Operation and maintenance of LNG nozzle

The LNG nozzle is important filling equipment for the LNG filling station. It is responsible for safely filling the LNG liquid into the LNG vehicle bottle. Proper operation and maintenance of the LNG nozzle are important. The LNG nozzle is connected to the LNG filling machine through a hose, which is convenient and different from the surrounding of the filling machine. Location vehicle to connect.

When using the LNG nozzle, the operator needs to wear protective clothing, protective masks, and protective equipment correctly. Improper operation and use will cause serious injury to personnel.

LNG filling station

1. Operation steps:

When adding liquid to the LNG truck, the operator aligns the dosing gun with the dosing gun seat on the LNG car and pulls the dosing gun handle back to open the dosing gun claw (Figure 1).

After inserting it into the gun seat, push the handle forward to rotate and close,

and the dosing gun is firmly fixed, and then the dosing gun starts to fill (Figure 2).

After the filling is completed, the operator gently pulls the handle back to open the jaws, pulls out the LNG nozzle,

and separates the LNG nozzle from the nozzle seat, and the operation process is completed.

Note: Both the dosing gun and the dosing gun seat are equipped with independent shut-off valves. When the two are separated, the built-in valve will automatically close,

which can prevent LNG from flowing out of the nozzle or the nozzle seat.

Figure 1

LNG nozzle Exterior

Figure 2

LNG gun show

2. Solutions to the problems encountered when adding liquid:

After the nozzle has been used for a period of time, there may be leakage during dosing,

difficulty in inserting and pulling the nozzle, and dripping after the nozzle is pulled out. The nozzle needs to be inspected and repaired.

S/N fault phenomenon possible reason Take measures Remark
When the nozzle is adding liquid, the top of the dosing gun has liquid leakage, dripping, etc.
Worn LNG nozzle seal It is recommended to replace the sealing ring See below for the sealing ring replacement procedure
After the last addition of liquid, the water vapor condenses on the sealing position of the nozzle head,

and it is not blown clean when the liquid is added next time, and it will freeze and leak when it is cold;

Before adding liquid, be sure to purge the tip of the LNG nozzle with dry and clean nitrogen.
The impurities in the gun seat are not cleaned up:

the gas cylinder is often exposed to the wind and the sun on the road, and the dust and water vapor in the nozzle seat adheres.

If it is not wiped and cleaned, it is easy to cause leakage of the seal and damage the sealing ring.

Please carefully check whether there are any impurities and moisture on each nozzle seat before adding liquid,

and please wipe it with a soft non-cotton fabric;

The barrel of the LNG nozzle is seriously worn,

or the size of the nozzle seat deviates so that the dosing gun cannot be horizontally sealed on the nozzle seat

You can find a suitable position for adding liquid by adjusting the position of the dosing gun by rotating it. If it still does not work, it is recommended to replace and repair the LNG nozzle.
After the liquid addition is completed and the nozzle is drawn,
there is still liquid leakage in the liquid addition nozzle
Worn gasket on disc assembly Replace valve disc assembly See below for valve disc assembly replacement steps
The residual water vapor and impurities after adding liquid are not cleaned up, and the water vapor and impurities are stuck in the inner sealing gasket during the next liquid addition process, causing scratches and poor sealing Before adding liquid, be sure to purge the tip of the dosing gun with dry and clean nitrogen. LNG nozzle part
The disc assembly and the filling pipe do not slide smoothly:


This problem is caused by the friction between the filling tube and the valve disc or the size mismatch caused by the wear of the guide ring in the valve disc assembly.

Please pay attention to whether the valve disc assembly is matched and whether the inner pipe wall is smooth. If the wear is serious, it can only be replaced
The LNG nozzle is difficult to push or pull out
The distance between the tie rods of the LNG nozzle changes, and the unreasonable tie rod spacing will result in laborious pushing, and there will also be premature decoupling when pulling out. Please adjust according to the following “Adjustment steps of dosing gun draw rod” to ensure that the distance between the fixing block and the spring gland meets the requirements
Serious wear on the LNG nozzle jaws This problem will cause the LNG nozzle to decouple when it is pushed and pulled out. Please contact the manufacturer to repair the LNG nozzle in time. LNG nozzle jaws
The shaft sleeve of the handle of the LNG nozzle is worn. The wear of the shaft sleeve will cause the stroke of the filling tube to decrease and the handle to move loosely, which may cause the valve disc assembly and the internal valve of the filling seat to fail to open normally. If there is often no flow of liquid after the nozzle is inserted, please contact the manufacturer to repair the liquid nozzle


1. Steps for replacing the sealing ring:

①. Push down the handle of the air-filling gun (as shown in P1), so that the filling pipe is at the orifice position,

remove the spring retaining ring 1 for the shaft with the circlip pliers,

and take out the sealing ring gland 2 and the yellow sealing ring 3 in turn;

②. Purge the replacement parts and various parts with dry and clean nitrogen;

③. Put in the yellow sealing ring (the opening direction is outward), and the sealing ring gland (the chamfered end is outward),

and install the spring retaining ring for the shaft into the groove with the circlip pliers.

LNG nozzle replacing the sealing ring

2. Valve disc assembly replacement steps:

①After disassembling the metal hose of the air gun, use a wrench to disassemble joint 1 and take out gasket 2;

②Use circlip pliers to take out the elastic retaining ring 3 for the hole (hold the pin shaft of the push tube with your hand when taking it out,

to prevent the push tube from popping out quickly when the circlip is taken out and causing injury);

③Take out the parts in turn (as shown in P3) push tube 4, pressure sleeve 5, spring 6, valve disc assembly 7,

and replace the valve disc assembly (dry and clean nitrogen is used to purge the inside of the filling tube during replacement);

④Put the valve disc assembly 7, spring 6, pressure sleeve 5, and push tube 4 in sequence,

clamp the elastic retaining ring 3 for the hole with the circlip pliers and push the retaining ring into the groove (you can use your hand when installing the retaining ring). hold the pin in the push tube);

⑤Put in gasket 2, and tighten joint 1.

LNG nozzle valve disc assembly

3. Adjustment steps of air gun lever:

①Open the air gun as shown in the figure below, and the two handles are in a relaxed state;

②Unscrew nut 1, clockwise and downward, and then loosen it;

③The tie rod can be clamped with a vise, rotated left and right, and the distance M between the lower plane of the fixed block and the spring gland can be adjusted symmetrically on both sides, and the factory M value is 152mm;

④After adjustment, turn the lock nut 1 counterclockwise.

LNG nozzle air gun lever


Before and after adding liquid, the LNG nozzle must be carefully handled and purged.

Do not leave the LNG nozzle on the ground without any protection; It gets stuck and sprays liquid;

Please ensure the normal operation and use of the LNG nozzle. The barbaric operation will reduce the service life of the LNG nozzle.

Please use the consumable parts produced by regular companies. unqualified consumable parts will also cause damage to the LNG nozzle.

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