MTS 318 Load Unit - Manual (Page 37)

318 Load Unit Safety 37
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.
Use only dry-pumped nitrogen to precharge nitrogen-charged accumulators.
(Dry-pumped nitrogen can also be labeled “oil pumped” or “dry water
pumped.”) Do not use compressed air or oxygen for precharging: the
temperature increase caused by rapid gas compression can result in highly
explosive conditions when hydraulic fluid is in the presence of oxygen or
compressed air.
• Always follow the recommended bleeding procedures before you remove or
disassemble components that contain pressurized gas. When you bleed a gas
or remove a fitting, hose, or component that contains a gas, remember that
many gases cannot support life. Therefore, as the ratio of released gas to
oxygen increases, so does the potential for suffocation.
• Wear appropriate safety devices to protect your hearing. Escaping air or gas
can create a noise level that can damage your hearing.
• Ensure that all pressurized air or gas is bled out of a pneumatic or gas-
charged device before you start to disassemble it. A thorough understanding
of the assembly and its pressurized areas is necessary before you undertake
any maintenance. Refer to the appropriate product information for the
correct bleeding procedure.
It might not be obvious or intuitive which bolts or fittings are used to
restrain a pressurized area. On some assemblies, you must remove a cover
plate to gain access to the structural bolts. Sometimes, to protect you from a
rapid release of trapped gases, a small port is exposed when you remove this
cover plate. Exposing this port ensures that the gas precharge is fully bled
before disassembly. However, this is not the recommended procedure for
bleeding a pneumatic or gas-charged device, because it can expose you to
the dangers of escaping compressed gas and particulates that are expelled
from the chamber or around the seals. Do not assume that cover plates and
ports are installed in all the critical locations.
Consult MTS when in doubt about the safety or reliability of any system-related
procedure or modification that involves devices that contain any type of
compressed gas.
Check bolt ratings and
torques
To ensure a reliable product, fasteners (such as bolts and tie rods) used in MTS-
manufactured systems are torqued to specific requirements. If a fastener is
loosened or the configuration of a component within the system is modified, refer
to the system and component assembly drawings (located on the System
Documentation CD) to determine the correct fastener, fastener rating, and torque.
Overtorquing or undertorquing a fastener can create a hazardous situation due to
the high forces and pressures present in MTS test systems.