Are Submersible Pumps Safe to Operate?

Submersible pumps are extensively used for industrial applications, including in oil wells, for pumping sewage, pumping slurry, in filtration systems and in other situations where it’s necessary for the motor or pump assembly to be submerged in the water or an alternative liquid. But how does an electrical system operate safely while submerged? Even as children, we know that electricity and water can be a recipe for disaster.

The liquids in which submersible pumps operate certainly cannot come in contact with electrical components, which can result in damage. To prevent this, pump manufacturers hermetically seal all internal components within cast iron or a synthetic casing.

Submersible pump casings have a robust construction to prevent damage. This is especially necessary since these pumps are usually required to operate in harsh environments. The casings are built to a high-degree of precision, so that different parts have a flush fit. Grooves and O-rings are used to fit different casing components, which further keep liquids away.

The wires carrying power to the internal components are also appropriately sealed. The cable cap assembly, which is the point where an external wire enters the pump, is often filled with epoxy as an additional safety measure. Also, non-wicking material is used for cables to prevent the absorption of moisture. Where seals are necessary, type-21 mechanical seals are utilized. These seals eliminate the need for adhesives (which can deteriorate over time) and can also rotate freely.

An added safety measure is the inclusion of oil and gas separators. In their most basic form, these separators are chambers that hold oil or gas and act as a barrier to the external medium in which a submersible is operating. In the event that the casing is breached due to an external damage caused by an accident or from regular wear and tear, a separator can prevent the external liquid from coming in contact with the electrical components immediately.

Moisture sensors act as the final safety measure for submersible pumps. In case water manages to breach the external casing and seals, it comes in contact with the separator (oil), and the increase in moisture level is detected by a moisture sensor, which is programmed to trigger an alarm or to automatically shut down the pump.

However, this water-tight construction of a submersible pump does not allow it to have a cooling mechanism like an external pump, which has fans to dissipate heat. Instead, submersible pumps are dependent on the liquid in which they are submerged to reduce heat build-up. For this reason, submersible pumps must not be operated externally for too long. The duration for which submersible units can operate outside a liquid varies from pump to pump. While some pumps are designed to operate for short durations without overheating, others simply should be used outside water.

To find out more about different types of submersible pumps and how to operate them safely, please reach out to us at or call our toll free number 1-800-367-4180. Our professionals can assist you with expert advice on all types of liquid handling equipment as well as installation services.