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Instruction Manual
D104420X012
Fisher
Yarway
™
Contents
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Introduction
Scope of Manual
This instruction manual includes installation and operation information for the AT-25 Desuperheater.
Do not install, operate, or maintain a AT-25 Desuperheater without being fully trained and qualified in
valve, actuator, and accessory installation, operation, and maintenance. To avoid personal injury or
property damage, it is important to carefully read, understand, and follow all the contents of this
manual, including all safety cautions and warnings. If you have any questions about these instructions,
contact your
Description
The AT-25 Desuperheater offers efficient desuperheating in steam pipelines of NPS 16 and less. It is designed primarily
for use in low-capacity superheated steam systems where the load is fairly constant. By utilizing a spray nozzle
assembly that is removeable from outside the desuperheater assembly, the AT-25 provides a venturi solution while
maintaining a high level of serviceability.
www.Fisher.com
AT-25 VenTemp Desuperheater
™
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Emerson sales office
before proceeding.
Figure 1. Fisher Yarway AT-25 VenTemp
Desuperheater
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X1962
AT-25 VenTemp Desuperheater
July 2023
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Table of Contents
Related Manuals for Emerson Fisher Yarway AT-25
Summary of Contents for Emerson Fisher Yarway AT-25
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Page 1: Table Of Contents
™ ™ Contents Figure 1. Fisher Yarway AT-25 VenTemp Desuperheater Introduction ....... . . -
Page 2: Educational Services
1. The pressure or temperature limits in the referenced tables and any applicable code or standard limitations should not be exceeded. 2. For availability of materials other than those listed, consult your Emerson sales office. Educational Services Emerson Educational Services Phone: 1-800-338-8158 E-mail: education@emerson.com emerson.com/mytraining... -
Page 3: Principle Of Operation
Instruction Manual AT-25 VenTemp Desuperheater D104420X012 July 2023 Figure 2. Detail View of the Fisher Yarway AT-25 Desuperheater SPRAY PIPE/NOZZLE ASSEMBLY DESUPERHEATER VENTURI STEAM FLOW SPRAYWATER INJECTION POINT Principle of Operation Superheated steam flowing along the steam line enters the AT-25 Desuperheater throat, increasing its velocity, while reducing its pressure. -
Page 4: System Considerations
This signal is transmitted to the positioner on the spraywater control valve. The positioner output signal is piped to the actuator, which strokes the spraywater control valve governing the amount of spraywater flow. Figure 3. Typical Control Loop with the AT-25 Desuperheater FISHER SPRAYWATER CONTROL VALVE SPRAYWATER FISHER YARWAY AT-25 VENTEMP DESUPERHEATER STEAM... -
Page 5: Preliminary Checks
3. Before installation, check the AT-25 Desuperheater for any visible damage. Make sure that the protective covers are removed, and that butt weld ends and flange faces are clean and without blemish. Any damage to the unit should be reported immediately to your Emerson sales office. Mounting Considerations D When installing the AT-25 Desuperheater, use gaskets and bolting material in accordance with the relevant piping... -
Page 6: Servicing
(if applicable) are available for rebuild if turnaround time for the repair is critical. Do not re-use the graphite gaskets. Review the drawing and specification sheet for clarification. If in doubt as to the construction, advise your Emerson sales office of the serial number and model number and ask for further clarification. Service Item... - Page 7 Instruction Manual AT-25 VenTemp Desuperheater D104420X012 July 2023 3. Insert the spray nozzle with the spray direction pointed in the downstream flow direction. 4. Install a new gasket at the surface between the nozzle mating surface and the water supply line flange. 5.
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Page 8: Troubleshooting
July 2023 D104420X012 Troubleshooting The following guide (table 2) is a basic first line troubleshooting guide. Contact your Emerson sales office for assistance if you are unable to resolve your field operation problem. Table 2. Fisher AT-25 VenTemp Desuperheater Troubleshooting... -
Page 9: Parts Ordering
Figure 4 can be used to help in part identification. WARNING Use only genuine Fisher replacement parts. Components that are not supplied by Emerson should not, under any circumstances, be used in any Fisher valve, because they may void your warranty, might adversely affect the performance of the valve, and could cause personal injury and property damage. - Page 10 Instruction Manual AT-25 VenTemp Desuperheater July 2023 D104420X012 Figure 4. Fisher Yarway AT-25 VenTemp Valve Assembly...
- Page 11 Instruction Manual AT-25 VenTemp Desuperheater D104420X012 July 2023...
- Page 12 Fisher and Yarway are marks owned by one of the companies in the Emerson business unit of Emerson Electric Co. Emerson and the Emerson logo are trademarks and service marks of Emerson Electric Co.
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