Yuanyin Cola Machine – Standard Operating Procedure for Air Circuit System Leak Detection
This procedure is a mandatory safety operation specification for Yuanyin commercial cola machines. The equipment must be powered off throughout the entire operation. Core detection logic: First, perform a static pressure-holding test. If the test passes, the safety verification is complete. If the pressure-holding test fails, perform foam leak detection to locate the leak point and take corrective action.

I. Core Safety Red Lines
Mandatory Power-Off Throughout: The equipment must remain powered off during the entire detection process (including pressure-holding, leak detection, leak point repair, and re-inspection). Power may only be restored after all steps have been completed successfully.

Keep away from open flames, heat sources, and flammable/explosive materials throughout the operation. Ensure good ventilation in the operating environment.

Do not forcibly turn the cylinder valve or line connections under pressure. Do not disassemble any air circuit component while it is under pressure. The high-pressure gas in the system must be completely released before disassembly.

Do not use open flames or lighters to check for leaks. Only the soapy foam method may be used for accurate leak detection.

II. Pre-operation Preparation
Tightening Tools: Fixed wrench / adjustable wrench, pliers

Leak Detection Materials: Food-grade dish soap, clean room-temperature water, spray bottle / soft brush

Auxiliary Tools: Clean absorbent cloth

III. Operating Steps
Step 1: Static Pressure-Holding Test (Mandatory First Step – If Passed, Detection is Complete)
Sealing Confirmation: Close all equipment air branch valves, confirming that the air circuit forms a fully enclosed cavity.

Pressurization and Stabilization: Slowly open the main cylinder valve. Observe the high-pressure gauge until it reaches the equipment’s rated working pressure, then close the valve. Let it sit for 30 seconds to confirm no sudden pressure drop.

Pressure-Holding Observation: Maintain pressure observation for no less than 10 minutes. Do not touch the valves or connections during this period. Keep the equipment powered off.

Result Judgment:

✅ Pass: If the high-pressure gauge shows no significant pressure drop during the pressure-holding period, the air circuit sealing is determined to be acceptable. No further action is required; the detection is complete.

❌ Fail: If the pressure continues to drop during the pressure-holding period, a leak is determined to exist. Proceed to Step 2 for foam leak detection.

Step 2: Precise Foam Leak Detection (Only performed when pressure-holding test fails)
Foam Solution Preparation: Mix food-grade dish soap with clean room-temperature water in a ratio of 1:5 to 1:8. Stir until a rich, persistent foam is produced. Place it in a spray bottle for use.

Pre-detection Requirements: Slowly open the main cylinder valve and adjust the pressure regulator to stabilize the system working pressure at 80–100 psi. Keep the cylinder open and the pressure stable within the specified range throughout the foam testing process. Then perform point-by-point leak detection.

Point-by-Point Leak Detection Specification: Strictly follow the order of “gas source end → equipment end” for each point. Do not miss any of the specified points.

Detection Point Operation and Judgment Standard Corrective Action
Cylinder valve connection point Apply foam evenly; let sit for 10–15 seconds. Continuous bubbling indicates a leak. Use a wrench to tighten the connection clockwise steadily until bubbling stops.
High-pressure gauge and air hose connection Apply foam thoroughly; let sit for 10–15 seconds. Bubbling indicates a leak. Depressurize first, then disassemble the connection. Check and reposition/replace the sealing gasket. Tighten with a wrench until no bubbling.
Air hose and equipment clamp connection Apply foam completely; let sit for 10–15 seconds. Bubbling indicates a leak. Use pliers to clamp the two ears of the clamp to increase clamping force. Do not clamp the hose body itself. Continue until no bubbling.
Right-side air hose connection point on the cola machine top cover Apply foam evenly; let sit for 10–15 seconds. Bubbling indicates a leak. Use a wrench/pliers to tighten the connection nut, reinforcing the joint until no bubbling.
Water level probe connection Apply foam evenly; let sit for 10–15 seconds. Bubbling indicates a leak. Use a wrench/pliers to tighten or clamp the connection until no bubbling.
Two ports of the pressure relief valve Apply foam evenly; let sit for 10–15 seconds. Continuous bubbling at rated pressure indicates a leak. Use pliers to tighten the valve body fixing structure. Do not block the pressure relief valve ports, as this creates an overpressure risk.
Step 3: Re-inspection After Leak Point Repair
After completing corrective actions for all leak points, apply foam again to the repaired points. Let sit for 10–15 seconds and confirm that there is no continuous bubbling.

Repeat the entire static pressure-holding test from Step 1. The pressure-holding duration must be no less than 10 minutes. No continuous pressure drop constitutes a pass.

If the re-inspection still fails, repeat the leak detection and repair cycle. If the leak cannot be resolved after three consecutive repair attempts, immediately close the main cylinder valve and contact Yuanyin official after-sales service for repair.

IV. Mandatory Detection Trigger Conditions
Whenever any of the following situations occur, this entire procedure must be performed. The equipment may only be started and operated after passing the test:

After each replacement of the gas cylinder.

After the equipment has been relocated or reinstalled.