21 Series 12V Fresh Water Pump | 3.8LPM Automatic

💧 SEAFLO 21 SERIES 12V FRESH WATER PUMP – 3.8LPM AUTOMATIC DEMAND PUMP

Compact Self-Priming 12V Pressure Pump for Caravans, Campers, Boats & Portable Water Systems

💦 The SEAFLO 21 Series 12V Fresh Water Pump is a compact automatic pressure pump designed for smaller water systems where reliable flow, low current consumption and simple operation are required.

Ideal for caravans, camper trailers, boats, 4WD water systems and portable installations, the 21 Series uses a self-priming diaphragm pump combined with an integrated pressure switch that automatically starts the pump when a tap is opened and stops it when the tap is closed.

Designed to supply one or two 3/8" (10mm) outlets at a time, it is a practical choice for compact sinks, hand-washing stations, water transfer, spraying, circulation, filtration and dispensing applications.

The pump can also run dry without damage, incorporates ignition protection and draws less than 3A across the supplied performance data, making it well suited to smaller 12V auxiliary electrical systems.

---

⚡ KEY FEATURES

💧 Automatic Demand Operation
The built-in pressure switch automatically starts the pump when a tap or outlet is opened and stops it again when the outlet is closed.

🚿 Suitable for 1–2 Fixtures
Designed to supply one or two 3/8" / 10mm water outlets at any one time.

💦 Self-Priming Diaphragm Pump
Designed to prime itself within a correctly installed water system, reducing the need for manual priming during normal use.

🛡️ Can Run Dry Without Harm
The diaphragm-pump design can operate dry without immediately damaging the pump, useful if the water tank temporarily runs empty.

⚡ Low 12V Current Requirement
Current draw ranges from approximately 1.56A at free flow to 2.96A at the highest listed pressure point.

🔥 Ignition Protected
Designed with ignition protection for compatible installations where this protection is required.

🔧 Compact 21 Series Design
Small footprint makes the pump easier to install in confined caravan, camper and marine storage areas.

🛠️ Industry Standard Mounting Pattern
Designed around a commonly used mounting arrangement to simplify installation or replacement applications.

📜 2 Year Warranty
Backed by a two-year warranty.

---

🚿 IDEAL FOR SMALL FRESH WATER SYSTEMS

The SEAFLO 21 Series is designed for compact water installations rather than large multi-outlet pressure systems.

It is particularly well suited to applications such as:

• 🚐 Caravan sinks
• 🏕️ Camper trailer water systems
• 🚙 4WD water tanks
• 🚤 Boat freshwater systems
• 🚿 Portable hand-washing stations
• 💧 Water transfer
• 🌱 Light spraying applications
• 🔄 Water circulation
• 🧪 Filtration systems
• 🚰 Water dispensing

For customers who only need to operate a sink or one or two small outlets, the compact 21 Series avoids unnecessarily fitting a much larger high-flow pump.

---

⚙️ AUTOMATIC PRESSURE SWITCH

The integrated pressure switch makes operation simple.

Open the tap and the pressure in the plumbing falls, causing the pump to start automatically.

Close the tap and pressure builds again, allowing the pump to stop without requiring a separate manual switch every time water is required.

This automatic demand operation makes the SEAFLO 21 Series particularly convenient in caravan and camping sink installations.

---

💦 SELF-PRIMING & DRY-RUN CAPABLE

The 21 Series uses a self-priming diaphragm design, allowing it to draw water into the pump when installed correctly.

It is also designed to run dry without harm, providing additional protection if the water tank empties unexpectedly or the supply is temporarily interrupted.

⚠️ While the pump is designed to tolerate dry running, continuously operating any pump without water unnecessarily should still be avoided.

---

📊 FLOW & PRESSURE PERFORMANCE

Pump flow naturally decreases as system pressure increases.

At 0 PSI / 0 Bar:

Flow: 1.09 GPM / 4.14 LPM

Current Draw: 1.56A

At 10 PSI / 0.69 Bar:

Flow: 0.84 GPM / 3.28 LPM

Current Draw: 1.89A

At 20 PSI / 1.38 Bar:

Flow: 0.75 GPM / 2.84 LPM

Current Draw: 2.25A

At 30 PSI / 2.07 Bar:

Flow: 0.69 GPM / 2.60 LPM

Current Draw: 2.60A

At 40 PSI / 2.72 Bar:

Flow: 0 GPM / 0 LPM

Current Draw: 2.96A

⚠️ FLOW RATING NOTE: The product is identified as a 3.8LPM pump, while the supplied performance data shows up to 4.14LPM at zero pressure. Actual flow will depend on plumbing restriction and operating pressure.

---

⚡ LOW CURRENT DRAW

The pump's relatively low current requirement makes it straightforward to incorporate into many 12V auxiliary battery systems.

Across the supplied performance data, current draw ranges from approximately:

• ⚡ 1.56A at free flow
• ⚡ 1.89A at 10 PSI
• ⚡ 2.25A at 20 PSI
• ⚡ 2.60A at 30 PSI
• ⚡ 2.96A at 40 PSI

This is a relatively modest electrical load compared with larger freshwater pressure pumps.

---

🔌 12V ELECTRICAL CONNECTION

The pump is supplied with approximately 13-inch long 18AWG electrical leads.

These leads allow the pump to be connected into a suitable fused 12V circuit.

⚠️ IMPORTANT: Fuse rating and any extension cable size are not specified here. Final electrical protection and wiring must be selected to suit the pump manufacturer's requirements and the actual cable length.

---

🚿 3/8" / 10MM WATER SYSTEM APPLICATION

The 21 Series is designed around compact water systems using 3/8" / approximately 10mm outlets.

It is capable of serving one or two such fixtures at a time, making it well suited to simple touring-water systems where very high flow is unnecessary.

For installations involving multiple showers, several taps or higher-flow fixtures operating simultaneously, a larger SEAFLO pump may be more appropriate.

---

⏱️ INTERMITTENT DUTY

The SEAFLO 21 Series is specified for intermittent-duty operation.

This makes it well suited to normal tap, dispensing and transfer applications where the pump cycles on and off as water is required.

⚠️ IMPORTANT: This model should not automatically be treated as a continuous-duty circulation pump simply because circulation is listed as an application. The pump is specifically rated for intermittent duty.

---

📜 STANDARDS & PROTECTION

The SEAFLO 21 Series is listed as:

• 🔥 Ignition Protected
• ✅ Meeting or exceeding RoHS requirements
• ✅ Meeting or exceeding SGS requirements
• ✅ Meeting or exceeding ISO standards

---

📋 TECHNICAL SPECIFICATIONS

Product Type: 12V Automatic Fresh Water Pressure Pump

Series: SEAFLO 21 Series

Voltage: 12V DC

Nominal Product Flow Rating: 3.8LPM

Maximum Listed Free-Flow Performance: 4.14LPM / 1.09GPM

Suitable Fixtures: 1–2

Fixture / Outlet Size: 3/8" / 10mm

Pump Type: Diaphragm Pump

Self-Priming: Yes

Dry-Run Capable: Yes

Pressure Switch: Built-In Automatic Demand Switch

Duty Rating: Intermittent Duty

Ignition Protected: Yes

Electrical Leads: 18AWG

Lead Length: Approximately 13"

Mounting: Industry Standard Mounting Pattern

Standards Listed: RoHS / SGS / ISO

Warranty: 2 Years

---

🔧 INSTALLATION CONSIDERATIONS

• Mount the pump securely using the supplied/appropriate mounting arrangement
• Use plumbing compatible with the pump's 3/8" / 10mm application
• Keep suction plumbing as unrestricted as practical
• Use suitable fresh-water-rated hose and fittings
• Install appropriate electrical fuse protection
• Use adequately sized cable if extending the supplied 18AWG leads
• Ensure correct 12V polarity before connection
• Check all plumbing fittings for leaks after installation
• Do not exceed the intended intermittent-duty operating cycle

---

❓ FREQUENTLY ASKED QUESTIONS

Will this pump be enough for a caravan sink?

Yes. A single caravan sink is an ideal application for a compact pump of this type. The SEAFLO 21 Series is designed to supply one or two 3/8" / 10mm fixtures at a time.

Can it run two taps?

Yes, it is listed as capable of supplying one or two fixtures. Keep in mind that opening both outlets simultaneously divides the available flow between them.

Would you use this for a shower?

It may supply a very low-flow shower or similar outlet, but with approximately 2.6LPM available at 30 PSI it is primarily suited to smaller water-demand applications. If stronger shower performance is important, a larger pump would generally be the better choice.

Will it automatically turn on when I open the tap?

Yes. The built-in pressure switch automatically starts the pump when system pressure drops as the tap opens and stops the pump when the tap closes and pressure is restored.

Do I need a separate pressure switch?

No. The automatic pressure switch is built into the pump.

Do I need to switch the pump on and off every time I use the tap?

No. Once the pump's main electrical circuit is switched on, the integrated pressure switch handles normal start and stop operation automatically as the tap is used.

Can it run dry if my water tank becomes empty?

Yes. The diaphragm pump is designed to run dry without harm, which provides useful protection if the tank temporarily runs empty.

Can I leave it running dry permanently?

No. Dry-run capability is useful protection, but unnecessary extended dry operation should still be avoided.

How much power will it use from my auxiliary battery?

The current draw is relatively low. The supplied data ranges from approximately 1.56A at zero pressure to 2.96A at 40 PSI. Because a freshwater pump normally operates only while water is being used, total daily battery consumption is generally modest.

Will it work with a lithium auxiliary battery?

Yes. It is a 12V DC appliance and can operate from a suitable 12V lithium electrical system. The wiring and circuit protection still need to be correctly configured.

Will it work with an AGM battery?

Yes. A healthy 12V AGM auxiliary system can power the pump without difficulty when correctly wired.

Can I connect it directly to my vehicle starter battery?

Electrically it requires a suitable 12V supply, but in a caravan or camping installation a dedicated auxiliary system is generally preferable so water-system use does not unnecessarily discharge the vehicle's starting battery.

Is the pump really 3.8LPM or 4.14LPM?

The product is identified as a 3.8LPM model, while the supplied performance chart lists a free-flow figure of 4.14LPM at zero pressure. Once normal plumbing pressure is introduced, flow decreases – for example, to approximately 3.28LPM at 10 PSI and 2.60LPM at 30 PSI.

Why does the flow drop as pressure increases?

This is normal pump behaviour. The more pressure the pump has to work against, the less water it can move. Real-world flow therefore depends on hose size, restrictions, fittings, filters, outlet type and required pressure.

Can I use it for transferring water between tanks?

Yes. Liquid transfer is one of the listed applications, provided the liquid and plumbing arrangement are compatible with the pump.

Can I use it with a water filter?

Filtration is one of the stated applications. However, restrictive filters increase pressure drop and may reduce available flow, so the filter needs to suit the pump and required water rate.

Can I use it for continuous water circulation?

The pump is listed for circulation applications but is also specifically rated as intermittent duty. It should therefore not be assumed suitable for continuous 24/7 circulation without confirmation of the intended duty cycle.

Is it suitable for a boat?

Yes. The compact design and ignition-protected specification make it suitable for compatible marine freshwater installations when installed correctly.

What size hose does it suit?

The listed application is for 3/8" / approximately 10mm outlets. Confirm the exact connection fittings required for your plumbing before installation.

Will I need an accumulator tank?

An accumulator tank is not listed as a requirement. The pump has its own automatic pressure switch and can operate as a compact demand system. Whether adding an accumulator is beneficial depends on the final plumbing arrangement and the desired cycling behaviour.

Is this a good replacement for an existing small caravan water pump?

Potentially, especially where the existing system only supplies one or two small fixtures. Compare the original pump's voltage, flow, pressure characteristics, plumbing connections, mounting arrangement and electrical requirements before replacing it.

What should I check before buying?

Confirm that a compact 3.8LPM-class pump provides enough flow for your application, check that your plumbing uses compatible 3/8" / 10mm connections, make sure you only need to supply one or two fixtures and remember that this model is intended for intermittent rather than continuous-duty operation.

---

💧 COMPACT, AUTOMATIC WATER PRESSURE FOR YOUR 12V SETUP

The SEAFLO 21 Series is an excellent choice when you need a small, efficient automatic water pump without the size and power consumption of a larger pressure system.

With self-priming operation, dry-run capability, an integrated automatic pressure switch, support for one or two fixtures and a low current draw of less than 3A across the supplied performance data, it is well suited to caravans, campers, boats, 4WDs and portable freshwater installations.

For a simple sink, water transfer system or compact touring setup, the SEAFLO 21 Series delivers practical 12V water pressure in a small and efficient package.