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      Model MK81A 

Page 2 of 3 

 

SUPPLY LINE

: The minimum recommended line size is 1-1/4” IPS with 30-90 psi (2-6 ATM) 

pressure.  Where sediment or mineral content is a problem, an inlet filter is recommended. 
 

PLUMBING CONNECTIONS

: Inlet supply is female 1-1/4" NPT.  

 

INSTALLATION

: A minimum of 5.0 cubic feet of porous gravel fill around check valve.  Flush 

line before attaching valve. 

 

TROUBLESHOOTING 

 

PROBLEM 

 

 

REPAIR CHECKLIST 

 

 

 

 

 

1.  Low flow/valve won't shut off. 

1.

 

Remove valve stem, check for debris.  
Clean valve and flush line. 

2.  Valve won't shut off. 

2. a. Check to see if stem seats on valve.  

There should be clearance between 
flag and top valve nut in closed 
position.  Adjust if necessary. 

 

 

 

b. Check to see if stem packing is 

excessive.  Excessive pressure will not 
allow spring to counter water pressure.  
Adjust as needed. 

 

 

 

c. High water pressure.  Shim spring to 

counter water pressure. 

3.  Valve leaks/won't shut off. 

3.  

Remove valve stem, check O-ring and 
rubber washer for damage.  Replace as 
needed using VRKMK81A repair kit. 

 

 
 

 

 
 

For more information about Haws products, see our website: 

www.hawsco.com

 

 

 
 
 
 
 
 
 
 

 

 
 
 

 
 
 
 
© 2010 Haws

®

 Corporation – All Rights Reserved 

HAWS

® 

and other trademarks used

 

in these materials are the exclusive property of Haws Corporation.

 

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