Instrumentation 2 Ch. 46-51 Test 4/final exam

the primary function of the National Electric Code is to safeguard people and property against hazards due to boiler explosions

False

electrical classifications for hazardous locations are identified by class, division, and ____

group

a class ____ location is a hazardous location in which sufficient quantities of combustible dust are present in the air to cause an explosion or to ignite the hazardous material

II (2)

a ____ is the classification assigned to each class based upon the likelihood of the presence of the hazardous substance in the atmosphere

division

a division 2 location is a hazardous location in which the hazardous substance is normally present in the air in sufficient quantities to cause an explosion or to ignite the hazardous materials

False

An enclosure ____________________ is a designation that specifies the maximum surface skin temperature obtained by a piece of equipment during testing by approval agencies.

temperature code

Explosionproof protection is a type of protection that excludes ignitable amounts of dust or amounts that can affect performance or rating.

False

A ___ is the classification assigned to each class based upon the likelihood of the presence of the hazardous substance in the atmosphere.

enclosure

A common enclosure for Class I hazardous locations is a Type ___ enclosure.

7

A(n) ___ enclosure is a nonhazardous enclosure that is pressurized and purged with air to allow it to be used in hazardous areas.

purged

the wiring requirements in hazardous areas are defined by ____

NEC (National Electric Code)

____ protection is where the electrical equipment, under normal or abnormal conditions, is incapable of of releasing sufficient electrical or thermal energy to cause ignition

intrinsically safe

A(n) ____________________ is a specially designed electronic circuit containing resistors and diodes which is used to prevent any electrical ignition energy from being carried into a hazardous area.

intrinsic barrier

A safety instrumented system (SIS) is a system consisting of sensors, logic solvers, and final control elements that bring a process to a safe state when ___.

normal operating conditions are violated

The Occupational Safety and Health Administration has publicly identified the ___ standard as a "good engineering practice" when following OSHA regulations on the management of highly hazardous chemicals.

ISA S84

Risk is used to evaluate ___ and the consequences if a failure does happen.

how often a failure can happen

One common theme in all safety systems is to have ___, which increases the integrity level and reduces the residual risk.

multiple levels of protection

A(n) ___ incident is one that could cause any serious injury or fatality on-site or property damage of $1 million off-site or $5 million on-site.

serious

A(n) ___ likelihood means that a failure, or series of failures, has a low probability of occurrence within the expected lifetime of the plant (1 in 100 to 1 in 10,000 per year).

occasional

The IEC, ISA, and AIChE define integrity levels in terms of ___, probability of failure on demand (PFD), and risk reduction factor (RRF).

severity

A(n) ___ is a highly reliable PLC that includes fail-safe designs, built-in self-diagnostics, and a fault-tolerant architecture.

safety PLC

With ___ polling, redundant tripping signals from dual PLCs are needed to shut down a system.

2oo2

System monitoring is the process of providing notification to an operator that there has been a failure in the process controlled by an SIS.

True

two common types of operations are continuous and batch processes

True

A(n) ___ control valve is an application where there are two or more control valves which operate using the same controller output signal range, with each valve using a portion of the controller output signal.

split range

Heating control valves are usually selected to have a fail closed action, and cooling control valves are usually selected to have a(n) ____________________ action.

fail open

Split range control valves can also be used to establish the order in which control valves are operated, and thus the priority between different operations.

True

A ___ is a device that compares two or three input signals and passes the highest or lowest signal to the output of the device.

selector

A ___ controller is used for those applications where control action is only desired above or below predetermined values.

gap action

A ___ controller is the arrangement of two controllers where a primary controller adjusts the setpoint of a secondary controller.

cascade

A(n) ___ selector can be used to select the highest of a group of measurements to be used as the controller input.

high

___ is the condition where a controller continues to change its output until the output reaches its limit.

rest windup

The amount of heat transferred in a heat exchanger depends on the temperature difference, the area of the exchanger, and the ___.

heat transfer coefficient

A thermal expansion ___ must be used to protect heat exchangers from excessive pressure if the fluids can be valved off and trapped in the exchanger.

safety relief valve

A ___ is a vertical vessel used in batch processing whose sides and bottom are covered with a steel shell and is used to contain a heating or cooling fluid.

jacketed reactor

A ___ is any piece of equipment that transfers heat from one material to another.

heat exchanger

A shell-and-tube heat exchanger typically consists of process fluid contained in ___ that run the length of the shell.

tubes

With a heat exchanger, the temperature of the process fluid can be measured with a temperature-sensing element inserted into the ___ fluid piping.

outlet process

If the process fluid temperature in a heat exchanger can get high enough to boil the cooling water, a(n) ___ must be used to handle any steam that can be generated.

relief valve

A steam-controlled heat exchanger has the steam throttled on the ___ to the heat exchanger.

inlet

In almost all steam heating applications, the control valve should have a(n) ___ action.

fail closed

For a steam valve with a fail closed action, the controller action should be_____.

reversed