resulting in pressure reduction value is very small. Pressure rise mainly and protection area of tightness and fire extinguishing concentration and pressure relief mouth design (automatic pressure relief) of sealing. Pressure rise value basically equal to the protection area fire design volume concentration ratio, increasing value of 8 «10KPa, the pressure value is more than light, high-rise buildings and General construction of 6 ~ 8 1.2KPa.
We in the tightness of 108m3 laboratory doing relief mouth opening action test, open the action pressure set to 1.1 + 0.1KPa, calculation of test for the nitrogen pressure value, the actual test pressure 1.45MPa value 3.8MPa, 2.62 times. This shows the concentration of small fire design heptafluoropropane fire extinguishing system, if the protective area of tightness better, gas release protection area pressure value still exceed 1.2KPa, this will give the protective envelope damage in the region, causing the system to not fire correctly.
Mixed in IG-541 gas fire extinguishing systems, fire extinguishing design concentration 37.5%-43%; carbon dioxide extinguishing systems, fire extinguishing concentration in 34% design ~ 62 per cent.That is when both extinguishing agent release to complete closure of the protection zone, the protection zone of the rapid expansion of the gas volume, the protective zone of the pressure value would exceed the permitted pressure of 25 times more 1.2KPa, enough to destroy the protection zone for the entire building envelope. A company in the long, wide 6m 6m, high 4m laboratory do IG-541 mixed gas test, protective zone having a diameter Φ 200 m m air vents, air vents on the exhaust fan to work correctly, when the laboratory into 7 70 liter cylinder group IG-541 mixed gases, the testing laboratory's door was pop open exhaust fan serious deformation.
In our laboratory, 100m3 above do IG-541 mixed gas extinguishing system actual fire testing, several rich gas extinguishing system simulation experience relief of research design and test personnel, a profound understanding of the pressure gas release of destructive power and, when asked to ensure that the fire test successfully and test laboratory equipment, wall, door and window is being destroyed, people can only pick one type and specification of the relief port installation, these officers are pronounced the following two options:
The first set of programmes: If you can only install one, choose no power-pressure relief. No power-structure preferred outdoor wall mount without power door type pressure relief. The reasons are: (1) no power-type pressure relief vents at the scene detection, then the test is 100% fail-safe; power-type pressure relief vents at the scene detection, due to its structure more complex still not 100% sure that no failure rate, such as: suddenly loses power, line bad, no device performance is not stable, and so on. (2)-indoor wall mount without power, the pressure relief device at theoretical opening pressure value is consistent with the experimental values of the parameter, this is due to its structure. When the protective area pressure value reached device set pressure value, at the opening, not on latency. There is no power supply-than-relief port about lag 0.3 seconds. And other non-power-pressure relief valve outlets device controlled by the driver of the opening of the executive body of the control, calculation of opening pressure value and the actual test parameters values vary considerably. Therefore, no power supply-type pressure relief mouth opening pressure values must begin actual gas injection into the simulation test parameter values.
The second set of programmes: install two, the first is no power supply-pressure relief, opening pressure value is set to open normally; 1.1KPa following another-without power or power-type pressure relief, and the value set in the opening pressure, which can ensure 1.3KPa test successful and reliable.
2.3 new specification explicitly extinguishing systems protection zones should be used for pressure outlet
March 2, 2006 GB50370-2005 published by the gas fire-extinguishing system design specifications ", from the design requirements terms and protection area of pressure relief area calculation formula of the provisions of the terms used, regardless of the protection area of the window and door seal of good and bad and protection area door installation is opened spring door outside or flexible door closer, such as the use of gas fire extinguishing system, the protection zone must be installed pressure relief. Pressure port is not an open but a pressure relief device. This device usually normally closed, when the reach or approach the protection zone to allow the pressure value for the automatic opening pressure relief, lower than the set pressure value is automatically turned off to avoid fire extinguishing agents, affect the normal extinguishing effect.
In recent years, a number of mouth with relief to some of the key projects and projects on the protective zone of temperature and humidity accuracy requirements are high, the protective zone of tightness requirements. So GB50370-2005 the gas fire-extinguishing system design code of standards, the use of protective gas extinguishing system shall be within the design and installation of relief. The revised new standards on the old standards and norms in ambiguous terms given. According to the fire engineering company and the company's after-sales service staff feedback at all levels of fire inspection, acceptance and monitoring of fire departments are strictly in accordance with the new standards, if fire project installed gas fire extinguishing system, it is first necessary to examine the protection area is installed on the relief port (automatic pressure relief device). 3 pressure orifice area design and calculation
3.1 protection area envelope maximum allowable pressure
Protective zone, doors, Windows allows pressure on glass should not be lower than the permitted pressure of buildings. At present, the design Department of the protective zone of envelope withstanding intrinsic pressure allows pressure, regardless of the building is light and tall buildings, or standard buildings and underground construction, are set to the value of set 1.2KPa is based on the 2005 standards GB50370-3.2.6 terms, reference to the United States NFDA12B-1980 standards given in the if design departments and users need to improve the protection of the regional envelope allows the pressure to architectural design sector test. Table 4 buildings of internal pressure allows pressure building type allows pressure (Pa)
Light and building 1200
Standard building 2400
Heavy or underground building 4800
3.2 relief area calculation formula
IG-541 heptafluoropropane and mixed gas fire extinguishing system in the protection zone of pressure relief area formula should be based on the 2005 standards GB50370-3.3.13 and 3.4.6 formula. Carbon dioxide extinguishing systems shall be based on GB50193-93 3.2.7 formula in the protective zone of the relief area.
3.3 design calculation
3.3.1 heptafluoropropane gas fire extinguishing system pressure relief area calculation

(1) a protection zone of envelope withstanding intrinsic pressure for 1200Pa.
(2) the protection zone volume and fire-fighting protection of objects into the design concentration in this table, you can quickly find a protection zone of total pressure relief area.
(3) choose a manufacturer model, quantity of pressure relief port area must not be less than the protection area of total pressure relief area.

4 pressure relief port names, types and models
4.1 relief port names
The name of the current pressure outlet is very large. Standards and specifications in the General name for the relief of mouth, called a gas fire extinguishing system protection area relief port. The design department, fire engineering companies and manufacturers and users more called pressure ports for the (fire) automatic pressure reliefDevice.
4.2 relief port types
The pressure of the product in the past two years, some new types and new products have been successfully developed. At present, there is no documentation and manufacturers to clear classification. I collected many domestic product information, samples and combined with our company on development of the product, this product has been classified. To see its name, we can clearly understand its main function, to the product name to standardized, unified direction perfection and development. Specific categories are as follows:
4.2.1 classification based on the installation mode
At present domestic relief (automatic pressure relief device) with indoor and outdoor installation of two types. Indoor and outdoor installation was divided into embedded and wall-mounted and ceiling-mount three structures.
4.2.2 based startup category
Pressure port boot method is divided into a power-up and no power supply two types of boot. There is a power-relief port is divided into two forms: a startup is driven actuators for pressure detector and gear motors; another for pressure detector and an electromagnet. No power supply-driven actuator pressure have weights type structure, pressure regulator structure, integrated structure.
4.2.3 valve structure
The pressure of the valve structure forms: one is the valve from the movie or two pieces of leaves, each leaf with linkage is rotate in order to achieve open and close; the second is-plate, the valve installed in the valve body, valve body stretching some distance to achieve open and close; the third is a compact structure, valve installed in the valve on the external box, wrapped in vitro box angle valve to achieve open and close feature. Plates and plate-type structure of the relatively good performance to seal.