JPS6219734A - Leakage checking method - Google Patents

Abstract

PURPOSE:To enable the highly accurate analysis of a fuel leakage without the need for a specialist by using the adequate and inexpensive collection instrument for leaking gas. CONSTITUTION:An air is mixed into the leaked gas inside a sample collection bottle 7 after the collection of the leaked gas of a fuel hydrazine by permitting to stand for about 10hr the sample collection bottle 7 which is evacuated together with the sampling boat of the airtight connection implement 5 connected to the leakage detecting part of fuel system via the rubber hose 6 for vacuum use. The ammonia density inside the sample collection bottle 7 is checked by an ammonia detecting tube 11 with the operation of a gas aspirator 12 by combining the tip of the ammonia detecting tube 11 set to the gas aspirator 12 with the combining part of the rubber hose 6a for vacuum use. Then, by converting the ammonia density into the leakage quantity of the fuel hydrazine the leakage of the fuel can be found.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides a method for injecting fuel hydrazine into a reaction control system (RCS thruster), which is an attitude control device for satellites, planetary probes, etc. The present invention relates to a simple and highly accurate method for checking leaks.

(Prior Art) Conventionally, as a method of checking the leakage amount and concentration of internal gas of a reaction control system (hereinafter simply referred to as an RCS thruster), which is a device for controlling the attitude of a satellite, etc., There are methods that use N, gas, He gas, etc., which are different from the fluid mounted on the vehicle, but since the object to be checked is different from the fluid actually mounted, the results often do not match the reality.

Therefore, it is desirable to perform an internal leak check of the fluid actually mounted on the RCS thruster.

By the way, this type of leak check method that has been commonly used in Japan is that after injecting fuel hydrazine into the RCS thruster, as shown in Fig. 3, <RCS
A dry condom 7a is fitted over the nozzle 4 of the thruster 1, and leak gas is collected in the dry condom 7a. Here, in the figure, 2 is an electromagnetic valve, and 3 is a catalyst for chemically reacting hydrazine, which is a fluid, to generate a high-temperature, high-pressure gas. Therefore, the internal leak check of the RCS thruster 1 is to check the amount, concentration, etc. of gasified hydrazine leaking through the electromagnetic valve 2 and the catalyst 3.

As mentioned above, the dry condom 7a is fitted onto the nozzle 4 of the RCS Suranuta 1 to collect the internal leak gas, but this state is maintained for a predetermined period of time, usually about 10 hours. put. As a result, the dry condom 7a is filled with the leaked gas and expands, and then, as shown in FIG. 4, the gas inside the dry condom 7a is sampled using the syringe 12a.

When this sampling is completed, as shown in FIG. 5, the sampled leak gas is injected into the gas chroma analyzer 14, the gas analysis results are obtained using a pen oscilloscope 15, etc., and the amount of gas leak and its concentration are calculated. .

The above is a conventional method for checking internal leaks of RCS thrusters, but according to this method, since the nozzle diameter of RCS thrusters with small thrust is small, there are no tri-condoms on the market that are suitable for this. Efforts are needed to achieve this. Furthermore, since the inside of the condom cannot be maintained in a vacuum state, it is impossible to suction and collect leak gas. As a result, it was also impossible to use an ammonia detection tube and GASTEC.

Therefore, as described above, it is necessary to use expensive analysis equipment such as a gas chroma analyzer or a pen oscilloscope for gas analysis after leak gas collection. However, the lower limit of the analytical accuracy of this gas chroma analyzer is at most 500 ppm per 1 cc of sample, and it is difficult to measure anything below that, that is, 500 ppm or less, making it impractical. Furthermore, the conventional leak check method described above does not allow for gas analysis by amateurs and requires an expert.

(Problems to be Solved by the Invention) As described above, in the conventional leak check method of this type, it is not only difficult to procure appropriate collection equipment for leak gas, but also it is impossible to suction and collect leak gas. As a result, there were various problems such as the necessity of using expensive and low-precision gas analysis equipment, and the analysis also requiring expertise.

The present invention was developed to solve these problems, and aims to provide a leak check method that can obtain highly accurate analysis results using inexpensive equipment and without the need for experts. It is something to do.

(Means for Solving the Problems) Therefore, the present invention provides a sample collection bottle that is evacuated together with a collection port of an airtight connection tool that is connected to a leak detection part of the fuel system via a vacuum rubber hose. After leaving it for 10 hours to collect leak gas from fuel hydrazine, mix air into the leak gas in the sample collection bottle and detect the ammonia concentration in the leak gas using Gastec and an ammonia detection tube. The method consists of converting the amount, and this is used as a means to solve the above-mentioned problems.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2.

First, to explain the device and its equipment used in this example, 1 is an RCS thruster, which is composed of an electromagnetic valve 2 and a catalyst container 3 that stores a catalyst inside. A trumpet-shaped nozzle 4 is formed through the section.

Reference numeral 5 denotes an airtight connection tool made of rubber or the like, which has the same outer shape as the nozzle 4 and has a through hole in its solid axis. This airtight connection tool 5 is tightly fitted into the nozzle 4 from its tapered portion, and the outer end of the through hole is connected to one end of the vacuum rubber hose 6a via a suitable connector. The other end of the vacuum rubber hose 6a is fitted into the spout of the sample collection bottle 7. The capacity of the sample collection bottle 7 is suitably about 500 cc. However, it goes without saying that the capacity is not limited to this. Another vacuum rubber hose 6b is pulled out from the spout of the sample collection bottle 7, and a glass cock 8 is disposed in the middle of the vacuum rubber hose 6b, and a jet sucker 10 ( A coupling portion 9 is provided for coupling to a suction pipe of a vacuum pump or an ammonia detection tube 11.

In addition, in the figure, 12 indicates a gas tech (suction device), and 13 indicates a heat dryer.

In this embodiment, the above-described apparatus and equipment are used to check for gas leaks in the RCS thruster, and the leak check method will be described below with reference to FIGS. 1 and 2.

First, in preparation for a leak check, one end of the two vacuum rubber hoses 6a and 6b are fitted into the sample collection bit zero port plug, and the airtight connection tool 5 connected to the other end of one vacuum rubber hose 6a is connected to the catalyst. It is fitted into the nozzle 4 of the container 3, and the suction pipe of the jet sun force 10 is connected to the other end of the other vacuum rubber hose 6b.

When this preparation is completed, the glass cock 8 is opened, the jet sucker 10 is activated, and the line from the sample collection bottle 7 to the downstream side of the solenoid valve 2 is evacuated, as shown in Fig. 1. After reaching a vacuum of about 20 Torr or less,
The glass cock 8 is closed and left as is for about 10 hours. During this time, the hydrazine leaking from the solenoid valve 10 undergoes a chemical reaction with the catalyst in the catalyst container and becomes a decomposed gas consisting of ammonia and nitrogen, which flows from the collection port 5a of the airtight connection tool 5 into the sample collection bottle 7. and 81
m is collected.

When the collection of the decomposed gas is completed, droplets of the collected decomposed gas may have adhered to the sample collection bottle 7, so first remove the sample collection bottle 7 from the outside using the heat dryer 13. Warm up from

Next, the connection between the jet sucker 10 and the vacuum rubber hose 6b is broken, and the glass cock is opened. At this time, since the inside of the sample collection bottle 7 is in a negative temperature and pressure state, air flows into the sample collection bottle 7 from the outside and is mixed with the decomposed gas inside. The reason why the outside air is once flowed into the sample collection bottle 7 is to make the situation consistent with the situation at the launch site of a satellite, etc., but normally the surrounding air during sampling is adjusted to be clean. , there is no risk of other impurities being mixed in, and a situation similar to the above situation can be set.

Once this air has been mixed in, use the Gastech (suction device)
Connect the tip of the ammonia detection tube 11, which is attached to the gas tube 12, to the connecting part of the vacuum rubber hose 6a.
The ammonia concentration in the sample collection bottle 7 is checked using the ammonia detection tube 11.

Finally, this ammonia concentration is converted into a fuel (hydrazine) leakage amount to determine the fuel leakage amount.

(Effects of the Invention) As explained above in detail, according to the present invention, it is sufficient to use commercially available checking equipment, and therefore, it is inexpensive and easy to obtain, and it is not necessary to purchase equipment that is difficult to obtain or expensive as in the past. There is no need to do so, and equipment costs can be reduced accordingly.

In addition, according to the present invention, the operation for leak checking is easy and does not require a high level of expertise, and in addition, the accuracy of the check is such that, for example, in the case of ammonia, measurements can be made from 50 to t ppm per cc of sample. It is now possible to achieve conventional accuracy (
>500 ppm/cc). Furthermore, based on the above points, in some cases, it is possible to directly check on-site.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the arrangement of various equipment when collecting leak gas according to the present invention, Fig. 2 is a sectional view showing the arrangement of various equipment when measuring leak gas concentration, and Fig. 3 is a sectional view showing the arrangement of various equipment when collecting leak gas according to the present invention. The equipment layout diagram at the time of collection, Figure 4 is the same (cross-sectional diagram of the equipment layout at the time of conventional sampling,
FIG. 5 is the same equipment layout diagram for conventional gas analysis. Explanation of the main parts of the diagram 1 - RCS thruster 4 - Nozzle 5 - Airtight connection tool 6 - Vacuum rubber hose 7 - Sample collection bottle 10 - Diesel filter 11 - Ammonia detection tube Figure 1

Claims (1)

[Claims] A sample collection bottle evacuated together with a collection port of an airtight connection tool connected to a leak detection part of the fuel system via a vacuum rubber hose was left for about 10 hours to collect leak gas from fuel hydrazine, and then the sample was collected. A leak check method characterized by mixing air into leak gas in a collection bottle, detecting the ammonia concentration in the leak gas using a gas tech and an ammonia detection tube, and then converting the amount of fuel leak from the ammonia concentration.