The roles of safety accessories for liquefied gas transport vehicle

The safety accessories of the tank body of the liquefied gas transport vehicle mainly include safety valves, emergency shut-off valves, ball valves, pressure gauges, thermometers, and liquid level gauges, which form a mobile pressure vessel with the tank body and the walking part. Operators should have a full understanding of the role of these accessories and standardized operations in order to complete the transportation task safely and effectively.

1. Safety valve

Function: Protect the tank body to work normally within the designed working pressure range. Working principle: When the pressure inside the tank increases or exceeds the designed working pressure of the tank due to some reasons (overloading, exposure, etc.), the safety valve opens automatically to remove the pressure in the tank. When the pressure in the tank drops to When in the safe range, the safety valve closes by itself. LPG safety valve opening and closing data (propane medium): opening pressure: 1.73MPa; discharge pressure: 1.93MPa. Emergency measures: when the safety valve takes off, drive the car to a safe zone and spray water on the top of the tank to reduce temperature and pressure. Note: The safety valve is equipped with a lead seal after leaving the factory or after being tested by the testing department, and it is not allowed to be disassembled and adjusted at will.

2. Emergency shut-off valve

The vehicle is equipped with two emergency shut-off valves in gas phase and liquid phase. Function: 1. When there is an emergency (fire, other reasons) and the gas path needs to be cut off instantaneously, the valve box button or the remote control handle at the rear of the car can be used to cut off the gas path instantly; 2. When the vehicle is on fire and people cannot approach the vehicle, be tight The low-temperature alloy pin on the cutting valve melts by itself when the temperature reaches 75±5 degrees, and the emergency shut-off valve automatically closes and cuts off the gas source; 3. The flow limitation function for loading and unloading prevents excessive flow and static sparks caused by fluid friction on the pipe wall. Burn and explode. The remote control handle at the rear of the car should be tested regularly to check whether the action is effective. After the low-temperature alloy pin is damaged, it shall not be replaced by other materials. Operation sequence: Whether loading or unloading, the opening or closing of the tight cut valve is before the opening or closing of the ball valve.

3. Ball valve

The car is equipped with two kinds of ball valves, gas phase and liquid phase. Function: Connecting with external equipment through the quick connector on the valve for loading and unloading gas. The valve body is equipped with a relief valve. When the loading and unloading hose needs to be removed after the loading and unloading is completed, first open the relief valve to remove the pressure in the pipe and then remove the loading and unloading hose. When removing the blocking cap of the quick-release joint or removing the loading and unloading hose, you must first open the relief valve to remove the residual pressure to prevent the compressed gas from hurting people.

4. Pressure gauge stop valve

The pressure gauge shut-off valve is installed at the bottom of the tank and communicates with the pressure gauge.

Common faults of the pressure gauge shut-off valve: The pressure gauge shut-off valve is installed at the bottom of the tank and communicates with the pressure gauge.

5. Pressure gauge

The pressure gauge is installed in the valve operating box. Function: Display the pressure in the tank. When the pressure in the tank is to be displayed, open the small valve between the pressure gauge and the gas-phase pipeline, and the pointer indicates the pressure in the tank. When not in use, remove the gas in the pipe and close the small valve. When the pointer of the pressure gauge exceeds the red line of the dial, the cause should be found out in time and the temperature and pressure should be reduced by spraying water. The pressure gauge is equipped with a lead seal after it is delivered or tested by the testing department, and it is not allowed to be disassembled and adjusted at will.

7. Thermometer

The thermometer is installed in the valve operating box. Function: Display the temperature in the tank. It changes automatically with the temperature in the tank. No human operation is required. There is a red line area on the thermometer. If the pointer exceeds the red line area, measures should be taken to cool down to prevent the temperature from being too high and causing the pressure in the tank to rise.

6. Level gauge

The level gauge is installed in the center of the rear head of the tank or the middle of the left side of the cylinder. Function: Display the height of the liquid level in the tank.

(1) When the rotary liquid level meter wants to display the liquid level, loosen the middle bleed nut and turn the handle. When liquid appears on the bleed nut, the reading pointed by the pointer is the liquid level. Note: Do not use excessive force when tightening the bleed nut to prevent the rubber pad from being crushed and tighten the lock nut. Replace the rubber pad in time after it is crushed.

(2) The float level gauge can directly observe the height of the liquid level without other operations.