FNW 681 User Manual

Figure 681

Check Valves

CAST IRON WAFER STYLE SILENT CHECK

The FNW gure 681 silent check
prevents ow reversal in pipelines,
allowing ow in only the indicated
direction. The spring backed disc
closes the valve when ow ceases
prior to pressure reversal, therefore
reducing slam or water hammer.

Features:

• 200 PSI Non-Shock

• Temperature Range -4°F to 176°F
(-20°C to 80°C)

• Wafer Style

• Non-Slam (Spring Actuated)

Check for Water or Clean Fluids

• Cast Iron Body, Aluminum
Bronze & Stainless Steel Internal
Components

• Vertical or Horizontal Installation*

• Replaceable Drip Tight Resilient

Seat

• Renewable Disc

• Epoxy Coated Body

* Use Flat-Faced Metal Flanges and

Full-Face gaskets only.

Not for Steam Service

Standards:

• Face to Face: MSS SP-125

• Inspection & Test: API 598

• Flange Drilling: ANSI B16.1

Class 125

• Flange Face Finish: MSS SP-6

• Markings: MSS SP-25

Cv & Weights

Size Cv Wt. (Lbs)

2

2-1/2

3

4

5

6

8

10

40 4.6

60 6.2

85 8.8

150 15.4

230 24.3

340 33.1

600 50.7

900 88.2

Cracking Pressure

Fig. PSI

681

1

Figure Number Matrix

FNW 681 Size

SIZE CODE
2 = K
2-1/2 = L
3 = M

4 = P

5 = S

6 = U

8 = X
10 = 10

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Figure 681

CHECK VALVES

CAST IRON WAFER STYLE SILENT CHECK

Dimensions (Inches)

Size ØD L

2 4.25 2.63

2-1/2 5.00 2.87

3 5.75 3.13

4 7.00 4.02

5 8.38 4.76

6 9.75 5.51

8 11.88 6.50

10 14.06 8.27

DOC: FNW681V10 Ver. 08/16

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The contents of this publication are presented for information purposes only, and while effort has been made to ensure their accuracy, they are not to be construed as
warranties or guarantees, expressed or implied, regarding the products or services described herein or their use or applicability. All sales are governed by our terms and

conditions, which are available on request. We reserve the right to modify or improve the designs or specications of our products at any time without notice. Always
verify that you have the most recent product specications or other documentation prior to the installation of these products.

Ref. No. Description Material

1 Body Cast Iron ASTM A126 Class B

2 Seat Ring Aluminum Bronze C95500

3 Seat Ring Seal EPDM

4 Seat EPDM

5 Disc Aluminum Bronze C95500

6 Bushing Aluminum Bronze C95500

7 Spring Stainless Steel AISI 304

8 Set Screw Stainless Steel AISI 304

Standard Materials