The use of sandwich-panels as a safety and easily thrown off designs for internal explosions

New method of explosion-proof ensuring for industrial buildings by usage of sandwich-panels as enclosures and easily thrown off designs by inside combustions is examined in this work. Possibility of dumping of an overpressure at internal explosion indoors the obligatory requirement at projection and operation of explosive rooms [7]. The acceptable results are achieved by two options:1) use of the weak protecting designs (glass, membranes); 2) use of loose couplings when fastening of the protecting designs to a building framework. In case of the former the protecting designs collapse, in the second communications collapse and the released protecting designs start moving, opening the aperture blocked by them. Through the opened apertures from the room gases expire that leads to pressure decrease. The best results are achieved at the quasistatic nature of explosion when wave processes are insignificant. The protecting designs serving for an explosion depressurization are often called the safety designs (SD) [4] or easily thrown off designs (ETD). [9]. Now most the energy industries enterprises are built with use triplex a sandwich panels which at the corresponding fastening can apply, owing to their small weight, to use as ETD. Full success is achieved, if the area does not allow the rise of the burst pressure to allowable values Рd , which is determined by the carrying capacity of protected structures. This success is possible, if the area of openings, covers easy detachable more than the required minimum, and easily thrown off designs are opened fast enough to provide the required area expires during the development of the explosion. It is necessary that the time development of the explosion was more than time for the opening of openings. Internal quasi-static explosion devoted many works [1, 2, 3, 4]. Most of the required area is determined by the expiration. Question how do you ensure this area remains on the sidelines with the exception of destructible structures: glass and membrane [4, 5]. In industrial hazardous locations more convenient to use light panels that have loose connections. The explosion destroyed the first, and the panels fly off under the action of pressure and release they overlap the square. In this paper the process of opening the light panels and the change in pressure directly after the destruction of relationships, retaining panel. The analysis is performed using the equations describing the pressure changes with increasing square of the expiration of the [4] and the equations of motion of the panel. This assumes that: * Corresponding author: Kiara_lion@mail.ru DOI: 10.1051/ , 0 (2016) MATEC Web of Conferences matecconf/2016 86 8604025

Possibility of dumping of an overpressure at internal explosion indoors -the obligatory requirement at projection and operation of explosive rooms [7].The acceptable results are achieved by two options:1) use of the weak protecting designs (glass, membranes); 2) use of loose couplings when fastening of the protecting designs to a building framework.In case of the former the protecting designs collapse, in the second communications collapse and the released protecting designs start moving, opening the aperture blocked by them.Through the opened apertures from the room gases expire that leads to pressure decrease.The best results are achieved at the quasistatic nature of explosion when wave processes are insignificant.
The protecting designs serving for an explosion depressurization are often called the safety designs (SD) [4] or easily thrown off designs (ETD).[9].Now most the energy industries enterprises are built with use triplex a sandwich panels which at the corresponding fastening can apply, owing to their small weight, to use as ETD.
Full success is achieved, if the area does not allow the rise of the burst pressure to allowable values 'Р d , which is determined by the carrying capacity of protected structures.This success is possible, if the area of openings, covers easy detachable more than the required minimum, and easily thrown off designs are opened fast enough to provide the required area expires during the development of the explosion.
It is necessary that the time development of the explosion was more than time for the opening of openings.Internal quasi-static explosion devoted many works [1,2,3,4].Most of the required area is determined by the expiration.Question -how do you ensure this area remains on the sidelines with the exception of destructible structures: glass and membrane [4,5].
In industrial hazardous locations more convenient to use light panels that have loose connections.The explosion destroyed the first, and the panels fly off under the action of pressure and release they overlap the square.In this paper the process of opening the light panels and the change in pressure directly after the destruction of relationships, retaining panel.The analysis is performed using the equations describing the pressure changes with increasing square of the expiration of the [4] and the equations of motion of the panel.This assumes that: 1.The movement of the panel is described by the equation: Where хdistance last the panel by the time of time t 2. Expire cold gases.
3. The average pressure acting on the panel: , where ' 'Р 1corresponds to the first maximum pressure immediately after opening, 'P Vpressure opening.From experiments and numerical solutions performed in [6] shows that 'Р 1 depends on 'Р V and the speed of combustion.And may exceed 'Р d .
4. Dealt with the pressure at which the velocity is described by the expression that overrides the carrying capacity of many buildings.However, this limitation does not matter.
Note the experimental fact that the maximum 'Р 1 occurs at the opening of sandwich panels with incomplete opening of the opening, i.e.Using assumptions 1-4 and condition of maximum pressure 0 dP dt is the value of this maximum: U g -the rate of combustion at the time of opening of easily thrown off designs, Q 1flow coefficient, N -is the number of opened panels, Mmass of the panel, V -the rate of expansion during combustion, U 0 -is the initial density of the gaseous medium.
The number of panels is determined from the condition that the area is completely uncovered openings provided for reducing the pressure of the explosion to 'Р d , at the time of the maximum speed of energy release, i.e. at the moment when there U g and F f are maximum (where F f -is the area of burning).
Thus, (N*a*b) has the necessary space required fully opened openings.This area is defined by the expression [4,6]: Substituting this expression into the previous one and requiring that would 'Р 1 <'Р d , after simple transformations, we obtain the condition: IPICSE-2016 Here K f is the shape factor of the premises, determined from: Fsurface area of the flame when deflagration internal explosion.
Using data on the known parameters of an internal explosion and properties of easily thrown off designs, you can pick up ' 'Р V to 'Р 1 does not exceed 'Р d .Table 1 The table shows that the magnitude of the pressure opening has a significant influence on the resulting blast load.In [6] experimentally studied the autopsy sandwich panels for some cases of attachment.The opening pressure depends on the thickness of the sheet, the thickness of the structure in which twists of «tapping» and the number of attachment points.
Pressure of opening depends on the leaf thickness from design thickness in which «selftapping screw» and from number of points of fastening twists and in each case is defined experimentally.
Experiments were made on two explosive cameras 1 of m 3 and 10 m 3 .The technique of carrying out an experiment is described in [6,7,8].The generalized results of experiments are presented in the table 2. Experiments were made with use of nominal «self-tapping screws»for fastening a sandwich panels.The aperture was blocked by a unity element a sandwich panel, results of experiments testify about: the nature of opening of the panel depends on thickness of a design to which it to fasten.At a thickness of design of 5 mm -with break of sheets of the panel, at 2 mmwith to pull out «self-tapping screw» from it; decrease of the size of washers under a head of «self-tapping screw» reduced opening pressure.In the absence of a washer pressure of opening decreased by 1.5 times; the cruciform cut of the panel under a washer, with a cut length to edge of a washer, was reduced by opening pressure by 2.5-3 times; at decrease of pressure of opening the maximal pressure immediately after opening according to (3) and table 1 decreased; pressure of opening can be estimated on a ratio: where feffort to a simple point of fastening during the opening, it is defined experimentally at a leaf thickness a sandwich panel, δ=0.5mm, nnumber of points of fastening, S -the area a sandwich panels.
Application a sandwich panels of the big size increases load of simple knot of fastening, therefore, more rational is use a sandwich panels of perhaps larger size.In this case there is a possibility of protection not only bearing, but also protecting a sandwich panels of the smaller size.
In the conclusion it is necessary to make two remarks: 1) at installation a sandwich panels they are adjusted to each other by means of the «groove in a groove» lock along the lengthiest party.Carrying out experiments with the block a sandwich panels was impossible.It is possible to consider this effect gathering the block from a sandwich panels so that cross sectional dimension of the block (n*b) was common more than length one sandwich panel or to use panels without latch fastening.
2) the second remark arises because opening of an aperture begins not at the time of a start of motion, as in an experiment, and at the moment when ETD passes distance x =δ to panel thickness.This circumstance is considered by the amendment to opening pressure to a look: This amendment is rather small.For typical values ' 'Р V =3*10 3 Pa, σ=7, U g = 1.5 m/seс,δ=10 -1 m, V 0 = 600 m 3 ,('Р V /'Р 1 )=1.004,(M/ab)=25 kg/m 2 .

Conclusions
1. Triplex a sandwich panel can be efficient easily thrown off designs.2. Comparison a sandwich panels with a glazing shows advantages of panels before a deaf double glazing so their application as ETD is preferable.3. Effectiveness of sandwich-panels as easily thrown off designs considerably is defined by opening pressure, that is effort to simple knot of fastening.The opening pressure in relation to the allowed pressure is less, the less robust constructions can be protected.

a
and bsides aperture.

Table 2 .
Results of experiments.