Winterizing Hydraulically Driven Submersible Pumping Systems: Cold-Weather Operation and Storage
As temperatures drop, hydraulically driven submersible pumps and hydraulic power units require additional attention to ensure reliable performance and prevent unnecessary damage. Cold weather can affect hydraulic oil viscosity, seals, hoses, fittings, and the water or slurry remaining inside the pump and discharge system. For industries that rely on submersible pumps year-round, proper winterization is an important part of protecting equipment and avoiding costly downtime.
Hydra-Tech pumps and HPUs are designed for demanding applications, but like any mechanical equipment, they must be operated and stored appropriately when temperatures fall. Following a few basic procedures can help protect the pump and hydraulic system.
Why Winterization Matters
Cold temperatures can create several problems for hydraulic pumping equipment.
One significant concern is hydraulic oil viscosity. As temperatures drop, hydraulic oil becomes thicker and will not flow through hydraulic components as easily as it does at normal operating temperatures. Attempting to operate a hydraulic motor with excessively viscous oil can increase system pressure, restrict flow, and place additional stress on seals and other components. We advise against operating with hydraulic oil that is too cold and viscous and recommend hydraulic fluid be at or above 50°F (10°C) before use.
Cold weather can also create problems when water or slurry remains inside the pump, discharge hose, piping, or other components. If that liquid freezes and expands, it can potentially damage components, leaving the equipment unavailable when needed.
Winterization therefore has two primary goals:
- Prepare equipment that will be placed into storage.
- Prepare equipment that will continue operating in cold temperatures.
Preparing a Hydra-Tech Pump for Winter Storage
If a Hydra-Tech pump won’t used for an extended period, it should be properly cleaned, drained, inspected, and stored.
- Thoroughly clean the pump
Begin by removing the pump from service and disconnecting the hydraulic power source.
Clean the pump thoroughly, paying particular attention to the volute, impeller, suction area, discharge connection, and wear components. This is especially important after pumping abrasive slurries, wastewater, sediment, or other materials that can accumulate inside the pump.
A pump that is clean going into storage is much easier to inspect and put back into service later.
- Drain water and other liquids
Remove as much water, slurry, or other pumpage from the pump as possible. Pay particular attention to areas where liquid can become trapped. Water left inside the pump can freeze and expand during prolonged exposure to freezing temperatures.
If the pump is connected to discharge piping or hose that will remain in place, the system should be arranged so that trapped water can drain. This is particularly important in permanent or semi-permanent installations.
- Inspect the impeller and wear components
With the hydraulic system disconnected and the pump safely isolated, inspect the impeller, wear ring/wear plate, shaft, and other accessible components.
Look for:
- Excessive or abrasive wear
- Cracks or damage
- Foreign material
- Damaged fasteners
- Evidence of seal leakage
- Damage to hydraulic fittings
Addressing wear or damage before storage is preferable to discovering the problem when the pump is needed again.
- Protect the pump from the elements
Whenever possible, store the pump indoors in a clean, dry location protected from freezing temperatures and precipitation. The pump should be positioned securely so it cannot fall or be damaged by other equipment. If indoor storage is not possible, use appropriate weather protection while still allowing moisture to escape. Avoid creating a situation where condensation becomes trapped against the equipment.
Preparing the Hydraulic Power Unit for Winter Storage
Winterizing the pump alone is only part of the process. If the pump is powered by a Hydra-Tech power unit, the HPU and hydraulic circuit should also be prepared for storage.
Before extended storage:
- Inspect the hydraulic reservoir and oil condition.
- Look for leaks.
- Inspect filters according to the applicable maintenance schedule.
- Make sure the reservoir is properly closed and protected from contamination.
- Follow the engine manufacturer’s procedures for preparing the engine for extended storage.
- Store the power unit in a dry, protected location whenever possible.
Operating a Hydra-Tech Pump in Cold Weather
Not every pump needs to be removed from service when temperatures fall below freezing. Hydra-Tech pumps can be used in cold-weather applications when the hydraulic system is properly prepared.
The most important rule is:
Do not immediately operate the pump at full speed with cold hydraulic fluid.
Hydraulic oil should be preheated by operating the power source at low speed. Hydraulic oil should reach at least 50°F (10°C) before the submersible pump is operated.
A basic cold-weather startup procedure
- Inspect the system.
Before starting, inspect the pump, hydraulic hoses, couplers, and power unit. Make sure connections are clean and properly installed.
- Check for frozen components.
Do not attempt to force a pump, hose, valve, or fitting that has frozen water or slurry inside it.
- Start the hydraulic power unit at low speed.
Allow the hydraulic system to warm gradually.
- Allow the hydraulic fluid to reach the appropriate temperature.
Minimum hydraulic oil temperature of 50°F (10°C) should be achieved before use.
- Connect and engage the hydraulic circuit correctly.
The hydraulic circuit should be properly connected before engaging hydraulic flow. Make sure pressure and flow connections are correct and are properly connected.
- Start the pump gradually.
Do not immediately run the pump at maximum speed. Allow the system to stabilize and verify that the pump is operating normally.
- Monitor the system.
Pay attention to hydraulic pressure; and beware of unusual noises, restricted flow, leaks, or other abnormal conditions.
How Cold Is Too Cold?
This is an important distinction in winter pump operation. We do not necessarily recommend a pumping system be taken out of service at a certain ambient air temperature. If hydraulic oil is sufficiently clean and not excessively viscous, and a minimum operating oil temperature of 50°F (10°C) can be achieved before the pump is deployed, the system will be safe for use. Again, operation with oil that is too cold or viscous can damage the hydraulic circuit or the pump’s motor and seals.
Therefore, an outdoor temperature below 50°F does not automatically mean the pump cannot be used. Conversely, simply having an ambient temperature above 50°F does not guarantee that the hydraulic oil is at the required temperature.
Do not attempt to overcome cold-weather restrictions simply by increasing hydraulic pressure or forcing the pump to run. Doing so can turn a temperature-related operating problem into a hydraulic-system or seal failure.
Don’t Forget the Hydraulic Hoses
Hydraulic hoses are another important consideration during winter operation. Cold temperatures can affect hose flexibility and make older or damaged hoses more susceptible to cracking or failure. Before winter operation, inspect the entire hydraulic circuit.
Check hoses for cracking, abrasion, cuts, damaged fittings, or other deterioration. Inspect quick-disconnect couplers and make sure they are clean and in good condition. Pay particular attention to the return side of the hydraulic circuit. Restrictions in the return hose or coupling can create excessive backpressure at the hydraulic motor. Return-side friction and backpressure can damage the hydraulic motor and potentially cause seal failure.
Before storage, cap or otherwise protect hydraulic connections from dirt, moisture, and contamination.
Winterizing the Discharge System
The pump isn’t necessarily the only component at risk of freezing.
When pumping water or other liquids during freezing conditions, inspect the entire discharge system. Water trapped inside discharge hoses, piping, valves, or low points in the system can freeze after shutdown.
Where applicable, provide a means for the discharge system to drain completely after use.
Before Putting a Winterized Pump Back Into Service
When winter is over, don’t simply reconnect the hoses and start the pump.
Before returning a stored pump to service:
- Inspect the pump for damage or corrosion.
- Check the impeller and wear components.
- Inspect the shaft and seals.
- Inspect hydraulic hoses and couplers.
- Check hydraulic oil level and condition.
- Verify that the correct hydraulic oil is being used.
- Inspect the discharge hose and piping for damage or blockages.
- Verify that all hydraulic connections are correct.
- Start the hydraulic power unit and allow it to warm up.
- Operate the pump gradually while checking for leaks, abnormal noises, vibration, or unusual pressure.
If any damage is discovered during inspection, contact us before returning pump to operation.
A Little Preparation Goes a Long Way
Winter weather doesn’t necessarily mean the end of the pumping season. With the right preparation, our pumps can continue performing in demanding cold-weather applications. The key is understanding that cold-weather operation is primarily a hydraulic oil and equipment condition issue—not simply an outside-air-temperature issue.
Taking these steps before winter arrives can help prevent seal failures, hydraulic-system damage, frozen components, unexpected downtime, and expensive repairs—while keeping your Hydra-Tech pump ready to work when you need it most.
For model-specific winterization, oil, or cold-weather operating recommendations, consult the applicable operation manual or contact us directly.
Note: This article is intended as a general maintenance and operating guide. Specific pump models, hydraulic power units, fluids, seals, and operating conditions may have additional requirements. Always follow the instructions and specifications for the particular Hydra-Tech Pumps equipment being used.