Diaphragm Pump

Guide to double diaphragm pumps and diaphragm vacuum pumps

A member of the positive displacement pump family, diaphragm pumps use mechanical diaphragms to create the combination of pressure and resistance required to move a pooled substance. Mechanical diaphragms are barriers that seal off multiple areas or chambers, usually round in shape, that create suction through motion.

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Air-operated diaphragm pumps are the standard design. Also known as diaphragm vacuum pumps, these machines build up air of varying pressure on one side of the chamber, and the liquid to be pumped out rests in the chamber on the other side. A combination of movement and varying air pressure causes the standing liquid to move, drawing it out through pipes and getting rid of the mess.

Uses of Diaphragm Pumps

Diaphragm pumps typically have low flow rates as a result of the relatively low pressure they generate. While you can get models with higher flow rates and pressure ratings (such as double diaphragm pumps), lower rates can actually be advantageous. They promote efficient suction and effectively "lift" liquid out of its standing position.

Diaphragm pumps are especially good at moving viscous liquids and liquids with a high volume of solid content. They are often used to move chemicals and have many applications in sanitation and sterilization practices. Miniature diaphragm pumps can be used to create the beating action of artificial hearts, and diaphragm metering pumps regulate the filters on aquariums and fish tanks.

Types of Diaphragm Pumps

There are three main variations on the diaphragm pump design. They are:

  • Sealed diaphragm pumps. These are diaphragm vacuum pumps in which pressurized air is sealed on one side of the diaphragm, while the liquid is contained on the other. When the diaphragm moves, the pressure alters, rising and falling, causing the liquid to be sucked out through a pipe.
  • Unsealed diaphragm pumps. These pumps use a similar mode of action, but they do not contain the pressurized air and liquid on separate sides.
  • Volumetric diaphragm pumps. These diaphragm pumps use a combination of electricity and mechanical action to alter the rate of positive displacement. They supplement their power with geared drives and cranks that very efficiently move even large and very viscous pools of liquid.