What is the working pressure of fire water?

Introduction to the working pressure of fire water 1. 1 Air pressure tank is also a common pressurization facility for fire water supply on the top floor. The main function of the air pressure tank is to provide enough fire water pressure, but a small amount of fire water is stored, and the indoor fire water of 10min is still stored in the roof water tank. Therefore, the fire pressure tank has a small volume, which is different from other pneumatic water supply systems.

2. 1 working principle of pneumatic tank

The overall integral of fire water in the fire pressure tank is divided into three parts, namely, fire water storage volume (adjustment volume), buffer water volume and stable water volume, as shown in the figure. The normal pressure of the system is provided by the constant pressure pump. When the pressure rises and reaches the high level of stabilized water, the stabilized pump automatically stops running. When the pressure decreases and reaches the low level of stable water, the stable pump will automatically start to raise the stable water to the highest level. This cycle is performed to maintain the high pressure state of the system. When a fire broke out, with the putting into use of fire hydrants, the system pressure began to drop. When it drops to the lowest water level of fire water storage, the pressure stabilizing pump stops and the fire pump automatically turns on to extinguish the fire.

Schematic diagram of pressurization operation of pneumatic tank

2.2 Design and Calculation of Pneumatic Tank

The design and calculation of the pressurization system of the air pressure tank mainly includes two parts, namely, the calculation of the total volume of the air pressure tank and the calculation of the pressure value of each pressure control point. The calculation of total volume determines the size of the selected pressure tank, and the calculation of pressure determines the start-stop range of the pressure stabilizing pump and the pressure value for starting the fire pump.

Total volume v of pneumatic tank

The total volume of the pneumatic tank is generally based on the formula V=? VX？ ( 1- ? B) calculation.

Where: v is the total volume m3 of the pneumatic tank; VX is the total volume of fire water, which is equal to the sum of fire water storage, buffer water and stable water; ? Is the volume coefficient of the pneumatic tank, and the volume coefficients of horizontal, vertical and diaphragm pneumatic tanks are 1.25, 1. 10 and1.05 respectively; ? B is the ratio of the minimum working pressure to the maximum working pressure of the air pressure tank (as an absolute pressure gauge), which should generally be 0.65 ~ 0.85.

Total storage volume for fire fighting (VX): The purpose of setting the air pressure tank is to ensure that the fire pump does not have the water pressure required by the fire hydrant and sprinkler before starting in the early stage of fire fighting, and this time is about 30s. Fire hydrant water supply system, calculated by using two water guns at the same time (the flow rate of each water gun is 5 L/s), and the fire water storage capacity is 2 * 5 * 30 = 300L L. For automatic sprinkler system, five nozzles are turned on at the same time, and each nozzle is calculated by 1 L/s, and the fire water storage capacity is 5 *1* 30 =/kloc-. When the two systems adopt pneumatic tanks, the total storage volume of fire water is 300+ 150=450L.

Buffer water V 1 is generally not less than 20L, and stable water V2 is generally not less than 50L.

2.2.2 Calculation of pressure value of pressure control point

The pneumatic box is equipped with four pressure control points as shown in Figure 2. Where: P 1 is the lowest working pressure point of the pneumatic tank or the inflation pressure of the pneumatic tank, that is, the lower water level pressure of the fire water storage volume is equal to the hydraulic pressure Hmin required by the fire hydrant at the most unfavorable point, and its calculation method is the same as that of the booster pump; P2 is the highest working pressure, that is, the pressure value for starting the fire pump. Calculated according to the following formula:

P2 =(P 1 + 0.098) b - 0.098

P0 1 is the lower limit water level pressure of stable water volume, and the stable pump is started at this time; P02 is the upper limit water level pressure of stable water volume, that is, the highest working pressure of air pressure tank. At this point, stop stabilizing the pump.

Because the pressure sensor has the requirements of accuracy and stability, the pressure difference between the upper and lower water levels of the buffer water volume is generally not less than 0.02 ~ 0.03 Mpa, and the pressure difference between the upper and lower water levels of the stable water volume is not less than 0.05 ~0.06Mpa.

p 0 1 = P2+0.02 ~ 0.03 MPa p02 = p 0 1.05 ~ 0.06 MPa = P2+0.07 ~ 0.09 MPa

2.2.3 Calculation example

The building height is close to 100m, and the top floor is stabilized by vertical air pressure tank, and the distance from the roof water tank to the fire hydrant bolt on the top floor is H = 4m. Head loss from roof water tank to top fire hydrant? H = 0.82m m.

Working pressure ratio of pneumatic tank:? b = 0.76

Total volume of air pressure tank: V=? VX？ ( 1- ? b) = 1. 1？ (300+20+50)? (1-0.76)= 1.70 m3

Optional: SQL 1000? 0.6 a pneumatic tank

Inflating pressure of pneumatic tank:

P 1 =Hmin= Hq+ Hd+ HK+？ H-h = 0.16+0.01.02+0.0082-0.04 = 0.14 (MPa)

Maximum working pressure: p2 = (p1+0.098) b-0.098 = 0.14? 0.76-0.098 = 0.22 MPa

Starting pressure of pressure stabilizing pump: p 01= p2+0.02 ~ 0.03mpa = 0.22+0.02 ~ 0.03 = 0.24 ~ 0.25 (MPa).

Stop pressure of pressure stabilizing pump: p02 = p2+0.07 ~ 0.09mpa = 0.22+0.07 ~ 0.09 = 0.29 ~ 0.31(MPa).

Head of pressure stabilizing pump: H = (P0 1 +:P02+:p02)? 2 = (0.24+0.39)? 2 = 0.27 MPa

Constant pressure pump flow: q? 5.0 l/s

Choose 40LG 12- 15? 2 two pumps, one for use and one for standby: q = 4.17l/sh = 27mn = 2.2kw.

2.2.4 flow rate of pressure stabilizing pump

As the flow rate in the initial stage of fire fighting is supplied by the air pressure tank, the flow rate of the pump only needs to consider the leakage of the system or the requirements of the air pressure tank for the flow rate, so the flow rate can be appropriately selected to be smaller. Fire hydrant system, the constant pressure pump flow is less than 1 fire hydrant, right? 5 liters/sec. The flow rate of the pressure stabilizing pump of the spray system is calculated as less than about 1 nozzle, yes? 1 liter/second.

Monthly fire control work summary (1) 1, main fire control work in June:

1. According to the requirements of An Zi [20xx] No.204 document of Chinalco, the fire safety inspection was carried out on the key fire-fighting parts of Shaanxi enterprises and Hua Ze Carbon Plant. Cha * * * issued two hidden dangers rectification notices, and found that the problems existing in Shanxi Carbon Factory are as follows:

2, fire rules and regulations are not perfect, the unit fire safety awareness is poor.

3. The indoor fire hydrants in the roasting workshop have no boxes and hoses, and most fire extinguishers have expired.

4. Acetylene bottles, oxygen bottles, paints and sundries are mixed in the warehouse.

5, fire pipeline maintenance is not in place, fire pump can't start normally, does not meet the requirements of fire emergency. Hua Ze Company has four questions, which have been written back to Hua Ze Company.

1, in order to ensure that Chinalco is in? Type three? The party organization's on-site meeting was successfully held, and fire safety inspections were carried out in key fire-fighting parts, visiting places, hotels, venues and other places to ensure fire safety during the meeting.

2. According to the Notice of Yuncheng Public Security Fire Brigade on Participating in the Training of Fire Administrators in Key Units of Provincial Fire Protection, with the consent of the factory leaders, the Armed Security Department of Shanxi Aluminum Factory drafted and issued the Notice of Participating in the Training of Fire Administrators in Key Units of Provincial Fire Protection Corps. Arrange 8 people from Shanxi Branch, 8 people from Shanxi Aluminum Factory 1 1 person and 9 people from * * *1person to participate in the training of fire management personnel in Taiyuan City.

This month, * * * approved the maintenance of fire extinguishers.

4. Fire situation: There were 4 fires in the factory this month, including 3 domestic fires: a car in Shuguang District 1, Zhao Xia 1 Building 7 1, and the spontaneous combustion of raw coal in the north coal yard of the First Alumina Plant1. A foreign aid: a fire broke out in a bungalow in Jin Hui community. Second, the fire control work plan in July:

1. According to the characteristics of fire control work in summer, electrical fire accidents are prone to occur. We will conduct fire safety inspection on electrical equipment and facilities to ensure the safe operation of electrical facilities.

2, cooperate with secondary units to do fire training and fire drills and other activities.

Monthly fire control work summary (2) March has ended, and the work of our team has been significantly improved under the leadership of department leaders. Through the efforts of team leaders and every employee, this month's fire control and public security work has been successfully completed. The fire and public security work in March of 20XX is summarized as follows:

This month's fire control work is closely around? Action to clear the fire? According to the plan, in the fire safety work of the factory, each team leader did his duty, conducted fire inspection every day, made detailed records, found hidden dangers in time, and put forward rectification in time, which ensured the normal operation of the company and the safety of employees and property.

First, intensify inspections.

Because it is in the dry season, it is prone to disasters. As the company's fire department, we have the responsibility to protect the safety of the company's employees and property. Therefore, every day, our department arranges full-time personnel to investigate hidden dangers in key fire-fighting parts, which involve restaurants and staff dormitories around the company to prevent fire safety accidents in places where people gather.

Second, strengthen study and skill training. In our fire brigade, new and old combatants each account for a certain proportion. According to the uneven quality of members, make corresponding training plans. Old members lead new members, help new members in skills and combat strategies, and strive to make new members meet the standards. This has enhanced the fighting capacity of our full-time fire brigade. According to this month's training plan, under the leadership and supervision of department leaders and monitor, the training is going very smoothly. Except for other delays, the daily training was basically completed as planned.

Three, strengthen the inspection of fire equipment, to ensure that the police quickly.

Vehicle equipment plays an inestimable role in fire fighting. Therefore, ensuring the integrity and ease of use of vehicle equipment is the premise of fire fighting, and drivers and combatants also shoulder heavy responsibilities. Every day, every shift should check the vehicles and equipment. Ensure that the vehicle does not break down during the preparation, ensure the safety of the vehicle and the integrity of the equipment during the fire fighting, and ensure the completion of the fire fighting task.

Four. Chen Tao Group's work this month: washing the slime bin 1 time, washing the ground twice, watering the trees twice, and going out to the police 1 time (on March 22nd, when the methanol truck leaked at the chemical gate, Chen Tao answered Chen Bo's call and led the team members to the scene to dilute it with water).