User Guide

ManualsBrandsBarber Colman ManualsHVAC Replacement Parts1-1/4" NPT Two-Way Valve (20 cv)

Application

VB-7273 series single seat, stem down to close,

two-way valves control water from 20 to 400°F

(-7 to 204°C) or steam to 400°F (204°C) max. in

heating or air conditioning systems. These valves have

stainless steel seat and plug. They are used for two-

position or proportional control applications. Valve

assemblies require an actuator and a valve linkage that

must be purchased separately.

Danger:

Do not use for combustible gas applications.

The VB-7273 series valve packings are not rated for

combustible gas applications, and if used in these

applications, gas leaks and explosions could result.

Features

• Valve sizes 1/2" to 2"

• 250 psig pressure rating per ANSI Standards

(B16.15–1985)

• Spring-loaded TFE packing

• American Standard Taper Pipe Thread (NPT)

connections

• Stainless steel seat and plug

Applicable Literature

• TAC Valve Products Catalog, F-27384

• TAC Cross-Reference Guide, F-23638

• TAC Reference Manual, F-21683

• TAC Application Manual, F-21335

• Control Valve Sizing, F-13755

• Valve Selection Chart for Steam, F-11366

• Valve Selection Chart for Water, F-11080

• EN-205 Water System Guidelines, F-26080

VB-7273 Series

1/2" to 2" Screwed NPT

Stainless Steel Trim

Stem Up Open, Two-Way Valves

General Instructions

Summary of content (12 pages)

PAGE 1
VB-7273 Series 1/2" to 2" Screwed NPT Stainless Steel Trim Stem Up Open, Two-Way Valves General Instructions Application VB-7273 series single seat, stem down to close, two-way valves control water from 20 to 400°F (-7 to 204°C) or steam to 400°F (204°C) max. in heating or air conditioning systems. These valves have stainless steel seat and plug. They are used for twoposition or proportional control applications. Valve assemblies require an actuator and a valve linkage that must be purchased separately.
PAGE 2
SPECIFICATIONS Table-1 Specifications/Models.
PAGE 3
Normal Position of Valve Assembly For a valve assembly (valve, linkage, and actuator) to have a normal (spring return) position, the actuator must be of the spring return type. See Table-2 for normal position of valve assemblies. Table-2 Required Compatible Actuators/Linkages. Actuator Series Required Valve Linkage Normal Position MA-318, MA-418, MA-419 AV-391 N.O. or N.C.
PAGE 4
100% 90% 80% Flow 70% 60% 50% 40% 30% 20% 10% Closed Stroke 90% 100% 80% 70% 60% 50% 40% 30% 20% 10% 0% 0% Open Figure-1 Typical Modified Equal Percentage Flow Characteristics. Rangeability Rangeability is the ratio of rated flow to the minimum controllable flow through a valve. Table-3 lists the rangeability for VB-7273 series valves. Table-3 Rangeability.
PAGE 5
270 psig (1863 kPa) Temperature — °F (°C) 400 (204) 350 (176) Maximum Media Temperature 300 (149) 400°F (204°C) 250 (121) 200 (93) 150 (65) 100 (38) 50 (10) Minimum Fluid Temperature 20°F (-7°C) 50 (345) VB-7273-0-4-P 150 (1034) 100 (689) 250 (1724) 200 (1379) 350 (2458) 300 (2068) 400 (2758) Pressure — psig (kPa) Figure-2 Temperature and Pressure Ratings for VB-7273 Series Valve Bodies. F-24390-2 © Copyright 2008 TAC All Rights Reserved.
PAGE 6
VALVE SIZING AND SELECTION Water Two-position Two-position control valves are normally selected “line size” to keep pressure drop at a minimum. If it is desirable to reduce the valve below line size, then 10% of “available pressure” (that is, the pump pressure differential available between supply and return mains with design flow at the valve location) is normally used to select the valve.
PAGE 7
Steam Two-position Two-position zone valves and direct radiation valves are normally sized using a minimum of 10% of inlet pressure (psig). Proportional Proportional control valves are normally sized using: • For low pressure (15 psig or less), use ΔP of 80% of gauge inlet pressure. • For steam pressures greater than 15 psig, use ΔP of 42% of absolute (gauge plus 14.7) inlet pressure. • When the Cv required is between two valve sizes, select the larger size.
PAGE 8
Cv Equation Cv = QK Q = 3 ΔP • P2 3Cv ΔP • P2 K Where: Cv = Coefficient of flow Q = Lbs. per hour of steam ΔP = Differential pressure in psi (pressure drop) P2 = Outlet pressure in psia (absolute) (P2 = Inlet pressure + 14.7 – ΔP) K = 1 + (0.0007 x °F superheat) (K = 1 for saturated steam) Cavitation Limitations on Valve Pressure Drop A valve selected with too high a pressure drop can cause erosion of discs and/or wire drawing of the seat.
PAGE 9
INSTALLATION Inspection Requirements Inspect the package for damage. If damaged, notify the appropriate carrier immediately. If undamaged, open the package and inspect the device for obvious damage. Return damaged products. • Tools (not provided): Pipe wrenches • Training: Installer must be a qualified, experienced technician • Appropriate accessories Caution: • Install the valve with the flow in the direction of the flow arrow (“A” port is the inlet and “AB” port is the outlet).
PAGE 10
Valve Assembly Tighten pipe using this pipe wrench. Use pipe wrench to prevent valve from turning. Figure-4 Installation of Screwed End Valves. CHECKOUT 1. Make sure the valve stem operates smoothly before installing the valve linkage and the actuator. 2. If the stem does not operate smoothly , it may indicate that the valve was twisted or crushed during installation or that the stem was bent by rough handling. These conditions may require that the valve be replaced. 3.
PAGE 11
Water System Maintenance All heating and cooling systems are susceptible to valve and system problems caused by improper water treatment and system storage procedures. These guidelines are provided to help avoid valve and water system problems resulting from improperly treated water or storage procedures in cooling and hot water systems, and to obtain maximum life from TAC valves. Durability of valve stems and packings is dependent on maintaining non-damaging water conditions.
PAGE 12
Copyright 2008, TAC All brand names, trademarks and registered trademarks are the property of their respective owners. Information contained within this document is subject to change without notice. F-24390-2 TAC 1354 Clifford Avenue P.O. Box 2940 Loves Park, IL 61132-2940 www.tac.