Automatically performing pressure attenuation integrity test of controlled atmosphere of refrigerated container

Abstract

The invention relates to automatically performing a pressure attenuation integrity test of a controlled atmosphere of a refrigerated container, and particularly provides a method of automatically performing a pressure attenuation integrity test of a container configured to be refrigerated by a transport refrigeration unit (TRU). The method includes connecting a controller programmed with a pressure decay integrity test of the container to a compressor of the TRU and a pressure transducer mounted in the container, and performing the pressure decay integrity test by the controller. The performing includes: starting the compressor to pressurize the container; receiving the reading of the pressure transducer; and determining, from the readings, whether the pressure attenuation integrity test is passed.

Description

Technical Field

[0001] This disclosure relates to refrigerated containers, and more specifically, to the automation of controlled atmosphere pressure decay integrity testing for refrigerated containers. Background Technology

[0002] A typical refrigerated cargo container, such as those used for transporting goods by sea, rail, or road, is a container modified to include a refrigeration unit located at one end. The refrigeration unit includes a compressor, condenser, expansion valve, and evaporator. A certain amount of refrigerant circulates throughout the refrigeration unit, and one or more evaporator fans in the refrigeration unit blow supply air across the evaporator, thereby cooling the supply air and forcing it away into the container. Summary of the Invention

[0003] According to one aspect of this disclosure, a method is provided for automatically performing a pressure decay integrity test on a container configured to be refrigerated by a transport refrigeration unit (TRU). The method includes: connecting a controller programmed with an automatic pressure decay integrity test for the container to a compressor of the TRU and a pressure transducer installed in the container, and performing the automatic pressure decay integrity test via the controller. The execution includes: starting the compressor to pressurize the container, receiving readings from the pressure transducer, and determining from the readings whether the automatic pressure decay integrity test has passed.

[0004] According to one or more additional and / or alternative embodiments, the method further includes recording an indication and reading of whether the automatic pressure decay integrity test has passed.

[0005] According to one or more additional and / or alternative embodiments, the implementation may also include stopping the operation of the TRU.

[0006] According to one or more additional and / or alternative embodiments, the pre-trip inspection of the container is performed afterward.

[0007] According to one or more additional and / or alternative embodiments, the execution can be completed before and after the container is loaded.

[0008] According to one or more additional and / or alternative embodiments, the pressure transducer is installed at the center of the TRU.

[0009] According to one or more additional and / or alternative embodiments, a prerequisite for passing the automatic pressure decay integrity test is that the gas conditions inside the container are met.

[0010] According to one or more additional and / or alternative embodiments, the pressure transducer includes a digital hybrid sensor package.

[0011] According to one or more additional and / or alternative embodiments, the digital hybrid sensor package includes a carbon dioxide sensor, an oxygen sensor, a relative humidity sensor, and a pressure sensor, and the automatic pressure decay integrity test is determined by the readings to compensate for the effects of relative humidity and pressure on the corresponding readings of the carbon dioxide sensor and the oxygen sensor.

[0012] According to one aspect of this disclosure, a method is provided for automatically performing a pressure decay integrity test on a container configured to be refrigerated by a transport refrigeration unit (TRU). The method includes: generating an automatic pressure decay integrity test for the container; configuring a controller programmed with the automatic pressure decay integrity test to signal communicate with the compressor of the TRU and a pressure transducer installed in the container; and performing the automatic pressure decay integrity test via the controller. The execution includes: starting the compressor to pressurize the container; receiving readings from the pressure transducer; and determining from the readings whether the automatic pressure decay integrity test has passed.

[0013] According to one or more additional and / or alternative embodiments, the method further includes recording an indication and reading of whether the automatic pressure decay integrity test has passed.

[0014] According to one or more additional and / or alternative embodiments, the implementation may also include stopping the operation of the TRU.

[0015] According to one or more additional and / or alternative embodiments, the pre-trip inspection of the container is performed afterward.

[0016] According to one or more additional and / or alternative embodiments, the execution can be completed before and after the container is loaded.

[0017] According to one or more additional and / or alternative embodiments, the pressure transducer is installed at the center of the TRU.

[0018] According to one or more additional and / or alternative embodiments, a prerequisite for passing the automatic pressure decay integrity test is that the gas conditions in the container are met.

[0019] According to one or more additional and / or alternative embodiments, the pressure transducer includes a digital hybrid sensor package.

[0020] According to one or more additional and / or alternative embodiments, the digital hybrid sensor package includes a carbon dioxide sensor, an oxygen sensor, a relative humidity sensor, and a pressure sensor, and the automatic pressure decay integrity test is determined by the readings to compensate for the effects of relative humidity and pressure on the corresponding readings of the carbon dioxide sensor and the oxygen sensor.

[0021] According to one aspect of this disclosure, a container system is provided, comprising a container configured for refrigeration by a transport refrigeration unit (TRU), the TRU including a compressor, a pressure transducer mounted in the container, and a controller programmed with an automatic pressure decay integrity test for the container and configured to signal-communicate with the compressor and the pressure transducer. The controller is configured to perform the automatic pressure decay integrity test by: activating the compressor to pressurize the container, receiving readings from the pressure transducer, and determining from the readings whether the automatic pressure decay integrity test has passed.

[0022] According to one or more additional and / or alternative embodiments, the controller is also configured to record indications and readings of whether the automatic pressure decay integrity test has passed.

[0023] According to one or more additional and / or alternative embodiments, the pressure transducer is installed at the center of the TRU.

[0024] According to one or more additional and / or alternative embodiments, the pressure transducer includes a digital hybrid sensor package that includes a carbon dioxide sensor, an oxygen sensor, a relative humidity sensor, and a pressure sensor, and the automatic pressure decay integrity test is determined by the readings to compensate for the effects of relative humidity and pressure on the corresponding readings of the carbon dioxide and oxygen sensors.

[0025] Additional features and advantages are achieved through the technology of this disclosure. Other embodiments and aspects of this disclosure are described in detail herein and are considered part of the claimed technical concept. For a better understanding of this disclosure and its advantages and features, please refer to the description and drawings. Attached Figure Description

[0026] To gain a more complete understanding of this disclosure, reference is now made to the following brief description taken in conjunction with the accompanying drawings and detailed description, wherein similar reference numerals denote similar parts: Figure 1 This is a perspective view of a refrigerated container according to an embodiment; Figure 2 This is a schematic diagram of a refrigeration unit according to an embodiment; Figure 3 This is a perspective view of the refrigeration unit according to an embodiment; Figure 4A This is a flowchart illustrating a method for automatically performing a pressure decay integrity test on a container according to an embodiment; Figure 4B This is a graphical illustration of the pressure decay integrity test according to the embodiment; Figure 4C This illustrates an embodiment. Figure 4AA flowchart of the additional features of the method; Figure 5A This is a perspective view of a pressure transducer according to an embodiment; Figure 5B It is a perspective view of the components of the container system according to the embodiment; and Figure 6 This is a flowchart illustrating an exemplary application of a pressure decay integrity test according to an embodiment. Detailed Implementation

[0027] To verify the airtightness of shipping containers used for controlled atmosphere cargo, technicians often need to pressurize the containers and record the pressure decay time as pressure leaks. For some systems and applications, it is required that the shipping container maintain an initial pressure of 2 IWG (inches of water column) and decay to below 1 IWG within no less than 4 minutes. However, such tests require the presence of technicians, and procedures may vary between operators.

[0028] Therefore, as will be described below, the present invention provides a method for automatically performing controlled atmosphere pressure decay integrity testing of refrigerated containers, using a pressure transducer with good resolution in the range of -10 to 10 IWG. An algorithm is created for running self-diagnostic tests that can be correlated with manual pressure decay procedures. An air compressor is used to automatically pressurize the cargo area, and pressure transducer data is used to verify test specifications.

[0029] refer to Figure 1 and Figure 2 The refrigerated container 10 has a generally rectangular structure, having a top wall 12, an opposing bottom wall 14, opposing side walls 16, and a front wall 18. The container 10 also includes one or more doors (not shown) located on a rear wall 20 opposite the front wall 18. The container 10 is configured to maintain cargo 22 inside the container 10 at a selected temperature using a refrigeration unit 24 (i.e., a transport refrigeration unit (TRU)) located on the container 10. The container 10 is mobile and is used to transport cargo 22 via, for example, a truck, train, or ship. The container 10 can be integrated with a trailer or chassis. The refrigeration unit 24 is located on the front wall 18 and includes a compressor 26, a condenser 28, an expansion unit 30 (e.g., a TXV or EXV), an evaporator 32, and an evaporator fan 34, as well as other auxiliary components.

[0030] like Figure 2As shown, the refrigeration unit 24 causes the return air 36 to flow through the evaporator fan 34 through the evaporator 32, thereby cooling the return air 36 to a selected temperature and causing the cooled return air flow 36 (now referred to as supply air 38) to enter the container 10 through the refrigeration unit outlet 40, for example, through an opening 42 in one or more T-shaped bars 44 extending along the bottom wall 14 of the container 10, to cool the cargo 22.

[0031] The refrigeration unit 24 is divided into an evaporator section 54 comprising an evaporator 32, an evaporator fan 34, and an evaporator fan motor 56, and a condenser section 58 comprising a compressor 26, a condenser 28, and an expansion device 30. In some embodiments, the expansion device 30 may be located in the evaporator section 54. In some embodiments, the evaporator section 54, located above the condenser section 58, is separated from the condenser section 58 by a panel 50 extending through the refrigeration unit 24. The condenser section 58 is exposed to ambient air and may be covered by a panel having openings formed therein. During operation, the refrigerant circulates in series through the compressor 26, condenser 28, expansion device 30, evaporator 32, and returns to the compressor 26. It should be understood that the refrigeration unit 24 may include additional components not shown (e.g., an energy saver, a receiver, an SMV, etc.).

[0032] refer to Figure 3 The refrigeration unit 24 includes a housing 46 to house its components. In some embodiments, the housing 46 is separate from and distinct from the container 10, while in other embodiments, the housing 46 is an integral part of the container 10. A condenser fan 29 is driven by a condenser motor (not shown) to drive airflow through the condenser 28 and exhaust air from the refrigeration unit 24. The condenser 28 may be radially arranged around the condenser fan 29. A controller 70 controls the operation of the refrigeration unit 24, for example, by controlling the compressor 26 (e.g., on / off / variable speed), the evaporator fan motor 56 (e.g., on / off / variable speed), the condenser fan motor (e.g., on / off / variable speed), etc. The controller 70 may be implemented as a processor-based device, including a microprocessor, memory, a user interface, I / O inputs, etc. The controller 70 controls the components of the refrigeration unit 24 to maintain a desired temperature inside the container 10. An air compressor 80 is located in the condenser section 58. The air compressor 80 is a component of the atmosphere control system, which operates to regulate the atmosphere inside the container 10.

[0033] refer to Figure 4A and 4B This demonstrates an automatic execution configuration for use via a TRU (such as...). Figure 1-3A method 400 for testing the pressure decay integrity of a refrigerated container (10 and refrigeration unit 24). Method 400 includes first installing a pressure transducer in the container (see...). Figure 1 as well as Figure 5A and 5B Pressure transducer 501 (block 401). According to an embodiment, the pressure transducer can be mounted at the center of the TRU along the central tube sheet extension above the evaporator coil of the evaporator 32 (see...). Figure 1 Method 400 further includes: generating an automatic pressure decay integrity test for the container (block 402); setting a controller programmed with the automatic pressure decay integrity test to signal communication with the compressor and pressure transducer of the TRU (block 403); optionally stopping the operation of the TRU (block 404); and performing the automatic pressure decay integrity test via the controller (block 406). In some cases, the automatic pressure decay integrity test performed via the controller in block 405 may be performed after the container's pre-trip inspection (block 405), and before and / or after loading the container. Furthermore, method 400 may also include recording an indication and reading indicating whether the automatic pressure decay integrity test passed (block 407).

[0034] The automatic pressure decay integrity test performed by the controller in block 406 may include starting the compressor to pressurize the container to a certain pressure level, then turning off the compressor (block 4061), receiving the readings from the pressure transducer (block 4062), and determining from the readings whether the automatic pressure decay integrity test has passed (block 4063).

[0035] Figure 4B An exemplary execution of the automated pressure decay integrity test of method 400 is shown in the figure. Figure 4B As shown, the pressure inside the container reaches its peak at the start of the test due to the compressor's activation. Once the desired pressure level is reached and the compressor shuts off, leakage within the container causes the pressure to decrease over time, and this pressure decrease is read by the pressure transducer. After a predetermined period, if the reading indicates that the pressure inside the container is below a certain pressure level, the automatic pressure decay integrity test fails; conversely, if the reading indicates that the pressure inside the container is equal to or higher than that certain pressure level, the automatic pressure decay integrity test passes.

[0036] The desired pressure level can vary based on a variety of factors, including but not limited to one or more of the following: the container's volume, the container's expected leak-proof seal, the compressor's power, and the type of cargo being transported at a given time. However, there are situations where pressurization to run an automated pressure decay integrity test is impossible or useless due to, for example, the container exhibiting high leakage (e.g., the container curtains not being properly installed). In these or other cases, Figure 4A Method 400 can be added Figure 4C Additional execution of method 400'. For example... Figure 4C As shown in the figure, method 400' begins Figure 4A The compressor is started at block 4061, and it is determined whether the container is being pressurized (block 4064). If so, method 400' includes determining whether the desired pressure level has been reached (block 4065), and if so, an automatic pressure decay integrity test is performed substantially as described above (block 4066). If not, pressurization of the container continues. If the determination at block 4064 that the container is being pressurized indicates that the container is not being pressurized, method 400' includes identifying and correcting the cause of the leak, such as the container curtain not being properly installed (block 4067), and then determining whether the cause of the leak has been corrected (block 4068). If the cause of the leak has been corrected, control returns to the determination at block 4065 that the desired pressure level has been reached, or if not corrected, a notification of a high-leakage container is issued (block 4069).

[0037] Continue to refer to Figure 1 , 4A And 4B, and additional reference Figure 5A and 5B The pressure transducer 501 may include or be configured as a digital hybrid sensor package 510, and / or in some embodiments, as an RS485 sensor package. Generally, the pressure transducer 501 includes wiring for a connector 5011, sensor electronics 5012, power and communication input / output connectors 5013, inlet, outlet, and gas (N2) sampling ports 5014, and a gas sampling mixing box 5015.

[0038] When the pressure transducer 501 includes or is configured with a digital hybrid sensor package 510, the digital hybrid sensor package 510 may include a carbon dioxide sensor 511, an oxygen sensor 512, a relative humidity sensor 513, and a pressure sensor 514. In these or other cases, determining whether the automatic pressure decay integrity test passes by readings in block 4063 may include using the corresponding readings of the relative humidity sensor and the pressure sensor to compensate for the effects of relative humidity and pressure on the corresponding readings of the carbon dioxide sensor and the oxygen sensor (block 40631).

[0039] According to an embodiment, carbon dioxide sensor 511 and oxygen sensor 512 measure the partial pressure of the gases they are designed for (CO2 for carbon dioxide sensor 511 and O2 for oxygen sensor 512). Relative humidity (RH) absorbs a certain amount of the atmosphere and thus reduces the readings for CO2 and O2 concentrations. Pressure transducer 501 measures the pressure deviation from atmospheric pressure, which alters the readings for the partial pressure measurements of CO2 and O2 gases. This information is then used to normalize the readings to data that would be equivalent to an atmosphere with no RH or a pressure higher than atmospheric pressure.

[0040] Continue to refer to Figure 1 , Figure 4A and Figure 4B And additional reference Figure 5A and Figure 5B A container system 500 is provided. The container system 500 includes a container 10 (see...). Figure 1 and Figure 2 ), Container 10 is configured to be transported via TRU (such as Figures 1-3 The refrigeration unit 24) provides refrigeration. The TRU includes a compressor 26 (see...). Figure 2 The container system 500 also includes a pressure transducer 501 installed in the container 10 (i.e., at the center of the TRU along the sheet extension above the evaporator coil of the evaporator 32). Figure 1 , 5A (and 5B) and controller 502. As mentioned above, pressure transducer 501 may include or be configured as a digital hybrid sensor package 510. When pressure transducer 501 includes or is configured as a digital hybrid sensor package 510, the digital hybrid sensor package 510 may include a carbon dioxide sensor 511, an oxygen sensor 512, a relative humidity sensor 513, and a pressure sensor 514.

[0041] The controller 502 includes a processor 503, a memory unit 504, and an input / output (I / O) unit 505. The processor 503 can be configured to communicate signals with the pressure transducer 501 and the compressor 26 via the I / O unit 505. The memory unit 504 has a program for performing an automatic pressure decay integrity test on the container 10 and executable instructions stored thereon. The executable instructions can be read and executed by the processor 503. When the executable instructions are read and executed by the processor 503, the processor 503 is prompted to perform the automatic pressure decay integrity test on the container 10. That is, when the executable instructions are read and executed by the processor 503, the processor 503 is prompted to start the compressor 26 via the I / O unit 505 to pressurize the container 10, receive readings from the pressure transducer 501 via the I / O unit 505 for at least a predetermined time period (such as 1-5 or 4 minutes) and thereafter, determine from the readings whether the automatic pressure decay integrity test has passed, and then record the indication of whether the automatic pressure decay integrity test has passed and the readings.

[0042] When the pressure transducer 501 includes or is configured to include a digital hybrid sensor package 510, and the digital hybrid sensor package 510 includes a carbon dioxide sensor 511, an oxygen sensor 512, a relative humidity sensor 513, and a pressure sensor 514, determining whether the automatic pressure decay integrity test passes by the processor 503 from the readings may include the processor 503 using the corresponding readings of the relative humidity sensor 513 and the pressure sensor 514 to compensate for the effects of relative humidity and pressure on the corresponding readings of the carbon dioxide sensor 511 and the oxygen sensor 512, as explained above.

[0043] refer to Figure 6 This illustrates an exemplary execution of the automated pressure decay integrity test described above, as part of the overall test scheme. Figure 6 As shown, the rear curtain seal for the container is installed (box 601), and a pre-trip check of the container is run (box 602). An automatic pressure decay integrity test is performed after the pre-trip check and includes starting the compressor (box 603), measuring the change in container pressure over time (box 604), and performing a pass-fail determination after a period of time (box 605). From Figure 6It can be seen that the automatic pressure decay integrity test can (but is not required) be marked at the end of the pre-trip inspection. Furthermore, it should be understood that the automatic pressure decay integrity test may or may not be a criterion for passing the pre-trip inspection (i.e., it can be a reference data point to record container leakage in case any problems occur during the controlled atmosphere cargo journey). According to embodiments, the pre-trip inspection may include at least one or more of the following: checking for structural damage to the container and / or cleaning debris from the T-bars; ensuring the floor drain is sealed; ensuring the drain hose in the evaporator section is undamaged and / or full of water; ensuring the manual fresh air panel is equipped with a collar and the label is in place; tightening the access panel bolts; loading the latest container software, etc.

[0044] In some cases, creating the correct, product-specific conditions within the container to achieve optimal cargo handling and leak-proof sealing results in fresh products, which depends on both oxygen and carbon dioxide partial pressures. In these or other cases, it may be desirable to select transported goods with pre-set standard gas conditions, so that the passing of automatic pressure decay integrity tests depends on gas conditioning. Therefore, according to embodiments, and as... Figure 6 As shown in the figure, the prerequisite for passing the automatic pressure decay integrity test is that the gas conditions inside the container are met (box 610).

[0045] The technical effects and benefits of this disclosure are to provide a method for automatically performing controlled atmosphere pressure decay integrity testing of refrigerated containers. This method reduces the burden on technicians to ensure that the pressure decay of the container body meets specifications, speeds up the integrity testing process, improves the repeatability of the integrity testing, provides all downloadable data that can be easily verified, supports stakeholders in legally confirming that the customer has ensured the integrity of the container body before loading, can be performed on the container after loading, and can be used as a runtime diagnostic for container integrity.

[0046] The corresponding structures, materials, actions, and equivalents of all devices or steps plus functional elements in the claims are intended to include any structure, material, or action for performing the function in conjunction with other claimed elements as specifically claimed. The description presented in this disclosure is for illustrative and descriptive purposes and is not intended to be exhaustive or limited to the technical concepts of the disclosed forms. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of this disclosure. These embodiments were chosen and described in order to best explain the principles and practical application of this disclosure and to enable others skilled in the art to understand the various embodiments of this disclosure with various modifications as suited to the particular purpose contemplated.

[0047] While preferred embodiments of this disclosure have been described, it will be understood that various modifications and enhancements falling within the scope of the appended claims can be made now and in the future by those skilled in the art. These claims should be understood as providing appropriate protection for the foregoing disclosure.

Claims

1. A method for automatically performing a pressure decay integrity test on a container configured to be refrigerated by a transport refrigeration unit (TRU), the method comprising: A controller programmed with the container’s automatic pressure decay integrity test is connected to the compressor of the TRU and the pressure transducer installed in the container. as well as The automatic pressure decay integrity test is performed by the controller, the execution including: The compressor is started to pressurize the container; Receive the readings from the pressure transducer; and The readings are used to determine whether the automatic pressure decay integrity test has passed.

2. The method of claim 1, further comprising recording an indication of whether the automatic pressure decay integrity test has passed and the reading.

3. The method according to claim 1 or 2, wherein, The execution also includes stopping the operation of the TRU.

4. The method according to any one of claims 1 to 3, wherein, The execution is completed after the pre-trip inspection of the container.

5. The method according to any one of claims 1 to 3, wherein, The execution can be completed both before and after loading the container.

6. The method according to any one of claims 1 to 5, wherein, The pressure transducer is installed at the center of the TRU.

7. The method according to any one of claims 1 to 6, wherein, The prerequisite for passing the automatic pressure decay integrity test is that the gas conditions inside the container are met.

8. The method according to any one of claims 1 to 7, wherein: The pressure transducer includes a digital hybrid sensor package. The digital hybrid sensor package includes a carbon dioxide sensor, an oxygen sensor, a relative humidity sensor, and a pressure sensor, as well as Determining whether the automatic pressure decay integrity test passes based on the readings includes using the corresponding readings from the relative humidity sensor and the pressure sensor to compensate for the effects of relative humidity and pressure on the corresponding readings from the carbon dioxide sensor and the oxygen sensor.

9. A method for automatically performing a pressure decay integrity test on a container configured to be refrigerated by a transport refrigeration unit (TRU), the method comprising: Generate an automatic pressure decay integrity test for the container; The controller programmed with the automatic pressure decay integrity test is configured to communicate with the compressor of the TRU and the pressure transducer installed in the container. as well as The automatic pressure decay integrity test is performed by the controller, the execution including: The compressor is started to pressurize the container; Receive the readings from the pressure transducer; and The readings are used to determine whether the automatic pressure decay integrity test has passed.

10. The method of claim 9, further comprising recording an indication of whether the automatic pressure decay integrity test has passed and the reading.

11. The method according to claim 9 or 10, wherein, The execution also includes stopping the operation of the TRU.

12. The method according to any one of claims 9 to 11, wherein, The execution is completed after the pre-trip inspection of the container.

13. The method according to any one of claims 9 to 11, wherein, The execution can be completed both before and after loading the container.

14. The method according to any one of claims 9 to 13, wherein, The pressure transducer is installed at the center of the TRU.

15. The method according to any one of claims 9 to 14, wherein, The prerequisite for passing the automatic pressure decay integrity test is that the gas conditions inside the container are met.

16. The method according to any one of claims 9 to 15, wherein: The pressure transducer includes a digital hybrid sensor package. The digital hybrid sensor package includes a carbon dioxide sensor, an oxygen sensor, a relative humidity sensor, and a pressure sensor, as well as Determining whether the automatic pressure decay integrity test passes based on the readings includes using the corresponding readings from the relative humidity sensor and the pressure sensor to compensate for the effects of relative humidity and pressure on the corresponding readings from the carbon dioxide sensor and the oxygen sensor.

17. A container system, comprising: A container configured for refrigeration via a transport refrigeration unit (TRU), the TRU including a compressor; Pressure transducer installed in the container; as well as The controller is programmed with an automatic pressure decay integrity test for the container and is configured to communicate signals with the compressor and the pressure transducer. The controller is configured to perform the automatic pressure decay integrity test by: The compressor is started to pressurize the container; Receive the readings from the pressure transducer; and The readings are used to determine whether the automatic pressure decay integrity test has passed.

18. The container system according to claim 17, wherein, The controller is also configured to record indications of whether the automatic pressure decay integrity test has passed, as well as the readings.

19. The container system according to claim 17 or 18, wherein, The pressure transducer is installed at the center of the TRU.

20. The container system according to any one of claims 17 to 19, wherein: The pressure transducer includes a digital hybrid sensor package. The digital hybrid sensor package includes a carbon dioxide sensor, an oxygen sensor, a relative humidity sensor, and a pressure sensor, as well as Determining whether the automatic pressure decay integrity test passes based on the readings includes using the corresponding readings from the relative humidity sensor and the pressure sensor to compensate for the effects of relative humidity and pressure on the corresponding readings from the carbon dioxide sensor and the oxygen sensor.

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