Design manual for external stored pressure HFC-227ea extinguishing system

The introduction of the external pressure type 7 fluoropropane fire extinguishing system

Outside storage pressure type of seven fluorin propane fire extinguishing system (aka for pressure type of seven fluorin propane fire extinguishing system) based on GB530370-2005 specification for design of gas fire extinguishing system and GB25972-2020 gas fire extinguishing systems and components, NFPA - 2000, China engineering construction standardization association standard CECS 386:2014 outside storage pressure of seven fluorin propane fire extinguishing system as the basis, such as technical specification will be seven fluorin propane fire extinguishing agent with liquid stored in the container, do not use nitrogen pressure, pressure storage is only agent of saturated steam pressure, while the power for the agent application power gas at a higher pressure is stored in another container. System is working, high pressure power gas after decompression by pressure-relief devices into fire extinguishing agent storage bottles, dynamic gas driving agent high speed movement along the pipeline network system, within the prescribed period of time from the nozzle jet, implement discharge fires.

The main difference between the external pressure gas extinguishing system and the internal pressure gas extinguishing system

The driving pressure of the extinguishing agent and the state of the pressure and the state of the extinguishing agent are the determinants of the distance of the fire-extinguishing agent. Fire extinguishing agents promote the greater the pressure the more persistent, fire extinguishing agent transport distance is more far, in addition in the pipe of fire extinguishing agents exist in liquid form cases than in the quality of the gas liquid two phase cases velocity is larger, the bigger the mass flow rate per unit time the greater the flow. The mass flow rate is defined as the mass flow of the fluid within the unit time of the unit, i.e. the mass flow of the unit's circulation area, which is usually expressed in G, and the unit is Kg/(m squared * s). Calculation of mass flow rate: G = W/A, where W is mass flow, and the unit is Kg/s; A is the area of circulation, the unit is m squared.

Storage pressure within the gas extinguishing system because the nitrogen is with seven fluorin propane fire extinguishing agent storage and in the same the cylinder pressure, so there must be a part of the nitrogen dissolve into seven fluorin propane fire extinguishing agent, when the transmission of seven fluorin propane fire extinguishing agent within the pipes, the cylinder and the pipe pressure falling at any time, dissolved with N2 of seven fluorin propane fire extinguishing agent released steam, produce large amounts of gas, produced in the pipe forming airbags and two-phase flow phenomenon, a direct impact on the flow performance of fire extinguishing agent, affect the traffic agent.

Outside storage pressure type gas fire extinguishing system is of seven fluorin propane fire extinguishing agent and as push high-pressure nitrogen stored in different cylinders respectively, only in need agent application of nitrogen through the relief valve into the fire extinguishing agent storage cylinder pushing agent application. So in the outside storage pressure type gas fire extinguishing system, because of the high pressure nitrogen and seven fluorin propane fire extinguishing agent contact time is shorter, so almost no nitrogen gas dissolved in the middle of seven fluorin propane fire extinguishing agent, so that greatly reduce the degree of the gas liquid two phase flow and single phase of seven fluorin propane liquid can obtain larger mass velocity.

The external pressure system has the following characteristics

● 2.5 Mpa level external pressure system is suitable for the protection of the transmission distance of more than 45 meters, as far as 370 meters;

● In the pipeline network, the extinguishing agent is flowing in liquid, so it can be used as a vertical diversion in the pipe network.

● The pressure of the external pressure system of the external pressure system at the level of 2.5mpa was the lowest, which was 4.2 Mpa * 1.15 = 4.83 Mpa.

● The external storage system can directly utilize the pipe network of the original 1301 system to reconstruct the project;

● The nozzle inlet pressure is high, improve the atomization effect of extinguishing agent, shorten the discharge time of the extinguishing agent, accelerate the fire fighting, and improve the fire-fighting efficiency.

● It is more suitable for long-distance transportation and large space protection area.

● The noise is small, the network is small and the impact is small.

Contrast between internal pressure and external pressure

2.5 Mpa type external pressure curve of the external storage pressure system

The pressure curve in the container

4.2 pressure curve of the external storage pressure system of the Mpa type

The pressure curve in the container

It can be seen from the figure above that the external storage pressure system of 2.5mpa type is compared with the external storage pressure system of 4.2 Mpa type, the former is more capable of providing more stable time and transport distance; The other is more nitrogen utilization than the latter, which is about 272L.

The axial test of the gas fire pipe network is divided into the external storage pressure

Schematic diagram of the gas fire extinguishing system of the external stored-pressure type 7 fluoro-propane mixture

System technical parameters