Air-Oil Heat Exchangers (5)
The “Drain” cooling method can only relieve part of the heat created by variable displacement pumps, whereby the remaining heat, from pump main-outlet to the working systems, will gradually increase the oil heat. Most people always focused on the fact that oil heat from the pump “Drain-Port” requires more attention, without realizing that the oil temperature level, from pump main-outlet, actually increases gradually and it also requires a similar attention.
Basically a “Separate” cooling method is advisable. If a “Return-Line” cooling method is used, a “by-pass” system is required, and in the case of incorrect installation, it may cause a cooler failure. In applying this method, one has to install a small pump, where the heated oil is circulated through the cooler and returns the oil back to the reservoir. This system has no pressure peaks within the hydraulic system. It will provide a safe & positive result. An economic coolant pump can be used in this “Separate” cooling system. In the case of a “Return-Line” cooling method being selected, please refer to your supplier for further assistance.
Most people felt that “Air-Oil Cooler” could only be effectively applied to lower Horse Power(HP) hydraulic systems, but with today’s technology, “Air-Oil Cooler” cooling system becomes more efficient for Heat Exchanger solutions. As a result, it could work with higher Horse Power(HP). e.g.: Even an “Air-Oil Cooler” unit with a single fan is able to work efficiently in a 100 HP Hydraulic Power Unit
The “Return-Line”cooling method is commonly used in China & Taiwan while the “Separate” cooling method is commonly used in USA & EUROPE. That is because, in China & Taiwan, hydraulic companies are using the assembling methods of “Water-Oil Cooler’ for “Air-Oil Cooler” application. you can find the disadvantages of using “Return-Line” cooling method in the following:
1). The absence of a “by-pass” or an incorrect cooling “by-pass” installation, may cause the cooler to burst.
2). Check Valve spring damage, caused by “Return-Line” flow action.
3). Inconsistency of heated oil from “Return-Line” flow will cause a negative effect on the hydraulic system.
4). Further to these factor, production stoppages fro repair purposes
“Separate” cooling method does not relate direct to the hydraulic system therefore will not have a negative effect despite the above disadvantages factors, because it is a separate unit entity by itself. Also the cooler unit failure will not effect the hydraulic operating system.
Flow Rate is one of the common ways that is mostly used to select a “Water-Oil Cooler” cooling system with no specific reason.Flow Rate is unable to provide a specific measurement of heat. Cooling is a supplementary support to Hydraulic systems and not just a part of the Hydraulic Components. Therefore a design and selection work is required before purchasing. For cooling measurement, equilibrium between the heat created by an Hydraulic system and the heat dissipated by a cooling unit is required.