Precautions for Heptafluoropropane Gas Filling and Cylinder Testing

　　As a gaseous fire suppression system, heptafluoropropane boasts advantages such as high efficiency, cleanliness, and zero corrosion. It is widely used across various facilities—installed in factories, distribution rooms, computer centers, server rooms, and even large-scale, precision equipment hubs. Of course, when it comes to deploying heptafluoropropane, as the saying goes: "It takes years of preparation to have troops ready for battle." Most of the time, heptafluoropropane remains on standby. Yet, what we need to check daily are whether the cylinder valves show any signs of leakage or deformation, and if the internal pressure remains within the normal range. Should any issues arise, the cylinders must be promptly sent to a professional manufacturer for thorough inspection and refilling. And today, our discussion will revolve precisely around this critical process of inspection and refilling.

　　Each reputable and professional manufacturer must undergo relevant qualification certification before supporting cylinder testing and gas cylinder filling permits, and must also hold the necessary licenses for cylinder inspection and gas filling operations before conducting these activities.

　　When transporting heptafluoropropane cylinders, we must handle them with care—lifting and placing them gently to avoid any bumps or impacts that could damage the cylinders themselves. Afterward, thoroughly inspect and record the received cylinders, properly manage the gas inside, remove the shock-absorbing ring from the cylinder valve, and then begin a comprehensive examination of the cylinder body. This inspection should include checking the exterior, listening for unusual sounds, examining the bottle mouth threads, and even conducting an internal assessment of the cylinder. Additionally, verify the condition of the valve at the bottle opening. If the cylinder fails inspection, it must be classified as scrap and disposed of accordingly. If it passes, proceed with a leak-tightness test on the cylinder valve, followed by the installation of a new valve. Ensure the interior remains completely dry before retesting the cylinder with both water pressure and air tightness checks. Finally, affix the appropriate color-coded steel stamp and issue the inspection report. Only cylinders that meet all criteria can be safely stored and issued for use.

　　Things to keep in mind when we are filling the heptafluoropropane gas:

　　1. Inspect the gas cylinder to ensure its steel stamp is within the valid usage range. Then, invert the cylinder and insert an air hose through the cylinder opening down to the bottom. Finally, purge the cylinder with nitrogen gas at a pressure of 0.4–0.5 MPa for 2 minutes.

　　2. First, attach the siphon tube to the bottle valve. Then, install the bottle valve onto the gas cylinder as required and securely tighten it (if the bottle valve comes with a protective sleeve, first mount the sleeve holder). Next, connect the filling adapter according to the specifications of the bottle valve, and use a nitrogen manifold to pressurize the cylinder to 2.5–3.0 MPa. Finally, perform a leak test by applying leak detection fluid to the bottle neck and all interfaces of the cylinder valve.

　　3. After confirming the leak test is normal, release the nitrogen gas from the cylinder and move it to the filling area for charging. Before starting the filling process, use calibrated weights to verify and adjust the electronic scale, ensuring it remains within the specified accuracy range. If any abnormalities are detected, troubleshoot the issue before using the scale for weighing during filling. Prior to placing the cylinder onto the electronic scale, first seal the cylinder’s nozzle with a plug. Once properly prepared, carefully position the cylinder on the scale for weighing and record the results accurately.

　　4. Weigh the raw material drums and measure the pressure (if the pressure is insufficient, use nitrogen to top up before re-weighing). Record the weight of the newly issued raw material drums as well as the weight of the nitrogen used for pressurizing. Properly connect the filling system for operation. Attach the filling adapter according to the specifications of the cylinder valve, then reset the electronic scale to zero. Set the alarm value on the electronic scale based on the required filling weight of HFC-227ea as specified in the sales and production schedule instruction sheet. When the set value is reached, the electronic scale will sound an alarm, alerting operators to monitor the process closely. Once the specified weight is achieved, immediately stop the filling process and record the final weight.

　　5. Remove the filling connector, move the cylinder onto the dedicated electronic scale for re-weighing, and record the results carefully. Reattach the nitrogen refill valve, adjust the pressure as required, then close the nitrogen filling valve and document the temperature, pressure, and weight. After refilling with nitrogen, roll the cylinder; after 20 minutes, check whether the pressure has dropped. Based on the temperature-pressure reference table, top up the pressure to the specified value.

　　6. Move the gas cylinder to the side of the pool, then lower it into the pool for leak testing. Once the cylinder is lifted out of the pool, use an air gun to blow out any accumulated water from each valve connection. Finally, measure the temperature and pressure, and keep a detailed record.

　　7. If the above procedures meet the requirements specified in the Sales Production Schedule Guide, such as insufficient weight or pressure, proceed with appropriate liquid or pressure replenishment.