Identifying Valves Used in Sigma Products (SB1001.01)

Valve with web
Is body machined for Variseal
or Standard o-ring?
Valves that use standard
o-rings have a slight undercut
at the base of the threads
for expansion of the standard
o-ring when the plunger guide
is tightened. Variseal bodies do
not have this undercut.
No undercut
Undercut
If you attempt to place a standard
o-ring in a Variseal body
the o-ring will not go in (image
1-49 on page 19). If you place
a Variseal o-ring in a standard
body the seal will be loose
(image 1-48, on page 19) and
allow leakage of coolant. See
page 10 for other ways to distinguish
the two body types.
Variseal
Standard O-ring
Location of
undercut
Image 1-47
Valve bodies machined
for Variseal o-ring
Valve bodies machined
for standard o-rings
Variseal o-ring\body
Valve is a Sigma 35105-109 (“B”
175 psi MOPD L–N 2
valve -
going obsolete at the end of
2001.) (A2025-S28)
Current Variseal valves have ID
stamps on the bodies see page
15 for details)
Standard o-ring\body
Valve is a Sigma A2025-S26
or “S26” (small 175 psi MOPD
L–N 2
valve - Obsolete)
Seal notes: Standard o-ring
seals MUST be replaced everytime
a valve is opened.
Note: Removing a Variseal
o-ring is only required every
10-15 servicing, unless the seal
is broken, damaged, or distorted.
SB1001.01-18