1. Introduction
This manual provides essential information for the safe and efficient installation, operation, and maintenance of your LEFOO LF19 Pressure Switch. Please read this manual thoroughly before using the product and retain it for future reference.
The LEFOO LF19 is a heavy-duty 26 AMP pressure switch designed for air compressor applications, featuring a 140-175 PSI pressure range, a single 1/4" NPT port, and an integrated ON/OFF switch with a 360-degree rotatable unloader mechanism.
2. Safety Information
Always observe the following safety precautions to prevent injury or damage to the product and connected equipment.
- Electrical Hazard: Ensure all power to the air compressor system is disconnected before installation, maintenance, or troubleshooting. Work should only be performed by qualified personnel.
- Pressure Hazard: Depressurize the air compressor system completely before working on the pressure switch or any connected components.
- Compatibility: Verify that the pressure switch specifications (PSI range, AMP rating, voltage) are compatible with your air compressor system.
- Proper Installation: Install the switch according to local electrical codes and manufacturer guidelines. Incorrect installation can lead to malfunction or hazards.
- Unloader Line: Ensure the unloader line is correctly connected and sealed to prevent air leaks and ensure proper compressor operation.
- Adjustments: Pressure settings are adjustable. Exercise caution when making adjustments and always verify the new settings with a reliable pressure gauge. Do not exceed the maximum rated pressure of your air compressor tank.
3. Product Overview
3.1 Key Features
- Heavy-duty construction for extended durability.
- Adjustable pressure settings (factory set 140-175 PSI).
- Integrated ON/OFF button on the front cover for convenient control.
- Single 1/4" Female NPT port for direct connection.
- Unloader mechanism rotates 360 degrees for flexible installation.
- Push-to-connect unloader port for 1/4" copper or nylon tubing.
- High 26 AMP rating for demanding applications.
3.2 Components
The LEFOO LF19 Pressure Switch consists of the following main components:
- Switch Body: Contains the electrical contacts and pressure sensing diaphragm.
- Front Cover: Houses the ON/OFF button and protects internal components.
- ON/OFF Button: Manual control for the compressor motor.
- Pressure Port: 1/4" Female NPT connection for air pressure input.
- Unloader Port: Push-to-connect fitting for 1/4" unloader tubing.
- Electrical Terminals: For connecting power supply and motor wires.
Figure 1: Front view of the LEFOO LF19 Pressure Switch, showing the "LEFOO PRESSURE CONTROL" branding and the red ON/OFF button.
Figure 2: Internal view of the LEFOO LF19 Pressure Switch mechanism (left) and the inside of the protective cover (right). This image illustrates the robust internal components designed for heavy-duty operation.
Figure 3: Bottom view of the LEFOO LF19 Pressure Switch, highlighting the single 1/4" NPT pressure port and the unloader connection port.
4. Setup and Installation
Follow these steps for proper installation of the LEFOO LF19 Pressure Switch. Ensure all safety precautions are observed.
- Disconnect Power: Ensure the air compressor is unplugged from its power source and cannot be accidentally started.
- Depressurize System: Fully drain all air pressure from the compressor tank.
- Remove Old Switch (if applicable): Carefully disconnect electrical wiring and air lines from the existing pressure switch. Note the wiring configuration for reinstallation.
- Mount New Switch: Thread the LEFOO LF19 Pressure Switch onto the 1/4" NPT port on your air compressor manifold. Use thread sealant (e.g., PTFE tape) to ensure an airtight seal. Tighten securely but do not overtighten.
- Connect Unloader Line: The unloader mechanism can rotate 360 degrees for optimal positioning. Insert your 1/4" copper or nylon tubing firmly into the push-to-connect unloader port until it locks in place. Ensure a tight seal. This line typically connects to the compressor's check valve or intake.
- Wire Electrical Connections: Connect the power supply and motor wires to the appropriate terminals inside the switch. Refer to your compressor's wiring diagram or consult a qualified electrician if unsure. The LF19 is a 2-pole switch suitable for single or three-phase systems (110/230/460V).
- Secure Cover: Once all connections are made and verified, securely fasten the front cover of the pressure switch.
- Initial Test: With the ON/OFF button in the "OFF" position, reconnect power to the compressor. Slowly open the air tank drain valve to ensure the system is still depressurized. Then, switch the ON/OFF button to "ON". The compressor should start and build pressure. Observe the cut-out pressure.
4.1 Adjusting Pressure Settings
The LEFOO LF19 pressure switch is factory set to 140-175 PSI. If adjustment is necessary, proceed with caution:
- Safety First: Disconnect power and depressurize the system before opening the switch cover for adjustments.
- Identify Adjustment Screws: Inside the switch, there are typically two adjustment screws: one for the cut-out (high) pressure and one for the differential (cut-in) pressure. Consult the internal diagram or markings if available.
- Adjust Cut-Out Pressure: Turning the main adjustment screw (usually larger) clockwise increases the cut-out pressure; counter-clockwise decreases it. Make small adjustments.
- Adjust Differential: The differential screw (usually smaller) adjusts the range between cut-in and cut-out. Turning it clockwise typically increases the differential (lower cut-in pressure for a given cut-out).
- Test and Verify: After each adjustment, reassemble the cover, reconnect power, and test the compressor's cut-in and cut-out pressures using a calibrated gauge. Repeat adjustments as needed until desired settings are achieved, ensuring not to exceed the compressor tank's maximum rated pressure.
5. Operating Instructions
Operating the LEFOO LF19 Pressure Switch is straightforward once installed.
- Start Compressor: Ensure the compressor is plugged into a suitable power outlet. Move the red ON/OFF button on the front cover to the "ON" position. The compressor motor should start and begin building air pressure.
- Automatic Operation: The pressure switch will automatically stop the compressor motor when the upper pressure limit (cut-out pressure, e.g., 175 PSI) is reached. It will then automatically restart the motor when the pressure drops to the lower limit (cut-in pressure, e.g., 140 PSI).
- Stop Compressor: To manually stop the compressor, move the red ON/OFF button to the "OFF" position. This will immediately cut power to the motor.
- Unloader Function: When the compressor stops (either automatically or manually), the unloader mechanism will briefly release air from the compressor head. This reduces starting load on the motor for easier restarts.
6. Maintenance
Regular maintenance ensures the longevity and reliable operation of your pressure switch.
- Inspect Periodically: Visually inspect the pressure switch and its connections regularly for any signs of damage, corrosion, or loose wiring.
- Check for Leaks: Listen for air leaks around the pressure port and unloader line connections. Tighten or re-seal as necessary.
- Clean: Keep the exterior of the switch clean and free from dust, dirt, and moisture. Do not use harsh chemicals.
- Electrical Contacts: Over time, electrical contacts can wear. If the switch exhibits intermittent operation or failure to start/stop, the contacts may need inspection by a qualified technician. (Note: Heavy-duty switches like the LF19 are designed with larger contacts to mitigate this issue.)
- Unloader Line: Ensure the unloader line is clear and not kinked or blocked, as this can prevent proper compressor startup.
7. Troubleshooting
If you encounter issues with your LEFOO LF19 Pressure Switch, refer to the table below for common problems and solutions.
| Problem | Possible Cause | Solution |
|---|---|---|
| Compressor does not start. |
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| Compressor does not stop at cut-out pressure. |
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| Air leaks around switch. |
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| Compressor cycles too frequently. |
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If troubleshooting steps do not resolve the issue, contact LEFOO customer support or a qualified service technician.
8. Specifications
| Feature | Detail |
|---|---|
| Model | LF19 |
| Brand | LEFOO |
| Pressure Range (Factory Set) | 140-175 PSI (Adjustable) |
| Maximum Operating Pressure | 200 PSI |
| Minimum ON Pressure | 70 PSI |
| Differential Pressure | 30-40 PSI |
| AMP Rating | 26 Amps |
| Voltage Compatibility | 110V / 230V / 460V (AC) |
| Phase | Single Phase or Three Phase |
| Port Type | Single 1/4" Female NPT |
| Pole Rating | 2 Pole |
| Unloader Port | Push-to-connect for 1/4" tubing (copper or nylon) |
| Special Feature | Heavy Duty, Integrated ON/OFF Switch |
| Material | Plastic (housing) |
| Color | Black |
| Item Weight | 1.08 pounds (approx.) |
| Package Dimensions | 4 x 4 x 4 inches (approx.) |
| UPC | 687927982901 |
9. Warranty and Support
For warranty information, technical support, or replacement parts, please contact LEFOO customer service. Keep your purchase receipt as proof of purchase.
You can typically find contact information on the manufacturer's official website or through your point of purchase. For general inquiries, you may visit the LEFOO Store on Amazon.
