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Gas Station Vapor Recovery System Installation Guide: NP Pump Working Principle

News 2026年 8月 3日 28

With stricter environmental regulations and increasing safety requirements in the fuel retail industry, gasoline recovery systems have become an essential part of modern gas stations.

During the refueling process, gasoline is generated when fuel enters the vehicle tank. Without an effective gasoline recovery system, these volatile organic compounds (VOCs) can escape into the atmosphere, causing fuel loss, environmental pollution, and potential safety hazards.

A complete gasoline recovery system consists of multiple components, including:

1. Gasoline recovery nozzles
2. Gasoline return pipelines
3. NP gasoline recovery pump
4. Electronic control valve
5. Pressure sensors
6. Control system
7. Monitoring system

These components work together to efficiently collect and control gasoline generated during refueling.

Among all components, the NP gasoline recovery pump is one of the most important core parts of the system.

It provides the suction power required for gasoline recovery, controls gasoline circulation, and helps maintain the correct air-to-liquid ratio during the refueling process.

This article explains:

1. How a gas station gasoline recovery system works
2. The function and working principle of the NP gasoline recovery pump
3. NP pump installation procedures
4. Electrical connection and commissioning requirements
5. Important technical parameters and installation precautions

1. How Does a Gas Station Gasoline Recovery System Work?

The main purpose of a gasoline gasoline recovery system is to collect gasoline generated during vehicle refueling and safely return it through the gasoline recovery pipeline.

The basic working process is:

Vehicle Fuel Tank
↓
Gasoline Recovery Nozzle
↓
Gasoline Return Pipeline
↓
NP gasoline Recovery Pump
↓
Electronic Control System
↓
Gasoline Recovery Tank / Treatment System

During refueling:

Gasoline continuously flows into the vehicle fuel tank, while the displaced gasoline is collected through the gasoline recovery hose and returned to the recovery system.

The NP pump creates negative pressure inside the gasoline recovery pipeline, allowing gasoline to be efficiently drawn back into the recovery system.

The system automatically adjusts the gasoline recovery volume according to the actual fuel dispensing amount, ensuring stable and efficient operation.

2. The Function of NP Gasoline Recovery Pump

Why Is the NP Pump Important?

The NP gasoline recovery pump is the power source of the entire gasoline recovery system.

Its main functions include:

1. Creating Negative Pressure

During operation, the NP pump generates suction force and creates a negative pressure environment inside the gasoline recovery pipeline.

This negative pressure drives gasoline back into the recovery system.

2. Controlling Gasoline Recovery Flow

The NP pump works together with:

1. Electronic regulating valve
2. Main control board

to automatically adjust gasoline recovery volume according to the amount of fuel being dispensed.

This ensures that the recovered gasoline volume matches the fuel delivery volume.

3. Maintaining a Stable Gas-Liquid Ratio

A correct gas-liquid ratio is critical for efficient gasoline recovery performance.

The required gas-liquid ratio range is:

0.9～1.3

If the gas-liquid ratio is too low:

Possible results:

1. Reduced gasoline recovery efficiency
2. Incomplete collection of gasoline

If the gas-liquid ratio is too high:

Possible results:

1. Excessive gasoline recovery volume
2. Reduced system stability

Therefore, proper NP pump adjustment and system commissioning are essential.

3. NP Gasoline Recovery Pump Installation Procedure

Before installing or replacing an NP pump:

The fuel dispenser must be completely powered off, and the gasoline recovery system must be safely isolated.

Step 1: Turn Off Power Supply and Close Gasoline Recovery Valve

Before maintenance:

The following steps must be completed:

1. Turn off the power supply of the fuel dispenser
2. Close the gasoline recovery pipeline valve
3. Confirm that the system is in a safe condition

This prevents accidental equipment operation and ensures technician safety.

Step 2: Remove the Existing NP Pump

The removal procedure includes:

1. Disconnect the NP pump power cable
2. Disconnect the signal cable
3. Remove the NP pump inlet and outlet copper pipes
4. Loosen the NP pump mounting screws
5. Remove the old NP pump from inside the fuel dispenser

During removal:

Avoid damaging:

1. Copper pipes
2. Electrical terminals
3. Sealing components

Any damage to these parts may affect system performance after reinstallation.

Step 3: Install the New NP Gasoline Recovery Pump

After removing the old pump:

Install the new NP pump according to the following steps:

1. Install the new NP pump in the original mounting position.
2. Secure and tighten the mounting screws.
3. Connect the power cable according to the original wiring method.
4. Connect the signal control cable.
5. Reconnect the NP pump inlet and outlet copper pipes.

After installation, carefully check:

1. Whether the NP pump installation direction is correct
2. Whether the pipeline connection position is correct
3. Whether all electrical connections are secure

Incorrect inlet and outlet connection direction may directly affect gasoline recovery performance.

Step 4: NP Pump Commissioning and Testing

After installation is completed:

The following commissioning procedures are required:

1. Open the gasoline recovery pipeline valve.
2. Power on the fuel dispenser.
3. Start the NP pump adjustment program.
4. Check whether the NP pump inlet and outlet direction is correct.
5. Test the system gas-liquid ratio.

The final gas-liquid ratio must remain within:

0.9～1.3

The equipment can only be put into operation after the entire system operates normally.

4. Online Gasoline Recovery System Installation Requirements

A complete gasoline recovery system does not rely only on the NP pump.

The final recovery performance is also affected by:

1. Gasoline recovery pipelines
2. Sensor installation
3. Communication wiring
4. Control system configuration

If any part of the system is installed incorrectly, it may result in:

1. Unstable gasoline recovery performance
2. Abnormal gas-liquid ratio
3. Communication failures
4. Incorrect monitoring data

Therefore, every component must be installed according to the required technical specifications.

Gasoline Flow Detection and Control System Installation

During installation, each fuel dispenser should be equipped with:

1. gasoline flow detection components
2. Electronic regulating valve pipeline
3. Pressure sensor system
4. Control and communication wiring

The control cables and data cables must be correctly connected inside the dispenser junction box.

For systems using communication control:

The:

RS485 communication cable

must be connected to the explosion-proof junction box according to the wiring requirements.

Before powering on and testing the system:

Confirm that:

1. Communication wiring is connected correctly
2. Signal transmission is stable
3. The control board communication is functioning properly

Pressure Sensor Installation Requirements

The pressure sensor is an important detection component in the gasoline recovery system.

Its main function is:

To monitor pressure changes inside the gasoline recovery pipeline and send feedback signals to the control system.

Installation requirements:

1. The pressure sensor must be installed in the designated mounting position
2. Wiring must follow the electrical diagram
3. Signal cables must be connected correctly

The pressure sensor wiring includes:

+24V / AD1

After installation:

The system should be tested to confirm that the sensor can accurately transmit pressure variation data.

A stable pressure signal is essential for precise gasoline recovery control.

5. Multi-Dispenser Gasoline Recovery System Configuration

For gas stations equipped with multiple fuel dispensers:

Each dispenser requires independent configuration and commissioning.

The recommended commissioning method is as follows:

First Fuel Dispenser Setup

Complete the following:

1. Install the NP pump
2. Connect communication cables
3. Configure the QK control board
4. Test gasoline recovery performance

Confirm:

1. All nozzles are online
2. Communication is normal
3. Gas-liquid ratio remains within:

0.9～1.3

Second Fuel Dispenser Configuration

After the first dispenser operates normally:

The second dispenser can be configured according to the parameters of the first unit.

The following items must be checked:

1. QK control board jumper settings
2. Fuel dispenser ID configuration
3. RS485 communication status
4. Individual nozzle testing

Different QK control board models may require different jumper configurations.

For example:

1. QK1000A
2. QK1000B

The jumper settings must follow the corresponding wiring diagram.

Incorrect jumper configuration may cause:

1. Communication errors
2. Control system failure to recognize the equipment

6. Relationship Between NP Pump, Electronic Valve and Control Board

The gasoline recovery system is actually a complete control system.

The gas-liquid ratio is affected by several components working together:

NP Gasoline Recovery Pump

Function:

Provides the power required for gasoline recovery.

Electronic Regulating Valve

Function:

Controls and adjusts gasoline flow.

Gasoline Flow Meter

Function:

Measures the recovered gasoline volume.

QK Control Board

Function:

Processes signals and controls system operation.

It is important to understand:

The QK control board does not directly control fuel dispensing output.

Instead, it works together with:

1. NP pump
2. Electronic regulating valve
3. Gasoline flow detection system

to achieve accurate gasoline recovery control.

7. Electrical Installation Requirements

Electrical installation is a critical part of ensuring safe and reliable operation of the gasoline recovery system.

All electrical work must comply with explosion-proof installation requirements.

Power Supply Requirements

The fuel dispenser power supply should use:

Three-phase four-wire 380V power supply

Each fuel dispenser must be equipped with:

1. Independent control switch
2. Reliable overload protection
3. Correct phase sequence connection

Cable Requirements

Recommended cable type:

RVV oil-resistant insulated cable

User power cable:

5×2.5mm²

Installation requirements:

1. Cable outer diameter must match the explosion-proof junction box sealing connector
2. Sealing gasket must not be removed
3. Metal washer must be installed correctly
4. Compression nut must be tightened to ensure proper sealing performance

Poor sealing may:

Reduce the explosion-proof protection capability of the equipment.

Communication Cable Requirements

For systems with communication functions:

Communication cables are used for:

1. Communication between fuel dispensers
2. Connect to gas station management system
3. Gasoline recovery monitoring systems

Important:

Communication cables must never be connected to:

1. 380V power supply
2. 220V power supply

Incorrect wiring may damage the control system.

The wiring system includes:

1. Three-phase power connection
2. RS485 communication
3. QK board wiring
4. Sensor wiring

8. Installation and Maintenance Safety Requirements

Because gasoline creates a flammable atmosphere, all installation and maintenance work must strictly follow safety procedures.

Proper safety practices are essential to protect personnel, equipment, and the entire gas station operation.

Explosion-Proof Safety Requirements

All electrical installation work must comply with:

Local explosion-proof electrical installation regulations

During maintenance, it is strictly prohibited to:

1. Open explosion-proof electrical boxes while power is connected
2. Modify wiring without proper confirmation
3. Damage sealing components

After wiring is completed, confirm that:

1. Explosion-proof box sealing has been properly restored
2. Cable glands are securely tightened
3. Protective components are correctly installed

Maintaining proper sealing is critical to ensure the explosion-proof performance of the equipment.

Pipeline Cleaning Requirements

Before installation:

The fuel tank and pipelines must be thoroughly cleaned.

Remove:

1. Welding slag
2. Rust particles
3. Dust
4. Metal debris

These contaminants may damage important gasoline recovery components, including:

1. NP gasoline recovery pump
2. Electronic regulating valve
3. Flow meter
4. Gasoline recovery components

Clean pipelines help improve system reliability and extend equipment service life.

System Testing Before Operation

Before the fuel dispenser is officially put into service, the complete system must be inspected and tested.

NP Pump Inspection

Confirm:

1. Rotation direction is correct
2. Pump operation is stable
3. No abnormal noise is present

Pipeline Inspection

Confirm:

1. No leakage exists
2. All sealing points are reliable

Communication Inspection

Confirm:

1. RS485 communication is working properly
2. Sensor data transmission is normal

Gasoline Recovery Performance Test

Check the gas-liquid ratio:

0.9～1.3

Only after all inspection items pass successfully can the gasoline recovery system be placed into normal operation.

Conclusion

A gas station gasoline recovery system is a combination of mechanical, pneumatic, and electronic technologies designed to reduce fuel gasoline emissions and improve operational safety. As the core component of the system, the NP gasoline recovery pump provides the necessary suction power to maintain stable gasoline circulation and ensure proper gas-liquid ratio control.

Correct installation, accurate adjustment, and reliable system integration are essential for achieving efficient gasoline recovery performance, reducing fuel loss, meeting environmental requirements, and ensuring long-term stable operation of modern gas stations.