Product Overview

The Spirax Sarco 25 and 26 Series Main Valve Rebuild Kit is a factory-original spare parts set designed for maintenance and overhaul of 25 and 26 Series main valves in industrial steam systems. The kit contains all critical components needed for valve maintenance, ensuring valve performance is restored to like-new condition and extending equipment service life.

Application Range

• 25 Series: ½" to 6" (DN15 - DN150)
• 26 Series: ½" to 4" (DN15 - DN100)

Kit Contents

½" to 2" Valve Rebuild Kit Components

Item	Description	Quantity
B	Bolts	4
C	Gasket cap	1
L	Diaphragm	2
M	Screen	1
O	Valve spring	1
P	Type 25 valve head	1
Q	Type 25 valve seat	1
R	Seat gasket	1
U, V	Transmission tubing	1
W	Pilot gasket	3

2½" to 4" Valve Rebuild Kit Components

Item	Description	Quantity
B	Bolts	4
C	Gasket cap	1
L	Diaphragm	2
M	Screen	1
O	Valve spring	1
P	Type 25 valve head	1
Q	Type 25 valve seat	1
R	Seat gasket	1
U, V	Transmission tubing	1
W	Pilot gasket	3

6" Valve Rebuild Kit Components (25 Series Only)

Item	Description	Quantity
B	Bolts	4
C	Gasket cap	1
L	Diaphragm	2
M	Screen	1
O	Valve spring	1
P	Type 25 valve head	1
Q	Type 25 valve seat	1
R	Seat gasket (G)	1
U, V	Transmission tubing	1
W	Pilot gasket	3

Component Information

All components are manufactured to original Spirax Sarco quality standards, ensuring complete compatibility with original parts.

Installation and Maintenance Instructions

Inspecting and Replacing Main Valve Head and Seat (½" to 4")

1. Unscrew copper tubings at (J) and (L)
2. Disconnect pressure control line at the pressure pilot connection
3. Remove main valve cover cap screws (1A)
4. Remove main valve cover, strainer, screen, and head spring
5. Head can then be removed by simply withdrawing with a pliers or similar tool
6. Inspect to determine if scale or other foreign material prevented tight closure of the head and seat
7. If head or seat shows signs of wear, this can be corrected by grinding using a fine grinding compound (400 grit), provided wear is not too severe. Check for body erosion
8. If necessary to replace valve seat, it can be removed from valve body using a standard hexagon socket (½" to 2" valves). When replacing valve seat, use a new gasket to ensure a tight joint. 2½" to 6" valves contain raised lugs for removal and seal metal-to-metal without a gasket

Important

Replacement heads and seats should be lapped in to ensure proper sealing

Inspecting and Replacing Main Valve Diaphragms (½" to 4")

1. Unscrew copper tubing connection at (G)
2. Remove main valve diaphragm bolts (1C)
3. This allows the lower diaphragm case to be removed
4. Inspect the 2 metal diaphragms (1H) to ensure they have not become distorted or fractured due to abnormal operating conditions
5. Remove any accumulation of dirt or foreign material from the diaphragm case
6. Check valve stem (1F) to ensure it moves freely and no scale or foreign material is lodged in the guide bushing
7. Before reassembling diaphragms, main valve head must be in place and held in closed position with return spring and main valve cover
8. Ensure pressure plate (1G) is set properly
9. Take care in centering diaphragms properly and equalizing bolt take-up uniformly

Professional Tip

When reassembling, tighten bolts in a diagonal sequence to ensure even diaphragm loading

6" Valve (25 Series Only) Maintenance

1. Unscrew copper tubing connections (G) to lower diaphragm chamber
2. Remove main valve diaphragm bolts (1C) and drop lower diaphragm case
3. Inspect and replace the 2 metal diaphragms (1H) if distorted or fractured
4. Clean any accumulation of dirt from the diaphragm case