The Universal Low Pressure (U3, UR) female threaded check valve is a one-piece body machined from bar stock and is designed for minimum pressure drop. The valve is light-weight, compact, and provides maintenance-free dependable service. NPT threads are per ASME B1.20.1 and this valve is also available with ISO 7 “Rp” threads (UR). For applications above 3000 PSIG, view our UN-10 series. For applications where weld joint are required view our UN-SW series.
Many valves in this series can be supplied with B16.34 certification. Give us a call for more information.
Size & Dimension
Nominal Pipe Size
Size Code
A
HEX SIZE B
C**
Orifice Diameter
3/8
C
2.16
13/16
3/8 NPT
0.348
1/2
D
2.71
1-1
1/2 NPT
0.464
3/4
F
2.95
1-1/4
3/4 NPT
0.593
1
H
3.64
1-5/8
1 NPT
0.890
1-1/4
I
3.91
2-1/4
1-1/4 NPT
1.135
1-1/2
J
4.36
2-12
1-1/2
1.385
2
K
5.85
3
2 NPT
1.555
2-1/2
L
5.50
3-3/4
2-1/2 NPT
1.555
3
M
6.25
4-1/2
3 NPT
2.025
4
N
7.13
5-1/2
4 NPT
2.560
NOTES (DIMENSIONS TABLE)*May be larger and/or round.
**Consult factory for ISO 7 "Rp" threads.
Alloy 20 (A2)
Alloy C-276 (HC)
Alloy 400 or MONEL®(MO)
Semi-standard
Alloy B (HB)
Titanium (TI)
Contact the factory for these or other materials.
Seat material and spring material selection may limit the recommended service temperature.
See seat ratings, spring ratings, and body material ratings for their respective recommended service temperatures.
Consult the factory for reduced P-T rating above 100 °F. Standard spring material is 316 Stainless Steel.
Flow Data
PRESSURE DROP PSI
Size
Cv
3/8
1.9
1/2
4.3
3/4
7.2
1
14.6
1-1/4
28.8
1-1/2
31.9
2
42.0
2-1/2
50.0
3
89.0
4
140
FOR WATER AT 72°F
WATER FLOWRATE - GPM
Note: All flow curves and Cv values presume the valves are fully open with 1/2 PSI cracking pressure springs. Consult the factory for more information.
Valve Weights
SIZE
PART NUMBER
SS, CS & Alloys
BRASS
3/8
U3C
3.0 oz.
3.3 oz.
1/2
U3D
8.5 oz.
9.1 oz.
3/4
U3F
9.6 oz.
10.1 oz.
1
U3H
1.2 lb.
1.3 lb.
1-1/4
U3I
2.9 lb.
3.2 lb.
1-1/2
U3J
3.6 lb.
3.9
2
U3K
6.5 lb.
7.2 lb.
2-1/2
U3L
9.2 lb.
10 lb.
3
U3M
14.3 lb.
15.5 lb.
4
U3N
21.7 lb.
23.9 lb.
Seat & Cracking Pressure Options
Valve Style
Size Range
Body Materials
Other Options
Allowable Seat Materials
Other Options
Standard Cracking Pressures.
Other Options
More Info.
Standard Spring Material
More Info.
U3
3/8" -1-1/4"
316 SS Brass
AFLAS®
EPDM
"Metal to Metal"
PTFE
Buna-N
Kalrez®
Neoprene
Viton®
1/8 PSI
1/2 PSI
1.5 PSI
3.5 PSI
316 SS
U3
3/8" - 1-1/4"
C. Steel
AFLAS®
Buna-N
Kalrez®
"Metal to Metal"
Neoprene
PTFE
Viton®
1/8 PSI
1/2 PSI
1.5 PSI
3.5 PSI
316 SS
U3
1-1/2" - 2"
316SS
Brass
AFLAS®
Buna-N
EPDM
Kalrez®
"Metal to Metal"
Neoprene
PTFE
Viton®
1/8 PSI
1/2 PSI
1.5 PSI
316 SS
U3
1-1/2" - 2"
C. Steel
AFLAS®
Buna-N
Kalrez®
"Metal to Metal"
Neoprene
PTFE
Viton®
1/8 PSI
1/2 PSI
1.5 PSI
316 SS
U3
3/8" - 2"
Alloy 20
Alloy C-276
AFLAS®
Buna-N
EPDM
Kalrez®
"Metal to Metal"
Neoprene
PTFE
Viton®
1/2 PSI
Alloy C-276
U3
3/8" - 2"
Alloy 400 or MONEL®
AFLAS®
Buna-N
EPDM
Kalrez®
"Metal to Metal"
Neoprene
PTFE
Viton®
1/2 PSI
Alloy 400 or MONEL®
U3
3/8" - 2"
Alloy B
AFLAS®
Buna-N
EPDM
Kalrez®
"Metal to Metal"
Neoprene
PTFE
Viton®
NOTES (DIMENSIONS TABLE)*May be larger and/or round.
