25 Series Main Valve Rebuild Kit

25 Series Main Valve Rebuild Kit
INSTALLATION AND MAINTENANCE INSTRUCTIONS
IMI 3.027
FEBRUARY 1999
25 Series Main Valve Rebuild Kit
Parts List
Item
B
C
L
M
O
P
Q
R
U,V
W
1/2"-2"
C
M
N
Description
Bolts
Gasket Cap
Diaphragm
Screen
Valve Spring
Type 25 Valve Head
Type 25 Valve Seat
Seat Gasket
Transmission Tubing
Pilot Gasket
B
O
Quantity
4
1
2
1
1
1
1
1
1
3
W
P
A
Q
R
J
V
S
H
U
L
L
2-1/2"-4"
M
N
G
C
W
O
B
A
E4
6"
C
P
P
Q
U
S
X
Q
B
J
O
W
L
L
H
I
J
U
D
K
G
C1
C1
B1
S
L
G
S
A1
H
Valve Sizes 1/2" thru 4"
Inspecting and Replacing Main Valve Head and Seat
(Refer to Figs. 3 and 5).
1.
2.
3.
4.
5.
Unscrew copper tubings at (J) and (L).
Disconnect pressure control line at the pressure pilot connection.
Remove main valve cover cap screws (1A).
Remove main valve cover, strainer, screen, and head spring.
Head can then be removed by simply withdrawing with a pliers or
similar tool.
6. Inspection should then be made to determine if scale or other foreign material prevented tight closure of the head and seat.
7. If the head or seat shows signs of wear, this can be corrected by
grinding, using a fine grinding compound (400 grit) providing the
wear is not too severe. Check for body erosion.
8. If it is necessary to replace the valve seat, this can be removed
from the valve body using a standard hexagon socket. (Valve
sizes 1/2" to 2"). When replacing the valve seat, a new gasket
should be used to insure a tight joint. 2-1/2" thru 6" valves contain
raised lugs for removal and seal metal-to-metal without a gasket.
Replacement heads and seats should be lapped in.
6" Valve Only
Inspecting and Replacing Main Valve Diaphragms,
Seat, and Head Assembly
(Refer to Fig. 7)
Diaphragms
1. Unscrew copper tubing connections (G) to lower diaphragm
chamber.
2. Remove main valve diaphragm bolts (1C) and drop lower
diaphragm case.
3. The 2 metal diaphragms (1H) should be inspected and replaced if
they have become distorted or fractured.
4. Clean any accumulation of dirt from the diaphragm case and ori-
Valve Sizes 1/2" thru 4"
Inspecting and Replacing Main Valve Diaphragms
(Refer to Figs. 3, 4 and 5).
1.
2.
3.
4.
5.
6.
7.
8.
9.
Unscrew copper tubing connection at (G).
Remove main valve diaphragm bolts (1C).
This will allow the lower diaphragm case to be removed.
The 2 metal diaphragms (1H) should be inspected to insure that
they have not become distorted or possibly fractured as a result of
abnormal operating conditions.
At the same time, any accumulation of dirt or foreign material
should be removed from the diaphragm case.
The valve stem (1F) should also be checked to make sure it is free
to move and that there is no scale or foreign material lodged in the
guide bushing.
Before reassembling diaphragms in 1/2" thru 4" sizes, main
valve head must be in place and held in a closed position with
the return spring and main valve cover.
Make certain pressure plate (1G) is set properly. (Refer to Fig. 4).
Care should be taken in centering the diaphragms properly and
equalizing bolt take-up uniformly.
For any additional information you may require, contact:
Spirax Sarco Applications Engineering Department
Toll Free 1-800-833-3246
SPIRAX SARCO, INC. • 1150 NORTHPOINT BLVD. • BLYTHEWOOD, SC 29016
PHONE 803-714-2000 • FAX 803-714-2200
©
Spirax Sarco, Inc. 1999
Printed in U.S.A.
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