Liquid Diaphragm Pumps
In liquid diaphragm pumps a flexible diaphragm is moved through the action of an eccentric on the motor shaft.
On the downstroke, the medium is drawn into the pump chamber and expelled on the upstroke. Internal valves mounted within the pump head function as check valves and control the direction of flow.
Thomas is one of the only manufacturers of dedicated liquid diaphragm pumps. Unlike gases, liquids cannot be compressed and therefore create high forces on the pump components and inducing pulsation. This leads to pump designs with smaller diaphragm strokes, stiffer diaphragm materials and more robust bearings compared to air pumps.
The pumps are ranging from 0.2 to 1.8 liters per minute and operating pressures up to 6 bar. Multiple head can be offered for high volume requirements. The Thomas range features an extensive range of brushed and brushless DC motors. Depending on the type of liquid, you can choose pump components in the most suitable material, such as EPDM, FKM, PTFE or FFKM.
Liquid diaphragm pumps show high resistance to pressure combined with continuous runtimes of 10,000 hours and more. Together with their optimal flow rate to size ratio, this makes liquid diaphragm pumps the best solution for many OEM applications.
For example digital inkjet printers use liquid diaphragm pumps for ink handling due to their high efficiency. Digital inkjet printer manufacturers rely on liquid diaphragm pumps due to their chemical resistance against aggressive inks. Another important feature for them is the ability to gently move inks for up to 2 years without maintenance.
Diagnostic equipment (IVD) such as hematology analyzers require liquid diaphragm pumps for cleaning the fluid handling system. There pumps need to operate with high pressure levels. Also vacuum pump duties are common, for example when aspiration of residue liquids is needed.
Peristaltic pump also referred to as hose or tube pumps operate using positive displacement. Fluid is fed through the tubing by rollers that rotate squeezing the tube against the pump housing.
As the roller moves over and past a point on the tubing, it expands to allow more fluid to enter. During operation, at least one roller is closing the tube. Therefore the need for extra valves is eliminated.
Since 2019 Thomas includes the flexible and high quality peristaltic pumps by the former manufacturer Oina. This increases the range and possibilities to provide solutions to demanding applications significantly. Thomas now features pumps with flow rates ranging from smaller than 0.1 up to 1,600 ml per minute. Various tube materials from silicone over medical grade tubing to FKM tubing are available depending on their compatibility with the media.
Peristaltic pumps are ideal for applications requiring minimal cross-contamination (carry-over). The only part of the pump to come into contact with the fluid is the tubing. The ease of replacing the tubing or cassette therefore a smooth process and ensures high process stability.
Whenever viscous fluids or liquids need to be transferred, peristaltic pumps are a possible solution as they do not incorporate valves.
Therefore many analytical instruments and bioprocessing equipment rely on peristaltic pumps, as avoidance of cross-contamination is key to process stability.
Examples of such equipment include bioreactors and cell harvesters.
Also medical devices often incorporate peristaltic pumps for handling fluids. For example in dialysis machines peristaltic pumps are used to feed blood and dialysate.
Linear pumps utilize an electromagnetic drive to apply force to a diaphragm positively displacing liquid. Alternating current reverses the magnetic field induced around a magnetized rod.
Thomas features linear pumps with flow rates up to 300 ml per minute and can be equipped with AC and DC motors.
Linear pumps are quiet and efficient. With fewer wearing parts than equivalent reciprocating pumps, linear pumps are regarded as long life, low maintenance devices. However, the hydraulic performance is limited to the strength of induced magnetic field, making them suitable for low differential pressure applications.
Those applications include delivery of methanol in fuel cells as well as constantly dispensing detergent in cleaning devices.
Tricontinent Precision Pumps
Next to the Thomas brand Gardner Denver also offers precision liquid handling equipment by Tricontinent. Tricontinent is a leading manufacturer of precision syringe pumps. They set the bar for precision and accuracy and offer a unique combination of low flow and low pulsation.
Moreover air displacement pumps are another high precision pump technology offered by Tricontinent. They are working like electronic hand pipettes by aspiring a medium from one vessel and dispensing it into another vessel.