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Monthly Archives for **September 2009**

## Flow Regimes

Flow regimes describe the nature of fluid flow. There are two basic flow regimes for flow of a single-phase fluid: laminar flow and turbulent flow. Laminar flow is characterized by little mixing of the flowing fluid and a parabolic velocity … Continue reading

## Reynolds Number Piping

The Reynolds number is a dimensionless parameter that relates the ratio of inertial forces to viscous forces. It can be expressed by the following general equation: The Reynolds number can be expressed in more convenient terms. For liquids, the equation … Continue reading

## Pressure Drop In Piping

Piping design in production facilities involves the selection of a pipe diameter and a wall thickness that is capable of transporting fluid from one piece of process equipment to another, within the allowable pressure drop and pressure rating restraints imposed … Continue reading

## Relief Header Design

The relief header is a system of piping connecting the outlets of all the relief valves into a common pipe or header that goes to the relief scrubber and then out the vent as shown in Figure 13-11. There are … Continue reading

## Relief Valve Vent or Flare Tip

A pipe that releases gas to disperse into the atmosphere is called a vent. If the gas is burned at the tip, it is called a flare. In its simplest form, a vent or flare tip is a pipe. Sometimes … Continue reading

## Relief Valve Vent Scrubber

A vent scrubber is a two-phase separator designed to remove the liquid from the relieving fluids before the gas is flared or vented. The liquid is returned to the process. Design of vent scrubbers is covered in two-phase separators. A … Continue reading

## Relief Valve Installation

Each relief valve should be equipped with inlet piping no smaller than the valve inlet flange size, and inlet piping should be as short as practical. Inlet piping should be designed so that the pressure drop from the source to … Continue reading

## Two-Phase Flow Standard Sizes

Two-Phase Flow There are no precise formulas for calculating orifice area for twophase flow. The common convention is to calculate the area required for the gas flow as if there were no liquid present and the area required for the … Continue reading

## Liquids Flow Rate

Conventional Valve, Balanced-Bellows Valve, or Pilot-Operated Valve The corresponding equations for liquid flow are the following: Note that a preliminary orifice size must be determined in order to calculate Reynolds number. If the viscosity correction is significant, it may be … Continue reading

## Orifice Gas Flow Rate

The flow rate for gas through a given orifice area or the area required for a given flow rate is obtained by: