1. Introduction
This manual provides essential information for the safe and efficient operation, installation, and maintenance of your SEAFLO 31-Series DC Diaphragm Pump. This 12V pump is designed for high-pressure applications, delivering a steady 1.8 GPM flow rate with a 100 PSI shut-off pressure. It is suitable for RV water systems, agricultural sprayers, marine use, and high-pressure cleaning applications. Please read this manual thoroughly before installation and use.
2. Safety Information
- Always disconnect power before installing, servicing, or performing any maintenance on the pump.
- Ensure the power source matches the pump's voltage requirements (12V DC). Incorrect voltage can damage the pump and pose a safety hazard.
- Do not pump flammable liquids or use the pump in explosive atmospheres.
- Protect the pump from freezing temperatures. Freezing can cause severe damage and void the warranty.
- Ensure all connections are secure and leak-free to prevent water damage or electrical shorts.
- Wear appropriate personal protective equipment (PPE) during installation and maintenance.
3. Product Overview and Specifications
3.1 Key Features
- Powerful High-Pressure Performance: Delivers 1.8 GPM flow rate with 100 PSI shut-off pressure.
- Self-Priming & Run-Dry Safe: Capable of self-priming up to 6 feet and protected from damage when water runs low.
- Built-in Automatic Pressure Switch: Automatically starts and stops based on demand.
- Quiet & Efficient Operation: Engineered for low noise and vibration.
- Durable Construction: Built with EPDM valves and a Santoprene diaphragm for harsh environments.
- Easy Installation: Features an industry-standard mounting pattern and threaded connections.
3.2 Technical Specifications
| Model | SFDP1-018-100-31 |
| Voltage | 12V DC |
| Flow Rate | 1.8 GPM (7.0 LPM) |
| Shut-Off Pressure | 100 PSI (6.9 BAR) |
| Max Draw | 9.0A |
| Priming Capabilities | 6 feet (1.8m) suction lift |
| Max Temperature | 140°F (60°C) |
| Ports | 3/8"-18 FNPT |
| Material | Stainless Steel (housing components) |
| Included Components | 1 Pump, 2 Fittings |
3.3 Product View

Figure 1: Angled view of the SEAFLO 31-Series DC Diaphragm Pump.

Figure 2: Side view of the pump, highlighting the product label with model and electrical specifications.
4. Setup and Installation
Proper installation is crucial for the pump's performance and longevity. Follow these guidelines:
4.1 Mounting
- Mount the pump in a dry, well-ventilated area, protected from direct sunlight and freezing temperatures.
- Use the integrated mounting feet to secure the pump to a solid surface. The industry-standard mounting pattern allows for quick installation.
- Mount the pump in a position that allows for easy access for maintenance and inspection.
- Ensure the pump is mounted below the water source for optimal self-priming, or within 6 feet (1.8m) of the water source if above.
4.2 Plumbing Connections

Figure 3: Top-down view of the pump, showing the 3/8"-18 FNPT ports and included fittings.
- Connect the inlet port (marked with an arrow pointing towards the pump) to your water source using appropriate 3/8"-18 FNPT fittings.
- Connect the outlet port (marked with an arrow pointing away from the pump) to your distribution system.
- Use flexible hose on both inlet and outlet to minimize vibration and noise.
- Ensure all connections are tight to prevent leaks. Do not overtighten plastic fittings.
- Install a filter on the inlet side to protect the pump from debris.
4.3 Electrical Connections
- Connect the pump to a 12V DC power source.
- Ensure correct polarity: Red wire to positive (+), Black wire to negative (-).
- Install an appropriate fuse (refer to pump specifications for Max Draw, 9.0A, and select a fuse slightly higher, e.g., 10A or 15A) in the positive (+) line as close to the power source as possible.
- Use marine-grade or automotive-grade wiring of sufficient gauge for the current draw and length of the run.
- All electrical connections should be waterproofed and protected from corrosion.
5. Operating Instructions
Once installed, operating the SEAFLO 31-Series pump is straightforward:
- Priming: Ensure the inlet line is submerged in water. The pump is self-priming up to 6 feet. Open a faucet or outlet on the discharge side to allow air to escape.
- Power On: Apply 12V DC power to the pump. The pump will run until the system pressure reaches the shut-off pressure (100 PSI).
- Automatic Operation: The built-in pressure switch will automatically turn the pump off when the system reaches the set pressure and turn it back on when the pressure drops (e.g., when a faucet is opened).
- Run-Dry Protection: The pump is designed to run dry without damage, but continuous dry running should be avoided to prolong pump life.
- Temperature: Do not exceed the maximum liquid temperature of 140°F (60°C).
6. Maintenance
Regular maintenance ensures optimal performance and extends the life of your pump.
- Inspect Connections: Periodically check all plumbing and electrical connections for tightness and signs of corrosion or wear.
- Clean Inlet Filter: If an inlet filter is installed, clean it regularly to prevent debris from entering the pump and reducing flow.
- Winterization (if applicable): If the pump is used in an environment where freezing temperatures are possible, drain all water from the pump and lines or flush with RV antifreeze to prevent damage.
- General Cleaning: Keep the exterior of the pump clean and free of dirt and debris.
7. Troubleshooting
Before contacting support, review the following common issues and solutions:
| Problem | Possible Cause | Solution |
|---|---|---|
| Pump does not run | No power; Blown fuse; Loose wiring; Faulty switch | Check power supply; Replace fuse; Tighten connections; Test switch. |
| Low flow or pressure | Clogged inlet filter; Air leak in inlet line; Restricted discharge line; Low voltage; Worn pump head. | Clean filter; Check inlet connections for leaks; Clear discharge line; Verify 12V supply; Inspect pump head. |
| Pump runs but no water | No water in tank; Air lock; Inlet line not submerged; Major air leak. | Check water level; Prime pump by opening outlet; Ensure inlet is submerged; Check all inlet connections. |
| Pump cycles on/off rapidly | Small leak in system; Pressure switch setting too low; Accumulator tank (if present) needs air. | Check for leaks in plumbing; Adjust pressure switch (if adjustable); Check accumulator tank pressure. |
8. Warranty and Support
8.1 Warranty Information
The SEAFLO 31-Series DC Diaphragm Pump is backed by a 4-Year Warranty. This warranty covers defects in materials and workmanship under normal use and service. Please retain your proof of purchase for warranty claims.
8.2 Customer Support
For technical assistance, warranty claims, or further inquiries, please contact SEAFLO customer support. Refer to the product packaging or the official SEAFLO website for the most current contact information.