Figure 4-5.-Spring-loaded bellows actuated valve.
inspections during equipment operations and according
PRESSURE CONTROL VALVES. There are
to the PMS.
several different types and models of pressure control
valves. For example, pressure control valves include
You can test this type of valve by using either of two
relief, reducing, and regulating valves. Because of the
methods: (1) by monitoring the valve during normal
large selection of pressure control valves, we will limit
operations to ensure it is maintaining the desired
our discussion to regulating valves.
temperature of the liquid or gas, or (2) by removing the
sensor bulb, artificially raising the temperature, and
There are two basic types of MRG LO pressure
monitoring the valve movement. Although you can raise
regulating valves used on gas turbine-powered ships:
the temperature by using either calibration equipment or
(1) pneumatic pressure regulating valves and (2)
a hot plate to heat the water, it is recommended that you
self-contained pressure regulating valves.
use the calibration equipment because it will provide
Pneumatic Pressure Regulating Valves. In
you with a better means of temperature control.
several sections of our discussion of automatic control
valves, we have already described the normal operation
and components of the basic pneumatic pressure
NOTE
regulating valve. For this reason, we will limit our
discussion to the following paragraphs on the
self-contained pressure regulating valves.
The ability to control temperature during a
test is crucial. Using a hot plate will not give
Self-Contained Pressure Regulating Valves. A
you that flexibility.
typical example of a self-contained pressure regulating
