Page 118 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

PIPING

2.68 CHAPTER TWO

FIGURE 2.39 Lower portion of conduit valve.

Flow Control Valve
This valve operates by using a calibrated orifice or venturi tube to control the flow of liquid
to a predetermined set point regardless of fluctuating line pressure.

Pressure Control Valve
Similar to the flow control valve, this valve limits the pressure of a flowing liquid to a
predetermined set point regardless of fluctuating flow rate.

Level Control Valve
This valve accurately controls the level of liquid in a tank or vessel. An altitude valve uses
a controlling device to maintain the level, and a float valve uses a movable float on an arm
(similar to that in a water closet) to stop the flow at a predetermined level.

Conduit Valve
A conduit valve (Fig. 2.39) is used where an unobstructed opening through the valve is
required, such as when pigs are used to clean the pipeline.

METALLIC ALLOY DESIGNATIONS

The Unified Numbering System (UNS) is intended to correlate the many metal alloy number-
ing systems currently administered by North American technical societies, trade associa-
tions, individual users, and ASTM. Prior to the introduction of the UNS by the ASTM,

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