FNW 6800 User Manual

Figure 6800

KNIFE GATE VALVES

STAINLESS STEEL BIDIRECTIONAL

RESILIENT SEATED KNIFE GATE VALVE

The  gure 6800 knife gate valve has an all cast stainless steel
body and yoke with investment cast packing follower. It is a
general purpose zero-leak bidirectional shutoff valve. Perimeter
gate sealing is not pressure dependent, so there is no minimum
differential needed for shutoff. Port sizing is similar to schedule
40 pipe, so the valve offers unrestricted fl ow and minimal
pressure drop.

Features

• Bidirectional Bubble-Tight Shutoff

• Maximum Pressure: 150 PSI CWP (30” is 50 PSI CWP)

• Maximum Temperature: 176°F (80°C)

• Non-Differential Pressure Dependent Shutoff

• Cast Stainless Steel Body, Yoke, & Packing Gland

• Thrust Needle Bearing

• Combination Chest Liner & Anti-Extrusion Strip

(Anti-Extrusion Strip Only on 14” and Larger Valves)

• Wire Reinforced & Retained Resilient Seat

• Stainless Steel Position Indication Arrow

• Stainless Steel Hardware

• Machined Gland Pocket Area

• Bonnetless, Outside Screw & Yoke

• Rising Stem

• Cast Iron Hand Wheel

• Gear-Operator Standard on 30” Valve

• Available in sizes 3” to 30”

• Standard design accommodates locking device

Standards

• Face-to-Face: MSS SP-81

• Flange Drilling: ANSI B16.5 (30” to MSS SP-44 Flanges)

• Testing:
○ Shell (Before Assembly): 1.5 Time Max. CWP (No Leak)
○ Seat: 1.1 Times Max. CWP (No Leak)

• Material: ASME B16.34

Figure Number Matrix

FNW 6800 Seat Size

SEAT CODE

Buna (Nitrile) = B
(SS Wire Reinforced)

3 = M
4 = P
6 = U
8 = X

SIZE CODE

10 = 10
12 = 12
14 = 14
16 = 16

18 = 18
20 = 20
24 = 24
30 = 30

Cv & Weight

Size Cv Wt (Lbs)

3 565 44
4 1,040 53

6 2,440 88

8 4,460 139
10 6,250 181
12 9,400 229

Weights are for general reference only.

Size Cv Wt (Lbs)

14 12,500 364
16 16,500 397
18 21,400 463
20 27,000 573
24 39,700 617
30 60,000 882

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Hand wheel is heavy cast iron, with a rounded grip
and epoxy coated hand wheel.

Double set screws prevent threaded-on hand
wheel from backing off or coming loose.

Stainless steel needle bearings reduce hand wheel
rim pull force.

Aluminum-Bronze thrust components for anti­galling operation.

Grease  tting for maintaining smooth drive sleeve
operation.

Cast stainless steel yoke arms provide optimum
fl exural rigidity.

Stainless steel position indication arrow is
standard

Stem-to-gate clevis is deliberately loose to allow
play in gate to minimize binding.

Stainless steel hardware is standard.

Horizontal clevis bolts provide fl exibility of the gate
during travel.

FEATURES

Multiple layers of PTFE impregnated square braid
packing provides excellent gland sealing at full
valve pressure differential.

Combination PTFE chest liner & anti-extrusion
strips (anti-extrusion strips only on 14” and larger
valves), enhance packing functionality while
centering the gate. They also act as a gate wiper,
and support the gate in horizontally mounted
valves.

The single piece cast all stainless steel body is
rugged and compact. It offers better leak tightness
than fabricated or two-piece designs.

The gate is high-quality, ground- nished stainless
steel. A generous gate thickness is well supported
by the packing.

Port sizing is similar to schedule 40 pipe, so the
valve offers unrestricted fl ow and minimal pressure
drop.

Perimeter gate sealing is not pressure dependent,
so there is no minimum differential needed for
shutoff.