RU2553296C1 - Aircraft cabin air sampler - Google Patents

Abstract

FIELD: aircraft engineering.

SUBSTANCE: invention relates to aircraft cabin air samplers, gadgets for analysis of admixtures in aircraft cabin air samples for analysis of concentration of contaminants in aircraft air conditioning systems and for determination of the composition of harmful admixtures and dangerous concentrations of gases and vapours in air. This sampler comprises evacuated vessel as air consumption booster, absorption cartridge with sorbent-concentrator composed of sharpened steel tube with plugs of glass wool at tube ends, with side bore in said tube filled with sorbent and glass wool. Evacuated vessel is composed of cylindrical case with inlet and outlet pipes fitted at case ends. Outlet pipe is provided with tube of vacuum rubber and metal plug to be fitted in the tube free end after evacuation. Inlet pipe is welded to the case end and features ID larger than that of the case inlet and internal thread. Aforesaid absorption cartridge with sorbent-concentrator is fitted in said inlet pipe and, partially, in evacuated vessel used also as a sampler of admixtures not absorbed by concentrator. Locking device composed of the tube with air sample passage inlet is screwed via seal ring in evacuated vessel surface neck to tight fit. Cover with stiffness ribs and rubber washer is secured to said locking device and aligned therewith. Lever with triangular cam at the end is articulated with the device on opposite side from the cover attachment side to lift said cover to unseal the system and to bleed air. Said lever and cover are secured to be revolved in one plane relative to axles of rotation and attachment. Springs secured from one side to locking device case and to cover stiffness ribs on opposite sides. This makes said cover opened and cover closed at lowered lever and cover located at lever can outer leg. Lever shifted, cover goes up to unseal the system and to bleed air.

EFFECT: higher sampler sensitivity, accuracy of analysis, accelerated in-flight experiment.

3 dwg

Description

The invention relates to techniques for taking air samples of aircraft cabins (LA), concentrating impurities in air samples of aircraft cabins to study the degree of air pollution by harmful substances entering air conditioning system (SCR) together with air and determining the composition of harmful impurities and dangerous concentrations in the air gases and vapors, increasing the sensitivity of their determination.

State of the art

The main source of air pollution in aircraft cabs is the removal of lubricating oil from the front engine mounts with its subsequent complete or partial decomposition in the compressor path of a gas turbine engine (GTE) in different modes of operation. A complex mixture containing vapors and aerosols of lubricating oil, vapors of aliphatic hydrocarbons, acrolein, formaldehyde, phenol, cresols, acetic acid, benzene, tricresyl phosphate, ethyl, propyl, butyl and isobutyl alcohols, acetone, toluene, xylene, oxide and carbon dioxide from the air conditioning system to the aircraft cabin. In addition, the air of the aircraft cabins is polluted by emissions from the cabin trim materials and anthropotoxins.

The proposed device can be used in factory and certification tests of aircraft for compliance with the requirements of §831 AP-25 (Aviation Rules. Part 25. Airworthiness standards of transport category aircraft. 2008), similar to AP-29 (helicopters) and AP-23 ( civilian light aircraft). Domestic requirements for the purity of air taken from aircraft gas turbine engines and supplied for ventilation of the premises for the crew and passengers are regulated in AP-25. In accordance with §25.831, along with the requirement that the ventilation system supply a sufficient amount of air (a) that does not contain “harmful and dangerous concentrations of gases and vapors” (b), the need to ensure the following conditions has been established:

- MPC of other toxic impurities (except for oxide and carbon dioxide), mg / m ³ , (d *):

fuel vapor - 300;

vapors and aerosol of mineral oils - 5;

vapors and aerosol of synthetic oils - 2;

acrolein - 0.2;

formaldehyde - 0.5;

phenol - 0.3;

benzene - 5;

tricresyl phosphate - 0.5;

dioctyl sebacinate - 5.0;

nitrogen oxides - 5.

Known devices for sampling and storing air samples in the form of glass non-calibrated gas pipettes with two single-pass valves, made in accordance with GOST 18954-73 "Glass instrument and pipettes for sampling and storage of gas samples."

Similar devices are made in the form of cans described in ASTM (2001): “Standard Test Method for Determination of Volatile Organic Chemicals in Atmospheres (Canister Sampling Methodology), West Conshohocken, PA, American Society for Testing and Materials (ASTM Standard D5466-01 ) ". In this case, the canister with a shut-off valve is used either pre-evacuated, or the selection is made by gas exchange (purging the canister with a large amount of air).

Various versions of such devices (sampling into gas pipettes, plastic bags, etc.) are suitable only for sampling air for the content of weakly adsorbed gases, and according to Russian airspace standards, the content of high-boiling compounds (oil, kerosene, tricresyl phosphate and etc.). The well-known "Complex of sampling air", patent for invention No. 2494366, comprising a housing consisting of interconnected vertical panels on which there are samplers with adsorption bags having concentrators, electromagnetic valves, filter-moisture separators, temperature and pressure sensors, a sampling collector installed in front of the GTE subject, a diffuser with nozzles, a vacuum pump and a control panel. However, this complex is used only for bench tests of engines. The disadvantages of this design include the fact that the shut-off devices (electromagnetic valves) are located after the samplers, some of the impurities may settle in the valves and, conversely, they themselves can emit foreign impurities.

The closest in technical essence to the proposed device is the device described in MU 1.1.258-99, introduced 01.07.2000 NIISU. These drawbacks are partially eliminated by the fact that air sampling is carried out due to the concentration of impurities on the adsorbent, and the evacuated capacity is used here as a calibrated flow inducer with good metrological characteristics. The design of the device for concentrating air impurities (sampler) includes a housing and a concentrator with a sorbent made of a pointed steel tube with a side hole and a pusher with an adjusting screw. The hub is centered and sealed in the housing using two rubber bushings. After sampling, the sampler is disassembled, the concentrator is disassembled for chromatographic analysis by desorption of impurities into the chromatograph evaporator, after which it is again suitable for sampling without special purification.

The disadvantages of this design include the fact that the locking devices (solenoid valves) are located after the samplers. During a long flight, especially on maneuverable aircraft, due to pressure changes in the cockpit, unaccounted air sampling will take place (pumping through concentrators to equalize the air pressure in the cockpit and the dead volume between the valve and the concentrator). A simple interchange of these units in places does not solve the problem, since some of the impurities may settle in the valves and, conversely, they themselves can emit foreign impurities. Passive parasitic selection for adsorbent in the concentrator is also possible, since the entrance to the concentrator will be constantly open here. In addition, background pollution of concentrators by emissions from rubber bushings is possible due to their large contact area with the concentrator. All this distorts the results of subsequent gas chromatographic analysis in the direction of their significant overestimation.

The technical result, which is achieved by the claimed device, is to increase the sensitivity of the determination of dangerous concentrations of gases and vapors in the air, the accuracy of the analysis by reducing background pollution, reducing the time of the ground and flight experiment to assess the air purity of aircraft cabins.

Essential features.

To achieve this technical result, in an air sampling device in an aircraft cabin containing an evacuated container as an air flow inducer, an absorption cartridge with a sorbent (concentrator) made of a pointed steel tube with glass wool plugs at the ends of the tube, with a side hole in the tube filled with sorbent and glass wool, the evacuated container is made in the form of a cylindrical body with inlet and outlet nozzles installed at its ends. The outlet pipe is equipped with a tube of vacuum rubber and a metal plug inserted into the free end of the tube after evacuation. The inlet pipe is welded to the end of the body, made with an inner diameter larger than the diameter of the entrance to the body, and with an internal thread. An absorption cartridge with a sorbent (concentrator) is installed in the inlet pipe and partially in a vacuum tank, which is also used as a sampler for impurities that are not absorbed in the concentrator. The locking device in the form of a tube with an inlet for the passage of an air sample is screwed until it is pressed tightly through a sealing ring to the neck of the surface of the evacuated container.

A cover with stiffening ribs and a rubber gasket is coaxially attached to the locking device at the entrance, and a lever with a triangular eccentric at the end is pivotally mounted on the side opposite to the side of the cover fastening, which is able to lift the cover when the lever is shifted, depressurizing the system and taking air out. The lever and the cover are fixed and rotatable in the same plane with respect to the axes of rotation and mounting, between them are springs attached on one side to the housing of the locking device, and on the other hand, to the stiffening ribs of the cover, providing, when the lever is lowered, when the cover lies on the external arm of the clown lever, the position - the cover is closed, and - the cover is open when raised and lies with the technological clearance on the internal arm of the clown, when the lever is shifted, the cover is lifted, depressurized I system and producing air bleed.

In addition, the device is ergonomic when performing the sampling procedure by a pilot in protective equipment, in the cramped cabin of a maneuverable aircraft by minimizing the number of actions during sampling.

Figure 1 presents a drawing of the proposed device for sampling air cabins LA.

Figure 2, 3 presents drawings of the housing of the locking device with the lever lowered, a triangular eccentric at the end and raised at the moments of closing and opening the lid.

The device selected as a prototype contains a vacuum tank, a hub.

The proposed device, see Fig. 1, contains a cylindrical evacuated tank 1, a hub 3 is installed in the inlet pipe 2 through an annular rubber seal 4, which is sealed by screwing the nozzle 2 of the closure device body into the neck in the form of a tube 5 with a threaded neck 6. At the tube inlet 5 on different sides are attached a cover 7 with ribs and a rubber gasket and a lever 8 with a triangular eccentric at the end. They are fixed and rotate freely in the same plane using the axes 9 and 11. Between them are springs 10, mounted on one side on the housing of the locking device 5, and on the other hand, on the edges of the cover 7, which ensure constant closure of the cover 7 with the lever lowered 8. From the opposite end of the tank 1, an outlet 12 is made with a rubber sleeve 13 and a plug 14, which are used to evacuate and determine the residual pressure before and after air sampling.

Device operation

The device operates as follows. At the entrance to the cylindrical evacuated container 1, a locking device 5 is installed with a lever 8 having two stable spring-loaded positions - closed when the cover 7 rests on the external leg of the cam eccentric, and - open when the cover is raised and lies with a technological clearance on the inner leg of the cam, see figure 2 and 3.

An absorption cartridge with a sorbent (concentrator) 3 is installed in the inlet pipe 2 and partially in a vacuum tank 1, which is also used as a sampler for impurities that are not absorbed in the concentrator. When the cover is in the closed position, the device is assembled and vacuumized through the second outlet pipe 12 with a tube of vacuum rubber (rubber sleeve) 13, which is then drowned out by introducing a larger diameter metal rivet 14 into the tube. In the open position (lever up), sampling takes place. After selection (1-2 min), the device closes with one movement of the pilot’s hand (lever down). Moreover, before and after sampling, pollution of the concentrator is excluded, which significantly reduces the error in determining the concentration of harmful impurities in the air of aircraft cabins. In addition, the fact that the locking device 5 is made with a cover 7 and a gasket without any lubrication and with a large bore, and not in the form of a needle or ball valve or valve, to avoid the deposition of impurities in the locking device 5 to the concentrator 3 and at the same time does not contaminate the sample with grease or other secretions from the valves. Air cabin air sampling devices are quite compact.

For reliable analysis of cabin air according to the requirements of the AP, according to existing methods, it is enough to pump air through 0.1-0.2 dm ³ concentrators (provided that the background pollution of the concentrators is quite small, which is provided by the proposed device design). If an elastic ring tape with “Velcro” is fastened to the evacuated cylindrical container 1, then with its help it is possible to fasten such devices in the required quantity to the head restraints of the aircraft cabin seats, placing the intake device in the breathing zone of passengers. Passing through the cabin, the experimental engineer opens the necessary devices with one movement, and closes them on the way back (selection time no more than 1-2 minutes). This allows you to significantly reduce the time and number of flight experiments to assess the air purity of the aircraft cabins. For maneuverable aircraft, the compactness and ease of operation of the proposed device are also very beneficial. The pilot can perform opening and closing operations even in protective equipment (for other designs this process is very difficult).

Claims (1)

A device for sampling air in the cockpit of an aircraft, containing a vacuum tank as an inducer of air flow, an absorption cartridge with a sorbent concentrator, made of a pointed steel tube with glass wool plugs at the ends of the tube, with a side hole in the tube filled with sorbent and glass wool, characterized the fact that the evacuated container is made in the form of a cylindrical body with inlet and outlet nozzles installed at its ends, the outlet nozzle is equipped with a tube of vacuum p a rubber and a metal plug inserted into the free end of the tube after evacuation, the inlet pipe welded to the end of the body is made with an inner diameter larger than the diameter of the entrance to the body, and with an internal thread, an absorption cartridge with a sorbent concentrator is installed in the inlet pipe and partially in an evacuated container, which is also used as a sampler for impurities that are not adsorbed in the concentrator, a locking device in the form of a tube with an inlet for the passage of an air sample is screwed up to pressing it through the sealing ring to the neck of the surface of the evacuated container, to the locking device at the entrance, a cover with stiffening ribs and a rubber gasket is coaxially attached, with a lever with a triangular eccentric on the end pivotally mounted on the device from the side of the cover fastening, made with the possibility of shifting the lever lift the lid, depressurizing the system and taking air, the lever and lid are fixed and rotatable in the same plane relative to rotations and fastenings, between them are springs attached on one side to the housing of the locking device, and on the other hand to the stiffening ribs of the cover, providing the lever eccentric with the lever down when the cover rests on the outer leg, the position is closed and the cover is closed open when raised and lying with a technological gap on the inner leg of the eccentric.

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