Computer Sizing (FIRSTVUE)
Fisher Liquid Sizing
Fortunately, sizing software allows specifiers to quickly calculate C v requirements and to evaluate veral different valve types and sizes. The fluid properties and rvice conditions that are required to perform a basic sizing calculation (no viscosity corrections and a non-cavitating fluid) are discusd below.
Fluid (Liquid) - Enter the name of the fluid, or lect a fluid that is in the databa. If a fluid is lected from the databa, some physical properties are automatically inrted in the proper fields. For liquids, Pc is supplied.
Specific Gravity (SG) - The SG of the fluid at flowing conditions may be found in process data and other sources. The Fisher Control Valve Handbook also lists physical properties for many fluids in the tables that begin on page 200.
P1 - The upstream pressure. Obrve the units option that has been lected. Recall that a pressure in psig is converted to psia by adding 14.7 (or the local atmosphereic pressure) to the pressure in psig.
dP - The differential pressure across the valve; i.e., P1 minus P2 - dimensionless. T - The temperature of the fluid at the valve inlet. Obrve units.
Q - The flow rate. Obrve units.
K m - The recovery coefficient of the lected valve. Values are published in Fisher Catalog 10 and they are shown in the C v tables in the FirstVue software.
P v - The vapor pressure of the fluid. Refer to supplied process data and the Control Valve Handbook tables that begin on page 200.
P c - Critical Pressure of the fluid. Refer to supplied process data and the Control Valve Handbook tables that begin on page 200.
Valve Type - Select from standard or specialty type valves from the pull-down menu.
Downs Pipe Size - Size, in the engineering units specified during tup, of the piping downstream of the control valve.
Downs Pipe Sched - Schedule of the piping downstream of the control valve. Select from a pull-down menu.
Figure3-23. FIR STV UE V alve Sizing Screen For the Fisher Liquid Method
Exerci 1. Size a Control Valve for Propane Flow A. Fisher Method
Using the Fisher Equations in FIRSTVUE, perform the following:
Procedures are given on the following page.
1.Launch and tup the software
2.Solve for the required C v using the Fisher liquid equations
3.Select a valve type
4.Develop a specification and enter the information that is required at the
bottom of this page.
General Information
Valve Type: Sliding Stem
Fluid:Propane (liquid)
Line Size: 14” Schedule 40
Shutoff: ANSI Class II
Characteristic: Equal Percentage
Service Conditions
Minimum Flow Maximum Flow Shutoff
P1, psig141011101450
DP, psi40015600
T, deg. F606060
Q, gpm127525000
Valve Specification
Minimum Flow C v:Maximum Flow C v:
Valve Type:Size (Body/Port): / ANSI Class:Body Material:
% Travel @ Minimum Flow:% Travel @ Maximum Flow: Yoke Boss Diameter:Stem Size:
Trim #:Packing:
Procedures for Exerci 1
Launch and Setup FIRSTVUE
For the steps that follow, refer to the figure above.
Step 1.To launch the FIRSTVUE Sizing Program, click on the Windows Start button, then lect Programs,Firstvue, and FIRSTVUE.
Step 2.Click on the Sizing tab.
Step 3.Ensure that only the Minimum and Maximum conditions are highlighted
Step 4.Click on the Sizing Config button. A screen similar to the one below will appear.
Step 5.Click on the All English button
Step 6.Review the other fields on this screen.
Step 7.Click on OK.
