Installation Guide
Page 1 of 2
Zurn Industries, LLC | Wilkins
1747 Commerce Way, Paso Robles, CA U.S.A. 93446 Ph. 855-663-9876, Fax 805-238-5766
In Canada | Zurn Industries Limited
3544 Nashua Drive, Mississauga, Ontario L4V 1L2 Ph. 905-405-8272, Fax 905-405-1292
www.zurn.com
Rev. M
Date: 6/17
Document No. BF-375ASTDA
Product No. Model 375ASTDA
Model 375ASTDA
Reduced Pressure Detector Assembly
Options (Sufxes can be combined)
    -  with flanged end OS & Y gate valves (standard)
  LM  -  less water meter
    -  with remote reading meter
    -  with gpm meter (standard)
  CFM  -  with cu ft/min meter
  G  -  with grooved end OS&Y gate valves
  FG  -  with flanged inlet gate connection and grooved 
    outlet gate connection
  MS  -  with Integral Relief Valve Monitor Switch
  PI  -  with Post Indicator Gate Valves
  BG  -  with grooved end butterfly valves with integral 
    supervisory switch
  BF  -  with flanged end butterfly valves with integral 
    supervisory switch
  –509  -  with AWWA C509 gate valves
  RV  -  with by-pass on right hand side
Accessories
  Air gap (Model AG)
  Repair kit (rubber only)
  Thermal expansion tank (Model XT)
  OS & Y Gate valve tamper switch (OSY-40)
  QT-SET Quick Test Fitting Set
Application
Designed for installation on water lines in fire protection 
systems to protect against both backsiphonage and back-
pressure of contaminated water into the potable water supply. 
The Model 375ASTDA shall provide protection where a po-
tential health hazard exists. Incorporates metered by-pass 
to detect leaks and unauthorized water use.
Standards Compliance (Horizontal)
•  ASSE® Listed 1047
•  AWWA Compliant C550
•  UL® Classified
•  C-UL® Classified
•  FM® Approved
•  CSA® Certified B64.4
•  Approved by the Foundation for Cross Connection Control 
  and Hydraulic Research at the University of Southern 
 California 
•  Meets the requirements of NSF/ANSI 61*
*
(0.25% MAX. WEIGHTED AVERAGE LEAD CONTENT)
By-Pass Backow Assembly 3/4" Model 975XLD
Materials
Main valve body    304L Stainless steel
Access covers    304L Stainless steel
Internals Stainless steel  300 Series
 NORYL™
Fasteners & Springs  Stainless steel, 300 Series
Elastomers    EPDM (FDA approved)
      Buna Nitrile (FDA approved)
Polymers  NORYL™
Sensing line    Stainless steel, braided hose
Features
Sizes:  2 1/2", 3", 4", 6", 8", 10" 
Maximum working water pressure    175 PSI
Maximum working water temperature  140°F
Hydrostatic test pressure      350 PSI
End connections (Grooved for steel pipe)  AWWA C606 
 (Flanged)  ANSI B16.1
 Class 125
Dimensions & Weights (do not include pkg.)
MODEL
375ASTDA with 
standard OS&Y
Relief Valve 
discharge port:
2 1/2"- 6" - 2.75 sq. in.
 8"-10" - 3.69 sq. in.
MODEL
375ASTDA with 
BG option
MODEL 
375ASTDA
SIZE
WEIGHT
WITH OS&Y
GATES (GXF)
WITH OS&Y
GATES(GXG) 
WITH 
BUTTERFLY 
VALVES (GXG) 
WITH 
BUTTERFLY 
VALVES (GXF) 
in. mm lbs. kg lbs. kg lbs. kg lbs. kg
2 1/2 65 137 62 127 58 104 47 114 52
3 80 155 71 143 65 109 50 122 56
4 100 229 104 209 95 112 51 134 61
6 150 364 166 334 152 176 80 206 94
8 200 681 309 627 284 364 165 387 176
10 250 900 408 842 382 536 243 594 269
MODEL
375ASTDA
SIZE
DIMENSION (approximate)
A 
A WITH 
BUTTERFLY 
VALVES
B LESS 
GATE
VALVES
C D
E 
OS&Y OPEN
E 
OS&Y CLOSED
E WITH 
BUTTERFLY
VALVES
F G
in. mm in. mm in. mm in. mm in. mm in. mm in. mm in. mm in. mm in. mm in. mm
2 1/2 65 31 7/8 810 28 3/4 730 n/a n/a 12 305 7 1/4 184 17 3/4 451 15 3/8 391 8 1/4 210 9 3/4 248 8 5/8 219
3 80 32 7/8 835 29 3/8 746 n/a n/a 12 305 7 1/4 184 20 1/4 514 17 432 8 1/4 210 9 3/4 248 8 5/8 219
4 100 34 7/8 886 30 1/4 768 n/a n/a 12 305 8  203 22 1/2 572 18 1/4 464 9 229 9 3/4 248 8 5/8 219
6 150 43 1/2 1105 36 1/2 927 n/a n/a 10 1/2 267 10 254 30 1/2 775 24 1/4 616 10 1/4 260 10 3/4 273 11 1/4 286
8 200 52 3/4 1340 45 3/4 1162 n/a n/a 15 1/8 384 11 279 37 940 28 1/2 724 18 1/2 470 15 5/8 397 13 1/4 337
10 250 55 3/4 1416 49 3/4 1264 n/a n/a 15 1/8 384 12 305 45 5/8 1159 34 3/4 883 18 1/2 470 15 5/8 397 13 1/4 337
G
D
C
F
E
 A
 B
G
 A
D
C
F
E
 B
NSF/ANSI 61
(SHOWN WITH OPTIONAL GROOVED END BUTTERFLY VALVES)


