Cla-Val DBF User Manual

INSTALLATION / OPERATION / MAINTENANCE

Duckbill Check Valves Flanged Style

Installation Procedures For DBF Style Check Valves

The Cla-Val Model DBF Series is a flanged, bolt-on duckbill Check
Valve manufactured with top quality elastomeric materials.
Custom engineered and manufactured for each application, its
design allows maximum flow with minimal pressure drop across
the valve. This flexible valve prevents flow from occurring in the
reverse direction. It will eliminate costly backflow from oceans,
rivers, or storm water and is the ideal valve for effluent diffuser sys­tems.
The Cla-Val Model DBF Series duckbill Check Valve is designed to
bolt on to an existing pipe flange (PVC, Concrete, Steel, etc) and
is held in place with bolted into place in tandem with retaining rings.
Installation is quick and simple. These valves require no external
power source or mechanical components to operate, unlike con­ventional Check Valves. The Cla-Val Duckbill Check Valves
require little or no maintenance, thereby virtually eliminating oper­ation and maintenance costs.
The Cla-Val Model DBF Series Check Valve can handle corrosive
or abrasive materials such as raw sewage, sludge, or slurries.
With a broad selection of elastomers, the Check Valve is suitable
for many types of media and a wide range of temperatures.

Normal Check Valve Operation:

Cla-Val Duckbill Check Valves are custom made and are intended
for specific applications. They are designed to respond to criteria
unique to its purpose, such as line pressure, backflow pressures,
and chemical compatibility. Should the conditions be altered or
changed significantly, it could affect the normal operation of the
valve. The Cla-Val duckbill check valves function is based on dif­ferential pressure. When the line pressure, (at the valve inlet),
exceeds the backpressure, (at the valve outlet), the valve opens
and flow is created (Figure 1 - left picture). When the backpres­sure exceeds or overcomes the line pressure, the bill of the valve
seals shut, thereby preventing any backflow from occurring, (Figure
1 - right picture).

The Duckbill Series valve allows

material to flow through...

SERIES

Resilient check valves are subject to deterioration when exposed
to ozone and non-compatible chemicals. Ozone, especially, may
cause the rubber to harden and become brittle.

• Store the Installation Operation Manual with the valve so it will be
readily available for installation.

YES

Figure 2a

Components and Terminology (refer to diagram below)
Cuff: The round portion of the valve connecting the flange to the

valve taper.
Taper: The taper transforms the round shape of the valve cuff to
the vertical shape of the valve bill. Reinforcement in the taper is
customized to suit each application’s expected inlet pressures and
backpressures.
Bill: The outlet end of the valve. The bill contorts to allow flow
through the valve yet closes tight during ‘no flow’ or reverse pres­sure conditions. The bill can be straight or curved (depends on
application).
Tube: The inner surface or valve ‘sleeve’. This is constructed using
an elastomer most suitable for the process fluid.
Cover: The outer surface of the valve. This is made from an elas­tomer most suitable for the expected operating conditions (usually
made from EPDM due to its resistance to light and heat).
Retaining Ring: Supplied with the valve, the duckbill flange is
‘sandwiched’ between the mating pipe flange and the retaining
ring.
Line Pressure: The fluid pressure applied to the valve inlet (used
to open the valve).
Backpressure: The fluid pressure exerted on the valve outlet.
Usually measured in feet or meters of fluid above the pipe invert.

DBF

NO

Figure 2b

Figure 1

Storage Procedures:

• Duckbill check valves should be stored vertically (Figure 2a) with
the bill facing upward, not on its side, (Figures 2b) in a cool, dry
location with maximum ventilation.

• Check valves should not be stacked nor should anything be
stored on top of the valves’ bills. They should remain on a skid
until ready for use.

• Do not drop, bend, or twist the valve as damage may occur.

• The valve should be wrapped in black plastic to avoid contact with
sunlight and/or ultra-violet light. This will extend the shelf life.

• Avoid exposure to light, electric motors, dirt, or chemicals.

...and then prevents it from

returning to its source.

Installation Procedures:
Preferred Orientation

The bill of the check valve should be installed as close to the ver­tical position as possible. In cases where clearance below the pipe
outlet is minimal, the duckbill should be rotated only enough as
required to avoid contact with the ground. Please contact your
Cla-Val Factory to discuss this application.

1. Remove all burrs or sharp edges from the pipe flange faces
and wipe clean of oil, grease, etc. Apply a thin coat of graphite or
glycerine to the pipe flange face. This will ease installation and
allow for easy removal at a later date.

Figure 3

2. Lift the duckbill check valve into position and align the bolt
holes of the pipe flange, check valve flange and the retaining ring.
Ensure the check valve’s bill is oriented in a vertical position or as
nearly vertical as is possible (rotate if limited ground clearance is
available).
Note: For Duckbill Check Valves 14” and larger, we recommend
nylon slings be used for lifting valves into position during installation.

3. After the duckbill check valve and retaining ring are in the cor­rect position, push two (2) bolts through to ensure alignment. After
the proper alignment has been obtained, install remaining bolts
and nuts, using washers at the split holes - if the Check Valve
comes with a retaining ring (See Figure 3).

4. Use two wrenches to prevent torque when installing the
Check Valve. Tighten all flange bolts in a criss-cross pattern simi­lar to the one shown in Figure 4 to the maximum torque recom­mended in Figure 5.

5. Do not weld near the Check Valve.

1

5

3

8

2

7

4

6

Figure 4

Pipe Size ID (in) Torque (ft-lbs) Torque (Nm)

1 - 2 20 27

2.5 - 5 25 34
6 - 12 35 48

14 - 18 50 68

20 and larger 60 82

Figure 5

1

Torque settings as recommended by the Fluid Sealing
Association Std FSA-PSJ-702-06 “Rubber Flanged Non-Metallic
Expansion Joint Installation, Maintenance and Storage” Manual
Figure 5

Notes:

a) To prevent leakage, the flange bolts should be retightened after
one week of operation and checked periodically thereafter.
b) Torque values are approximate. After installation the system
should be pressurized and examined to confirm a proper seal. For
hydrostatic systems, torque values may need to be increased.

Installation Problems:

If the valve does not fit properly:

• During the installation, if fit appears to be a problem, contact your
Cla-Val Regional Office or Cla-Val Factory.

If the valve will not close fully or check flow in the reverse
direction:

• Possible obstruction in the line. Inspect the valve for entrapped
foreign objects, which may have lodged between the lips of the
valve.

• Insufficient clearance may exist below the valve (forcing it open).
Verify there is clearance between the bottom of the bill and the
ground and that no debris is trapped between the ground and the
valve bottom.

• The backpressure may not be sufficient to seal the bill completely.

If the valve leaks between the flanges:

• Check that all bolts are sufficiently tightened. Increase the torque
on all bolts by 5 ft-lbs in a cross pattern. Continue this procedure
until the leakage stops.

• Check that no foreign material has become lodged between the
mating flanges.

Maintenance:

• Periodically, an inspection should be performed to verify the
valve’s performance.

• If a build up of debris occurs within the valve, line pressure should
flush it out. In some instances, a wooden plank 1” x 4” or 1½” x
12” may be temporarily inserted into the bill of the valve and rotat-
ed 90°. This will clear the check valve of any debris that may be
trapped in the bill.

• A periodic visual inspection of the valve is also a good idea.
Inspect the tube and cover for cuts, checking, and fissures. Do not
be alarmed if small cuts have formed in the outer cover. If neces­sary, repairs can be made on site with a repair compound. If sig­nificant fissures are noticed where fabric is exposed and torn, the
valve must be replaced. Upon inspection of the inside of the bill, if
blisters, deformation, or delamination is noted, this is an indication
that the media or higher than expected temperatures are attacking
the tube. The valve should be replaced as soon as possible.
Further research into the actual operating conditions (media &
temperature), is required so that a more appropriate check valve
may be supplied. Please contact your Cla-Val Regional Office or
Cla-Val Factory to discuss any concerns you may have regarding
duckbill check valves.

Additional Tips:

• Do not modify the valve without first consulting Cla-Val. Doing so
would void your warranty.

• Do not over-torque flange bolts.

• Use metal washers - at least where the bolts go through the
retaining ring split holes. Keep the valve in its proper shipping
package and in an upright position until ready for installation.

• Tighten the valve flange bolts evenly.

IMPORTANT NOTE:

Debris caught under the valve can potentially effect its operation.
Therefore, make certain there is 6” of ground clearance between
the bill of the valve and the ground during and after installation.

P.O. Box 1325 • Newport Beach, CA 92659-0325 • Phone: [phone] • Fax: [phone] • E-mail: [e-mail] • Website cla-val.com

©

CLA-VAL

Copyright Cla-Val 2008 Printed in USA Specifications subject to change without notice.

N-DBF