MTS 85X Damper - Manual (Page 20)

Damper System Operation 20 Safety
Remember, when hydraulic power is interrupted on a servohydraulic system, it is
likely that stored accumulator pressure will persist for some time within the
system. In addition, it is likely that as stored energy dissipates, gravity will cause
portions of the system to move.
Be aware of
component movement
with hydraulics off
A load frame crosshead can slowly drift down the columns if the locks are turned
off and when hydraulic pressure is turned off. The crosshead can damage any test
fixtures, grips, and specimen in its path. Unlock the crosshead only to reposition
it. Always lock the crosshead after you have repositioned it and never leave the
crosshead unlocked.
The actuator rod can also drift down when hydraulics are turned off hitting
anything in its path. This uncommanded movement is because of oil movement
between the pressure/return ports and oil blow by across the piston hub. Be aware
that this can happen and clear the area around the actuator rod when hydraulics
are turned off.
Know electrical
hazards
When the system electrical power is turned on, minimize the potential for
electrical shock hazards. Wear clothing and use tools that are properly insulated
for electrical work. Avoid contact with exposed wiring or switch contacts.
Whenever possible, turn off electrical power when you work on or in proximity
to any electrical system component. Observe the same precautions as those given
for any other high-voltage machinery.
Make sure that all electrical components are adequately grounded. Grounds must
remain connected and undisturbed at all times.
Keep bystanders
safely away
Keep bystanders at a safe distance from all equipment. Never allow bystanders to
touch specimens or equipment while the test is running.
Wear proper clothing
Do not wear neckties, shop aprons, loose clothing or jewelry, or long hair that
could get caught in equipment and result in an injury. Remove loose clothing or
jewelry and restrain long hair.
Remove flammable
fluids
Remove flammable fluids from their containers or from components before you
install the container or component. If desired, you can replace the flammable
fluid with a non-flammable fluid to maintain the proper proportion of weight and
balance.
Know compressed gas
hazards
Most servohydraulic systems contain accumulators that require a high-pressure
gas precharge (pressures that exceed 138 bar [2000 psi]). In addition, some
systems can contain devices, such as static supports, that are pneumatically
operated. High-pressure devices are potentially dangerous because a great
amount of energy is available in the event of an uncontrolled expansion or
rupture.
Observe the following safety practices when you work with high-pressure air or
gases:
• When you charge an accumulator, follow all the charging instructions
provided in the appropriate product information manuals. When precharging
accumulators, properly identify the type of gas to be used and the type of
accumulator to be precharged.