Freshwater Hydrophore Pump

medium 110 models total

A hydrophore pump charges a closed pressure tank with freshwater and air so cabin and galley taps get steady pressure without the pump cycling on every draw, and its condition decides whether the domestic water system feels reliable or erratic to the crew.

Read more — Freshwater Hydrophore Pump explained ▾

What Sets the Hydrophore Pump Apart

Unlike a pump that runs continuously to feed an open system, a hydrophore pump works against a closed, part-air-filled pressure vessel. The pump charges the tank to a set upper pressure, then stops; as water is drawn off at cabins and galley outlets, tank pressure falls, and the pump restarts at a set lower pressure to recharge it. The air cushion in the tank absorbs small draws without the pump cycling every time a tap opens, which is what makes the domestic supply feel steady rather than pulsing. This is a pressure-maintenance function, distinct from a fire pump or bilge pump that runs continuously against an open system; sizing and control logic both revolve around the tank's air charge rather than around a fixed flow duty.

Main Components

Pump

Usually a multistage centrifugal pump sized for the peak simultaneous draw expected across the accommodation, not the average daily consumption.

Pressure Vessel (Hydrophore Tank)

A vessel holding both water and a compressed air cushion, or fitted with a diaphragm or bladder separating the two, which sets the pressure swing the pump has to work against.

Pressure Switches

Cut-in and cut-out switches that start the pump when tank pressure drops to the low setpoint and stop it at the high setpoint.

Air Charging Arrangement

Either an automatic air compressor topping up the cushion as air gradually absorbs into the water, or, on bladder-type tanks, a pre-charged bladder that does not need topping up in normal operation.

Non-Return Valve and Strainer

A check valve preventing backflow from the tank into the suction line, and a strainer protecting the pump from debris in the freshwater supply.

Selection and Sizing

Peak instantaneous demand, estimated from the number of outlets likely to be open simultaneously, which sets pump capacity, not average daily usage.
Tank volume and pressure swing, which together determine how often the pump cycles under typical draw patterns.
Required delivery pressure at the highest and most remote outlet on the ship, accounting for static head and pipe losses.
Redundancy, since most vessels fit two pumps on the same tank so one can be maintained while the other covers the load.

Regulations and Class

The hydrophore system falls under class rules for domestic freshwater supply arrangements, which typically require sufficient pump capacity and, on larger vessels, standby capacity so a single pump failure does not remove accommodation water supply entirely. There is no cargo or safety-critical regulatory regime specific to this equipment beyond general accommodation habitability requirements referenced in class rules; it is treated as auxiliary machinery rather than essential service equipment, though loss of it quickly becomes a habitability issue.

Typical Faults

Fault	Cause	Consequence
Rapid pump cycling	Lost air cushion, either from air absorption into water or bladder failure	Excessive starts, premature motor and contactor wear
No pressure buildup	Pressure switch failure or a stuck non-return valve	Pump runs continuously without the system reaching set pressure
Low pressure at remote outlets	Undersized pump for actual peak demand, or a partially blocked strainer	Poor water pressure in cabins farthest from the pump room
Waterlogged tank	Failed or leaking bladder, or air compressor not functioning	Very short pump run times and rapid pressure switch wear

What to Look for in a Supplier

Pump curve data at the actual system pressure range, not just the rated duty point, since the pump works across the whole cut-in to cut-out band.
Tank construction type, bladder or plain air cushion, matched to how much manual air-charge maintenance the crew is realistically able to do.
Pressure switch range and differential suited to the desired cycling frequency, adjustable rather than fixed.
Availability of spare mechanical seals and switches, since these wear faster than the pump casing itself.

If the pump starts and stops within a few seconds of each draw, check the tank's air charge before suspecting the pump, a waterlogged hydrophore tank is the single most common cause of that complaint.

8000h

Service Interval

15 yr

Typical Lifetime

Typical Manufacturers

Grundfos Wilo DAB

Inspector Mode Show All 110 total

7 manufacturers · 110 models

Grundfos Marine

44 ✓ 43 verified

CM 10-3

10 m3/h · 2.2 kW · Freshwater · multi-stage centrifugal pump with integrated pressure vessel

Common Failures & Inspection Points

Poor suction conditions, blockage or air ingress cause low flow, cavitation-like noise or unstable discharge
Seal, packing or gasket wear causes visible leakage and falling system pressure
Bearing, shaft or coupling wear causes vibration, abnormal noise or rising temperature
Impeller, screw or other pumping-element wear or fouling reduces capacity and may increase drive load
Motor, hydraulic-drive, valve or control faults cause failure to start, reduced speed or protective trips

Service: Inspect suction condition, strainers, seals, bearings, coupling or drive, foundation, leakage and associated valves. Trend pressure, flow, vibration and drive load where available. Investigate cavitation, abnormal noise or recurring trips promptly. Refer to the manufacturer documentation for the exact figure for clearances, wear limits and pressure settings.

Spare Parts: Carry seals or packing, bearings where appropriate, coupling parts, gaskets, filters and critical hydraulic or electrical control spares for the installed pump type.

Strengths

Compact, space‑saving design thanks to the built‑in pressure tank
Self‑priming capability reduces installation complexity
Good efficiency for low‑to‑moderate flow rates typical of domestic water supply
Robust construction (often stainless steel) suitable for marine environments
Easy access for routine maintenance and inspection

Weaknesses

Limited maximum flow and pressure compared with larger dedicated fire‑water pumps
Membrane tank can become waterlogged if not regularly checked
Impeller prone to scaling in hard‑water conditions, requiring periodic cleaning
Pressure switch failures have been reported and may need spare parts on board
Air charge in the pressure vessel must be monitored to maintain performance

Typical Vessels: General cargoContainer shipBulk carrierFerryYacht

Decision Guide: Choose if you need a reliable, compact pump for continuous domestic freshwater supply with moderate flow and pressure requirements and want to minimise space usage. Avoid if the vessel demands high flow rates, higher pressures (e.g., fire‑fighting), or redundancy beyond a single unit.

Use Cases: Cooling, ballast, bilge, fire, fuel, lubricating-oil, cargo and general liquid-transfer duties.

Datasheet

SCALA2 3-45 ✓ verified

Application

Domestic freshwater pressure boosting, single pump integrated unit

Common Failures & Inspection Points

Area: Inlet pressure exceeds maximum rated specification (MQ max 45 psi, CMBE max pressure rated)
Check: Verify inlet pressure gauge reading does not exceed pump datasheet maximum inlet pressure specification
Area: Pump cavitation due to inadequate inlet conditions or excessive suction lift
Check: Check suction line for air leaks, ensure suction lift does not exceed 1 meter, verify intake filter is not clogged
Area: Diaphragm tank pressure setting incorrect or tank bladder failure (CMB, MQ, SBA models)
Check: Measure tank pressure with gauge when pump is off; pre-charge pressure typically 0.8-0.9x minimum operating pressure
Area: Discharge pressure exceeds 10 bar (145 psi) design maximum causing component stress and leakage
Check: Monitor outlet pressure gauge continuously; pressure relief valve should activate at maximum rated pressure
Area: Water temperature exceeds +55°C causing seal damage and reduced pump life
Check: Install thermometer on discharge line; verify liquid temperature stays within -20°C to +55°C operating range

Typ-universelle Inspektionspunkte fuer Pumps (verifiziert, 2026-06).

[08.08.2026] Datenblattlink entfernt (nicht erreichbar): https://www.grundfos.com/content/dam/local/en-us/activity-assets/domestic-cold-water/downloads/Grundfosliterature-6820958-SCALA-data-booklet.pdf

Datasheet

SCALA1 3-45 ✓ verified

Application

Domestic freshwater pressure boosting, fixed-speed single pump

Common Failures & Inspection Points

Area: Inlet pressure exceeds maximum rated specification (MQ max 45 psi, CMBE max pressure rated)
Check: Verify inlet pressure gauge reading does not exceed pump datasheet maximum inlet pressure specification
Area: Pump cavitation due to inadequate inlet conditions or excessive suction lift
Check: Check suction line for air leaks, ensure suction lift does not exceed 1 meter, verify intake filter is not clogged
Area: Diaphragm tank pressure setting incorrect or tank bladder failure (CMB, MQ, SBA models)
Check: Measure tank pressure with gauge when pump is off; pre-charge pressure typically 0.8-0.9x minimum operating pressure
Area: Discharge pressure exceeds 10 bar (145 psi) design maximum causing component stress and leakage
Check: Monitor outlet pressure gauge continuously; pressure relief valve should activate at maximum rated pressure
Area: Water temperature exceeds +55°C causing seal damage and reduced pump life
Check: Install thermometer on discharge line; verify liquid temperature stays within -20°C to +55°C operating range

Typ-universelle Inspektionspunkte fuer Pumps (verifiziert, 2026-06).

[08.08.2026] Datenblattlink entfernt (nicht erreichbar): https://product-selection.grundfos.com/us/products/scala/scala1/scala1-3-45-99631742

Datasheet

SCALA1 3-25 ✓ verified

Application

Domestic freshwater pressure boosting, lower head variant

Common Failures & Inspection Points

Area: Inlet pressure exceeds maximum rated specification (MQ max 45 psi, CMBE max pressure rated)
Check: Verify inlet pressure gauge reading does not exceed pump datasheet maximum inlet pressure specification
Area: Pump cavitation due to inadequate inlet conditions or excessive suction lift
Check: Check suction line for air leaks, ensure suction lift does not exceed 1 meter, verify intake filter is not clogged
Area: Diaphragm tank pressure setting incorrect or tank bladder failure (CMB, MQ, SBA models)
Check: Measure tank pressure with gauge when pump is off; pre-charge pressure typically 0.8-0.9x minimum operating pressure
Area: Discharge pressure exceeds 10 bar (145 psi) design maximum causing component stress and leakage
Check: Monitor outlet pressure gauge continuously; pressure relief valve should activate at maximum rated pressure
Area: Water temperature exceeds +55°C causing seal damage and reduced pump life
Check: Install thermometer on discharge line; verify liquid temperature stays within -20°C to +55°C operating range

Typ-universelle Inspektionspunkte fuer Pumps (verifiziert, 2026-06).

Freshwater Hydrophore Pump

What Sets the Hydrophore Pump Apart

Main Components

Pump

Pressure Vessel (Hydrophore Tank)

Pressure Switches

Air Charging Arrangement

Non-Return Valve and Strainer

Selection and Sizing

Regulations and Class

Typical Faults

What to Look for in a Supplier

Typical Manufacturers

7 manufacturers · 110 models

Grundfos Marine

Iron Pump

Azcue

DESMI

Shinko Industries

DNV

Wilo Marine