Revision 1
immobilized in the "OFF" position by means of a safety catch. The gun may be fitted
with a shoulder pad or hand grips to facilitate back thrust control.
16.
Retro
gun
- A retro safety gun is fitted with forward and backward facing jets. This
reduces the thrust experienced by the operator. This type
of
gun is used mainly for
underwater high pressure water jetting operations. The retro balance jet protection tube
should be sufficiently long or constructed so as to prevent the operator from directing a
retro balance jet at himself.
17.
Changeover
valve -
An
operator-controlled valve designed to properly direct high
pressure water flow from the pump (IIID#l above) to one (1) or another items of
equipment at the operator's choice.
It
shall be designed to withstand the maximum
pressure and can be power operated.
E.
Care
and
Maintenance of Equipment
1.
High
Pressure
Water
Jetting
Unit
- The unit shall be maintained in accordance with
NLB's instructions. Where applicable, this should include daily checks on the
following items:
a.
Drive - Lubricating oil, water, hydraulic fluid, and fluid levels
b.
High
pressure
pump
- Lubricating oil and gear box oil levels
c.
Hydraulic
hose reel - Lubricating oil and fluid levels
d.
Condition
of
guards
and
shields - Wear and/or damage
2.
Filters
and
strainers
- All water filters should be checked at regular intervals,
dependent upon the supply water conditions and in accordance with NLB's
recommendations.
Extreme care should be taken
to
filter the water source through proper micron
filtration, to prevent foreign particles from cutting changeover valves and seating
surfaces and to prevent clogging the changeover valve operating mechanism. Such
clogging can cause a loss
of
control, which can be dangerous
to
the lance/gun operator.
3.
Hose assemblies - All hose assemblies shall be inspected prior
to
use with respect to
the following:
a.
Correct pressure rating and size
b. Free from external damage - e.g., exposed or broken wires
c.
All end fittings and couplings are in good order and of the correct pressure rating for
the unit operating pressure
4.
Nozzles - All jetting nozzles shall be kept clean and the orifice shall be checked
to
ensure that it is not obstructed or damaged before installation. Defective nozzles shall
not be used but should be replaced or repaired before installation. During the start-up,
© Copyright January,
2001
NLB Corporation
2-17
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