Vacuum Cup Lesson 101

Occasionally we receive questions regarding the differences between suction cups and vacuum cups, and the best way to secure mounts with vacuum cups to the glass.

Suction cups are cup-shaped devices, usually made of rubber, silicone, or other flexible compounds, that use negative fluid pressure of air or water to adhere to nonporous surfaces and in the process create a partial vacuum.[1] Suction cups are inexpensive and available in a variety of configurations. Suction cups require pressure to adhere to any given surface and the larger the cup the more pressure required for a secure mount in most cases.

Suction cups work well for attaching small lightweight parts like inspection mirrors, compact UV lights or other small parts that do not have a lot of back pressure against them.

Vacuum cups are also typically made of rubber, silicone, or other flexible compounds, but unlike suction cups, feature a lever, button, or pump that pulls the center of the cup up away from the glass, thereby creating a vacuum that holds the outer edges of the cup securely to the mounting surface. A vacuum cup is generally flatter, allowing more surface area to contact the glass, thus providing a more secure attachment with very little downward pressure regardless of the cup size. Attached properly, vacuum cups are also typically far more rigid than suction cups.

Vacuum cups are preferable over suction cups for attaching glass repair holding devices (bridges) to a broken windshield for several reasons:

  1. Less pressure is required to attach a vacuum cup securely to the glass, significantly minimizing the chance of causing a crack to run.
  2. The rigid mount holds the injector firmly in place against the glass, greatly reducing end seal leaks, and again, requires less pressure against the glass to minimize the chance of a crack out.
  3. A properly mounted vacuum cup is far less likely to “come loose” and fall off the glass, minimizing the potential damage to equipment and to the customer’s vehicle. Bridges have back pressure against the injector and the leveling screw(s) so maximum holding power is necessary.
  4. A small vacuum cup has far more holding strength than a suction cup several times as large and is therefore easier to carry, store and use.

Delta Kits uses high quality vacuum cups on all mounts and bridges to ensure a stronger and more reliable adherence to the glass. While many Delta Kits UV lights feature factory mounted suction cups for cost effectiveness and convenience, versatile vacuum cup mounts are available and adaptable to all Delta Kits UV lights.

In order to get the most out of all vacuum cups and suction cups it is important to make sure the glass and the cup are clean before each use. It is also very important that you don’t mount vacuum cups and suction cups over cracks in the glass. Doing so could create a loss of suction and cause the cup to fail.

To remove dirt and debris from a Delta Kits vacuum cup, simply clean with soap and water, wiping dry with a lint free towel. Another option is to wipe the cup with denatured alcohol. Caution: Do not soak a Delta Kits vacuum cup or suction cup in the alcohol as this will cause them to harden and will void the warranty! Do not allow alcohol or water to come in contact with filters or to get inside the chamber of pump style vacuum cups.

For more information on Delta Kits vacuum cups, mounts and bridges, please visit or call us at (800) 548-8332.


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