A pancake compressor is a small, portable air compressor used for home and commercial jobs where a smaller volume of air is needed. The term "pancake" refers to the flat, oval-shaped tank used to store the compressed air, resembling a pancake served for breakfast. These compressors are small, portable and can run on normal household electrical circuits, making them useful for homeowners and small businesses requiring occasional compressed air.
Most small air compressors are oil-free, which means oil does not leave the compressor with the air, requiring an oil separator. The compressor oil is sealed inside the unit, and other than an occasional cleaning, no maintenance is typically needed on a pancake compressor. A user can plug the unit into an electrical outlet, hook up a compressed air hose and connect to many small compressed air tools.
Air tools are normally rated by the volume of air required to operate them at a listed pressure. Pancake compressors can provide adequate air capacity for smaller tools, but may be too small for commercial or industrial applications. Air volume decreases as the operating pressure increases, so users should check the air requirements for their tools before purchasing a pancake compressor.
Small size and portability are the key attributes for a pancake compressor, with many units weighing less than 65 pounds (30 kilograms). Designs can vary, but most have the pancake air tank at the bottom with the compressor installed on top, which minimizes the amount of floor space needed. A carry handle is common, and most units will have rubber feet to reduce vibration and floor damage.
It is important when purchasing a pancake compressor to check that the unit has a water drain on the bottom of the tank. Water condenses to a liquid in an air compressor during operation, and will collect in the bottom of the air tank. If not regularly removed, the water can cause corrosion of the tank and eventual damage.
For the same reason, any auxiliary tank used to store compressed air should be designed for that purpose, and not a propane or other compressed gas cylinder. Many gas cylinders are unpainted inside, and if used for compressed air will rust and can fail, with property damage or injuries a possibility. Compressed air cylinders are paint or epoxy-coated on the inside to minimize rusting from water.
If using a pancake compressor outdoors, some simple safety precautions can reduce the chance of injuries. Always plug the unit into a circuit protected by a ground fault circuit interrupter (GFCI), which will sense any current flowing to ground and shut off the circuit to prevent electrocution. Inspect the compressor, hose and all tools for damage or air leaks, and repair or replace them before use. Do not place any compressor on a ladder or roof above people working below, because the compressor vibration can cause it to fall and injure someone.