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age and appropriate steps must be taken <strong>to</strong> con‐<br />

tain the spillage from polluting soils or under‐<br />

ground water sources. The seriousness of the<br />

regulation can be demonstrated by a spill incident<br />

at a site own by the Brookhaven National Labora‐<br />

<strong>to</strong>ry (BNL) in New York. A ruptured hydraulic hose<br />

has resulted in the removal of 50 cubic yards of<br />

contaminated soil and disposed as <strong>to</strong>xic material.<br />

This incident has led BNL <strong>to</strong> adopt the usage of<br />

environmentally safer hydraulic fluid based from<br />

canola oil [2].<br />

In order <strong>to</strong> make a hydraulic fluid <strong>to</strong> be safer for<br />

the environment the hydraulic fluid must be read‐<br />

ily biodegradable or in other word the fluid must<br />

be able <strong>to</strong> be completely converted <strong>to</strong> carbon<br />

dioxide and water quickly and naturally by diges‐<br />

tion or consumption process by naturally occur‐<br />

ring organism in water, oil and soil systems [2].<br />

Any spillage can then be cleaned up normally<br />

without the added cost of hazardous material<br />

handlings.<br />

To obtain the biodegradable features, previous<br />

researches has lead <strong>to</strong> the application of synthetic<br />

base fluid such as synthetic esters and polyglycols<br />

(organophosphate and polyalphaolefin). These<br />

synthetics base fluids were developed mainly for<br />

high temperature and/or fire risk operations and<br />

are able <strong>to</strong> biodegrade easily compared <strong>to</strong> petro‐<br />

leum based fluids [3]. The synthetics based fluids<br />

perform better compared <strong>to</strong> petroleum based<br />

fluids in term of viscosity at low and high tem‐<br />

peratures, volatility, pour point, wear protections<br />

and oxidations [3]. However, synthetic esters are<br />

expensive <strong>to</strong> produce and even for their superior<br />

lubrication performance, the high costs limit its<br />

usage. Polyglycols are less costly but can be quite<br />

<strong>to</strong>xic <strong>to</strong> living organisms especially when mixed<br />

with lubricating additives [3,4].<br />

<strong>MIMET</strong> Technical Bulletin Volume 1 (2) 2010<br />

Thus, a cheaper non <strong>to</strong>xic alternative <strong>to</strong> be used is<br />

vegetable oil as the base oil for hydraulic fluids.<br />

Among vegetable oils which has been researched<br />

and developed as hydraulic fluids are the canola oil,<br />

rapeseed oil, soybean oil and palm oil.<br />

Properties of Hydraulic Fluid<br />

Primary purpose of hydraulic fluids is <strong>to</strong> maintain<br />

lubrication and fluid characteristics while in use<br />

within the system so as <strong>to</strong> maintain appropriate<br />

pressure <strong>to</strong> operate hydraulic actua<strong>to</strong>rs (cylinders<br />

and mo<strong>to</strong>rs) assemblies in machineries on demand.<br />

An ideal hydraulic fluid will have the following char‐<br />

acteristics [3, 5,6]:<br />

Viscosity<br />

1. Constants viscosity at all temperature<br />

range<br />

2. High anti‐wear characteristics<br />

3. Thermal stability<br />

4. Hydrolytic stability<br />

5. Low chemical corrosiveness<br />

6. Low cavitation tendencies<br />

7. Long life<br />

8. Fire resistance<br />

9. Readily biodegradable<br />

10. Low <strong>to</strong>xicity<br />

11. Low cost<br />

For hydraulic fluids, the temperature effect on<br />

viscosity is very important. A good fluid can main‐<br />

tain a minimum required viscosity at high operat‐<br />

ing temperature yet does not become <strong>to</strong>o viscous<br />

at lower temperature. Too much viscosity may<br />

result in difficulty for the fluid <strong>to</strong> transmit hydrau‐<br />

lic power at low temperature especially at system<br />

start.<br />

Anti Wear<br />

The ability of the fluid <strong>to</strong> coat moving metal parts<br />

with a thin protective oil film. The oil film will re‐<br />

| MARINE FRONTIER @ <strong>UniKL</strong><br />

63

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