Environmental Engineering Reference
In-Depth Information
4.14.4.1.2 Trap Testing
Note: A word of caution is advised before testing any steam trap.
Inspectors should be familiar with the particular function and types of
traps and should know the various pressures within the system. This
can help to ensure inspector safety, help avoid misdiagnosis, and allow
proper interpretation of trap conditions.
The three main categories of online trap inspection are visual, ther-
mal, and acoustic. visual inspection depends on a release valve situ-
ated downstream of certain traps. A maintenance operator opens these
valves and looks to see if the trap is discharging condensate or steam.
Thermal inspection relies on upstream/downstream temperature varia-
tions in a trap. It includes pyrometry, infrared, heat bands (which are
wrapped around a trap and change color as temperature increases), and
heat sticks (which melt at various temperatures). acoustic techniques
require a maintenance operator to listen to and detect steam trap opera-
tions and malfunction. This method includes various forms of listening
devices such as medical stethoscopes, screwdrivers, mechanical stetho-
scopes, and ultrasonic detection instruments.
Note: A simple trap test—just listening to the trap action—tells us how
the trap is opening and closing. Moreover, if the trap has a bypass line
around it, leaky valves will be apparent when the main line to the trap is
cut off, forcing all of the fluid through the bypass.
4.15 PiPing anCillaries
Earlier, we described various devices associated with process pip-
ing systems designed to protect the system. In this section, we discuss
some of the most widely used ancillaries (or accessories) designed to
improve the operation and control the system. These include pressure
and temperature gauges, vacuum breakers, accumulators, receivers,
and heat exchangers. It is important for us to know how these ancillary
devices work, how to care for them, and, more importantly, how to use
them.
4.15.1 system Parameters
To properly operate a system, any system, the operator must know
certain things. As an example, to operate a plant air compressor the
operator must know: (1) how to operate it, (2) how to maintain it, (3)
how to monitor its operation, and, in many cases, (4) how to repair it. In
short, the operator must know system parameters and how to monitor
them. Simply, operating parameters refer to the physical indications
of system operation. The term parameter refers to the limits or restric-
tions of a system. Let's consider, again, an air compressor. Obviously, it
is important to know how the air compressor operates or at least how to
start and place the compressor online properly; however, it is also just
as important to determine if the compressor is operating as per design.
Experienced operators know that to ensure that the air compressor is
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