A washer is a round, flat piece of hardware with a hole in the center that is often placed between a screw or nut and a surface in order to increase tension. A rubber washer is such a piece of hardware that has been manufactured from rubber. Most often, a rubber washer is used in applications that require a tight seal; those that require some degree of give in the washer; and those that are exposed to water, humidity or other liquids.
The hole in a rubber washer allows a screw or bolt to pass through the center of the material. In some cases, a larger item, such as a threaded pipe or conduit, may be passed through the center instead. The overall diameter of the washer should be larger than the head of the screw or other hardware piece that is placed through it, and the hole in the center should be smaller than any nut or other fastener used to secure it. This helps ensure that the washer will be held in place.
Wet areas commonly require the use of rubber washers. Washers are often made of metal, which can rust when exposed to moisture. Rubber washers are both durable and resistant to fluids. This makes them ideal for use in plumbing and in systems that might experience condensation, such as in a Heating, Ventilation, and Air Conditioning (HVAC) system. They are also common on boats, swimming pools, pressure washers and other water-related equipment.
Another benefit of rubber washers is that they are more flexible than metal washers. This allows the fasteners to be secured more tightly and also allows for the slight expansion and contraction necessary in some applications. Foam washers may be used to help meet these needs, but they can deteriorate over time. A rubber washer, being stronger and less prone to damage, will last longer, particularly if the fasteners around the washer are frequently tightened and loosened.
A rubber washer also has the potential to create a seal. In this case, the washer can be used to prevent fluid or air from leaking. This is due both to rubber's flexible nature and its water-resistant quality.
Not all applications are ideal for rubber washers. For instance, they should not be used with corrosive liquids, and they may interact negatively with some other types of liquids. They also should not be placed in extreme heat, as melting can occur. Additionally, rubber washers exposed to differences in temperature, especially in combination with changes in humidity, must be replaced occasionally.