Product Overview

ManualsBrandsBarber Colman ManualsHVAC Replacement Parts1" NPT Two-Way Valve (12 cv)

TAC

1354 Clifford Avenue

P. O. Box 2940

Loves Park, IL 61132-2940

www.tac.com

Application

VB-7253 series single seat, stem down to close,

two-way valves control water from 20 to 340°F

(-7 to 171°C) or steam to 340°F (171°C) max. in

heating or air conditioning systems. These valves have

stainless steel trim with a Teflon

disc. 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-7253 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 Teflon disc

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-7253 Series

1/2" to 2" Screwed NPT

Stainless Steel Trim with Teflon Disc

Stem Up Open, Two-Way Valves

General Instructions

Summary of content (12 pages)

PAGE 1
VB-7253 Series TAC 1354 Clifford Avenue P. O. Box 2940 Loves Park, IL 61132-2940 www.tac.com 1/2" to 2" Screwed NPT Stainless Steel Trim with Teflon Disc Stem Up Open, Two-Way Valves General Instructions Application VB-7253 series single seat, stem down to close, two-way valves control water from 20 to 340°F (-7 to 171°C) or steam to 340°F (171°C) max. in heating or air conditioning systems. These valves have stainless steel trim with a Teflon® disc.
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 MA-318, MA-418, MA-419 MA-5210, MA-5211, MA-5213 Normal Position AV-391 N.O. or N.C.
PAGE 4
Rangeability Rangeability is the ratio of rated flow to the minimum controllable flow through a valve. Table-3 lists the rangeability for VB-7253 series valves. Table-3 Rangeability.
PAGE 5
than 60°F (33°C) for conventional heating systems, higher pressure drops across the valve are needed for good results (Table-4). Table-4 Conventional Heating System. a Design Temperature Load Drop °F (°C) Recommended Pressure Dropa (% of Available Pressure) Multiplier on Load Drop 60 (33) or More 50% 1 x Load Drop 40 (22) 66% 2 x Load Drop 20 (11) 75% 3 x Load Drop Recommended minimum pressure drop = 5 psi (34 kPa).
PAGE 6
Table-6 Steam Capacity in Pounds Per Hour for VB-7253 Series. Differential Pressure (ΔP in psi) a Valve Body Part Number Cv Rating 2 psig Inlet 5 psig Inlet 10 psig Inlet 15 psig Inlet 20 psig Inlet 25 psig Inlet 0.2 1.6 0.5 4 1 8 1.5 12 2 14 2.5 16 VB-7253-0-4-1 0.4 2.2 5.9 3.7 9.5 5.8 14 7.8 18 9.7 20 12 23 VB-7253-0-4-2 1.3 7.1 19 12 31 19 45 25 57 32 66 38 76 VB-7253-0-4-3 2.2 12 32 20 52 32 76 43 96 53 112 64 129 VB-7253-0-4-4 4.
PAGE 7
For example, if a valve is controlling 200°F water at an inlet pressure of 18 psig, the maximum pressure drop allowable would be: Pm = 0.5 [(18 + 14.7) – 11.53] = 10.6 psi (Vapor pressure of 200°F water is 11.53 psia.) If the pressure drop for this valve is less than 10.6 psi, cavitation should not be a problem. Systems where cavitation is shown to be a problem can sometimes be redesigned to provide lower inlet velocities. Table-7 Vapor Pressure of Water Table.
PAGE 8
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 9
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 10
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 2006, 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. TAC 1354 Clifford Avenue P.O. Box 2940 Loves Park, IL 61132-2940 F-24388-1 www.tac.