The suction power of flues is crucial. It not only affects building safety but also directly impacts people's lives. Therefore, considerable attention must be paid to the design and installation of flues. This requires not only advanced technology but also the expertise and commitment of construction personnel.

Generally speaking, ventilation ducts and flues are both indispensable parts of a building. Although they have different divisions of labor, they both carry important missions. Ventilation ducts require precise positioning and node connections, while flues need to maintain strong suction. Only in this way can we jointly create a safe and comfortable living environment. In front of the mysterious cave door, three heroes, Xiao Yi, Li Mei, and Fan Zun, are gathered here. They are determined to protect the safety of the residents in the cave and are preparing to install heavy explosion-proof airtight doors on the outermost layer of the cave. This door is like an indestructible steel fortress, heavy and solid enough to withstand any external invasion. Its existence is like a guardian angel, silently guarding everything in the cave.

"Li Mei, you will guide us to the precise location. Fan Zun, you will ensure the stability of the door." Xiao Yi gave the order decisively. The three of them worked in perfect harmony, like dancers on the battlefield, graceful and courageous.

Li Mei expertly measured the position, his eyes as sharp as a torch, seemingly able to see through the solid stone wall. Fan Zun followed closely behind, pounding the ground vigorously to ensure it was level and ready for the blast-proof door's installation.

With their joint efforts, the heavy explosion-proof airtight door began to slowly rise. It was like a natural moat, stretching across the entrance of the cave, building a solid barrier for the residents inside.

At this moment, they seemed to have become the guardians of the cave, using their wisdom and strength to write a legendary story. Their actions were not only to prevent the invasion of foreign enemies, but also to respect life and pursue safety.

When the blast-proof door was finally firmly installed in its designated location, the residents of the cave were deeply moved. They felt proud to have these three heroes guarding their home.

Xiao Yi, Li Mei, and Fan Zun knew this was only the beginning of their mission. They would continue to shoulder the heavy responsibility of protecting their home until the very end. The choice of drilling holes and the location of the gravity points on the rock face became crucial. This not only affected the success of the entire project but also directly impacted the lives of those involved. Faced with this heavy responsibility, these brave explorers remained steadfast, rising to the challenge and determined to overcome it.

After much trial and error, they discovered that choosing the right location was crucial. This required not only precise measurements and calculations, but also extensive experience and intuition. They tirelessly experimented, compared, and even learned from their failures.

Over time, they gradually mastered the art of the process. Each attempt presented a new challenge, and each success was inseparable from the team's hard work and wisdom. After several setbacks, they finally determined the optimal position.

At this point, drilling holes in the rock face and choosing the right position for the weights were no longer difficult problems. They had demonstrated with their actions the power of human wisdom and courage. This experience, in turn, became a precious treasure in their lives, inspiring them to continue exploring the unknown and pushing their limits. In the deep night, a pitch-black airtight door seamlessly merged with the mountain, like a mysterious door, guarding unknown secrets. Its presence instilled a strong sense of security, as if no danger could overcome this solid barrier.

This airtight door, like a silent guardian, stood silently at the foot of the mountain. Its surface was as smooth as a mirror, reflecting the surrounding environment, like a giant mirror, absorbing all the surrounding rocks and trees.

At night, the door becomes even more mysterious. Moonlight casts a faint silver sheen on its pitch-black surface, lending it an otherworldly allure. From afar, it blends seamlessly with the night sky, evoking a sense of wonder and awe, like a portal to the underworld.

Yet, this seemingly mysterious airtight door is also a vital line of defense for our homes. It's not just a sturdy barrier, but also a source of spiritual comfort. Under its protection, people can sleep peacefully, free from worries.

This pitch-black airtight door, though seemingly ordinary, holds profound meaning. It has witnessed people's joys and sorrows, carrying countless stories and memories. It is not only a symbol of protecting our homeland, but also a testament to human wisdom and courage. The moment the airtight door slowly closes, it feels as if an invisible barrier separates us from the outside world. The once fresh air seems to freeze in an instant, the cold and clamor of the outside world firmly shut out.

At this moment, in this quiet space, only the sound of our breathing, soft and even, intertwined, like a harmonious symphony, echoing in every corner of the cave.

The closing of the airlock door not only brings tranquility to the outside world, but also gives us inner peace. Protected by this indestructible barrier, we feel an unprecedented sense of security, as if the whole world is being gently embraced.

We can't help but feel that this airtight door is like a loving mother, shielding us from the ups and downs of the outside world with her broad heart. And under this shelter, we have found inner peace and strength.

In this quiet cave, we learned to listen to our inner voices and feel each other's presence. The closed airtight door not only blocked out the clamor of the outside world but also taught us the power of silence. In this tranquil space, we grew and progressed together. Amidst this tense yet orderly atmosphere, Yu Wei was not idle. He worked alongside Si Feifei, hardening the building materials that Shen Wei had transformed with his supernatural powers.

These materials, transformed by Shen Wei's magical powers, seem to have surpassed the scope of conventional building materials in the eyes of ordinary people. They seem to have life, full of mystery and vitality.

Yu Wei and Si Feifei's mission is to harden these materials to make them stronger and more durable. This process requires extremely high skills and experience. The slightest mistake can lead to damage to the materials or the dissipation of their special powers.

As time passed, the quenching process gradually entered a critical stage. Yu Wei and Si Feifei concentrated on controlling the temperature, beads of sweat on their foreheads. With their combined efforts, the building materials seemed to be given new life, emitting a dazzling light.

After hours of painstaking work, the hardening process was finally completed. The building materials had become stronger, more durable, and possessed a powerful energy source. At this moment, smiles of satisfaction appeared on the faces of Yu Wei and Si Feifei. They knew that these transformed building materials would become a vital force in protecting their homes.

After installing the first airtight door, Shen Wei and Cheng Mao demonstrated excellent teamwork, not only magically transforming the building materials, but also efficiently completing the installation of the flue and ventilation ducts in the bedroom and living room where everyone was temporarily staying.