Chapter 9: Pneumatic Actuators, Dampers, and Valves

Valve _____ is the relationship between the maximum flow and the minimum controllable flow through a valve.

turn down ratio

A(n) _____ valve has two pipe connections.

two-way

A(n) _____ is a device that controls the flow of fluids in an HVAC system.

valve

A(n) _____ is a valve component that consist of a metal shaft, normally made of stainless steel, that transmits the force of the actuator to the valve plug.

valve stem

Spring range is the difference in pressure at which an actuator shaft moves and stops.

True

Steam valves are always two-way valves because steam does not require a return to the steam header or boiler.

True

Most air handling systems use normally open outside air dampers because the outside air causes excessively cold conditions in the winter and excessively hot and humid conditions in the summer.

True or false. It depends on the location.

_____ characteristics are the relationship between the valve stroke and flow through the valve.

Valve flow

A(n) _____ is a device that accepts a signal from controller and causes a proportional mechanical motion to occur.

actuator

A(n) _____ valve is a valve with a round plate that rotates to control flow.

butterfly

A(n) _____ is an adjustable metal blade or set of blades used to control the flow of air.

damper

A(n) _____ is a flexible device that transmits the force of the incoming air pressure to the piston.

diaphragm

A(n) _____ valve is a valve is a valve in which the flow through the valve is equal to the amount of valve stroke.

linear

A(n) _____ valve is a three-way valve that has two inlets and one outlet.

mixing

A(n) _____ valve does not allow fluid to flow when the valve is in its normal position.

normally closed

Spring range _____ is a condition in which actuators with different spring ranges interfere with each other.

overlap

A(n) _____ is a device that transfers the force generated by the air pressure against the diaphragm to the spring and shaft assembly.

piston cup

Valve _____ is performed when a valve is mechanically damaged or the internal parts are worn by foreign material or wire drawing.

rebuilding

A normally closed valve allows fluid to flow when the valves is in its normal position.

False

_____ is a bulk deformable material or one or more mating deformable elements reshaped by manually adjustable compression.

Packing

_____ blade dampers are the most common damper used in HVAC systems.

Parallel