Gear pumps are the most common positive displacement devices. They are used in almost every industry in which dense liquid transfer is required. There are two major types of gear pumps internal and external. Both these types are explained as under:
Internal gear pumps
Internal gear pumps have two types of gears. One is known as drive and the other is known as an idler. Thin and thick liquids are pumped at the same speed using this pump. With a large density range there are many applications which use internal gear pumps. This type of pump also has a high range of temperature and the variation is also great. The end clearance has single point due to which the temperature alteration is handled. The internal pump has clearance which can also be altered. The clearance factor is one which allows the internal gear pumps to work with high efficiency. There are several other factors which are associated with clearance. The pumping and density of liquids are made more efficient if the clearance value is altered.
Advantages of internal pumps
There are several advantages which are associated with internal gear pumps. Some of these are as follows:
- The internal gear pumps are self-priming.
- Such pumps can also run dry for small intervals
- The rotation is multi-dimensional which means that internal gear pumps can also be used for other purposes.
- The internal pumps are very reliable and are easy to install. The maintenance cost is also close to zero which means that over cost reduction is likely to increase of this pump is used.
- These pumps require no technicalities for operation. Even a novice user can be deployed to operate these pumps as their structure is too easy to understand.
External gear pumps
As compared to internal gear pumps the external ones are applied in a large number of industries. The main applications of external pumps are oil stations, gas pumps and large food industries. There are many types of external gear pumps. Some of these are as follows:
The spur type pumps offer rough passage of fluids as compared to helical and herringbone types. Mostly herringbone types are used as they have less sound and the smooth passage is allowed. Another astonishing fact is that the large external pumps operate slowly as compared to small pumps. The shafts of external gear pump also allow support from both ends. They are ideal as they work in line with the hydraulic mechanics. Precision is another factor which external pumps offer. The internal tight clearances allow preserving precision factor. Operators enjoy full control over fluid transfer which makes it most used the device in many industries.
Advantages of external gear pumps
- These devices have high speed and work very swiftly
- The less sound make them ideal for all environments
- The design can be customized and a wide range of fluids can be pumped
- The pressure as compared to all other types is high and offers precise measurement of liquids