RU2518782C1 - Safety valve of single action - Google Patents

Abstract

FIELD: energy industry.

SUBSTANCE: safety valve of single action comprises a housing with a tear-off element mounted in it. The tear-off element is made as a stem with a neck in the middle part of it, and a notch. The notch is a stress riser on the neck. The diameter of the said neck is calculated for the actual tensile strength of the stem material. The stem comprises at its ends a male thread. With one threaded end the stem is screwed into the disc with delivery outlets, mounted in the housing by male adapter of the input. With another threaded end the stem is screwed into a threaded hole of the piston compacted in the housing. The radial holes are made in the wall of the housing, which are hermetically separated from the male adapter of the input by the piston seal.

EFFECT: creation of the safety valve of single action with a stable actuation pressure.

2 cl, 2 dwg

Description

The invention relates to the field of energy and can be used in military equipment.

The single-acting safety valve is designed to automatically release a gaseous or liquid working medium from a high-pressure system with an excessive increase in pressure in it to the atmosphere and to ensure the safe operation of installations and prevent accidents.

Known safety valve single action (patent RU 2105916 from 1998.02.27, IPC F16K 17/40), in which the bore of the housing is blocked by a piston. The piston has supporting elements made in the form of rods. The rods are located along the axis of the passage opening of the housing and have a beveled protrusion at the end that abuts against the protrusion of the housing. When a predetermined overpressure is reached, the support elements lose their bearing capacity, and the piston opens a passage opening in the housing. The disadvantage of this safety valve is the insufficient accuracy of the response pressure due to the instability of the elastic modulus E of the material, the availability of tolerances for a large number of rod sizes and the instability of the coefficient of friction of the rods over the body.

The closest known from the technical nature and the achieved result to the proposed single-acting safety valve is a safety valve, in which the passage opening in the housing is closed by a tear-off cap (Kondratyeva T.F. Safety valves, L .: Engineering, 1976, p.25, 170 - prototype).

The disadvantage of this safety valve is the insufficient accuracy of the response pressure due to the instability of the temporary resistance σ _{in the} cap material.

Roughly the average tear-off (destructive) pressure of the cap is determined by the formula

$$P=\left[{\left(\frac{d_n}{d}\right)}^2-\mathrm{one}\right]\cdot {\sigma }_{\mathrm{at}},(\mathrm{one})$$

where d _n , d - respectively, the outer and inner diameter of the cap;

σ _in - temporary resistance of the material of the cap (see ibid., p. 171).

The aim of the invention is to provide a single-acting safety valve with a stable response pressure.

The goal is achieved by the fact that in the safety valve containing the housing with a tear-off element installed in it, according to the invention, the tear-off element is made in the form of a rod with a neck in the middle part on it and a risk - a stress concentrator on the neck, the diameter of which is calculated according to the actual temporary resistance of the material rod, and with an external thread at its ends, while one threaded end of the rod is screwed into a disk with consumable holes fixed in the housing with a screw inlet fitting, the other threaded end of the rod vinca compacted into a threaded hole in the piston housing and in the housing wall provided with radial openings, sealingly separated from the screw-spout seal input piston. The piston has a cylindrical shank located on the end opposite the end with a threaded hole, while the end part of the shank is installed in the bore of the housing, and the end of the shank is buried relative to the end of the housing by a distance less than the piston stroke when the valve is actuated.

The design of the safety valve single action (hereinafter referred to as the valve) is shown in figures 1 and 2, where:

1 - housing;

2 - disk;

3 - the piston;

4 - stock;

5 - a supply hole;

6 - screw inlet fitting;

7 - neck;

8 - risk;

9 - a rubber ring;

10 - a protective PTFE washer;

11 - radial hole;

12 - cylindrical shank;

13 - hole;

14 - end face of a cylindrical shaft 12;

15 - end face of the piston 3;

16 - the end of the housing 1.

Figure 1 shows the valve in its original position, figure 2 - in the position after actuation.

The valve comprises a housing 1, in which a disk 2, a piston 3, and a rod 4 are mounted. A disk 2 having flow openings 5 is fixed in the housing 1 with a screwed inlet fitting 6.

In the middle part of the stem 4, a neck 7 is made with a risk 8 applied thereon, which is a stress concentrator. At the ends of the stem 4, an external thread is made. One threaded end of the rod 4 is screwed into the disk 2, the other into the piston 3, sealed in the housing 1, for example, a rubber ring 9 with a protective fluoroplastic washer 10. In the wall of the housing 1 there are radial holes 11, which can be arranged in several rows. The total area of the radial holes must be at least the nominal diameter of the hole in the screw fitting of the inlet 6. The piston 3 has a cylindrical shaft 12 installed in the hole 13 of the housing 1. In the initial position, the end face 14 of the cylindrical shaft 12 is buried in the hole 13 of the housing 1.

The proposed valve operates as follows.

At a medium pressure below the set pressure, the valve is closed. The piston 3 and the stem 4 are in the position shown in figure 1. In this position, a force is applied to the piston 3

F _p = (S _p -S _sh.pcs ) · P, (2)

where F _p - the force acting on the piston,

S _p - the cross-sectional area of the piston 3;

S _Шшшт - cross-sectional area along the neck 7 of the rod 4;

P is the pressure of the working medium.

The piston 3 is kept from moving by the rod 4. When the working medium pressure increases to the response pressure, the piston 3 exerts a force exceeding the strength of the rod 4 along its neck 7, and the rod 4 breaks along the neck 7. The piston 3 not held by the rod 4 with a part of the broken rod 4 moves before landing with its end face 15 on the end face 16 of the housing 1. The position of the valve parts after its operation is shown in figure 2. In this position, the inlet cavity of the inlet fitting of the inlet 6 communicates with the environment through the supply holes 5 of the disk 2 and the radial holes 11 of the housing 1, and the working medium is discharged into the environment. In this case, the end face 14 of the cylindrical shank 12 extends from the housing 1, thereby signaling the operation of the valve.

The stability of the response pressure of the proposed valve is ensured by the stability of the tensile force along the neck 7 of the rod 4, which in turn is ensured by the manufacture of rods 4 with a design diameter of the neck 7, taking into account the actual temporary resistance of the material of the rod 4, determined on the samples in the middle part of which is also made , as on the rod 4, the neck 7 with the risk 8 - a stress concentrator.

Claims (2)

1. A single-acting safety valve comprising a housing with a tear-off element installed in it, characterized in that the tear-off element is made in the form of a rod with a neck in the middle part on it and a risk - a stress concentrator on the neck, the diameter of which is calculated according to the actual temporary resistance of the rod material , and with an external thread at its ends, while one threaded end of the rod is screwed into a disk with consumable holes fixed in the housing with a screw inlet fitting, the other threaded end of the rod is screwed into the threads e densified hole in the housing of the piston and the housing wall provided with radial openings, sealingly separated from the screw-spout seal input piston. 2. The single-acting safety valve according to claim 1, characterized in that the piston has a cylindrical shank located on the end opposite to the end with a threaded hole, while the end part of the shank is installed in the opening of the housing, and the end of the shank is buried relative to the end of the housing, less than the piston stroke when the valve is triggered.

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