Asco 8551 Series - User Manual



 







Service Notice
Except for coil replacement, the Series 8551 are not repairable.
When any performance problems are detected during routine
inspection, replace valve immediately.
For catalog numbers prefixed WT or EF, see separate solenoid
installation and maintenance instructions for information on:
Wiring, Solenoid Temperature, Cause of Improper Operation
and Coil Replacement.
DESCRIPTION
     

          
       



         

         
       
See Flow Selection
And Mounting section.
        



APPLICATIONS













Port Markings: 



 







 
OPERATION
IMPORTANT: Minimum operating pressure differential 30 psi;
maximum 150 psi.
Breather Function 3-way (3/2) mode only: 
           

Single Solenoid:       



Solenoid De-energized: 

  
Solenoid Energized:  




 









 



Solenoid De-energized: 


Solenoid Energized: 





 





 
Dual Solenoids:      
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 
 
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Asco 8551 Series Specifications

General

Series	8551
Media	Air, inert gas
Operating Temperature	-20 to 60°C
Body Material	Aluminum
Seal Material	NBR
Port Size	1/8" to 1/4 inches NPT

Summary

Operation

Single Solenoid Operation

Ensures automatic return on power failure or loss of main pressure.

Dual Solenoid Operation

Maintains position on power failure; operates when one solenoid is energized.

Metering Device Operation

Metering Device Adjustment

Installation

Safety Warnings

Warning regarding electrical shock from open-frame solenoids.

Product Specifications

Flow Selection and Mounting

Piping Instructions

Maintenance

Safety Warning for Maintenance

Warning to turn off power, depressurize, and vent fluid before servicing.

Preventive Maintenance Schedule

Causes of Improper Operation

Lists common issues: incorrect pressure, faulty control circuits, burned-out coil, low voltage.

Coil Replacement Procedure

Step-by-step guide for disconnecting, removing, and installing a new coil.