MTS Hydraulic Power Unit Model 506-92 - Manual (Page 17)

Service 3-5
3.1.2 Hydraulic Fluid
Regular maintenance of hydraulic fluid maximizes the service life of the
system and its components.
Daily fluid checks Check the fluid-level in the transparent gage. A low level can indicate a
leak. A high level can indicate water contamination from the heat
exchanger. If the fluid appears to have changed significantly, obtain a
sample from the HPU reservoir and check it for the following qualities:
• Considerable darkness, burnt odor, or an opaque quality of the fluid
indicates chemical breakdown. It may also indicate that the fluid
temperature was too high. Replace the fluid.
• During operation, a milky appearance indicates water is present in
the fluid. If the system is not in operation, water separates from the
hydraulic fluid and settles at the bottom of the reservoir. If water
contamination is present, correct the source of the water leakage and
replace the hydraulic fluid.
Monthly fluid
checks Perform these checks monthly or every 150 operating hours (whichever
comes first).
• Keep records of the maximum reservoir temperature. High operating
temperatures can cause the fluid to break down.
• Check for contamination and fluid breakdown. Take a fluid sample
and test the pH level using a pH kit (available from chemical stores).
Also, check the sample for color and odor.
• Take a fluid sample and let it stand overnight. Sediment at the bottom
of the fluid indicates collapsed, ruptured or clogged filters.
Yearly (every 500
operating hours)
fluid checks Obtain a sample of the fluid and have it analyzed. The fluid tests should
include chemical analysis, particle count, and viscosity checks. Record the
results and replace the fluid if necessary.