Preparing Hydraulic Systems for Cold Weather

In our previous post about the effects of heat on a fluid power system, we reflected on how heat can lead to problems in a hydraulic system, and ways to mitigate it.

With winter fast approaching, it’s important to begin considering the effects of the cold, as fluid systems are also not immune to the effects of lower temperatures. If you manage or maintain a fluid power system, it’s time to prepare your plan.

What Happens to a Fluid Power System in the Cold?

When exposed to cold temperatures, problems culminate in a hydraulic system. This often starts with an increase in oil viscosity and cavitation, possibly leading to damaged or inefficient machinery, and this leads to an increased chance of system failure.

Fortunately, it’s not difficult to prepare and winterize hydraulic systems by doing fluid checks and following through with consistent techniques.

Winterizing is vital to maintaining fluid power systems, and can help to prevent:

Damaging increases in viscosity
Trapped moisture in piping
Ice build-up
Cavitation and lack of lubrication
Loss of hydraulic pump and motor function
Damaged hydraulic hoses, seals, mountings, fittings, and other rubber components

Even though the freezing point that causes hydraulic oil to gel and become unusable is -10 degrees Fahrenheit, a much lower threshold than the ambient freezing point of 32 degrees Fahrenheit, fluid can still increase in viscosity before gelling, causing performance issues with hydraulic pumps and motors.

Taking a few simple measures to winterize fluid systems can save lots of complex repairs and replacements, as we’ve outlined below. Making viscosity considerations and fluid checks, then preparing equipment before use, and finally by storing fluids, equipment, and components properly, hydraulic systems can continue running smoothly throughout winter months.

Viscosity & Fluid Checks

Viscosity should be the first consideration when preparing fluid power systems for the cold.

Using fluid with the right viscosity for the application can help to protect equipment from friction, abrasion, and adhesive wear rise.

The wrong viscosity can have the opposite effect. In particular, high oil viscosity can lead to starved pumps, cavitation, and lack of lubrication. Lower temperatures cause hydraulic fluid to increase to a higher viscosity. Close attention should be placed on grade, pour point (and added depressants), as well as the viscosity index (VI) of fluids.

Most hydraulic parts made of steel or iron may not be affected by temperature. However, friction and wear, particularly on seal material, can occur due to a higher viscosity in fluids.

To prepare fluid systems, choose hydraulic fluids with a low VI, which is measured when subjected to change in temperature. The higher the viscosity index, the higher the resistance to change in viscosity.

Consider checking VI requirements and fluid levels within hydraulic equipment prior to starting. If any fluid is too thick to drip off the end of a dipstick, it is too viscous to function properly, especially in the cold. It is also wise to check fluid levels before each use, and refill after each use.

Equipment Prep

Along with making sure fluid viscosity is appropriate for the expected temperatures, it’s important to do a proper warm-up of equipment to prepare fluid systems in the cold months.

For best cold weather performance, run the hydraulic pump or use a hydraulic tank heater before operation. It is best to check and ensure the hydraulic oil temperature is reading 150 degrees Fahrenheit prior to running to ensure proper lubrication throughout the system.

Proper Storage

Keeping equipment in a closed facility is the most effective way to shelter the exterior of machinery, but also vital to keeping fluid systems protected.

Internal fluids could freeze if machinery is exposed to sub-zero temperatures, so make a plan to store even heavily used equipment.

Further, make sure to have a space to store all hydraulic oils and fluids at room temperature to protect viscosity.

Other tips for winter storage that protect fluid power systems:

Remove any attachment parts and store them separately
Inspect for cracks and tears on rubber components
Keep spare seals, rubber mounts, and fittings in closed storage
Replace any hydraulic hoses, tires or belts that have abrasions
Store protective wraps and sleeves

Preventing Winter's Wrath

Drops in temperature do not have to mean damage or hydraulic system failures.

Prevention is as easy as following the steps above – make solid viscosity choices and fill up, use a quick warm-up technique, provide the proper storage for equipment, and you’ll reap the rewards of having maintained your system well through the winter and into the springtime.