1.7
Peristaltic pumps — an overview
Peristaltic pumps are the simplest possible pump, with no valves, seals or glands to clog or corrode. The
fluid contactsonly the bore of a tube, eliminating the risk of the pump contaminating the fluid, or the fluid
contaminating thepump. Peristalticpumpscan operate dry withoutrisk.
How they work
A compressible tube issqueezed between a roller and a track on an arcof a circle, creating a sealatthepoint
of contact. As the roller advances along the tube, the seal also advances. After the roller has passed, the
tube returns to its original shape, creating a partial vacuum which is filled by fluid drawn from the inlet
port.
Before the roller reaches the end of the track, a second roller compresses the tube at the start of the track,
isolating a packet of fluid between the compression points. As the first roller leaves the track, the second
continuesto advance, expelling the packetof fluid through the pump’sdischarge port. Atthe same time, a
newpartialvacuum iscreated behind thesecond roller into which more fluid isdrawn from theinletport.
Backflow and siphoning do not occur, and the pump effectively sealsthe tube when it isinactive. No valves
areneeded.
The principle may be demonstrated by squeezing a soft tube between thumb and finger and sliding it
along: fluid isexpelled from oneend of thetube while more isdrawn in attheother.
Suitable applications
Peristalticpumping isidealfor mostfluids, including viscous, shear-sensitive, corrosive and abrasive fluids,
and those containing suspended solids. They are especially usefulfor pumping operationswhere hygiene
isimportant.
Peristaltic pumps operate on the positive displacement principle. They are particularly suitable for
metering, dosing and dispensing applications. Pumps are easy to install, simple to operate and
inexpensive to maintain.
1.8
Safety notes and standards
In the interests of safety, this pump and the tubing selected should only be used by competent, suitably
trained personnel after they have read and understood this manual, and considered any hazard
involved. If the pump is used in a manner not specified by WMFTG, the protection provided by the pump
may beimpaired.
Any person who isinvolved in theinstallation or maintenance of thisequipmentshould befully competent
to carry out the work. In the UK this person should also be familiar with the Health and Safety at Work Act
1974.
There are moving parts inside the pumphead. Before opening the pumphead guard or track,
ensure that the following safety directions are followed:
•
Ensure thatthepump isisolated from themainspower.
•
Ensure thatthere isno pressure in thepipeline.
•
If a tube failure hasoccurred, ensure that any fluid in the pumphead hasbeen allowed to drain to a
suitable vessel, container or drain.
•
Ensure that protective clothing and eye protection are worn if non-flammable hazardousfluidsare
pumped.
•
Primary operator protection from rotating parts of the pump is provided by the pumphead
safeguard. Note that safeguards differ, depending on the type of pumphead. See the pumphead
section of thismanual.
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