ANCILLARY DEVICES IN HYDRAULIC SYSTEM
Ancillary hydraulic devices are significant components that do not fall under the main categories of pumps, conductor, and actuators. Some of the main ancillary devices are accumulators, reservoir, pressure gauge, heat exchanges, and filters and strainers.
Filters and strainers: A filter has a filter element which contains millions of tiny pores. A strainer is a course comprises of a wire screen with openings usually greater than 149 microns. A bypass valve is sometimes included in a filter to protect against the filter-burst (Parambath 2016, p.68). The diagram below depicts filters categorized according to installation locations. Suction strainer, for example, is installed at the pump suction side. It is a coarse filter made of a piece of wire mesh, having a mesh width greater than or equal to 149 microns. It provides protection to the pump from the coarse particles (Parambath 2016, p.73).
Figure 1: A partial hydraulic system schematic with various location-specific filters (Parambath 2016, p.74)
Hydraulic reservoirs: a reservoir system requires a sufficient amount of high-quality fluid every moment for the realization of efficient operation. A properly designed reservoir should have the following. It permits a reasonable dwell time for the system fluid, helps in dissipating heat from the fluid, and permits most of the foreign matter to drop out of the fluid. It also allows air bubbles within the fluid to come to the surface and get dissipated, compensates for the fluid volume changes that may occur in the system that is caused by temperature variations, and provides a convenient mounting place for the system pump-motor unit and valves (Parambath 2016, p.88). The reservoir should be located in an area in which air properly circulates for speedy dissipation of heat (Parr 2011, p.149). The servicing parts of the reservoir such as filters must be located in accessible areas for the ease of maintenance.
Heat exchangers: when the cooling effect from the reservoir is inadequate, then a heat exchanger must be fitted to raise the rate of heat dissipation in the hydraulic system. The heat exchangers are expensive, and their maintenance is not economical. The two commonly used heaters in a hydraulic system are water-cooled heat exchanger and air-cooled heat exchangers (Parambath 2016, p.94).
Pressure gauge: this device is used for measuring pressure level in the hydraulic system. It offers the safety measures as it serves the purpose of monitoring the overpressures in the system and aids in troubleshooting (Parambath 2016, p.90). A pressure gauge is fitted with shut-off valve or gauge isolator which enables personnel to conduct maintenance without interrupting the hydraulic system (Parr 2011, p.19; Parambath 2016, p.90). Also, the gauge isolator helps in prolonging the service life of a permanently fixed pressure gauge.
Accumulators: they serve many purposes in a hydraulic system. The primary functions are energy storage and shock absorber. Others include dampening of pressure pulsation, compensating leakages, energy recovery, and auxiliary power unit (Parambath 2016, p.286).
To sum up, ancillary devices in any real hydraulic system play crucial roles. Proper designing with correct specifications and locations are significant for high performance.
Parambath, J., 2016. Industrial hydraulic systems: theory and practice. Boca Raton, FL: Universal-Publishers.
Parr, E. A., 2011. Hydraulics and Pneumatics: a technician’s and engineer’s guide. Oxford, UK: Butterworth-Heinemann.